bluuebunny/crossref_metadata_2025 huggingface dataset:
The Processing of Positive and Negative Information
Authors: Wason P. C.
Published: March 2008

An affirmative statement which is known to be false and the complementary negative statement which is known to be true, provide the same information, i.e. that something is not the case. Similarly, an affirmative statement which is known to be true and the complementary negative statement which is known to be false, both imply that something is the case. (If P is false, not-P is true and if P is true, not-P is false.) Hence there are four kinds of statement (“conditions”): true affirmatives, false affirmatives, true negativee and false negatives, but only two kinds of information: positive and negative.

This experiment investigates the times taken to process information presented in these ways. The task was to select two alternative words which would make affirmative or negative conjunctive statements agree or conflict with given situations. The four conditions were presented six times in different serial orders, so that each occurred once in every block of four trials. The mean response times were: true affirmatives 8–99 sec, false affirmatives 11 19 sec., true negatives 12–58 sec, false negatives 15–17 sec. This order was the same at each of the six presentations of the conditions, the differences being significant at the 0 001 level in each case. There was a pronounced decline in errors (without knowledge of results) for three of the conditions. These results are discussed in relation to (i) the assumption of a positive set, established through a long learning process; (ii) the inferential nature of negative information in relation to experience; and (iii) the possible emotional effects of negative terms.
Visual Discrimination with a Single Manipulandum following Temporal Ablations in the Monkey
Authors: Ettlinger George
Published: March 2008

The aim of this investigation was to determine what effect variation in the conditions of cue presentation and response availability has on the visual discrimination performance of monkeys with bilateral inferior temporal ablations. Six animals were trained on one of two versions of a test of successive brightness discrimination. Common to both versions of this test was the availability of a single lever, manipulation of which in the presence of the positive cue constituted the correct response. Performance on this test was compared with performance on a pattern discrimination, for which the customary simultaneous two-choice procedure was used. It was found that the temporal removals were followed by definite impairment on the pattern discrimination (as expected), but no consistent change in efficiency at brightness discrimination could be attributed to the lesions. Alternative interpretations, making reference to the amount of pre-operative training on the brightness discrimination or the lack of differentiation between the correct and alternative responses in this test, are discussed.
Sequential Redundancy and Speed in a Serial Two-Choice Responding Task
Authors: Bertelson Paul
Published: March 2008

The task used is a self-paced 2-choice serial responding task, involving two neon lamps as signals and two response keys in simple spatial correspondence with the signals. In Experiment 1, three conditions with respectively 1/4, 1/2 and 3/4 alternations between successive signals were compared. It appeared that subjects go faster with 1/4 than with 3/4 alternations. From the point of view of information theory, both conditions present the same amount of information per signal. The asymmetry in the effects of both forms of sequential redundancy could be attributed either to some bias in the expectations of the subjects or to some inertia phenomenon favouring responses to repeated signals. It was reasoned that if the last explanation was true, the asymmetry would be reduced if a time-lag was introduced between end of response and appearance of next signal. This was done for one group of subjects in Experiment 2. These subjects worked on the same three conditions, with a time-lag of 0.5 sec. The asymmetry was significantly reduced when compared with another group of subjects who worked with the same 0.05 sec. time-lag as in Experiment 1. Analysis of separate RTs confirmed the main conclusion that choice processes involve a transitory residual effect favouring repetitions.
Shorter Articles and Notes: On the Recall of Stimuli Presented Alternately to two Sense-Organs
Authors: Broadbent D. E. , Gregory Margaret
Published: March 2008

Recently Moray established that digits presented alternately to the two ears could readily be recalled in the actual order of arrival, a result which appears to show that the switching time of attention between the ears is very rapid. In the present experiments it was found that, for this type of stimulation, recall was not significantly different whether the listener knew in advance or not if the digits were to be recalled ear-by-ear or in the actual order of arrival. It was also shown that Moray's result does not apply to digits presented alternately to eye and ear.

