Directional Control-Response Compatibility 

Relationships Assessed by Physical Simulation of 

an Underground Bolting Machine 

Lisa Steiner, National Institute for Occupational Safety and Health, 

Pittsburgh, Pennsylvania, Robin Burgess-Limerick, University of Queensland, 

Australia, and William Porter, National Institute for Occupational Safety and 

Health, Pittsburgh, Pennsylvania 

Author(s) Note: The author(s) of this article are U.S. 

government employees and created the article within the 

scope of their employment. As a work of the U.S. federal 

government, the content of the article is in the public domain. 

Objective: The authors examine the pattern of direction errors made during the manipulation of a physical

simulation of an underground coal mine bolting machine

to assess the directional control-response compatibility

relationships associated with the device and to compare

these results to data obtained from a virtual simulation of

a generic device. 

Background: Directional errors during the manual

control of underground coal roof bolting equipment

are associated with serious injuries. Directional controlresponse relationships have previously been examined

using a virtual simulation of a generic device; however, the

applicability of these results to a specific physical device

may be questioned. 

Method: Forty-eight participants randomly assigned to

different directional control-response relationships manipulated horizontal or vertical control levers to move a simulated

bolter arm in three directions (elevation, slew, and sump) as

well as to cause a light to become illuminated and raise or

lower a stabilizing jack. Directional errors were recorded during the completion of 240 trials by each participant. 

Results: Directional error rates are increased when

the control and response are in opposite directions or

if the direction of the control and response are perpendicular.The pattern of direction error rates was consistent

with experiments obtained from a generic device in a virtual environment. 

Conclusion: Error rates are increased by incompatible directional control-response relationships. 

Application: Ensuring that the design of equipment

controls maintains compatible directional control-response

relationships has potential to reduce the errors made in

high-risk situations, such as underground coal mining. 

INTRODUCTION

Underground coal mining remains a domain

in which the manual control of equipment, such

as bolting machines, is ubiquitous. The risks of

these activities are well documented and include

injuries associated with direction errors, that is,

operating a control in a direction that produces

the opposite effect from that intended (BurgessLimerick, 2011; Burgess-Limerick & Steiner,

2007; Helander, Krohn, & Curtin, 1983; Miller

& McLellan, 1973). 

One means of reducing the probability of

such errors is to ensure directional compatibility

between control movement and response. Previous research into directional stimulus-response

compatibility provides robust and consistent

evidence that compatible relationships between

stimulus and response directions result in faster

and more accurate performance (Chua, Weeks,

Ricker, & Poon, 2001; Fitts & Seeger, 1953;

Proctor & Reeve, 1990). It has been argued that

this compatibility effect occurs because compatible arrangements have “properties in common,

and elements in the stimulus set automatically

activate corresponding elements in the response

set” (Kornblum, Hasbroucq, & Osman, 1990,

p. 253). It has also been suggested that “if stimuli share features with responses or, more precisely, with the perceptual effects these responses

produce, they are able to prime these responses,

which facilitates response selection in conditions of stimulus response compatibility but

hampers response selection under incompatible

conditions” (Hommel, 2005, p. 10). Although

performance in consistently incompatible situations improves with practice, even after extensive practice, performance has not been found to

reach that of consistently compatible relationships (Dutta & Proctor, 1992; Fitts & Posner,

1967). 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Although this area has a long history of study

(e.g., see Loveless, 1962, for a review), the

research has almost without exception involved

relatively artificial laboratory tasks and reduced

cue environments. Although such paradigms

may be satisfactory for application to topics

such as aircraft attitude displays (e.g., Yamaguchi & Proctor, 2010), the findings may not

translate well to the complex combinations of

movements inherent in equipment such as

underground bolting rigs. 

Industrial equipment, such as that used in mining, provides examples of equipment design

that appear to violate the principles obtained in

previous research. For example, it is relatively

common to find situations in which downward

movement of a horizontal control lever causes

upward movement of the controlled element,

such as a boom, timber jack, or drill steel. Some

authors (e.g., Helander, Conway, Elliott, & Curtin, 1980) have suggested that this design is a violation of compatible directional control-response

relationships. Simpson and Chan (1988), however, suggested on the basis of an examination of

participants’ reported expectations that this directional control-response relationship is compatible

and that operators assume a “see-saw” mental

model of the situation whereby moving the near

end of the control downward causes the far end

(and the controlled element) to move upward. 

