3

56

NATIONAL BUREAU OF STANDARDS REPORT

4873

PRSLIMBlAEY REPOST

OR

A STUDY OP CHILD BEHAVIOR

IN RELATION TO SAFETY RELEASE DEVICES

POR REPRIGSRATORS

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

POR USE OP NEM

TECHNICAL COMMITTEE

Al'ID N3S PROJECT STAPP GNLT

NOT FOR PUBLICATION

OR DISTRIBUTION

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing

of the divisions and sections engaged in technical work. In general, each section is engaged in

specialized research, development, and engineering in the field indicated by its title. A brief

description of the activities, and of the resultant reports and publications, appears on the inside

of the back cover of this report.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instru- ments. Magnetic Measurements. Process Technology. Engineering Electronics. Electronic

Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Engineering Metrology.

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Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems.

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Gas Liquefaction.

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Research.

Radio Standards. High Frequency Standards. Microwave Standards. • Office of Basic Instrumentation • Office of Weights and Measures
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

3030-42-7364 OctolDer 5, 1956 4373

PRELIMIMI REPORT

ON

A STUDY OP CHILD DEPL.YIOR

IN RSLiiTION TO SAPETY RELEASE DEVICES

POR PiEPRIGERATORS

Sponsored Dy

Tire National Electrical Manuiaxtur er s Association

POR USE OP NEFa

technical COMI'UTTSE

jiND NBS PROJECT STAPP ONLY

NOT POR PURL I Cat I ON

OR DISTRIBUTION

<^BS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, reprinting, or reproduction of this report in any form, either in whole or in part, is prohibited

unless permission Is obtained in writingfrom theOffice of the Director, National Bureau of Standards, Washington

25, D. C. Such permission is not needed, however, by a Government agency for which a report has been specifically prepared if that agency wishes to reproduce additional copies of that particular report for its own use.
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1. Introduction

1.1 Background

1.2 Purpose a.nd authorization

1.3 Organization and sta.ff

1.4 Contrihutions from outside consultants

1.5 Prelimina.ry tests

2. Description of test equipment

2.1 Environment for e:xperiraent

2.2 Test enclosiue

2.3 Devices utilized

2.4 photographic equipment

2.5 S ound-r e c 0 r

d i ng e quipme nt

3. Test methods

3.1 Design of e.:Kperiment

3.2 Sources of test subjects ......

3.3 Records

3.4 Test procedui’e

4. Results

4.1 Description of sample

4.2 Pact or s affecting success

4.3 Effect of device on success 4.4 Types of helia.vior

(a) Vocalization

(h) Reactions in playhouse

(c) Types of effort

(d) Examination of the interior . . . 4.5 Force efforts 5 . Conclusions

6. List of ta,hlss

7. Acknowledgements

S. Appendix

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ABSTRACT

This preliminary report presents a summary of the findings of a study

of children's behavior in relation to safety release devices for refrigei'ators under simulated conditions of entrapment. Two hundred and one children were tested and records were obtained of behavior in relatioii to

different devices. Behavior patterns in the problem situation covered

and a multiplicity of factors affected the degree of success attained. The most iinportant factors affecting success are the age, height,

and weight of a child and the degree to which he applies purxjoaeful,

properly directed physical and mental recources. A statistical aiial/sis is

not included in this preliminary report but will be available-. later,

six

a wide range.

rif

li INTRODUCTION

1 . 1 Background

Diiring the past two years there has been increasing av.’areness ca the part of

the public and the Congress of the fact that every year a number of children

perish as a result of entrapment in iceboxes, refrigerators, and freezers. As

numbers go, these are few compared with accidental deaths from other causes, tut

the appalling spectacle of even a small number of helpless children suffocating

under this condition has aroused widespread interest in the problem. Congressional

interest took the form of requests to the industry to provide inside release

devices so that refrigerators might be opened easily from the inside. Several

hearings were held in connection with proposed legislation requiring inside safety

release devices, culminating in the passage of Public Law 930 at the Second Session

of the 84th Congress, signed by President Eisenhower on August 2, 1956. This Act

requires "certain safety devices on household refrigerators shipped in interstate

commerce" that would allow the doors of such refrigerators to be opened easily

from the inside. It further requires the development of standards for such release devices.

Consideration of the problem indicated that it was not only an engineering

problem, but also a problem in child behavior.

In 1955, a subcommittee of the House Committee on Interstate and Foreign

Commerce requested the National Bureau of Standards to work with the refrigerator

industry in developing performance criteria for safety release devices. The

industry contact was the National Electrical Manufacturers Association. Because

of the element of child behavior inherent in the problem, the aid of the Children's

Bureau was enlisted, NBS and NEMA developed a set of performance criteria on

which agreement was reached with the principal exception of the magnitude of the

force efforts which children might be expected to exert in attempting to free

themselves from entrapment.
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Late in 1955, the Children's Bureau and KBS conducted tests on children in

nursery schools in an attempt to gain information on this point. In this preliminary experiment, some 60 children between the ages of two and five were tested

in an experimental enclosure--which simulated a refrigerator only with respect to

inside dimensions. The enclosure was suitably camouflaged to represent a gay red

"Santa Claus chimney." The children were urged to use, and rewarded fcr ucing,

their utmost strength in competitive pushing against the door of the enclosure,

from both sitting and standing positions. These tests indicated that a significant

proportion of the young children tested failed to exert forces in excess of 10 lbs.

From practical manufacturing considerations, it is difficult to design a release

device which will respond to a direct push of this magnitude on a refrigerator

door.

At a hearing on May 28, 1956, the Subcomiaittee recommended that another investigation be conducted at MBS with the cooperation of the Children's Bureau.

The Subcommittee at this hearing indicated that the investigation should provide

additional information on the force efforts of children, as well as information

on child behavior in general with respect to release devices currently obtainable,

the experiment to be carried out under conditions simulating actual entrapment as

closely as possible. No studies had been made under such conditions, insofar as

could be determined.

1,2 Purpose and Authorization

The purpose of the study was to investigate the behavior of children under

conditions simulating entrapment in a refrigerator, using inside release devices

currently available and to observe child behavior with respect to children's

ability to utilize such devices. The investigation was recommended by the Subcomniittee on Health and Science of the House Committee on Interstate and Foreign

Commerce, and financed in large part by the National Electrical Manufacturers

Association, who provided a sum of $15,000 for this purpose.

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1.3 Organization of Staff

The project staff consisted of two Study Directors, and two assi^/i:ants from the

field of child psychology recruited by the National Bureau of Standards. The Study

Directors were Mrs. Marion L. Faegre, formerly of the University of Minnesota staff,

and, until recently. Consultant in Parent Education at the United Staces Children's

Bureau, and Mr. Robert S. Wyly of the NBS staff. The two research assistants were

Mrs. Ncruia Gordon and Mrs. Elizabeth M, Lee. In addition to Mr. Wyly, another

engineer, Mr, John J. Lantz, was assigned to the project to aid Mr. Wyly in designing

constructing, and maintaining the equipment required for the study and to assist the

Study Directors in whatever ways might be necessary. Niraierous other persons at the

National Bureau of Standards cooperated in the project in important ways, notable

among these being Mr, Warren Richardson and Mr. William Smallwood, who were responsible for the photographic services, and Drs. William Connor arid Norx^an Severe of the

Statistical Engineering Section of the Applied Mathematics Division, who provided

advice on the design of the experiment and who are presently engaged in makitig a

statistical analysis of the results. Figures 1 to 3, inclusive, show members of

the project staff and others who provided consultation services and assisted in

analyzing the data.

One of the many qualms felt in connection with using children in this study was

the possible harmful effect on them of being enclosed. If it had not bean for the

use to be made of the results, the originators of the plan would not even have considered testing children under fear-invoking conditions.

Reassurance was given by the pediatricians and the child psychiatrist who served

as advisers. They mentioned, as well, that children must often be subjected to painful experiences in medical diagnosis. Parents themselves pointed out that children

often inadvertently get into situations as startling as this one would prove to be,

without any apparent untoward effects. The degree to which a child would be upset

FIGURE 1. Mrs. Marion L. Faegre and Robert S. Wyly, Codirectors of the project.
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FIGURE 2. Robert S, Wyly and John J. Lantz, engineers, discuss problems with Dr, William S. Connor and Dr, Norman C,

Severo, statisticians.
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FIGURE 3. Mrs. Norma Gordon and Mrs. Elizabeth M. Lee talk

over coding problems with Dr. William S. Connor and Dr.

Samuel R. Pinneau.

-3ais not so much a function of one situation as of the child’s earlier experience. In

other words, a child's reactions might well reflect his relationships with the

people who have made up his world.

That young children recover very rapidly from a brief experience makes tbcii*

fearful or angry has been substantiated by research. In an effort to make the entrapment bearable, not only by the children but by the experimenters, a time limit

was proposed. Three minutes was suggested as the maximum time that the childreti

might safely be allowed to cry. Actually, no child was allowed to cry that long.

Especial care was taken to see that after-test experiences were pleasant and

that the children left in a cheerful, relaxed frame of mind.

1.4 Contributions from Outside Consultants

lu addition to having the cooperation of the Children’s Bureau on this study,

consultation was given by local e:eperts in a number of fields. Dr. Katherine Bain

and Dr. Marian M. Crane, pediatricians, served as liaison with the Children’s

Bureau and made a number of visits during the course of the study. They were also

present at an all-day conference following the preliminary testing (described in

1.5 below) when contributions were made by the following individuals from outside

the two Bureaus:

Dr. Nancy Bayley, Chief

Child Development Section

Laboratory of Psychology

National Institute of Mental Health
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Dr. Reginald S. Lourie, Director

Department of Psychiatry

Chlldreiti's Hospital

Washingtc'a, D. C.

Dr. Samuel R, Pinneau

Assistant Research Psychologist

Institute of Child Welfare

Unix-ersity of California.

Dr. Pinneau also spent two days with the project staff at the time cf this

conference, developing test procedure, and returned for a week's stay in

working then with the statisticians deciding on the statistical problems involved

in analyzing the data.

Dr. Lourie ‘s statement, at the conference, that he believed the experience

of being briefly enclosed in a small dark place would not be a harmful one, was

relied upon by the project staff in making decisions relating to the length of

time which could be tolerated safely by children entrapped in a dark enclosure,

and to the general procedure to be used in handling the children who would participate in the tests.

Dr. Lourie visited the project later, and viewed the motion picture records.

He returned again when the data were being analyzed and gave advice which was

very helpful in drawing conclusions.

1.5 Preliminary Tests

A preliminary test series on 16 Subjects was begun on July 6, 1956, using

the release device reacting to a minimum push of 18 lbs., which was identical to

that referred to later in this report as ’’device On these first 16 tests,

the interior of the playhouse was brightly lighted before the child entered and

during the test period. Movies were made of several of these tests on standard

film. On the first 11 tests, one or both parents accompanied the child to the

test room and were near the playhouse when the child entered it. For the first

11 children, a small ledge on the rear wall of the playhouse was baited with
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minlature marshmallows. Four of these 11 children removed the candy by reaching

in without making a complete entry. They were then asked to paste a decal on an

inside wall. One large boy of seven removed candy and pasted several pict.ui:es

with only a partial entry and was then asked, "Do you think you could fit into

the house?” Dr. Pinneau was the Experimenter with five other children, who were

engaged in an elaborate game of hide-and-seek, which was begun on the lavra and

continued into the test room. The children imitated the Experimenter after he had

first used the playhouse as a hiding place. The door was not closed until after

the child had used the playhouse as a hiding place several times.

Before formal testing was begun on July 24, the following techniques were

adopted and plans completed for their implementaticn;

1. To limit the Subjects to two through five years of age

2. To test children on each device in blocks of 16 with an equal

number of each age and sex

3. To use a Disney cartoon with sound effects as a Irrre, projected

on a recessed screen on an interior wall (It was felt that

this lure might have the most universal appeal to the Subjects.)

4„ To test the children in complete darkness in order to mere closely

simulate the actual conditions of entrapment

5. To regard as maximum, three minutes of restriction for children

who were moderately upset, and to release children earlier who

were more upset, at the discretion of the Observer.