These results are interpreted as showing that attention can select the general class of auditory stimuli rather than the particular class of stimuli on one ear: so that the apparent conclusion about switching time is not in fact correct.
Partial Reinforcement in the Turtle
Authors: Eskin Rochelle M. , Bitterman M. E.
Published: March 2008

Two matched groups of young turtles, Pseudemys scripta elegans, were trained in a simple runway, one with partial and the other with consistent reinforcement, following which both were extinguished. The two groups did not differ significantly in resistance to extinction. This finding constitutes further evidence against the hypothesis that the paradoxical effect of partial reinforcement which is found in higher animals is a perfectly general one, to be understood in terms of the simplest principles of learning.
Observing Responses and Discrimination Learning
Authors: Zeigler H. Philip , Wyckoff L. B.
Published: March 2008

An operant response in the pigeon, whose performance results in exposure to the discriminative stimuli, is described and suggested as an experimental analogue for “observing.” Such an operant response is then used to explore the relationship between observing responses and discrimination learning in a variety of discrimination situations, of progressively increasing complexity. In general, the results support the contention that the development and maintainence of observing responses is closely related to the degree of differential behaviour manifested toward the discriminative stimuli. Certain modifications are suggested in the theoretical formulation underlying the concept of “observing responses.”
A Further Investigation of Apparent Size and Retinal Size as Determinants of the Figural After-Effect
Authors: Day R. H. , Logan J. A.
Published: March 2008

A figure which is more distant from the eye than another but subtends the same visual angle is usually seen as the larger. This phenomenon is called perceptual size constancy. Experiments have been reported which show that sometimes the apparent and sometimes the retinal sizes of the stimulus figures determine the direction of the figural after-effect. These experiments are reviewed and two further experiments are reported. In the first experiment two types of stimulus figure (discs and annuli) which subtended a visual angle of 1° 36′ resulted in figural after-effects, the direction of which would have been predicted by the retinal sizes of the figures. In the second experiment larger figures were used which subtended a visual angle of about 4° and which were the same as those used by Sutherland (1954). In this experiment the after-effects were generally in a direction which would have been expected if apparent size determined the direction of the after-effect. In the interpretation of the results attention is drawn to the “Central Tendency Effect” which has been observed in size judgements of stimulus figures of varying size. Two hypotheses are suggested; one is that the true figural aftereffect has been obscured by the “Central Tendency Effect” in successive judgements, and the other is that time error in successive judgements of size is essentially a figural aftereffect. Some supportive evidence for the latter hypothesis is reported. It is concluded that apparent size is not a critical determinant of the figural after-effect.
Is the Figural After-Effect Accompanied by Changes in Discrimination?
Authors: Wilson J.
Published: March 2008

In the figural after-effect one part of the visual field is apparently expanded relative to the rest, and it is suggested that the expansion might correspond to an improvement in discrimination. An experiment, in which subjects were required to judge the direction of curvature of lines after fixation of a straight line, showed no such improvement.
Figural After-Effects and Apparent Size
Authors: Sutherland N. S.
Published: March 2008

Sutherland (1954) obtained results which suggest that when the retinal size of test and inspection figures is equal, the direction of the FAE may be determined by the relative apparent sizes of the two figures. Other investigators have reproduced this result when exactly the same conditions were used: when the conditions were changed the result was not obtained. In the present paper these results are discussed and an attempt is made to determine why the effect is not obtained with small variations in the experimental conditions. It is further shown that some FAE phenomena cannot be explained by the two main existing theories; these phenomena could be explained if some analysis of the stimulus is being performed before the stage of the nervous system at which the process underlying FAEs occurs. Some recent physiological evidence (Hubel and Wiesel, 1959) supports this hypothesis. If this hypothesis is correct, it is likely that further work on FAEs determined by apparent size may help to throw light on the physiological mechanisms underlying size constancy, and some further experiments are suggested.
Periodicity of Response in Operant Extinction following Continuous and Fixed Ratio Reinforcement
Authors: Hurwitz H. M. B.
Published: March 2008

The rate of response during an extinction session of two groups of rats, trained under a continuous and a fixed ratio reinforcement schedule respectively, was examined. It was found that both sets of data required a two factor analysis, factor rA describing the rate of response during response burst periods and factor tQ the rate of quiescent, non-response periods. Both reinforcement and extinction sessions were analysed with respect to response pattern distributions. It was found that on this variable the two groups differed significantly from each other.
An Investigation of Reversal Learning in Octopus Vulgaris Lamarck
Authors: Mackintosh J.
Published: March 2008

Eighteen octopuses were trained by a method of successive discrimination training to discriminate between a vertical and a horizontal rectangle. They were then overtrained for either 20 or 60 trials, after which they learnt the reverse discrimination. At the beginning of each reversal they were given 20 trials pretraining on the new positive stimulus. The subjects completed from two to nine reversals.