Burgess-Limerick, Krupenia, Wallis, PratimBannerjee, and Steiner (2010) addressed this

discrepancy in two experiments that involved a

virtual simulation of a generic device controlled

by a bank of four levers. The response of the virtual device included changing color, lengthening

or shortening, slewing left or right, and elevating

or depressing. The levers that controlled these

responses varied in orientation (horizontal or

vertical) and in the direction of the resulting

response. The position of the bank of levers with

respect to the participants also varied across the

experiments. 

The results confirmed the general applicability of the principles of consistent direction

and visual field compatibility (Worringham &

Beringer, 1998). In particular, the finding that

directional error rates were minimized when

upward movements of a horizontal lever caused

upward movements of the controlled device was

consistent with the data reported by Mitchell and

Vince (1951) and not with the participant expectations reported by Simpson and Chan (1988).

This discrepancy raised the possibility that selfreported directional expectations are not necessarily predictive of behavior. Hoffmann (1997),

and Chan and Chan (2003) have similarly

reported discrepancies between reported directional expectations and actual behavior. 

It has also been observed that reported directional expectations derived from drawings were

not entirely consistent with reported preferences

derived from the use of a computer-generated

version of the same situation (Kaminaka & Egli,

1984). Although an expectation that a vertical

lever would be pushed to cause vertical movement was reported on the basis of a drawn representation of the situation, no consistent preference was reported from a situation in which a

lever was used to cause a virtual image to be

raised or lowered. 

Burgess-Limerick et al. (2010) also noted that

the control of slew (swing) was associated with a

relatively high probability of direction errors in

most of the situations examined, with the exception of situations in which a vertical lever located

to a participant’s right or left was paired with a

directional control-response relationship such

that moving the lever away caused the device to

swing in the same direction. Directional error

rates were relatively high when the direction of

movement of the slew was perpendicular to the

movement of the control, and it was concluded

that these situations should be avoided. 

Virtual environments have also been used to

assess directional control-response relationships

for other situations. Zupanc, Burgess-Limerick,

and Wallis (2007, 2011) and Burgess-Limerick,

Zupanc, and Wallis (2012) used a virtual analogy

of a shuttle car used in underground coal mines to

assess directional compatibility of steering wheel

and joystick steering systems, respectively. 

Although experimental paradigms involving

a virtual environment have a number of advantages, the lack of ecological validity is potentially problematic. It may be that the behavior

exhibited when controlling physical objects may

differ from that observed during the manipulation of objects in a virtual movement. Consequently, it could be that the conclusions reached

by Burgess-Limerick et al. (2010) on the basis of

investigations in a virtual environment are not
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1. (A) Simulated roof bolter arm, (B) participant performing the experiment, and (C) 

schematic representation of the bolter arm movements. 

applicable to a specific application within a

physical environment. 

Objectives

The aim of this experiment was to examine

the pattern of direction errors made during

the manipulation of a physical simulation of

an underground coal mine bolting machine to

assess the directional control-response compatibility relationships associated with the device

and to compare these results to data obtained

from a virtual simulation of a generic device. 

METHOD

Apparatus

A physical simulation similar in configuration to a single-boom Fletcher Roof Ranger I

bolting machine was used. The apparatus consisted of a bank of five levers that controlled

a simulated boom (Figure 1). Four of the five

levers controlled hydraulic actuators that caused

the physical simulation to move in the following

directions: (a) slew (swing) of the boom about a

vertical axis of rotation toward or away from the

operator; (b) elevation or depression of the boom

via rotation about a transverse axis of rotation,

which caused the simulated drill head to raise

or lower; (c) sump (horizontal translation) of the

boom in-bye (in this case, to the operator’s left)

or out-bye (to the operator’s right); and (d) raising or lowering of a simulated stabilizing jack.

The remaining lever caused a light mounted on

the end of the boom to become illuminated in

one of two colors (red or yellow). The levers

were orientated either horizontally or vertically. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1: Two-Way ANOVA Results for Direction Error 

Direction Errors

Orientation CRR Interaction 

Lever F p F p F p

Color 

Boom elevation 

Slew (swing) 

Sump 

Stabilizing jack 

2.67 

6.70 

0.278 

2.45 

3.54 

.110 

.013 

.601 

.123 

.066 

3.90 

6.08 

1.89 

14.7 

2.85 

.056 

.018 

.176 

<.001 

.099 

1.23 

0.001 

25.43 

1.99 

0.023 

.275 

.941 

<.001 

.165 

.879 

Note. All degrees of freedom (1, 44). CRR = control-response relationship. 