On July 23, four children, one in each age two through five years, were

tested in the dark and the cartoon was used as the lure. These tests were conducted under the planned conditions for the purpose of gaining experience and

facility with equipment and techniques before starting the tests which are presented later in this report.
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2. DESCRIPTION OF TEST EQUIPMENT

2.1 Enviroiun.^rit for Experiment

Considerable thought was given to the problem of a satisfactory cnvirori7:ien.t

for the exx->eriment , Obviously, the ideal environment should approach that to

which children are accustomed at home or at play. After due conoidsratict; , which

will be treated in some detail later In the report, the choice of space in a

building on the National Bureau of Standards grounds originally built as a private

mansion was made. Two large first-floor rooms of the building, separal^e^j!^^

a

flagstone terrace, were assigned to the project--one room b^'"'‘ ‘ .and

reception quarters and the other for testing quartern FT rA

2.2 Test Enelosuige- ^

The test enclosure consisted of a plyw^j^sfcnicture somewhat resembli-ng a

child's playhouse, suitably decorated, complete with door, roof, and chifliney. (See

Fig. 14.) The Inside dimensions of the compartment provided for the children to

enter were, approximately , 40 inches high, 18 inches deep, and 25 inches wide.

These dimensions were arrived at after making measurements of a number of currently

available household refrigerators of 8 to 11 cu, ft. capacity, and are believed

fairly to represent the maximum inside dimensions of refrigerator , boxes excluding

the space occupied by the freezing unit. A safety-glass panel was provided at the

rear of the enclosure for the purpose of direct observation of the behavior of the

children through a "snooperscope" which will be described later. Another safetyglass panel was provided at the top of the compartment occupied by the children

while under test, for the purpose of taking motion pictures of the children from

above. The walls of the playhouse extended upward about 16 inches above this

glass panel to join the removable roof section and to house a 16-nim motion-picture

camera and associated illumination equipment. (See Fig. 21.)

Included in the design of the playhouse were provisions for forced ventilation. A number of small holes were provided in the floor of the structure.
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passages were provided joining the lower and upper compartments (the lower terminals of these passages being covered by grilles), and aii air blov?er was incorporated in the roof structure to exhaust the air pulled through the lower and

upper compartments. (See Fig, 14.)

Three different identical doors were provided into which different release

devices and latches were incorporated. (See Fig. 20.) This greatly reduced the

time required for changing from one release device to another as tests proceeded,

since the change-over was largely reduced to the matter of substituting a door

with the appropriate release device already positioned in the door structure.

Provisions were also made on the door jamb to facilitate the change of door

keepers which accompanied changing from one door to another. (See Fig, 22.) These

provisions also included an adjustable spring-loaded plunger in the door jamb (See

Fig. 22.) for the purpose of simulating gasket pressure and setting the desired

releasing force on certain devices.

2.3 Devices Utilized

Three different release devices were furnished by the refrigerator industry

for use in the experiment. Two of these devices were designed to operate on the

application of sufficient direct force on the door panel. The third device was

designed to operate by depressing a trigger mounted on the door panel near the

latch edge of the door. Three additional devices were studied in the experiment,

one of these being a modification of the trigger device submitted by the Industry.

The modification consisted of the utilization of a doorknob-like arrangement

responding to turning in either direction, pushing, or pulling. Another of the

additional devices consisted of a movable floor panel so designed that horizontal

thrust in any direction caused the door to open. The third additional device was

similar to the second, except that it was arranged, not to open the door, but to
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give an indication on the dial of a gage of the amount of hcrizontal thrust

exerted on the floor panel by the children while in the test enclosure. The

various devices were designated Di, D2 » D3, D4, D5 , and D5. Further desciipticn

of the various devices follows.

Device Dl consisted of a hocking latch mechaninm so designed that diieot

force of sufficient magnitude applied to the door panel caused the hook to d?.sea--

gage by cam action from the roller which served as the door keeper- (See door at

extreme right in Fig. 20c) The most effective point of application for releasing

force was at the latch edge. The required releasing force increased steadily with

distance toward the hinge edge. Before removing the latch from the refirigerator

on which it had been installed by the manufacture, force measurements were made,

and observations taken on its operation in releasing. In addition, similar

measurements and observations had beer, made on another similar, interchangeable

latch furnished by the manufacturer. Preliminary measurements (on the re.fr igerator

supplied for test) made of the releasing force applied near the latch edge of the

door, with the latch and keeper unchanged in adjustment from that made by the

manufacturer, shewed that a force of 18 to 20 ibs. was required to open the door.

In the tests on children made using the test enclosure described in 2.2 above, the

latch mechanism included on the refrigerator furnished was used, and was adjusted

to release with a force of 18 lbs. applied to the door panel at the junction of

the inside edge of the door jamb and the door panel —in other words, at the

closest point to the latch edge of the door accessible to a child. Observations

of the latch mechanism, both in the refrigerator and in the test enclosure tn

which it was later incorporated, showed that the releasing action occurred in two

stages. The first stage consisted of a partial disengagement of the hook accompanied by a slight outward movement of the door, this taking place with the
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application of a force somewhat less than 18 lbs. If this force was removed, then

the door showed a distinct tendency to move back into the fully closed positionOn the other hand, if the force was further increased in magnitude to the full

18 lbs., the second stage of action occurred, this being final disengagt-nenb of

the hook with full release. Final disengagement could occur only when the latch

edge of the door moved away from the door jamb a distance of the order of 1 /^ to

3/8 liich.

Device D 2 consisted of a permanent magnet near the latch edge of the door

xi/hich made contact with a metal plate in the door jamb. (See middle door in

Fig. 20.) Preliminary measurement of the releasing force required against the

door panel of the refrigerator on which this device was furnished showed that at

the junction of the door pai:el and the door jamb at the latch side of the door

panel a force of 11 to 12 lbs. was required to open the door. When this device

was incorporated into the test enclosure described under 2.2 above, the releasing

force was set for 12 lbs. As in the case of device Di> bhe releasing force increased with distance towards the hinge edge of the door. Device D 2 released

positively when the required force was applied to the door panel. This could have

been predicted since it is well knoim that the magnetic pull in a situation like

this would decrease very rapidly with separation of the magnet and its strike

plate which served as the door keeper in this device.

Device D3 consisted of a hocking-action latch supplemented by a trigger

release mechanism to which was connected a luminous ring placed on the door panel

near the latch edge of the door. (See door at left in Fig. 20.) When the door

was closed, the luminous ring was clearly visible from inside the enclosure and

the manufacturer's name and trade-mark designation could be read clearly. The

word "push” printed in the center of the ring was not legible, since the luminous

10

material did not extend into this area, Preliininary ineasureTaents of the force required at the center of the ring for triggering the device chowed that a force of

6 to 8 lbs, was required, depending on the velocity of doer closiare and on the

particular adjustment of the latch and strike, those measurements being made on

the refrigeratur furnished by the manufacturer. Obviously, release could occur only

when force was applied to the ring or the lever to which it was attached. Direct

force on the door panel would not open the door. Release occurred positively when

the necessary force was applied to the ring, this action taking place when the

trigger mechanism retracted the roller used to engage the doc£ keeper back to the

point at which it disengaged from the keeper, at which time spring tension in the

latch mechanism caused the roller to roll outward on a sloping surface of the

keeper, thereby starting the door to owing open, Ivi the tests made in the enclosure

described under 2.2 above, the device was adjusted to release when a force in the

range of 5 to 6 lbs. was applied at the center of the lu-minous ring at right angles

to the door panel, with the exception that in 10 tests the releasing force was cf

the order of 8 to 10 lbs. However, these 10 tests were later repeated with a releasing force of 5 to 6 lbs.

Device D4 consisted of a modification of device D3

» this modification a

steel shaft was extended horizontally from front to rear through the door panel,

mounted on sleeve bearings just above the latching mechanism. Near the midpoint of

the shaft a V-shaped piece of sheet metal was welded to the shaft and was extended

down to engage the latching mechanism in such a manner as to act as a trigger when

the shaft was turned in either a clockwise or counter-clockwise motion, or when it

was pushed in or pulled out. Release occurred with a turning motion on the order

of 30 degrees, or with a pushing or pulling movement on the order of 1 inch. A

knurled knob of about 2 3/8 inches in diameter was mounted on the inner end of the
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shaft and the luminous ring 2 1/4 inches in diameter (described in connection wich

device D3 above) was attached tc the face of the knurled kncb. Meascremer’.ts made

on this device showed that the following forces and turning moTrie-'ts we'ce required

to release the door: a pull of 3,5 lbs., a push of 5o0 lbs., a cloote/ise moriicnt

of 4,2 in..- lbs.,, or a counterclockwise momerit cf 2„5 fri..--ibs-.

Device D5 consisted of a conbinaticn of device D2 '^itb a floor pauei floating

on ball bearings. (See Fig. 24.) A steel plate attached to the center of the

bottom of the floating floor panel carried a machined and polished conical cavity,

the cone having a total included angle of 90 degrees. The iiiverted conical cavity

rode on top of a brass sphere which in turn was firmly attached co the rearward end

cf a metal bar extending beneath the floating floor panel to the fc;o;j.ard edge of

the test enclosure and pivoted on bearings at its midpoint. (See Fig. 25.) The

forward end of this "see-saw" bar was cvit off in a plane about 20 degrees from the

vertical a'ad this surface polished, A similar mating surface was provided on the

face of a steel plate attached rigidly to t he lower part of the door panel midway

between the latch and hinge sides of the door. When sufficient horizontal thrust

occurred on the floor panel, this resulted in a slight horizontal moveiBent which

depressed the brass sphere riding below the conical cavity; this caused the rear

half of the "see-saw" to move downward and the front half tc move upward, the door

being forced open as a result of movement of the slanting surface of the front end

of the "see-saw" bar against its mating surface on the door panel. A horizontal

thrust of approximately 12 lbs. on the floor panel loaded with a weight of 30 to

50 lbs. was sufficient to open the door, A special feature of this device was

that a child standing on the floor panel and directing a thrust against the door

panel would also be exerting an equal and oppositely-directed thrust on the floor

panel. These two force efforts were then additive, and decreased the amount of
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effort required to open the doer as compared to the case when a thiust was directed

at a side or rear panel. This vras verified during the tests by securing the cooperation of a particularly advanced 5-year-old girl who was able to nanipuiace a

pressure gage and to read the dial of the instrument accurately. Hci report of

forces registered while standing on the floor panel and pushing at various points

with the Instrumexit verified almost exactly what would have been expected from the

construction of device D5 . For instance, she reported a releasing force of 12 lbs.

from pushing on a side panel, and 6 lbs. X'jhen pushing on the d.ao'r next to the latch

edge. Incidentally, this girl was a test subject who had just previously been

successful in releasing herself from the test enclosure.

Device was identical to device D5 insofar as the movable, floating floor

panel was concerned. The essential difference was that instead of employing the

door and latch used with device D5 , the door and latch originally included in the

D3 arrangement was used with the releasing trigger mechanism and luminous ritig

removed. In addition, a second "see-saw" bar was mounted through the lower part

of the door in such a manner that horizontal thrust on the floor panel was tra-nsmitted through the first "see-aaw", thence through the second "ses-saw" x-;hich was

attached to a force gage where it extended through the door panel, at which point

the force was registered on the dial of the gage. A locking bar was provided

beneath the floor panel (See Fig. 25.), with access behind the test enclosure,

so that prior to a test, the floor panel could be immobilized in a centralized

position, and could afterwards be activated at will by the testing personnel.

The readings on the dial of the force gage were transmitted by a system of

mirrors to the lens of a telescope mounted at a suitable location behind the

-13-

scenes, * so that an observer at that point could record the force efforts resulting from horizontal thrust on the floor panel. (See Figs. 18 and 19.) No

child could escape by his own efforts from the test ericlosura using device br.t

his actions transmitted certain forces to the floor panel. These were reccrdc.i,

the various other types of record were obtained on him, and, at the Observer's

decision, he was released.