It was found that the amount of overtraining had no effect on the rate of learning the subsequent reversal. The first four reversals all took significantly longer to learn than the original problem, but did not differ significantly from one another. However, examination of the raw data suggests that later reversals do take longer to learn. The performance when learnt (i.e. on the first day of overtraining) was as good after reversal learning as after the learning of the original problem.

The results do not show definite signs that could be interpreted as an exhaustion of a limited supply of neurones available for learning.
A Test of Two Theories of Shape Discrimination
Authors: Dodwell P. C.
Published: March 2008

An experiment is reported which confirms a prediction from the writer's theory of shape recognition. The same experiment is held to refute an alternative theory, but this refutation is not conclusive, since the alternative theory has not been clearly stated and can be interpreted in several conflicting ways. It is shown that these possible interpretations of the alternative theory all yield predictions which are not confirmed by the present findings.
A Further Study of Partial Reinforcement in the Turtle
Authors: Gonzalez R. C. , Bitterman M. E.
Published: March 2008

Two matched groups of mature painted turtles, Chrysemys picta picta, were trained in a simple runway, one with partial and the other with consistent reinforcement, following which both groups were extinguished. The partially reinforced animals ran more slowly in acquisition, but showed somewhat greater resistance to extinction. The results are compared with those obtained in analogous experiments with other animals.
The EEC, Eye-Movements and Dreams of the Blind
Authors: Berger R. J. , Olley P. , Oswald I.
Published: March 2008

It was found that characteristic frontal EEG waves significantly often precede the rapid eye movements of dreaming. The rapid eye movements were absent during dream periods of three men with life-long blindness, and of two men, 30 and 40 years blind respectively, but were present during dream periods in three men blind only 3, 10 and 15 years respectively.
Reversal of Learning in Octopus and the Effect of Removal of the Vertical Lobe
Authors: Young J. Z.
Published: March 2008

Experiments are described on reversal of learned responses in the octopus. It is shown that normal animals are able to reverse learned responses to vertical and horizontal rectangles shown successively but that animals lacking vertical lobes are unable to reverse such a discrimination. These, and related, results are discussed in relation to the hypothesis that learning consists in appropriate conditioning of cells in the optic lobes that respond to particular visual features but that the vertical lobe plays an important part in making the memory effective, perhaps by generalising the conditioning to optic lobe cells other than those directly stimulated in the process of learning.
Communication Theory and the Constellation Hypothesis of Calculation
Authors: Thomas H. B. G.
Published: March 2008

It is assumed that in translation tasks the brain behaves as an information-processing system for which the time-requirement (t) of a translation is strictly proportional to the information which must be handled in performing it. Writing Q[calc] for the information-requirement of a given calculation, the problem is to define a procedure Q which may be applied to calculations involving various arithmetical operations on numbers of varying magnitudes, such that Q[calc] = k.t. The constant k would then give the information-handling rate.

Experiments with six subjects on seven types of simple addition-sum lead to a definition of Q which satisfies this condition for 25 out of 42 observations. Of the other 17 observations, 14 are accounted for by a modified definition of Q and at least one more on the assumption that “redundant information” may be handled in some cases. The main hypothesis, with these two subsidiary assumptions, accounts well for all observations in a further experiment with four subjects on six types of addition, subtraction and multiplication.

The definition of Q is next generalized by analogy to deal with more complex multiplications. A prediction concerning multiplications of the type [x. log x] is borne out by 11 out of 12 subjects and the subsidiary assumptions are not required. Information-rates found by this rapid method range from 2.07–5.78 binary units of Q[calc] per second (BU/sec.) and there is reason to believe that 1 BU is equivalent to 1 bit.
Direct Transfer from a Horizontal-vertical Discrimination to a Brightness Discrimination in the Rat
Authors: Mackintosh N. J.
Published: March 2008

Eight rats were trained on a discrimination between horizontal and vertical striations, and subsequently between black and white vertical striations. Subjects originally trained with horizontal positive preferred black to white and subjects trained with vertical positive preferred white to black.