Two sets of directional control-response relationships were defined. In Control-Response

Relationship 1 (CRR1), an upward movement of

a horizontal lever, or a movement of a vertical

lever away from the participant, caused either

(a) the color to change to red; (b) the boom to

slew toward the participant; (c) the boom to elevate, raising the drill head; (d) the boom to sump

(translate) in-bye; or (e) the stab jack to lower.

These relationships were reversed in ControlResponse Relationship 2 (CRR2). 

Participants and Procedure 

Forty-eight participants (32 male and 

16 female; ages 21 to 61, M = 45.3, SD = 12.9) 

were randomly assigned to (a) one of two direction compatibility conditions (CRR1, CRR2) 

and (b) vertical or horizontal levers. 

Following a demonstration of the function of 

the levers, each participant completed six blocks 

of 40 trials. In each trial, the participants were 

presented with a short video clip of the simulated roof bolter arm responding in 1 of the 

10 possible ways. The participants were required 

to choose a lever and move it in one of two 

directions to attempt to achieve the response 

indicated by the video clip. Equal numbers of 

each stimulus video clip were presented in random order in each block of trials. 

Following each response, the participant 

returned the bolter arm back to the starting position using the control bank and depressed a button located to the right of the control bank to 

indicate that he or she was prepared for the next 

trial. The next stimulus was presented 2 s later.

Each trial lasted approximately 10 s. A 1-min

break was provided every 40 trials (approximately every 6 min). 

Analysis 

Direction errors were defined as a movement

of the lever in the direction opposite to that

required by the stimulus. A direction error was

determined to occur if the participant both chose

the wrong lever and moved it in the wrong

direction. 

Direction errors were expressed as percentages. Error data are bounded by zero, and the

distributions were consequently skewed. Hence,

median and interquartile ranges for these data

are presented graphically, and inferential statistical analysis (factorial ANOVA) was undertaken

on log transformed accuracy (100% error) data. 

RESULTS AND DISCUSSION 

Two-way ANOVA (Lever Orientation × Control-Response Relationship) for direction errors

are provided in Table 1. 

Color 

No significant effects of orientation or directional control-response condition were found for

the color lever, indicating that the randomization

was effective in providing equivalent groups of

participants in the four conditions. The median

direction error for the color lever was 2.1%.

This median direction error rate is higher than
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2. (A) Boom elevation (elevate-depress) direction error and (B) clockwise elevation

direction error data from Experiment 2, Burgess-Limerick, Krupenia, Wallis, Pratim-Bannerjee,

and Steiner (2010). 

the 1.25% median rate reported by Burgess-Limerick et al.’s (2010) Experiment 2. This difference

may reflect differences in experimental protocol

or participants. 

Boom Elevation

Significant effects of both directional control-response relationship and lever orientation

were found for the elevating and depressing

of the boom of the simulated single arm bolter

(Figure 2A). Very few directional errors were

made by participants assigned to the horizontal

lever and CRR1 condition in which raising the

horizontal lever caused the boom to elevate.

When the controls were oriented vertically, fewer

errors were also made by participants assigned

to the CRR1 condition. In this case, moving the

vertical lever away from the participant caused

elevation of the boom and drill head; however,

more errors were made in this situation than in

the horizontal CRR1 condition. 

These results are consistent with those

obtained from the virtual simulation of a generic

device (Burgess-Limerick et al., 2010). The

comparable situation examined in the previous

virtual simulation is clockwise elevation of the

virtual device controlled by horizontal and vertical levers located to the participants’ right

(Experiment 2, Burgess-Limerick et al., 2010).

These data are plotted in Figure 2B for comparison. An identical pattern of direction errors is

observed, although as for the color lever, the

magnitude of error rate is greater in the current

experiment. 

These results reinforce the importance of

optimized directional control-response compatibility for reducing directional error probability.

This is particularly important for the drill feed

function given the history of fatalities in the

United States arising from bolter operators being

crushed between the boom and roof or between

boom and bolting machine structure (Mine

Safety and Health Administration, 1994). 

Slew 

A significant interaction was found between

lever orientation and directional control-response

relationship for the slew lever (Figure 3). When

lever orientation was horizontal, fewer directional errors were made by participants assigned

to the CRR1 condition in which an upward

movement of the horizontal lever causes the

boom arm to swing toward the participant.