2.4 Photographic Equipment

A 16-nim motion-picture caraera was mounted in the upper compartment of the

test enclosure described under 2.2 above, shooting downward at a slight forward

angle through the safety-glass panel separating the upper and lower compartments

of the test enclosure. Illumination suitable for infrared photogr?phy was provided by four 50-watt light bulbs, in the four cor'ners of the upper compartment,

filtered by 4-X-4-lnch squares of infrared photographic filters. Two vertically

positioned plywood separators were used to divide the upper compartment horizontal!

into two subcompartments for illumination and one subcoinpairtmerii: for connecting the

camera lens and the safety-glass panel which divided the upper and lower compartments. Each of the illuminating subcompartments housed two 50-watt light bulbs

and two infrared filters, was 6 Inches in width and 81/2 inches in depth, and

extended from the front to the back of the test enclosure. The light bulbs were

attached to removable covers which fitted over the subcompartments, each cover

being provided with four 1-inch diameter holes for the purpose of ventilation. The

filters were placed directly beneath the light bulbs, recessed into a wooden light

* It was necessary for the telescope operation to be behind the scenes so that

his presence would not be known to the children. The force gage and adjacent

mirror arrangement on the door were not noticed by the children prior to the

test, as a child and the gage and mirror were on opposite sides of the open door

at that time.
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shield covering the safety-glass panel which formed the bottom of the subcompartments. In this way, with suitable lightproofing around the filters the ricor,

the only illumination that entered the lower conir: artment vjhen the door was closed

was infrared, this being insufficient for the children to see anything by. A black

felt hoed was used to connect the lens of the camera, to the top of tl-e subcompartment formed between the illumination chambers and extending dowii to the safety-glass

panel. This assured that white light from the light bulbs coraing through the ventilation holes in the light chamber covers could not reach the camera lens. The air

blower in the roof assembly provided ventilation for the children being tested in

the lower compartment, and cooling for the light bulbs and filters, as a result of ta

passage of air through the light chambers. The felt connecting hood x^jas designed

so that its upper terminus could be secured around the camera lens by mears of a

heavy rubber fitting which could be slipped off easily to allow of the

camera.

The motion picture camera was motor driven permitting photography the full t?lme

the subject was in the enclosure if so desired. The lens was a 15 irm wide angle

covering as large an area as the construction of the test enclosure would permit.

The lens opening was F2.8 and the distance set at about two and a half feet giving

a depth of field of approximately two feet which covered the action of the Subject

in the area of greatest interest. The motion pictures were taken with high speed

infrared film:fln 100 ft. spools using a camera speed of 16 frames per second which

permitted the taking of a maximum number of pictures per reel of film.

The problem of a standard technique to attract the children to enter the test

enclosure voluntarily required considerable thought. Prellir«inary tests in which

the children were asked to paste pictures on the interior or in which candy was

placed in the enclosure did not seem to be satisfactory. Another technique was

tried in preliminary tests, consisting of a game of hide-and-seek between the
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Experimenter and the test subject. This seemed to have p/'o.xiising posoib-ilities

,

but was abandoned because of the excessive amount of time it cons>imed. After a

number of preliminary tests were made under these conditions, it was decided to

project a miniature Walt Disney color cartoon on a frosted glass screen recessed

into the side of the test enclosure. This proved quite attractive to the children,

and was used throughout the tests from that point onward, A projector was

(continued on page 15)

used to project the cartoon. The image was projected cuto a vertical mirror at 45°

to the line of projection, from v;hich it was directed to the screen. A sound

speaker was placed beneath the floor of the test enclooure. . The location of the

screen in the recess made it necessary for the children to get all the v/uy into the

enclosure in order to view the cartoon. A hinged sliutter was provided to per^iit

closing off the projected image at will and at the same time shutting off all light

transmitted through the screen. The outside of the shutter carried another minor

at 45° to the line of projection for the purpose cf {projecting the cartoon onv.o

another screen which could be viewed from outside the enclosure after couipletioxi of

the test

A "snooperscope” was used by the Observer to view the children under infrared

illijmination while they were inside the test enclosure. This piece of equipmcint converted infrared light into white light so that the Observer could view the activities of the children. The field of view of the "snooperscope" was limited to about

8 inches in width, but by mounting the scope on a universal swivel, it was possible

to observe the full area to be covered. This equipment was powered by a 6 -volt

automobile battery,

2,5 Sound-Recording Equipment

A tape recorder was used to obtain a direct report by the Observer who watched

the child through the snooperscope. The same tape recorded all vocalization by the

child. One microphone was provided at the rear of the test enclosure to pick up the

vocalization of the child and another near the snooperscope to catch all comments

made by the Observer. In one group of tests, a second tape recorder and microphone

were provided so that the telescope operator might report readings of force which he

observed on the dial of a pressure gage through the telescope.

2.6 Force-Recording Equipment

Two different approaches to the problem of forces exerted by the children were

used. The first approach, used in connection with tests on device Di> utilized an

electronic gage designed to measure deflection and a recorder to obtain a permanent
V
-16-

record of the deflection. The latch keeper for device was attached at the midpoint of a steel bridge approximately 6 inches long, 1/8 inch thick, and 1 inch wide

When the door was closed, the force with which the latch held the door closed caused

a small initial deflection of the bridge and any thrust on the inside panel rf the

door caused an additional slight deflection of the bridge, which was registered on

the recorder. By the use of a force gage, it was possible to calibrate the recorder

trace directly in terms of force transmitted to the keeper.

The second approach, used in connection with device D5 » consisted of the use

of a force gage attached to the outside of the door, two mirrors, and a telescope.

The force of horizontal thrust on the floor panel was registered on the dial of the

force gage and observed by an operator stationed at the telescope. This

obtained the force record by speaking into a microphone attached to reccr

This arrangement was described in some detail under 2.3 abov

TEST METHODS

3.1 Design of Expetifllierit

The sampling procedure for the experiment was c^^^ned with the help of the

• Statistical Engineering Section of the Applied Mathematics Division, National

Bureau of Standards. The items considered were (1) device, (2) experimenter, (3)

sex of Subject, and (4) age of Subject. It was considered desirable to consider

also a fifth item, socio-economic group. However, it proved impractical to include

this factor because of the difficulties of securing children for test properly

grouped according to the four other factors and at the same time grouped into the

desired socio-economic group. This problem was further complicated by the fact that

a significant majority of the available Subjects would be drawn from the higher

socio-economic group. In order to include this factor it would also have been

necessary for parents volunteering more than one child to make multiple trips to
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bring their children on different days. The number of years of school attendance

cf both parents was listed, along with parents’ occupations, which p ovLcied a

rough index of socio-economic status.

Tests were set up for ages 2, 3, 4, and 5 years, with equal numbers of

children in each age. Plans called for two groups cf 16 tests each for each device

tested, with change of devices after each 16-Subject group, which included two boys

and two girls of each age. Insofar as practicable, each of the two Experimencers

handled equal numbers cf children of each age. Three Observers were used, but the

distribution of the Observers among different ages and devices did not follow any

consistent pattern. This was partly the result of a practical problem resulting

from the fact that one of the Observers could be present only three days a vreek.

3o2 Sources of Test Subjects

A letter to the staff of the National Bureau of Standards was distributed,

explaining the nature of the study in broad terms and Inviting the cooperation of

the staff through volunteering their children and grandchildren for the tests. The

response was generous and gratifying, and most of the Test Subjects were obtained

as a result of this letter, A number of Subjects were obtained as a result of a

similar letter distributed to the staff of the Diamond Ordnance Fuze Laboratories,

an organization located adjacent to NBS. Additional S^:bjects were obtained as a

result of requests made of personal acquaintances and neighbors of project staff

members and parents who had volunteered children for test earlier.

3.3 Records

A record card was kept on each child who was tested. Parents were asked to

fill in their names, years spent in school, and occupation, and to give their

children's names, sex, and birth dates. A staff member recorded on this card the

date of tost, device tested, and child's height and weight. A complete narrative
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about behavior during the child's experience in the test enclosure was recorded on a

tape as It was observed through the snooperscope. Time vjas recorded, i';>: ler>-

second intervals, on this same tape by au Engineer. At the conclusioa of t“ue test,

the Observer filled out a written suumary of all the enclosure behavior regat'ded as

pertinent

.

After the test, the Experimenter filled out a report describing briefly v.he

procedure followed, a brief personality description, and the reactions of the child

before and after the test.

For the series of tests on device D^, a verbal report cf forces, exerted by

the children and registered on the dial of a pressure gage, was recorded on tape

during each test. This record was later correlated with the time record appearing

on the Observer's tape record. In connection with tests on device Di, f-.n unsuccessful attempt was made to obtain force records by another method.

A movie record was made of the behavior of the first 42 Subjects and of the

last 38 Subjects during their tests. It had been planned to obtain a movie record

of each test. Unfortunately, insurmountable problems concerned with the procurement

of the specially prepared and highly perishable infrared film required made it impossible to obtain the complete film record that had been planned originally.

3.4 Test Procedure

It was realized early in the planning stage that the ideal environment would

approach that to which children are accustomed in the home or at play. However, it

was also recognized that practical problems and the requirement for all possible

haste in obtaining results precluded the possibility of conducting the experiment

in children's hemes or at nursery schools. Furthermore, the environment of a formal

laboratory or office building did not appear to be desirable. These considerations

dictated the choice which was finally made--that of space in a large building on the

National Bureau of Standards grounds originally built as a private mansion. The
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spacious, well -landscaped la\m surrounding the house, toget.her with the large

terrace in the rear of the building contributed much to nhe eiiviroruaeri'.. desired,

T^i?o rooms of the. building, separated by a flagstone terrace, were assigne-i to the

project. The room used as office and reception quarters had three ertrances , one

through the front door of the mansion and the large center hall, another opened onto

the terrace, and the third opened directly onto the lawn. The other roc.m was used

as the test room, entrance normally being across the terrace from the side door cf

the reception room. ?^n inclement vzeather, entrance to the test roam was through the

center hall.

In the office-reception room, toys, crayons, and coloring books were provided

for the children, and magazines for the parents were placed in cbvioui’ view.

After greeting the mother (and/or father) and child, the Experimenter who was

to handle the child during the test chatted with the parents and made friends with

the child. She diverted the child's attention to the toys and most of the children

played happily in the office-reception room until it was time for them to go wich

the Experimenter to play ball on the terrace and from there to the test room. The

length of time the Experimenter spent with the child depended somewhat on the day's

schedule of tests. Parents remained in the office while each child was individually

taken to the test room. The separation from the parent sometimes required finesse,

particularly in the case of younger children. It was a good deal easier to become

acquainted with the children if the parents were occupied. The parents were given

forms to fill out covering the needed information. Once they were "on their own"

,

the children could almost invariably establish a satisfactory relationship with the

Experimenter and go willingly with her to the test room. In only three cases were

children so determinedly noncooperative that attempts to test them had to be

abandoned

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After playing on the terrace, the Experimenter brought the child into the test

room. After weighing and measuring the child, the Experimenter contluiied playing

ball with the child, gradually leadi.ng him across the room in the direction of the

playhouse. Many children were curious about the playhou.se from the time they

entered the room, but the attention of other children had to be drawn to it. The

experimenter signalled to the Engineer behind the scenes when she considered the

time was right to start the cartoon in the playhouse.

The sound track with its music and Donald Duck chatter often attracted the

child into the playhouse. In some cases, the Experimenter would stimulate the

child's interest in going in to see the movie by talking about tha movie to the

child. The film was projected onto a screen 5X8 inches recessed on the left

anterior wall of the house, and tha child had to go comipletely inside to see the

cartoon. Sometimes, if it seemed necessary, the Experimenter bent dovm to look at

the movie and told the child what v;as going on to further interest him in going

inside.

As soon as the child was absorbed in the film, the Experimenter told him she

was leaving to go back to the office, or otherxjise tried to convey to him the idea

that he would be alone. At that time, the Observer, who was all this time behind

the playhouse observing the child through a mirror placed high on the wall of tha

test room, closed the playhouse door. Simultaneously the cartoon stopped, the

playhouse became dark, the shutter closed on the screen, the sound- and forcerecording equipment began to function, and the movie camera (concealed in the

chimney) began taking Infrared pictures of the child from above his head. The

Observer viewed the child through the snooperscope and recorded her observations

on tape. The operators who manned the recording equipment also put on tape appropriate comments with respect to time read from a stopwatch, to the force output of

FIGURE 4. Mrs. Elizabeth M. Lee greets a mother arriving with

three children to be tested.