The present note reports briefly on a transfer effect in rats, observed incidentally in an experiment designed for a different purpose. The rats were trained in a jumping stand to discriminate between horizontal and vertical striations, and when training was complete, were tested on a brightness discrimination.
Verbal versus Manual Reaction Time in Schizophrenic and Normal Subjects
Authors: Rosenthal David , Zahn Theodore P. , Shakow David
Published: March 2008

On the assumption that schizophrenia involves a disturbance in interpersonal relations it is predicted that the verbal reaction time responses of schizophrenic subjects should have disproportionately longer latencies than manual reaction time responses as compared to normal subjects. Using data presented in this Journal by Venables and O'Connor (1959). the prediction is confirmed for patients whose reaction time level is relatively fast, but not in those with relatively slow reaction times. Several possible mechanisms are postulated to account for the results, including differential reinforcement, amount of practice, and complexity of verbal responses, and degree of pathology of the patients.
The Tactile Perception of Size: Some Relationships with Distance and Direction
Authors: Liddle D. , Foss B. M.
Published: March 2008

The results of a series of experiments carried out by Bartley (1953) demonstrated a tendency for the size of a tactually perceived object to be underestimated with increased distance of the object from the eyes. He took this to indicate that visual imagery played a part in the spatial organization of tactile data. In the present investigation this effect of distance was further examined under various conditions with sighted and blind subjects. The tendency was found to exist, but there is clear evidence that it is not due to the participation of visual imagery. No hypothesis was found to explain the tendency adequately. An interesting difference emerges between the situation where the subject extends his arm when making the comparison and that in which the arm is retracted when making the comparison.
The Origin of the Autokinetic Effect
Authors: Gregory R. L. , Zangwill O. L.
Published: March 2008

The effects of unbalanced fatigue of the ocular and neck musculature on the auto- kinetic effect are described. It is shown that after deviation of the eyes to an extreme position, fixation of a small light source with the eye in the central position gives rise to an immediate and pronounced autokinetic effect. This apparent movement is typically in the same meridian as that of the ocular deviation and is often, at all events at first, in the opposite direction. Similar, though less clear-cut, results are obtained after induction of unbalanced fatigue in the neck musculature. It is argued that the autokinetic effect observed under these conditions warrants treatment as a primary illusion of movement and does not involve a “framework” or standard of reference. In an appendix, a speculative model of the ocular control system and some preliminary observations are presented. It is concluded that the autokinetic effect is principally due to spontaneous minor fluctuations in the neural system which monitors the outward signals controlling eye movement.
The Effect of Repeated Presentation of Items on Paired Associate Learning
Authors: Warr Peter B.
Published: March 2008

An experimental design is outlined which allows the probability of an item being learned to be related to the number of presentations of that item. The results of an experiment of this design are considered in relation to the hypothesis that learning is a single trial occurrence. The results are found to support neither the single trial hypothesis nor the incremental hypothesis. A “dual factor” hypothesis is put forward and considered in relation to these and other experimental findings. The scoring procedures employed allow consideration of the response learning and the associative phases of paired associate learning. It is suggested that the response learning phase may be explained by the single trial hypothesis and the associative phase by the dual factor hypothesis.
Visual Discrimination in the Toad
Authors: Parriss J. R.
Published: March 2008

Using a method of successive discrimination, 10 toads (Bufo bufo), were trained to discriminate between horizontal and vertical rectangles each 5.0 ± 7.5 cm. After training, one optic nerve was severed in certain animals and the stumps pushed well apart to delay regeneration. The non-operated animals retained their learning over the rest-period of 10 weeks at a level similar to training. The animals with one eye showed considerably less retention than the non-operated animals.
Serial Rote-learning: Incremental or All-or-none?
Authors: Jensen Arthur R.
Published: March 2008

If the associative connections in a serial list are acquired in an all-or-none fashion, rather than gradually with every trial adding an increment of associative strength, then changing the serial order of the middle items in the list during the course of practice should have no effect on the rate of learning the list as a whole or even of the particular items that have been interchanged. Thirty subjects learned a serial list by the anticipation method. The middle items of the list were reversed in serial order approximately half-way through the number of trials required for mastery. The subjects took no longer to learn the list and made no more errors than did 30 control subjects for whom there was no change in serial order. The serial-position curves of the two groups were almost identical. It was also shown that the learning “curves” of single items in the series, when plotted for individual subjects do not reveal a gradually increasing probability of the correct response, but show instead a sudden jump on one trial from the chance guessing level to a level close to 100 per cent, correct responses. The results are consistent with a non-incremental theory of serial learning.
Slippage of Contact Lenses and other Artefacts in Relation to Fading and Regeneration of Supposedly Stable Retinal Images
Authors: Barlow H. B.
Published: March 2008