When the lever orientation was vertical, fewer

directional errors were made by those participants assigned to the CRR2 condition in which

moving the vertical lever away from the participant caused the boom to swing away from
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3. Slew (swing) direction error. 

the participant. In both situations, however,

the direction of the lever movement, whether

horizontal or vertical, was perpendicular to the

movement of the boom rotation. Consequently,

the median direction errors were greater than

5% in all situations examined, indicating that

controlling rotation of the boom in the transverse plane (about a vertical axis of rotation)

with either horizontal or vertical levers mounted

as illustrated in Figure 1 is a relatively errorprone situation. These results are consistent

with those obtained from the virtual simulation

of a generic device (Burgess-Limerick et al.,

2010) in that slew was generally associated with

relatively high error rates; however, there was

no directly comparable situation in the virtual

simulation. Given that the operator is located

between the slewing boom and the mine wall,

direction errors of this nature have potential for

serious unwanted consequences.

Sump

A significant effect of directional controlresponse condition was found; however, there

was no significant effect of lever orientation,

nor was the interaction significant (Figure 4).

The fewest direction errors were made by participants assigned to the vertical lever orientation and CRR2. In this situation, a vertical lever

was moved away from the participant to cause

the model boom to move out-bye (to the right).

When the lever orientation was horizontal,

relatively many directional errors were made

regardless of the control-response relationship

condition. Although this situation is not directly

comparable to any of the relationships examined

in the previous experiments, the results are consistent with the principle of consistent direction

and demonstrate that error rates are increased

when the lever movement is perpendicular to

the response direction. 

Figure 4. Sump (in-out) direction error. 

Stabilizer Jack

Fewer errors were made in the horizontal

lever condition when raising the horizontal lever

caused the stabilizer jack to be raised. When the

lever orientation was vertical, fewer errors were

made when moving the vertical lever away from

the participant caused the stabilizing jack to be

raised. These differences were not statistically

significant, however, illustrating variability in

the participants’ interpretation of the control

response. This variability arises because activating the stab jack lever may be interpreted as

lowering the stab jack, or it may be interpreted

as stabilizing or raising the bolting machine

in preparation for bolting. This situation is not

comparable to any of the movements of the

virtual device examined in the previous experiments. It does serve to illustrate the difficulty in

determining an optimal design when the user’s

interpretation of the response may vary. 

CONCLUSIONS

The pattern of direction errors observed

during the use of the physical simulation of
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a specific piece of underground coal mining

equipment is consistent with those observed

in previous experiments involving a virtual

simulation of a generic device. This finding

provides confidence that the principles derived

in previous experiments in virtual environments

may be generalized to physical environments.

The results emphasize the importance of ensuring consistent direction of control and response

movements to reduce the probability of errors,

which may have serious consequences. The

probability of direction errors is increased if

the control and response movements are in

opposite directions or, importantly, if the direction of the control and response movements are

perpendicular. Designers of bolting equipment

should avoid providing the directional controlresponse relationship that have been identified

here as being associated with relatively high

error rates. The results provide evidence to support the validity of other experiments conducted

in virtual environments (e.g., Burgess-Limerick

et al., 2012; Zupanc et al., 2007, 2011) as

a means of examining directional controlresponse relationships. These findings have

been adopted in guidance material, such as

Mining Design Guide 35.1 (Industry & Investment NSW, 2010), which provides assistance to 

designers of such equipment. 

ACKNOWLEDGMENTS 

The authors recognize technical assistance from 

Tim Matty, experimental assistance of Mary Ellen 

Nelson and Al Cook, and the graphic assistance of 

Patrick Roth (NIOSH, OMSHR). The findings and 

conclusions in this article are those of the authors and 

do not necessarily represent the views of the National 

Institute for Occupational Safety and Health. Mention of any company or product does not constitute 

endorsement by the National Institute for Occupational Safety and Health. 

KEY POINTS 

x	 Discrepancies exist in the directional controlresponse relationships found in mining equipment. 

x Previous experiments in a virtual environment 

have supported the general applicability of the 

principles of consistent direction and visual field 

compatibility; however, the applicability of these 

results to a physical environment is open to question. 

x	 The patterns of direction errors observed in a 

physical simulation of a specific piece of underground coal mining equipment are consistent with 

previous experiments involving a virtual simulation of a generic device. 

x	 The probability of direction errors is increased if 

the control and response movements are in opposite directions or if the directions of the control 

and response movements are perpendicular. 

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