I

FIGURE 5. A mother and her three children are greeted by

Mrs. Marion L. Faegre as they arrive for the test.

FIGURE 6. Mrs. Norma Gordon and

a child enjoy ball play on

the terrace before

a test.

FIGURE 7. The playhouse as it appeared to the child before

the test.

FIGURE 2. The experimenter, ready to comfort this child after

the test, finds reassurance unnecessary.

FIGURE 9 . This child after the test takes his experience

seriously, but with composure.

FIGURE 10. A 2-year-old comes out tearfully.

FIGURE 11. After the test, this child quickly hecomes absorbed in the color cartoon projected on screen outside

playhouse

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FIGURE 12. At the conclusion of testing, four brothers and

their sister enjoy seeing a second showing of the color

cartoon.
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FIGURE 13. After testing, these children are viewing the

Disney cartoon.

FIGURE l4. "Playhouse" test enclosure.

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FIGURE 1^. Equipment behind the test enclosure to obtain

behavior records.

FIGURE l6. Projectionist, time-sound coordinator, and observer during a test.

FIGURE 17. Observer at Snooperscope, hand grasping lever used

to close enclosure door.

FIGURE 12. Operator using telescope and tape recorder to

obtain a record of force efforts registered on pressure

gage.

FIGURE 19. Pressure gage and mirror on exterior of door.

FIGURE 20. The three separate, interchangeable doors provided

for facilitating changeover from one release device to

another.

FIGURE 21, Motion picture camera and lighting equipment used

for obtaining Infrared pictures of children in test enclosure (during actual testing the camera vras concealed beneath the roof assembly; see fig. 14-).

FIGURE 22. Assembly In door Jamb to which door keepers for

different release devices were attached (molding has been

moved to right to show assembly).
1
FIGURE 23. Construction detail of knob release responding to

push, pull, or turn.

FIGURE 24. Movable floor panel designed to respond to horizontal thrust.
1
FIGURE 25. Construction detail' of movable floor panel, illustrating ball-and-cone assembly and ball-bearing tracks.

21

the child, and to such other iteoas as appeared to be pertinent. If the child did

not. effect his own release, the Observer determined from the child's hebavior ’^^hen

it was time to let him cut. Her determination was formed on the basis cc the aiucutn

of effort he was putting forth avid on the degree to which he was beccmicg d ur.be

The moment the door opened, either by the child's releasing himself cr by

his being released by the Observer, the Eiiper imetite.c v;.a& theroj ready to greet hin.

and comfort him. At this the cartoon was coniinv.cd cn aaother screen visible

from cutolde the playheuse. The child was then iiivited to see the cartccvi or to

bring his parents into the tc-.se room to see the ear tocn avid pl.ayhoase. This ceeiued

to be an effective way to calm the Subject, take his mind off hia brief e-tperionce

in the playhouse, and help him carry awa}' a happy Impraasion oi hia

exact procedure employed after the test depended ca the age of tlv^^t^f'-'‘ar..d

his siblings or other children were in the waiting rccra.

4. RES-JLTS

4.1 Description of jsSiirxle'"

A total of 201 tests X/as made in the formal to.ching pr jgrvim. Six devices were

tested. Table 1 indicates the distribution of te.scs according to devicec.

Originally, three devices had been submitted by the rofrigaratcr irciustry for

testing. Later, three additional erperivcental devices were added. The last device,

D5 , was included primarily for obtaining force records.

The sequence of testing is indicated in Table 2. For methodological reasons,

the testing of these devices was staggered. Originally, a third series of tests

was intended on devices Dp, D 2 ) and D 30 Horjever, after the completion of two series

of tests on these devices, enough information was obtained so that a tiiird series

of tests seemed unnecessary. It was then possible to include the experimental

devices and still complete the testing program within the allotted time.

- 22 -

The total sample included 100 girls and 101 boys. The range of age is 21 to

71 months, the average age being 46.7 months. The accompany- ing tables will describe

the sample according to average age, height, and weight. Also iacIudeJ in these

tables are data relating to parental background. The children tested represented

157 families. The sample is not representative of the general populatioo., berng

heavily weighted in the direction of higher ediiC.ational and- occupaulcual -leve^}.

,

However, inspection of the tables indicates that the groups tested on each device

are sufficiently sirailer so that the results obtained on each device tested can be

compared. Time has not permitted a thorough statistical analysis of the sample.

Table 1 shows the distribution of tests by device.

Table 1, Distribution of Tests by Device

Device Tests

Number

^1 31

D2 32

D3

41«

^4 50’<-

D5

15 -A**

J>6 31

Total 201

* Tests made on device totaled 41 because of a necessary duplication of several

tests arising from maladjustment of the releasing force.

** Tests made on device totaled 50 because of the need for obtaining infrared

movies for which film was unobtainable while the first 32 tests on D4 were being

conducted. *** Tests made on devi.ee D5 totaled only 16 because of time limitations and con- fusion as to which of the two releasing principles combined in this device was responsible for release when children released themselves.

23

Table 2 shows the time sequences of tests, indicating ai wnac poinfs in tv-e

test schedule changes of devices were made. Wo systematic rotation of devices wa

applied in the tests on devices D4, 05, and D5 because of time 1 imitatior-s and the

fact that these were experimental devices in a different category from the first

three devi.ces , provided by manufacturers

,

Table 2. Sequence of Tests by Device

: Device Series Children Te.sted :

: Di 1

Number : 16 :

! ^2 1 16 :

: °3 1 25* ;

: D3 2 13 ;

: 2 15

: D2 2 16 :

:

- 33 :

; D5 - 16*"* :

: D5 - 31 ;

D4 - 17*** :

: Total • • • 0

* TT'?enty-six tests were made on D-, in series 1 because the first 10 tests were inadvertently made with the device improperly adjusted with respect to required re- leasing force. Although there was no evidence that this affected the results in

these particular tests, they were, nevertheless, repeated, which gave a total of

26 tests instead of 16,

** Only 16 tests were made on device D5 because two different. relea.si»r.\g principles

were in operation, which created confusion in some cases as to which principle was

utilized by the Subject when he was successful in releasing himself,

•*** These additional tests wesce raade on device D4 for the purpose of obtaining a motion-picture record, for which infrared film had not been available earlier.
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Table 3 describes the sample in terms of average height, weight, age, r.-.ii

parents' education. The fact that the number of Subjects tested on device D5 was

small in comparison to the nunbers tested oii other devices may, in part, accoanu f ;r

the divergeace of the values associated with this subs-ample frora the general average

for the other subsamples.

Table 3. Description of Sample

: Device Total Average Average Average Parents' education Sex : tested weight height age average Boys

1

.. KOo LDo • In. Months i G No. No, :

•• 31 35.2 40,5 46.8 29.5 16 15 :

: 32 35,2 40,0 46.4 29.4 15 17 :

; D3 41 34,7 40.2 46,7 30.7 22 19 :

; D4 50 35.1 40,3 46.5 28,2 25 25 :

; D5 16 38.

S

41,1 48,2 25 c 6 7 9 i

: De 31 37.1 40ol 46,8 29.0 16 15 :

: Totals 201 — — — — 101 100 :

: Averages — 35,6 40.3 46.7 29.0 — :

Table 4 shows the age distribution for each of the six devices, as well as the

age distribution for the total sample.

Table 5 shows the distribution of parents' education for the children tested on

each device.

Table 6 shows the grouping of father's occupation for the children tested on the

six devices.

Table 7 gives the distribution of father's occupational groups by age for the

children tested on each device.

Table 8 shows the distribution of tests for each device, by Experimenter,

25

Table 4. Age Distribution in Months

: Device Total Age in Months

Tested 18 to 30 31 to 41 42 to 54 55 to 65 66 to 78:

No. No. Percent No. Percent No. Percent Wo. Percexit No. Fercei

; Di 31 6 19.3 3 9.7 13 ^1.9 5 16.1 4 12.9

: D2 32 7 21.9 4 12.5 11 34.4 5 15.6 5 15.6

; D3 41 7 17.1 9 21.9 9 21.9 12 29.3 4 9.7

; d4 50 8 16.0 12 24.0 11 22.0 18 36.0 1 2.0

; d5 16 2 12.5 4 25.0 5 31.2 1 6.2 4 25.0

• De 31 5 16.1 9 29.0 5 16.1 7 22.6 5 16,1

•.Totals 2Ci 35 41 — 54 48 — 23

: Averages: -- 17.4 — 20,3 26.9 23,9 — 11.4:

Table 5. Distribution of Total Years of Parents' Education

: Device Children

tested

Education in Years

16 to 20 21 to 25 26 to 30 31 to 35 36 to ^0:

No. years years : years years years ;

: Di 31 - 4 : 13 13 1 :

: D2 32 - 6 14 8 4 :

: D3 41 - 4 : 16 16 5 :

: D4 50 4 11 : 14 18 3 :

: D5 16 - 10 : 6 - :

: D6 31 2 4 13 12 -

26

Table 6. Description of Sample by Father’s Cccepatlon

Device Tested Occupational Group ; Professional Nonprofessional

No. No. No.

Dl 31 12 19 :

D2 32 16 16 ;

^3 41 31 10

D4 50 24 26 :

D5 16 6 10 :

^5 31 16 15 ;

Totals 201 105 96

Table 7. Description of Sample by Age, by Father's Occupational Group

Father ' s Occupation Group

[ Device Professional Nonprofeg si onai : Age of Subjec U Age of S-abject : 2 3 4 5 6 2 3 4 5 6

No. No. No. No. No. No. No. No. No. No. ;

: Dl 3 - 8 1 - 3 3 5 4 4 ;

: D2 4 2 6 1 3 3 2 5 4 2 :

; D3 6 8 5 10 2 1 1 4 2 2 ;

: D4 3 6 5 10 - 5 6 6 8 1 :

: D5 - 3 1 2 2 1 4 1 2 :

: D6 1 6 3 5 1 4 3 2 2 4 : ‘Totals 17 25 28 27 8 13 16 26 21 15 •

-27-

Table 8. Distribution of Tests by Experimenter

• Device Exp er iment er

1

Experiraenter : 2 :

: 14 17

: 13 19 :

: D3 18 23

D4 22 28 i

; ""5 8 8 i

15 36 : •Totals 90 ill •

4.2 Factors Affecting Success

The ability of children to utilize successfully a safety release device seems

to be very much affected by age and the physical growth and accompanying development

taking place as children become older. Height and weight seem related to success as

a factor associated with age. For exaraple, many large three-year -old children are

less capable of succeeding than smaller four-year-old children,*

Table 9 presents the results of the testing of children’s ability to utilize

release devices as affected by such basic factors as age, sex, height, weight, and

parents' education and occupation. Also included in this table are data on the

effect of the Experimenter and Observer on the results. Included In the values shown

in Tables 9 and 10 are the results of tests on device Dg, the device which no child

could utilize for escape. The classification of success or failure for the 31 tests

using this device was made on the basis of whether the child was known to have exerted

at least a 12-lb. force on the door panel as registered by the pressure gage. Because of the incomplete record on these 31 tests and because of possible Inaccuracy

* According to the statistician, simple correlatiore between age, height, and

weight, in the sample used in this study, are as follows; weight and height - .84;

weight and age - .74; height and age - .92.
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in the forces registered, this classification is not as raeaningful or precise it

should be for comparison with the results of tests on the other five devices about

which there was no question as to success or failure. In any further use of the

data following the issuance of this preliminary repurt, it is considered pr

that no classification of the data ou device D5 by success or failure be made.

Table 9, Children's Success in Utilizing Safety Release Devices

(a) As affCvCted by child's age

: Age Tested Success Fail i.'C'e

: Months No. No. Percent No, Percent

: 18 to 30 35 5 14.3 ' 30 85.7

: 31 to 41 41 16 39.0 25 61.0

: 42 to 54 54 28 51.8 26 48,2

; 55 to 65 48 34 70i-8 14 29,2

; 66 to 78 23 14 60.8 9 39.2

: Totals 201 97 - 104 « - ra

(b) As affected by child's se:i

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: Boys ; 101 : 49 48.5 : 52 51.5 :

: Girls 100 : 48 48,0 : 52 52,0

: Totals : 201 : 97 ---- : iC4 ;

(c) As affected by child's weight

: Weight

: lb.