After-image experiments reveal that scleral-fitting contact lenses slip through several minutes of arc. Experiments in which they have been used to procure “stabilized” retinal images must therefore be reinterpreted. Light-weight, suck-on, limbal-seating cups are much better, but complete stabilization cannot be relied upon. Other possible artefacts in stabilized image work are described and are thought to be responsible for certain features of previous accounts of the appearance of stabilized images. Discounting features caused by artefacts, the image appears to blur, losing detail, and fade, losing contrast, within the first few seconds. Contrast and detail are not regained, but the milky, textureless image that remains fluctuates in appearance for a minute or so. Finally the fluctuations die out and a very blurred, cloudy version of the original scene persists.
Habit Reversal in the Turtle
Authors: Kirk Kathleen L. , Bitterman M. E.
Published: March 2008

Two groups of mature “painted” turtles were trained in a T-maze. One group had five trials per day, with correct and incorrect turns reversed for each animal whenever it reached the criterion of five errorless trials on a given day. The second group had 10 trials per day, with correct and incorrect turns reversed daily, irrespective of the performance of the animals. Only in the data for the second group did there appear some indication of progressive improvement in habit reversal. The results are considered in relation to those obtained in analogous experiments with other species.
A Zeigarnik-like Effect in the Recall of Anagram Solutions
Authors: Baddeley A. D.
Published: March 2008

Subjects were asked to solve a series of 12 anagram problems. For each of these they were allowed 1 min. and if they did not solve it in this time they were told the solution. When asked to recall the solution words at the end of the series, subjects remembered items they had failed to complete almost twice as often as those they had solved.

It is suggested that this phenomenon is analogous to the Zeigarnik effect, but that it has the advantage of occurring in conditions which are easy to specify and control.
The Development of Finger Differentiation
Authors: Kinsbourne M. , Warrington Elizabeth K.
Published: March 2008

The ability to perform discriminations based on the classification of sensory input from the fingers in terms of the individual fingers stimulated in their correct spatial arrangement, was tested in a group of normal children aged 4 1/2 to 7 1/2 years. The results showed that the acquisition of this ability depended upon chronological age in a regular fashion, suggestive of maturation of a unitary function (“finger sense”) in a population subject to normal variation. The significance of this finding in the wider context of the acquisition of abilities during normal development is discussed.

The ability to move single fingers, leaving the others at rest, is acquired at the age of about 6 years (Rey, 1952). This skill must have its sensory counterpart. The ability to classify sensation from the fingers in terms of the particular finger from which it was derived (“differential finger sensation”) ought to be detectable by appropriate testing. The four fingers, morphologically somewhat similar, are distinguishable chiefly on the basis of their positions relative to one another. In this respect they differ from other parts of the body, with the exception of the toes. The questions arise, at what stage in maturation does it become possible to perform discriminations based on the differentiation of sensations from the fingers, and does it at the same time become possible to succeed in tasks requiring an appreciation of their spatial arrangement?

To answer these questions, and to make it possible to detect the postulated abilities in a reliable manner, three new test procedures were designed. They are described below, and the results obtained presented.
The Effect of Instructions on the Judgement of Brightness
Authors: Landauer A. A.
Published: March 2008

A brightness constancy experiment using ten subjects showed that different instructions significantly affect the subject's PSE judgement. Variations in the reflectance of the standard target and in the background and illumination of the variable target did not influence the effect of different instructions. The use of the D-ratio as constancy index in this study confirms an earlier theoretical finding that other brightness constancy ratios introduce an artefact into experimental results.
On the Resolution of Small Time Intervals and the Effect of Conduction Delays on the Judgement of Simultaneity
Authors: Halliday A. M. , Mingay Rosemary
Published: March 2008

In the course of experiments on the cerebral evoked potential, recorded by a summation technique through the scalp, it was possible to measure directly the latency of the potential due to afferent conduction time. In two subjects the response following electrical stimulation of the toes was found to occur approximately 20 millisec. later than that following stimulation of the fingers. Using similar stimuli to finger and toe, parallel experiments have been carried out to determine whether there is any corresponding error in the judgement of when two stimuli are simultaneous.

The same subjects were presented with pairs of stimuli at a series of intervals up to 100 millisec. and made judgements as to whether they occurred at the same time, or if not, which was first. A control situation, in which the stimuli were given to the two index fingers, was compared with the experimental situation, in which stimuli were presented to finger and toe on opposite sides. The results showed a significant difference in the mean interval at which the two stimuli were judged simultaneous when the conduction pathways were of unequal length, and this difference was in the direction expected should the judgement of simultaneity depend on the simultaneous arrival of the afferent volleys centrally.

However, in only one subject was this difference of the order of 20 millisec, as might be expected were the relevant event the onset of the cortical evoked potential. Further, in the other subject the point of apparent simultaneity in the control situation, in which stimuli were given to the right and left index fingers, does not correspond with the point of true simultaneity, as would be expected with conduction pathways of equal length.

It is concluded, therefore, that while the temporal relationship of two stimuli is judged on the time of their central arrival rather than on the time of their occurrence at the periphery, judgements may be affected by factors other than conduction delays.
Effects of Stimulus Probability on Reaction Time in a Number-Naming Task
Authors: Stone George C. , Callaway Enoch
Published: March 2008

Subjects were required to respond to the visual presentation of numerals by uttering syllables closely resembling the names of the numerals. Information in stimulus ensembles was varied by manipulating the number of alternative stimulus configurations that could appear, the relative frequencies of stimuli within an ensemble and the probability of a response being required. An increasing linear function was a good first approximation to the relation between reaction time and information transmission. Systematic deviations from this function were found and an attempt is made to explain them by introducing an intervening variable, “effective probability.”
The Influence of Signal Probability and the Number of Non-signal Categories on Selective Response Times
Authors: Brebner John , Gordon Ian
Published: March 2008

Signal probability and the number of non-signal categories were varied independently in a selective response task. Response latencies were significantly affected by changes in signal probability but not by changes in the number of non-signal categories.
Directional Information and Apparent Movement—the Apparent Movement to Apparent Simultaneity Threshold
Authors: Jeeves M. A.
Published: March 2008

This paper reports a study of changes in apparent movement to apparent simultaneity thresholds as a function of the directional information of the second point of light. An earlier paper (Jeeves and Bruner, 1956) reported changes in thresholds from apparent movement to apparent successiveness when the same experimental variable was manipulated. In interpreting the results the authors proposed an hypothesis in terms of “attentional disarticulation.” Brown (1956) commenting on this earlier paper put forward an alternative explanation of the results in conventional informational terms and he predicted the changes in the apparent movement to apparent simultaneity thresholds which should occur if studied under the same experimental conditions. He further showed that his predictions would differ from predictions made on the basis of our own explanation. The results of the experiment reported here uphold the predictions of our own earlier theory and fail to fit those made by Brown. However, in attempting to understand the results from the two experiments considered together, it is suggested that a factor must be included which was omitted from our own earlier explanation but emphasized by Brown. This factor as stated by Brown (1956) is “that the threshold for a discrimination tends to increase with the information content of any discrimination which has to be made concurrently.”
The Running Memory Span for Words
Authors: Postman Leo , Turnage Thomas W. , Silverstein Albert
Published: March 2008

This experiment investigates the running memory span for English words of high and of low frequency of usage. The running memory span is measured when a sequence of uncertain length is interrupted and the subject is required to recall the most recent part of the message. The span for the two classes of words was studied as a function of the length of the message and amount of prior practice. In the early stages of practice the span varied inversely with frequency of usage and increased with the length of the message. As practice continued, the difference between words of high and low frequency was largely eliminated and there was a relative decline in the span for the longest series. The major variables which are assumed to determine the length in the span are (a) the number and strength of pre-experimental associations of the items; (b) intraserial and interserial interferences developed during exposure to the series, and (c) the subjects' strategies of deliberate rehearsal.
Error-correcting Perceptual Mechanisms
Authors: Andrews D. P.
Published: March 2008

The metric of the visual field is generally accurate but subject to changes dependent on stimulation. It is suggested that these changes indicate how the metric develops initially, and that the features of the visual signal which control the metric are the distributions of contours and of contour-curvatures over the field. These distributions are genetically prescribed for the organism; they correspond well with the distribution of these features in patterns derived optically from the environment; hence visual shapes and physical shapes are maintained in correspondence.