: 20 to 25 11 2 IS, 2 . 9 81.8

26 to 30 43 11 25 c 5 32 74.5 :

: 31 to 35 49 26 53,0 23 47.0 :

; 36 to 40 52 29 55.7 23 44.3 ; 41 tio 45 32 19 59.3 13 40,7 :

; 46 to 50 7 4 57.1 3 42.9

: 51 bo 55 4 3 75.0 i 25, C :

: 56 to 60 3 3 100.0 6 ;

: Totals 201 97 — 104 :
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-29-

Table 9. Children's Success in Utilizing Safety Release Devices - cont

(d) As Affected by child's height

Tested Success Failure

; Height

: in.

: 30 to 35 32 6 18.8 26 81c 2

: 36 to 40 67 26 38.8 41 61 .

; 41 to 45 79 50 63.2 29 36.8

; 46 to 50 22 14 63.6 8 36 ,4

: 51 to 55 1 ] 100.0 0

: Totals 201 97 — 104 ----

(e) As affected by total parents' education

; Year s

; 16 to 20 6 5 83.0 1 ?:7.0 :

: 21 to 25 39 26 66„7 13 33.3 ;

: 26 to 30 76 35 46.0 41 54.0 :

; 31 to 35 67 24 35,8 43 64.2

; 36 to 40 13 7 53,8 6 47.2 :

; Totals 201 97 a. 104

(f) As affected by parents' occupation

: Occupational

: group

: Professional

1

1C5 45 42.8 60 57.2 :

: Nonprofessional; 96 52 54.2 44 45.3 :

; Totals 201 97 104 — — ;

(g) As effected by experimenter

: Experimenter

No . 1 90 42 46.6 48 53.4 :

; No . 2 111 55 49.5 56 50.5 ;

; Totals 201 97 ; 104 ;

(h) As affected by observer

: Observer

: No. 3 119 53 44.5 66 55.5 :

; No, 1 38 20 52.6 13 47,4 :

: No. 2 44 24 54.5 20 45,5 :

; Totals 201 97 - - ^ * 104 ;
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It is evident that no one factor can be predictive of succeijs, t:.ccpL the ccrelated factors of age, height and weight. No effect ou success because of sex is

apparent. However, the child's reactions in the test enclosure very definitely

affected his ability to escape. No significant difference is apparent due to Experimenter or Observer.

The fact that almost half of the children tested (97 successes in GOl tests)

nade their escape from the enclosure is closely related to the relatively greater

success of the older children (who were also heavier and tallei; in general) in

utilizing release devices, as noted elsewhere. The relative degree of success

achieved by the total sample is very slightly greater than noted above if the tests

on device are not considered, there being 83 successes in 3.70 tests in that case,

Whether or not the individual Experimenter had any bearing on the children's

success or failure with escape devices becomes of great interest in the light of

personality differences and consequent unavoidable variations and mod ii'Icat ions of

manner, approach, and technique.

Regrettable though it is that the number of children, and also their age and

sex, could not be evenly distributed between the two Experimenters, the results obtained by the two Experimenters show close correspondence, as shown in tables 9 and

10 .

A minor question arises in connection with device B- : Whether some children

may have been disturbed by a feeling of insecurity because of very slight horizontal

motion that occurred when they stepped on the movable floor panel. It seems barely

possible that some children wwre afraid to move, in much the same way that some

young children hesitate to get onto scales to be weighed. If there were such instances, fear associated with the slight movement of the floor panel may have interfered with efforts to escape.

-31-

Table 10. Success in Relation to ExperimenLer

SUCCESS F A I LURE :

: Device Age Experimenter Experimenter Experimenter Experimenter : No, 1 No, 2 No, 1 No, 2 ; years No. No. No. No. :

2 . . 1 5 : 3 1

- 1

0c. ,

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- 1 : 6 - 2 2 ; 2 - - 2 5 : 3 1 3 - :

: D2 4 5 3 2 1 5 1 4 : 6 1 3 1

-

2 - - 4 3

3 1 -

0 6 :

: D3 4 1 1 0

L. 5 ; 5 - 3 6 3 : 6 1

- 1 2 :

2 1 1 2 4 : 3 1 4 2 5 : ^4 4 4 7

- - 5 10 6 i 1 : 6 - - 1 : 2 - 1

- 1 : 3 2 1 1

- 4 2 1 1 1 : 5 1 - - ; 6 1 3 - : 2 - 2 3

- 3 2 1 5 1 : 4 - 1 1 3 : 5 2 3 1 1 : 6 1 2 - 2 :

: Total

9

42 55 48 56

The classification of age by years from 2 to 6 , inclusive, need in Table 10 l.

in several tables appearing later represents the corresponding age groupi.ngs by

months used in Tables 4, 7, 9, 12, and 15.

4,3 Effect of Device on Success

The construction and operation of the devices tested have been explained in

the description of equipment under Section 2,3. Considering all children tested,

grouped according to device only, Table 11 summarises the success associated with the

different devices. (See Table 11,)

According to this table, device B5 had the highest rate of success. Since

only 16 children were tested on thi,s device, there is greater uncertainty in the percentages pertaining to this device than for devices D|-. l>2> ^3 ^4

* than half

of all the children tested on devices D 2

(65.67c.) and (68.C7o) released themselves.

A much smaller proportion of children succeeded in rcl Basing themselves in tests on

devices (29,07.) and D3

(17.17.).

The success of 45 .IT, for device Dg, is not reliable to the s.-mia extent as the

values given for devices D2 , D3 and D^. The discussion under 4.2 pointed out that

the maximuin efforts of sorae children tested on device may have been classified incorrectly.

Table 11. Effect of Device on Success

: Device Tested Success Failure : No. No. Percent No. Percent :

: D 1 31 9 29.0 22 71,0 :

; Dj 32 21 65.6 11 34.4 ;

; D

3

41 7 17.1 34 82.9 :

i 50 34 68.0 16 32.0 :

; 16 12 75.0 4 25.0 ;

D 6 31 14 45 1 17 54.9 ;

: Totals 201 97 — 104 ;

- 33 "

Table 12 lists successes axid failures on each device for the xcy.-^cvo ago

groups. The following statements are based on the data presented in this table.

1. None of the children in the youngest age group (18 to 30 months) v;as

successful in utilizing devices or J> 2 , both of which required a direct push on

the door. Also, in the next older age group (31 to 41 months) none of the 3 children

successfully utilized device Di* This device required 50% greater force tor release

than did device D 2* In tests on device D 2

> ^ children tested in the 31-

to-41-morith age group released themselves.

2. In all age groups where any successes occurred in tests with devices Dq

and D 2 > a higher degree of success was associated with device D2

- Device Dq requited

an 18-lb. push at the letch edge of the door; device. D2 a 12-lb. push at the same

edge. In making comparisons of results from tests using devices Di and D2 j it should

be noted that the releasing action associated with device required an effort of a

more sustained nature than was the case for device D 2

=. The construction features

responsible for this difference are explained in some detail under Section 2.3.

Short bursts of force result from the banging and slapping of the less-purposeful

and more-random efforts frequently observed in the behavior of 2-year-old and 3-yaarold children. The fact that such momentary force efforts were less effective in

opening the door on which device D]^ was used may be a factor in the lower proportion

of successes with this device..

3. To open the doeor in the tests in which device was used, it was necessary to push a luminous ring. On tests in which device was used, it was necessary

to manipulate a knob which reacted to clockwise or counterclcckwisa turning or to

push or pull. A greater proportion of children in each age grotjp was successful in

releasing themselves in tests using device than in tests using device D^. This

may be partly explained by the fact that a doorknob and its operation are familiar to

most children.
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-34-

Table 12. Effect of Device* on Success for Differeiit Ages

; Age Device Tested Success Failure

No. No. Wo, : 1 6 0 6 : raonths* ; 18 to 30 ** 2 7 0 7 : 3 7 0 7 : 4 8 2 6

; subtotal -- 28 2 26 : 1 3 0 3 :

: 31 to 41 months 2 4 4 0 : 3 9 1 8 : 4 12 5 7 :

: subtotal 28 10 18 : 1 13 . -S 10 ;

: 42 to 54 months 2 11 8 3 : 3 9 2 7 : 4 11 11 0 :

: subtotal 44 24 ZIO : 1 9 6 3 :

; 55 to 78 months*** 2 10 9 1 : 3 16 4 12 : 4 19 16 3 :

; subtotal 54 35 19 : Totals — 154 71 83 :

* Tests using experimental devices D5 and B6 omitted^ For reasons stated

elsewhere, the results would not have reliable meaning if compared with the

results of the tests using the four other devices

** The youngest child tested was actually 21 months,

***The oldest child tested was 71 months.

Table 13 enumerates the success data on all devices. The actual ages of the

successful children are indicated and compared with the total sample. The range

and distribution of the ages of the successful group can be obtained from inspection of this table

35

Table 13 » Diotributicn of Successes

by Device

Age In Months

Device Dt Device D2 Device D5 Device D 4

42 34 41 24 ; 50 36 44 28 : 54 38 47 35 ; 56 39 62 36 : 61 ( 2 ) 41 63 38 (3) : 63 42 65 43 : 69 43 71 44 : 71 46 45 : 48 (2) 46 (2) : 49 47 (2) : 50 48 : 56 50 : 58 51 : 61 54 : 62 56 (4) : 63 57 (2) : 67 59 : 68 60 : 69 (2) 51 (5) : 63 :

: 65 (5) :

: Average Age of 58.6 51.8 56,1 5Cc6

; Successes

: Average Age of 46.8 46.4 46,7 46.5

: Sample

:No. Below 1 8 2 12 :

: Average Age

:No. Above 8 13 5 24 :

: Average Age

ouecGsses 9 21 7 36 :

:No. Tested 31 32 41 50 :

4.4 Types of Behavior

Under conditions simulating, to a degree, the entrapment of children in refrigerators, behavior of wide variety appeared among the Subjects. To be suddeul;/

and unexpectedly confined in a very small dark place ^ even wivhout the added discomfort of a limited air supply, j.s a discomfiting experJeru*,e. The patterns of

children’s reaction to this experience in the present study range all the way from

complete passivity, with no attempts whatever to use their mental or physical resources, to violent activity, either purposeful or undirected. A few children sac

quietly for as long as 15 minutes, apparently waiting for the movie, with no

evidence of perturbation during or after their stay in the enclosure; others, also

few in number, became panicky and emotionally upset as soon as they foimd themselves shut in, and by their agitation hampered what ability to get out they might

otherrjise have displayed. All manner of in-between behavior was observed.

The most noticeable factor associated with children's ability to raake successful use of the escape devices was age. Two-year-olds to a great extent reacted

helplessly, showing no grasp of the problem situation in which they fotind themselves

They broke down and cried, floundering hopelessly or rsiging, apparently in the hope

that someone would help them out of their predicament <, They did not always appear

as frightened as did some of the older children. In ether words, helpless behavior

is appropriate in a 2-year -old. By the age of 3 and 4, when children have developed

to the point of being aware of the many dangers that lie in wait around them, they

may become really frightened, or even terror-stricken.

How a child reacted to being enclosed not only differed greatlj’- according to

age but also was affected by personality and background experietice. The brief time

spent with a child did not give sufficient fariiiliarity with him so that any hypothesis concerning the effect of his personality on his behavior in the enclosure could

be formulated. Certain behavior patterns could be noted.
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Most of the children remsiried oriented toward the door, and a great; naii;,’

them used considerable energy in a proper direction of effort. Some cblldreu began

to work purposefully at gettir'g cut of the playhouse as soon as the door closed;

their behavior was task-oriented and appropriate to the situation. In ether words,

if there was a knob they soon di?:ected their effort to it; if they were confronted

by a blank door, their efforts were purposefully directed to the doer. As the

results indicate, age is a definite variable affecting the appropriaceness of

behavior.