Further short discussions concern physiological hypotheses and the extension of the above to senses other than vision.
Redundancy in Non-sequential Patterns
Authors: Staniland Alan
Published: March 2008

Recognition, discrimination and delayed discrimination tasks were carried out with selections of composite visual patterns, ordered in terms of a generalized measure of redundancy based upon transmission between determinates under four determinables. Results in the recognition experiment showed a significant relationship with redundancy and there was indication of a similar effect in delayed discrimination. Redundancy levels, however, appeared irrelevant to simultaneous discrimination, where each response could be made discretely without reference to the structure of the selection as a whole.
Grouping of Stimuli in Pattern Recognition as a Function of Age
Authors: Rabbitt P. M. A.
Published: March 2008

Two groups of subjects aged 20–40 and 40–60 years learnt identifying responses to a set of eight patterns. The groups did not differ in rate of learning, but an analysis of confusions between patterns revealed systematic differences in the extent to which rules underlying the construction of patterns were used in recognizing them as members of sub-sets before identifying responses were mastered.
Temporal Structure of Letter Groups and Span of Perception
Authors: Michon J. A.
Published: March 2008

The span of perception for letter groups depends on number of letters presented, length of presentation and structure of the groups. The experiment reported varied the temporal structure of the groups, leaving the total number of letters constant. Groups of 12 letters were presented as a whole or in two or more successive “units.” The total time of presentation was 1–5 sec. In the first experiment each unit was visible until the next appeared, in the second experiment units were visible only during 1/4 sec., although intervals between successive units were kept constant.

The following conclusions emerged:

(a) The visual presence of units did not affect the reproduction for durations over 0.25 sec., except in the 12-letter presentations.

(b) 2×6 letters gave better results than either simultaneous presentation or other divisions; temporal separation was 0.75 sec.

(c) Higher order approximations to Dutch have more influence on 3 × 4, 2 × 6 and 1 × 12 letters than on 4 × 3 and 6 × 2 letters.

(d) A serial order effect exists: central units are reproduced less well than first and last units.

It is suggested that handling a fixed amount of information within a fixed period is limited on the one hand by confusion between simultaneous elements and on the other hand by the interaction between successive units presented too rapidly to allow for proper operation of immediate memory.

The difference between span of perception and span of memory is stressed.
A Further Experiment on the Discrimination of Open and Closed Shapes by Rats
Authors: Sutherland N. S.
Published: March 2008

In a previous experiment on the visual discrimination of open and closed shapes by rats (Sutherland, Carr, and Mackintosh, 1962) it was found that (1) at the beginning of training the animals exhibited a strong preference for the more open shape; (2) shapes differing in their horizontal projections only were more discriminable than shapes differing in their vertical projections only. The present experiment is a replication of the earlier one using different shapes and different apparatus. The first result was fully confirmed and some confirmation was obtained for the second, although late in training the differences between groups trained with shapes differing on opposite projections were not statistically significant.
Visual Discrimination of Shape by Humans
Authors: Butler J.
Published: March 2008

Reaction times to tachistoscopic exposure and a card-sorting task are the two methods by which visual discrimination of shape is studied. The results of experiments using both methods tally, i.e. the order of difficulty of the following shapes was: (1) (easiest) circle vs. triangle; (2) circle vs. square; (3) square vs. triangle; (4) (most difficult) triangle vs. diamond. These results are compared with those obtained by Sutherland, using octopus, and it is concluded that it should be possible to establish to what extent the system of visual analysis in humans differs from that postulated for both octopus and rat.
Noiseless Electronic Switch and Timer
Authors: Keay C. S. L. , Rodda M.
Published: March 2008

In psychoacoustic testing and experimentation the avoidance of extraneous stimuli is most important, but the elimination of such cues is often difficult. A circuit is described which enables sound stimuli to be switched on and off in a manner which produces no unwanted transient signals. The circuit may be adapted to function as a noiseless changeover switch.
Repetition and the Recognition of Paired Associate Items
Authors: Warr Peter B.
Published: March 2008