Another, and intelligent, type of behavior was the expenditure of time and

energy in searching for a "way out." This exploratory behavior sometimes preceded

direct physical effort, but many times the very calm child confined his efforts to

feeling along the edges of the door, as though groping for a clue, and made no other

effort except when a knob or latch was present.

Some children's efforts, if they could be so called, were almost completely

random and diffuse, and produced no results whatever. In these cases the children

seemed much disturbed by the small size and darkness of the playhouse. Other effort

were ineffective either because the children did not use enough strength to secure

release, or because they misdirected their energy. For example, some children

stamped up and down, ethers knocked on the door or the walls. They seemed incapable

of coordinating their behavior to effect a successful solution to the problem. Stil

others gave vent to loud calls, shouts, or screams, which they obviously expected

would be effective in bringing help from someone outside.

In another variety of behavior, children became upset and helpless. These

children cried very hard and made no effort at all to get out. They clenched their

hands, twisted their fingers, or covered their faces with their hands. Some assumed

an almost rigid posture of fear while screaming.
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Speaklng In very broad tertDB, trapped children react in a wide vavlety of

ranging from showing calmness and control to becoming panicky. The effectiveness of

any safety device must depend upon these facts. The equipment and technique of this

studyw.c not like the real situation in which a child might become entrapped. In

the real-life situation, only fragmentary information exists as to what children are

doing before they are actually entrapped, what play situations precede their entrapwhen

ment, |and consequently how they might react /• they became entrapped. No Information

exists as to what type of child is most likely to get trapped in a refrigerator.

In paragraphs (a) through (d), below, some results of observations on specific

types of behavior are presented.

(a) Vocalization -- By far the greater mmiber of children vocalized at some time

during their entrapment. As would be expected, older children were less apt to cry,

though they called out as often as younger ones. Some older children remained completely quiet, as they might have done in a hide-and-seek situation. Seme were

quiet, evidently because they were waiting for the movie to show agaih.

While a few children cried all the time they were enclosed and made no physical

effort to extricate themselves, others cried continuously along with the physical

efforts they were making. In Table 14, the small number of children who cried while

making an effort to utilize device D4 may be the result of the speed with which many

children released themselves by means of this device. (See Table 15.)

Despite efforts to give the children the impression that they were alone when

the door of the playhouse closed on them, the type of calls and shouts to which mtiay

children gave vent indicated that they expected to make themselves heard. (See

Table 16.)

Table 16 indicates the nature and distribution of the several types of vocalization exhibited by children tested on the six devices. The numbers in the columns do

not necessarily total horizontally equal to the number of tests made because some of

the children made two or more types of vocalization, and some made no vocalization.
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,. • M 'C. V j , _ V ^vatt kitt ’in

* • - L

' '

•

'

• < '>'iif.ii»ff'ft<lT ; . -t •/»{> ji-Jkft . .fiwf:i -lijis^tii^i^^a • ’j

. .. ,,'- r-' _. 0''.f;''

' -. ^ .r ’ V/'.. i , •. ;.7r 'ihipiVi !to •m*i{t)ittS. '

'

4''

‘ , , “ .'. . ----— j|

. "'V ..UJ
-39-

That children's calls were more often to their parents tbaii to the Expc:_’eiil

suggested that while they knew their parents were well out of hearing distance, their

natural tendency, at the ages studied, was to call their mother or father when la

trouble. This was as true of 5 -year-olds as of younger children.

Table 14. Crying in Rel-;i£.>:oe./ to Effort

: Device Tested

Continuous

,

with no

physical

effort

Continuous

,

v/ith

physical

effort

Interrupted,

with no

effort

Interrupted, : Interrupted,

with efforts ;witli

interspersed: physical

: effort.

No. D I S TRIBUTE D BY D E VICE

NO. NO. NO. NO. NO. :

• \ 31

1 4 10 4 2

-

; 32 2 10 4 5

! ^3 41 5 13 2 4 2 :

: D4 50 7 6 2

- ;

; 05 16 - 1 2 - 1

•• De 31 2 13 3 2 1

•.Totals 201 20 53 17 13 4

: Age* No. D I S T R I B U T ED BY A G E

: 2 35 13 14 2 2

: 3 41 3 13 7 4 2

: 4 54 3 13 5 3 1 :

: 5 48 1 10 2 1 1 :

: 6 23 - 3 1 3

-

; Totals 201 20 53 17 13 4 :

* The classification of age by years used in this table is based on the classification by corresponding month intervals used in Tables 4, 7, 9, 12, and 15.

in

t-4

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1—1 H

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rr5 • 4J O in vO 00 <! mT O- OH S «-l CM cn r-4 <31

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r» JZ tj • 1 1 1 1 1-4 CO 4J (U o

0) CO s o <0

•ri }J o > o <}• (U S Q

<U01

CS C7^ 0) cn

CM

(U CD Pi O TO tf u ci . O I r-4 1 1 1 r*4 t3 o

cu o Cl N 00 o

•H CO r—

•H

4.4

w

m>

CTi o fn

1-4 f-H <c

t-H CQ p O TJ •

<4-1 4J ci

O 1 1 1-4 cn r-4m CO S I CO O O!

tti CM

G P3 ! f,J f;

r-l CO 1 j cn Q t O CM W

JP

CT> 00 C?^ <M

•vj- <n

r>.

C3

(U T3I—

T ? .CJ 0

>.

0)1<

01o

r-tUW

r*

CUCCO

<ya

•HH

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CO •yH

W I i '^i o ri ». ! -(-j o i I O fq so 0J| I vD W (M

cnI

m >>o <t 04

K

tn CD j CO Tl * O rijM

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4J

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_ cj'q O dJi ! cn w • en r-< cn <>4 cn

C5^

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04 CD

1—4

'«/ o r:

i-t O!o o 1' rM CO

CO

i3 Tv

DJ J.", -C Q

!J

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1'

IT C‘J CD

a' o

t-3

J.. 11 .. i ® r-i CM

m -d" cn i }i

C.5 f.j

<,tm CO ; CO Ol -ct in 5 Cl o C) o o o

4.} 4J VI 1.! o

o;j C'l

m r-i cn •«T

M

CO

l:'

*^1

tDPQM

PiH

c<3 wQ

O')

m

m o

1-4 Cm <j-

:;3

i-s i o

IH

H4 I

04 cn

m

cn V40

1*4 o^

cn <y»

04 in

C4 cv

uM>wo

>4

PO (I®

)Wh!E3

jpQ

!m

os

E-4 COMO

CO o~

m

If!

till

04 I I 04

m I o~ cn 04 vO CTi

I-) 04 r-1 CM CO <T,

cn CM cn CM lT^

1-4

04 OCM C^

<!•

C.

O!! CQ

61

T-)

ctf

C -4

JoH

0)

t)

n-! I >c

CM Qcn O

a

mQ

v43 Q ctf 4JcH ^

Certain

values

shown

in

this

table

are

based

on

results

of

tests

using

device

D^,

classified

as

successful

according

to

the

criterion

explained

under

4.2

above,

and

hence

are

subject

to

the

same

comments

as

given

there.
,

'(

'

a s'l'*

fcv* fi

»

' i

!>*:

I '. v»

l;

:, V?

I r .j

C C

.» >

^ 4*1* in _ , ^ }l' f- O

<i>
-41-

Tabie 16. Vocalization

: Device Tested

Talks or Calls out Cries Screaras

No. No. No. No. :

; 31 10 13 11 :

; d2 32 11 21 2 :

; D3 41 23 32 17 :

: D4 50 9 18 6

; D5 16 3 4 4

: 31 12 18 11 :

: Totals 201 68 106 51 :

Table 17. Reactions of Children in Playhouse

; Device Tested Calm Moderately

upset

Very

upset

Panicky

No. Wo. No. NOo No

31 8 11 8 4 :

32 9 10 11 ;

= ^3 50 7 11 19 4 1

: D4

41 29 11 8 2

: D5 16 10 2 4 ;

S De 31 6 7 13 5 :

: Totals 201 69 52 63 15 :

(b) Reactions in Playhouse -- Inspection of the values in Table 17 indicates that

the greatest proportion of children reacted calmly to device D^, the device which

many children seemed to consider as a doorknob, the use of which was familiar to

them. These data also indicate that relatively few children reacted calmly to

device D3 , this device being the one to which many children directed the wrong type

-42-

of effort, possibly because of unfamiliar it, y vcith the use of a.-r-.y si.iilat' AlvSa,

relatively few children reacted calnly to device this bei.ng the device which was

not designed to permit children to release themselves.

No correlation between reaction and device is evident for those chiTdro.n who

became moderately upset. The fact that a relatively large number of cbildren became

very upset in their reactions to device D3 may be explained in Rome cases by thair

frustration following failure in attempting to open the door by pulling on the device

this being an improperly- directed effort.

The fact that relatively more children became very upriet or even panicky in

their reactions to devices D3 and than to the other devices is consistent with the

finding that relatively fewer children reacted calmly to these same two devices.

However, it should be noted that actually only a iexj children became panicky under

any of the conditions set up.

(c) Types of effort — What a child did to extricate himself from the playhouse bore

a strong relationship to his age, not coirs idering the oldest group. The proportion

of children who pushed at the door, or pushed, pulled, or turned the Ivimiincus knob or

ring increased steadily with age up to age 6 . Shis oldest group showed a performance

in this respect about the same as the 2-year-old group. A possible reason for this

is that a number of older children seemed to be ivaitlng for a corttinuarion of the

cartoon rather than doing anything about getting out of the enclosure. However, in

all age groups, the successful children gave much more attention to the above mentioned types of effort than did the unsuccessful ones. (See Table 18.)

Knocks, slaps, or bangs occurred much more often than kicks at the door or v;alls

These activities often generated considerable force, but for cuch brief periods as

to prove ineffective.

-43-

(d) Exarjilnatlcn of t:he Interior — In the interest: of considering a type >j£ to. .nno

that would be highly effective, the question of whether or not children oCi:\:ally

examine the interior of the enclosure becomes of uiomezit. (See Table 19 0

The oldest age group directed the most attention to examining their G’ij-.ro<;rOi.cg.v

.

and the youngest groups the least. The 3-year-old group directed more atben'.ivTn to

examining their surroundings than did the 2-year-old group, and the 4-year -old group

directed more attention to examination than did the 3 -year" old groijp. However, the

5-year-old group performed in this respect only slightly better chan the 2-yea::-old

group

.

In general, the older children looked around, felt along the walls or door jambs,

examined the luminous knob or ring, or looked up at the ceiling. Some of the childroi

who appeared the most curious did several of these things, carefully appraising their

unseen surroundings in terras of what opportunities they seemed to offer for escape.

4.5 Force Efforts

In the tests on device Dj , a number of force records were obtained as a result

of activities of the children while being tested. However, these records are not

complete and in some cases are unreliable, hence the.y are not presented in this

report. This unfortunate circumstance was the result of t\’;o things. First, the

plywood structure of the playhouse was subject to y.'* elding in its entirety whenever

any substantial force effort was directed at any of the enclosing panels, and this

yielding was transmitted as a force indication, even if, for example, the child

jumped up and down on the floor panel. Because of the fact that the calibration was

in terms of force transmitted to the door keeper as a result of direct force on the

door panel, the type of effort directed at other panels gave a record without meaning

Second, the recorder responded well to very short -duration forces such as might

occur with knocking and slapping efforts, and failed to register accurately the most

effective type of effort, such as a steady push of appreciable time duration.

44

Eventually, this defect was corrected, but not until all tc:’ts ou de^'ice were couipleted. Time did not permit the proper development of this met;bod of measuring forces

ICnocking, kicking, or slapping efforts freqviently registered forces in excess of

the amount required to open the door if the effort had consisted of a steady puctr.

The inertia of the door and the friction in the latch and releaslag mochanism were

Important factors preventing release with short -duration force efforte. Sijtue children

directed efforts against the door ixx which device Dj^ was installed sufficient to

initiate releasing action. Tliis was shown by the fact that the door opened a iractioci

of an inch, but these efforts were either not great enough in magnitude or were of

too short duration to complete the release, whereupon the door snapped shut again as

soon as the force was removed from the door panel.

Reasonably satisfactory force data were obtained in tests using device where

horizontal forces exerted on the movable floor panel were registered directly ou the

dial of a pressure gage, observed through a telescope and recorded on sound tape.

Table 20 gives the maximum horizontal components of forces registered by the 31

children tested on device D^. Because of the particular construction of this device,

the force values given in Table 20 represetAt horizontal forces irrespective of point

of application. If, for example, a child jumped up and do^Oi without touching the

door or any side panel, a horizontal force conpoxient. laight be registered.

The force efforts shown in Table 20 are classified in terms of "success” nr

"failure" because it was considered desirable to include the results of these 31

tests in the total sample; and these data appear listed as "success" or "failure" in

a number of other tables relating to success on all devices tested.
:v“

s:-.

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C' J ii.ti I

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;

. ?

a iv-. A -

' jl

• i

' ‘ ':. '..'•• T ft- ,?i j .. £ ' T. VjiJ 4JJI

•_.y J'.6t ;. :>^

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II. .V ::.^P

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,-. ? -•. .\ r

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' ''• '.I'y

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: i

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isiWy.u';*
-45-

Table 18. Success* in Relation to Type of Effort

: Type of Effort sue C E S F A I L U R E

Age of Sub j6 cts** Age of Subjects** ; 2 3 4 5 6 All 2 3 4

c; 6 All : No. No, No. No. No. No. No. No. No- l':0

.

No. No . :

: Pushes 2 8 14 12 10 48 10 7 9 4 1 31 :

: Knocks or

: bangs - 5 4 8 1 18 10 4 5 6 5 30 ;

: Slaps - 3 1 3 2 9 4 6 5 1 2 18 :

; Kicks door - - - 1. - 1 4 3 4 1 - 12 ;

: Pulls luminous

: knob or ring 1

- 1 2 - 4 2 5 - 4 1 12 ;

: Pushes lurai-

: no’.JS knob or

: ring - - - 5 1 6 - - - - - :

; Turns knob or

: ring 1 3 11 14 - 29 1 1 2 3 * 7 :

: Totals 4 19 31 45 14 113 31 26 25 19 9 :li0 ;

* Certain values shewn In this table are, in par^, based on results of tests using

device Dg, classified as success or failure according to the criterion explained

under 4.2 above, and hence are subject to the same comments as given there.

*r-AXhe classification of age by years used in this table is based on the classifica

tion of age by corresponding menth intervals used in tables 4, 7, 9, 12, and 15

o

Table 19. Success* in Relation to Exaiaiaation of Interior

: Type of SUCCESS F A T. I. U R E

Ai;e of Subjects** : Ag^?. of Subjects*^'

2 3:4:5 6 Ail : 2 3 4 : 5 6 All : No, No.:NOo : No, No, No, : No, No. No. : No, No. No. :

: Looks around . 3 : 1 ; 2 4 10 : 6 4 9 : 3 4 26 :

: Feels alo»--g :

'

: walls 1 1:1:2 2 7 : 3 3 7 : 1 1 15 :

: Feels door

: jambs 1 - : 1 : 2 2 6 : 4 3 6 : 2 3 18 :

: Examines lumi- nous knob or

: ring - - : - : 3

- 3 ; - 5 3 : 5 1 14 :

: Looks up - 1 : - : 2 4 7 : 1 6 8 : 1 2 18 :

: Other 1 2:1:2 - 6 : " - 2 : - 2 :

: Totals 3 7 : 4 : 13 12 39 :14 21 35 : 12 11 93 :

* Certain values shown in this table are, in part, based on results of tests using

device D^, classified as success or failure according to the criterion explained

under 4.2 above, and hence are subject to the same conm\ents as given there.

**The classification of age by years used in this table is based on the classification of age by corresponding month intervals used iu tables 4, 7, 9, 12, and 15.
'

."y

X
-46-

Table 20. Maximum Horizontal Forces Exerted by

Children T; sted on Device D.

D

•.Test

; No. Age Sex

Maximum

force

Approxima.iic

tliae of

occurrence

Total time

in

enclosure

Gucc;ess* :

years lbs. seconds seconds

: 158 B 14.5 40 to 50 65 Yes

: 169 2 B 14.5 30 to 35 35 Yes :

: 175 2 B 19.0 0 f.o 10 15 No :

: 176 2 B 16.7 0 to 10 25 No :

: 147 2 G 14„5 50 to 60 33 Yes

: 148 2 G 0.0 0 to 10 65 No :

: 164 2 G 10.0 100 to 110 1.40 No

: 168 2 G 13.4 80 80 No :

: 146 3 B 12,3 10 to 20 80 No :

: 150 3 B 6.8 60 to 70 200 No :

: 170 3 B 9.0 40 to 50 195 No :

: 172 3 B 14.5 30 to 40 45 No :

: 154 3 G 16.7 50 to 60 80 Yes :

: 160 3 G 5.6 170 to 180 250 No :

: 171 3 G 7.9 60 65 No :

; 163 4 B 17.3 60 to 64 64 Yes :

: 155 4 B 23,4 20 to 30 30 Yes ;

: 156 4 B 11.2 100 to 110 150 No :

: 157 4 B 15.6 1C5 105 Yes ;

; 159 4 B 10,0 240 to 250 r-, '-5 r* ^35 No :

; 152 4 G 12,3 180 180 Yes ;

: 153 4 G 19.0 130 to 140 1.40 Yes :

: 167 4 G 10.5 0 to 10 95 No :

: 151 5 B 16.7 40 to 50 55 Yes :

: 161 5 B 19.0 0 to 10 345 No :

: 162 5 B 16,7 30 to 40 110 Yes

: 166 5 B 22.3 130 to 137 137 Yes :

: 149 5 G 29.0 20 30 Yes :

; 165 5 n 10.0 70 to 80 87 No :

: 173 5 G 22.3 0 to 10 10 Yes :

: 174 5 G 29.0 0 to 10 10 No :

* "Yes" means that at least 12 lbs. of force c/applied to door. "No" means

less than 12 lbs, of force were applied to dcor, that th.e. maxlrm-rai

effort was applied elsewhere than on the door, or that Insufficient infoim.ition is available to determine the point of application. Certain comments with

respect to this classification are made under 4»2

- 47 -

The age classificaticn adopted in table 20 is based on the assumption

that a child at least 20 months of age but less than 36 months is 2 years

old, a child at least 36 mojiths of age b’lt less than 48 months is 3 yeais

old, etc.

Figure 26 is based on the data in table 20 for the 31 cases as a group

withotit resi^ect to age or sex. The ordinate for each plotted point

represents Che percexitage of the children who exerted a horizontal force on

the floor panel i*a excess of the value represented by the cortosponding

abscissa. For cotaparisou, the other plotted points represent the perfoiimance

of children tested on devices , D

2 , and where it was possible for them to

release themselves c In device , for example, it is known that the successful children exerted a force of at least 18 lbs, on the door panel and those

in device D

2 exerted a similiar force of at least 12 lbs. In device D5 , it

is certain that the successful children exerted at least 6 Ibe. against the

door panel, if their releasing efforts were directed at the door, or more if

their releasing efforts were directed elsewhere. If it is assumed that the

values plotted for device D5 represent fairly the maximum horizontal force

potential of children irrespective of point of application, then the extent

to which the performance of the children on devices Dp, D 2 , and D5 fails to

measure up to their potential performance is indicated by the magnitude of

the downward displacement of the Dp, D 2 j and D 5 points below the general

line of the D 5 points. Figures 27, 28, 29, and 30 show the same type of

data for each age group. These are based on samples in the range of 4 to 8

Subjects only. However, inspection of figures 27-30, inclusive, suggests

that the ability of children to direct their maximum force potential against

the door panel tends to increase with age, 2 -year-olds having the poorest

showing in this respect and 5 -year-olds the best showing.

- 48

The force data presented in Table 20 and Figures 26-30, iAiclusive,

are not precise because of the lack cf coraplote film records on all test

and the lack of time to develop certain refinements in irAStruineAdation,

These circumstances prevented making a thorough con elation cf force

efforts with behavior. However, it is believed that the data presented

In Table 20 and la Figures 26-30, inclusive, do have predictive value

in ludicating the nature of the probleiCo lucocipicte as they are the data

seera to justify the qualitative conclusions dra'^oiio

%

Of

Childreii

Exerting

in

Excess

of

Indicated

Force

I 00

90

80

70

60

50

40

30

20

I 0

0

0 5 10 15 20 25 30

Force, Lbs.

FIGURE 26, Horizontal components of forces exerted by

children, ages 2 through 5 years.

00

90

80

70

60

50

40

30

20

10

0

Device Number

tested

Number who

released

themselves

Symbol

1 8 0 •

2 8 1 ©

5 > 2 0

6 0 O

*A11 released by observer.

9-

5 10 15 20 25 30

Force, Lbs.

Horizontal components of forces exerted by

age 2 years.

%

Of

Children

Exerting

in

Excess

of

Indicated

Force

I

100

90

80

70

60

50

40

30

20

10

0

0 5 10 15 20 25 30

Force, Lbs.

FIGUFIE2S. Horizontal components of forces exerted bychildren, age 3 years.

Device Number

tested

Number who

released

themselves

Symbol

1

2

56

8

8

17

30

•©

d

o

/ _i

*A11 released by observer.

O ©

V

o

( ) o

cr

° •
V

,** ' j

'

• V

<, -

••i'

f

A*

it^« k

-'i

V#.* X,i^‘

.

/!/»'^ J'

' <’

> .> r

A '.' f ^ A . :J \ Ji, W
%

Of

Children

Exerting

in

Excess

of

Indicated

Force

100

90

80

70

60

50

40

30

20

10

0

0 5 10 15 20 25 30

Force, Lbs.

FIGURE 29 . Horizontal components of forces exerted by

children, age 4 years.

Devi ce Number

tested

Number who

released

themselves

Symbol

1

2

56

7

8 •i

36

30

•

©

d

0

*A11 released by observer.

c ) ]

e

0

u

•

0

0

C

r ^

c\) —
\

I- V

/

f ;

1 I
00

90

80

70

60

50

40

30

20

I 0

0

Devi ce Number

tested

Number who

released

themselves

Symbol

1

2

56

8

8 *8

574

0

•©

e

o

r

V Q r\

r V ^

''All released by observer.

( CD o O

9

/kV|J

o ) 0 ——

o

5 10 15 20 25 30

Force, Lbs,

Horizontal components of forces exerted by

age 5 years.

CHILDREN PUSHING ON DOOR

I. Successful Efforts

FIGURE 31. Boy opens door on

first push (5 years).

FIGURE 32. By shoving with

his buttocks, boy releases

himself (4 years;.

FIGURE 33. Girl stands waiting before movie screen, then

bends down and pushes with

both hands. Picture shows

door opening (5 years).
f * -

I

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tif-.

1 f‘- >

>: .:«3/' ri"'

sny^fi vi:' mi^xm

t

,,.l

*

. I

*. %

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•

. .S^ • • .• s

' > , v- .

r'j-

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' f'’ . V-

'« « . Jvt "

=-yd

'^rf»

^ f*

f Ml.' 'i^fq ’>' r. V -5 ;»,.. , .1- 1 . .P/',
CHILDREN PUSHING ON DOOR

II. Types of Strenuous Effort

FIGURE 34. Boy pushes shoulder against door, left of

center (5 years).

FIGURE 35. Boy, backing up,

rams door with shoulder push

(5 years).

FIGURE 36. Boy stretches

body to put force into a

two-hand push on door

(3 years).

CHILDREN PUSHING ON DOOR

III, Purposeful Efforts

FIGURE 37. Girl pushes on

door from squatting position

(3 years).

FIGURE 3^. Girl makes a firm

two-arm push on door (2 years).

FIGURE 39. Same girl directs

all fxirther efforts at side

wall (2 years).

CHILDREN HANDLING LUMINOUS RING

FIGURE 40 . Girl pulls ring

with ri^t hand, bracing

herself with left hand on

door {5 years).

FIGURE 41* Girl touches ring

gingerly, without further

exploration (2 years).

FIGURE 42. Boy thumbs

luminous ring ineffectively

(2 years).

ILLUSTRATIONS OF REACTIONS TO DOORKNOB

FIGURE 43* After approaching

knob with left hand, girl continues to hold it, but makes

no attempt to use it to release

herself (2 years).

FIGURE 44* Boy with hand on

knob, thumb at center, fails

to use knob effectively

(2 years).

FIGURE 45. Sitting in corner,

boy reaches for doorknob,

turns it clockwise to release

himself (3 years).
L-1 0
ILLUSTRATIONS OF REACTIONS TO DOORKNOB

FIGURE 46 . Girl grasps underside of doorknob, turns counterclockwise, releasing

herself on first try (4 years).

Figure 47* Boy^s hand is too

small to grasp the doorknob

effectively (2 years).

FIGURE 4^« Girl grasps

doorknob with left hand,

turns it clockwise, promptly

releases herself (5 years).

ILLUSTRATIONS OF REACTIONS TO DOORKNOB

FIGURE 49. Boy approaches knob

with left hand after squatting

in comer (3 years).

FIGURE 50 . Same boy later

grasps doorknob in both hsmds,

turns it clockwise to release

himself (3 years).

FIGURE 51* Boy uses both

hands, pushing knob while

turning it clockwise, opening

door (3 years).

ILLUSTRATIONS OF REACTIONS TO DOORKNOB

FIGURE 52. Boy reaching, from

far corner, for doorknob

( 5 years)

.

FIGURE 53* Same boy, as he

later grasps doorknob and

releases himself.

EXAMPLES OF CHILDREN IGNORING THE DEVICE

FIGURE 54* Boy has withdrawn

to comer (4 years).

FIGURE 55* Boy’s palms are

outspread on door at chest

level (2 years).

FIGURE 56, Boy rubs eyes

with left hand, slapping

door above luminous ring

(2 yeeirs)

,

SAMPLES OF VIGOROUS KNOCKING BEHAVIOR

FIGURE 57* Boy, intending

to knock, makes a fist

(5 years).

FIGURE 5B. With clenched

fist, same boy completes

knock on door ( 5 years )

FIGURE 59* Kneeling, girl

raises hands shoulder high

to slap door (4 years).

SAMPLES OF VIGOROUS KNOCKING BEHAVIOR

FIGURE 60 . Left hand in^

mouth, boy knocks with right

fist (5 years).

FIGURE 61. Boy, later quite

upset, tentatively touches

door with back of hand

(4 years)

.

FIGURE 62. After long wait,

boy knocks on wall opposite

movie screen (5 years).

EXAMPLES OF EXPLORATORY BEHAVIOR

FIGURE 63. Girl completes

exploration of door. Starting

from hinge side, she felt

across top and down latch

edge to floor (5 years).

FIGURE 64* Boy, searching

for release, feels mounting

plate (4 years).

FIGURE 65. Boy reaches up to

touch ceiling with both

hands, after exploring with

one (4 years).

CHILDREN SEARCHING FOR RELEASE DEVICE

FIGURE 66. Position of girl’s

hand suggests she is groping

for a release device (5 years).

FIGURE 67* Boy’s hand returns

again and again to mounting

plate (5 years).

SERIES SHOWING TWO-YEAR-OLD BOY REVOLVING IN THE ENCLOSURE

FIGURE 6'S. FIGURE 72.

FIGURE 71.

«« - FIGURE 69.

FIGURE 70.

FIVE-YEAR-OLD BOY WAITING TO BE RELEASED

FIGURE 74* After waiting in

above position, he turns

head without changing bodyposition and taps door gently

several times.

FIGURE 75* He continues

tapping door lightly with

finger tips.

EXAMPLES OF DISORIENTATION

FIGURE 76. Boy pushes on

hinge edge of door (2 years).

FIGURE 77 . Sitting with back

to hinge edge of door, girl

slaps forcibly with open palms

at screen and back walls

simultaneously (5 years).

FIGURE 7^. Boy pushes hard

on movie-screen wall

(5 years).

CHILDREN EXHIBITING HELPLESSNESS

FIGURE 79* Boy, distraught,

makes many hand-to-face

movements, intermittently

clasping and unclasping

fingers (3 years).

FIGURE SO. Boy retreats to

wall farthest from screen and

rubs eyes many times

(4 years).

FIGURE SI. Boy»s right

thumb goes to his mouth

repeatedly (4 years).

s. CONCLUSIONS

1. children's behavior takes a variety cf i'orias u»d^ coiidrcioas'^

simulating entrapmenc in a refrigerator .* These are discussed in

section 4.4 of this report.

2.

Considering the total sample, no device tested approached 100% effective"

nessc

3.

None of the devices used in testing children in this invest igaticn

was designed in such a way as to insure release uivler all conditions

as, for exaiiple, in connection with the foiiowing types of behavior:

(a) Pushing efforts directed at the door when the proper effort

would have been to use a knob or trigger device

(b) Efforts which consumed time and energy in a search for a

release mechanism on a door which reacted only to a push

(c) Efforts directed at some surface other than the dcor

(d) Cases of no effort whatsoever, or of efforts cf a random and

diffuse nature

(e) Efforts of a proper type,but applied with insufficient force,

or for an insufficient period of time to effect release

(f) Improperly directed efforts to manipulate a release mechanism,

4.

The correlated factors of age, weight, and height appear to have an

Important effect on the success of children in utilizing a release

device. This suggests that weight, height, physical abilities, and

behavior patterns of the youngest age groups for which protection is

to be provided should be considered in designing a release device.
.'o

^^,70

*s
- 50 -

5o The specific type of behavioi’ exhibited by any particular child unCsr

conditions of entrapment is a vary important factor af:fe(;ting ouccess.

This suggests that the behavior of the children who/twien entrapped ,

become helpless or d±sorg.mized^should be considered :n designing a

release device* This type of behavior watj observed, in this

investigation, most frequently in 2-year-old children, and to a lesser

degree in 3-yaar-old children.

6o Limited experience in design of experimental devices carried out in

this investigation seems to indicate that it would be possible to

build release devices reacting to a very low order of force. However,

the expense involved and other possible objectionable features might

preclude adoption.

7. The test results indicate that the most effective devices which seem

to be practical are:

(a) A luminous knob release reacting to push“p:ill-turii (ideally, also

to deflection). Such a knob, it appears, should resemble the

smaller domestic-type doorknobs in size and shape. In addition,

the turning moment to effect release should not exceed that for

modern domestic doorknobs. The turning raoment for the doorknob

device used in this investigation has been given in section 2,3

of this report.

(b) A push-type door which reacts to a low order of force. This type

of device should release positively and quickly on application of

short -duration force to overcome lag or sticking caused by friction

or inertia. Data on the performance of children tested on push-type

doors in this investigation have been presented in section 4,3 and

elsewhere in this report.

51

8. The present study has opened up a new field of investj.gat ion, and has

indicated the existence and general nature of unsolved problems in the

field of child safety, especially in regard to psychological aspects.

The results in no way preclude the possibility of further study in

child research centers.

9. The results of this Investigation appear to have given sufficient

information to be useful in the development of criteria for a standard

for release devices providing a reasonable degree of protection.

-51"

LIS? CJ TxiSLiilS

Ta,ble 1,

2 , 3.

4.5.6 . 7-g.9-

10 . 11 . 12 . 13.

14.

15 .

iS.

17 . 18.

19.

20 .

Pi str iloul ion of Tests "by Pevice 22

Sequence of Tests Py Pevice

Description of Sample . . p4

Age Distribution in Months 28

Distribution of Total Yecurs of Parents' Education 25

Description of Sample by Eather's Occupation 26

Description of Sample by by father's Occupational Group 26

Distribution of Tests by Experimenter 27

Children's Success in Utilizing Safety Release Devices 2S. 29

buccess in Relation to Experimenter

Effect of Device on Success ^2

Effect of Device on Success for Different Ages 34

Distribution of Successes by Device

Crying in Relation to Effort C,0^<

Total Time Spent in Enclosure by Children Who Succes

Utilized Release Devices

VocaUization

Reactions of Children in Playhou.se . . . . Success in Relation to Tji)e of Effort^.^^

Sara i nat i 0 or

s Exert i^Ptjy cMildre>jf6^

Success in Relation to E: Maximum Horizontal Eorces Exerti^'By

Tested on Device Dg . . . . .

4i

45

45

^'0
J t M>i, V'jr. ",

'^’«/v- to 1

'otr

t,^

''o„
„52~

7. ACKlTOWL^DC-El'iSrTS

The Child Safety Pro.lect Staff offer grateful tha,nks for the assistonco

so graciously given on many occasions "by a nujnher of persons not specifically

mentioned earlier. Their specialized tr'aining in various fields has contributed much to the successful completion of the project. Included ejnong the-se

are the follovring:

William. R. Allen Jean h. H'uhhell

Riclmrd V/. Armstrong Edward C. Lloyd

Theodora C. Bailey William J. heese

Ri c ha,r d L . Bari ow Conrad E. Peters

Gilda T. Cotz Sexhio Saito

Raymond S. Cudmore Hazel S. Snider

Lester W. Fiirlow Erandc Taller ico

Peaul E. Golciliagen William R. Tilley

Margar e t C . Tr em e a,r no

-53-

g . APPEI©IX

1. SUCCESS IK REMTIOK TO ITEI 59^

In the "body of this report frequent mention has 'be^0g5»#e^f the correlated

(0*

factors of age, vfeight, and height as factors c^P?cting success, figures 1,

3 , and 4 of this appendix show the height and weight of each child tested on devices Eq , Dp, h'^, and Dh, respectively, vuthout reference to age. These figures

clearly distinguish between success a.nd failure.

Inspection of these data fails to indicate a clear distinction hetvreen the

genere.1 helght-v-elght curves for the successful and non-successful children. It

appears that the±-e is a greater concentration of failures in the lovfer left areas

of these figures, and a grea.ter concentration of successes in the upj.^er right

areas, althoiogh there are several exceptions to this genera.l trend. Probably

this is partly eop)lained by the fact that in general the younger children wei'e

the most likely to fail on all devices, and that most of the younger children

were the smallest, ilo distribution curves for weight and height ha.ve been made

for the successes and failures vfithin ea.ch age group. This should be considered

worthy of doing in connection with any further analysis of the deita.

2. EXPLAMTIOK OE DISCREPANCY IN AGE CLASSIEICATION

In several tables presented in the body of this report, the age classification used is in terms of month-intervals. It wa.s intended t]is.t these intervals

would be of equal widths. Inadvertently, some intervals turned out to be 11

months and others 13 months in width. Nhen this discrepancy was noted, there was

not sufficient time to re-working of the data on which the affected tables

were based. However, in the opinion of the statisticians, this vmevenness in

interval width does not appear to irffect the conclusions in any substantia.l v;ay.
' ' } . 7/ 
WEIGHT,

LBS.

YES —9

NO O

HEIGHT, IN.

FIGURE I. SUCCESS IN RELATION TO HEIGHT AND

WEIGHT FOR ALL AGES TESTED FOR DEVICE D,

YES— e

NO O

60

55

50

(/)

GO

“^45

H

X

o

UJ$40

35

30

25 30 35 40 45 50 55

HEIGHT IN.

FIGURE 2. SUCCESS IN RELATION TO HEIGHT AND

WEIGHT FOR ALL AGES TESTED FOR DEVICE D^
f vl

' .W THDV3H

iO Wa3Ta3TS3^-4|A1^C« T

»'.,{ im int -.i*. .•.

,

• • -V,;..®
60

NO O

55

50

I ai 45

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LlJ

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I 35

I 30

1

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c o> O i

o o

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oo

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V LI ( •

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20 25 30 35 40 45 50

HEIGHT IN.

FIGURE 3 SUCCESS IN RELATION TO HEIGHT AND

weight for all ages tested for device Dj

I

I

WEIGHT,

LBS.

60

55

50

45

40

35

30

25

o

d

0•

1 A

o

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9

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20 25 30 35 40 45 50

HEIGHT, IN.

FIGURE 4. SUCCESS IN RELATION TO HEIGHT AND

WEIGHT FOR ALL AGES TESTED FOR DEVICE D^

THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

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