It is suggested that incremental learning of paired associate items will be observable if learning is measured by recognition rather than by recall. An experiment is reported which fails to support this hypothesis. Some factors which may be influencing the performance of subjects are briefly discussed.
Selective Strategies in the Assimilation of Successively Presented Signals
Authors: Sanders A. F.
Published: March 2008

It is found that performance in experiments on the psychological refractory period is highly affected by instructions. In the present experiment subjects were instructed either to handle the signals successively or to group them. Both instructions were obeyed. This seems to indicate that the human organism has various strategies available. Which strategy is actually applied is likely to depend on the structure of the experimental situation, and partly also, on momentary preference. This may explain the variety of results in the literature on this subject.

Finally, it is found that, when two signals are presented simultaneously, the total reaction time is considerably shorter if the signals are “grouped” than if they are “handled successively.” This difference disappears at interstimulus intervals of 0.2 sec. and 0.4 sec. The hypothesis is put forward, that the gain in time at the former case is due to simultaneous perceptual processing of the signals.
A Hullian Reasoning Situation
Authors: Anthony W. S.
Published: March 2008

An experiment on a well-known but little-investigated situation proposed by Hull, is reported. The results are inconclusive.
Adaptation and Repulsion in the Figural After-effect
Authors: Wilson J.
Published: March 2008

An experiment is reported which shows the effect of inspection of a curved line on the apparent curvature of a curved test line for a range of curvatures of both I and T lines. A second experiment extends the range of I curvatures, using only one T line, a straight line. The experiments showed both adaptation and repulsion components in the FAE.

An experiment by Kohler and Wallach which could not be reconciled with these results was repeated in the relevant part; the results were in agreement with the first experiment here and did not agree with those obtained by Kohler and Wallach.

An argument is presented that both adaptation and repulsion effects could be produced by a cell adaptation mechanism.
Short-term Memory for Repeated and Non-repeated Items
Authors: Wickelgren Wayne A.
Published: March 2008

Digit sequences containing repeated items are retained differently in short-term memory from sequences containing no repeated items. The repeated items are remembered better or worse than items in the corresponding positions of “all-different” sequences depending on the number of times the item is repeated, the number of items repeated, the number of items intervening between the occurences of a repeated item, and the position of the repeated items in relation to the beginning and end of the sequence. In every type of repetition studied, except one, memory for the non-repeated items in sequences with repeated items is better than for the corresponding items of all-different sequences. This is true in some cases despite significant specific interference between the (non-repeated) items following the separated occurrences of repeated items. The negative effects in memory for repeated items and the positive effects in memory for non-repeated items are greater when the items are presented at the rate of five per sec. than at one per sec., contrary to the hypothesis that differential rehearsal is responsible for these effects. The results are interpreted as supporting an “associative,” as opposed to a “non-associative,” theory of short-term memory, as this distinction is defined in the paper.
Vocalization-at-presentation and Immediate Recall, with Varying Presentation-Rates
Authors: Murray D. J.
Published: March 2008

An experiment is reported in which the subject read visually presented lists with four different degrees of vocalization; immediately after reading each list he was required to reproduce it either aloud or in writing. Each list consisted of eight consonants and presentation rates were varied between I and 4 letters per sec. For any given series of lists, the subject was asked either to read the letters silently, or to mouth them silently, or to whisper them, or to say them aloud while reading.

At the fastest presentation-rate immediate recall improved monotonically with the degree of vocalization during reading of the lists; at slower rates this generalization held less well, especially for the lower degrees of vocalization. Vocalization was most helpful at the highest presentation-rate.

The overall amount correctly recalled was better for more slowly presented lists and for written as opposed to spoken recall. Analysis of the errors suggested that acoustic confusions were affected by the conditions of presentation; and that serial order intrusions were independent of presentation-or recall-conditions. An apparent variation of transpositions with voicing-and-recall-method failed to reach statistical significance. Theoretical implications of the experiment are discussed, including reference to Broadbent's theory of short-term memory (1958).
An Investigation of Vigilance in the Rhesus Monkey
Authors: Wilson Jerusa C.
Published: March 2008

The experiments reported here investigated the effects of immediate reinforcement contingent upon detection of a signal in a vigilance task.

Three Rhesus monkeys were trained to report the presence of a 2-sec. signal over a 4-hr. watch. They received a food pellet for each randomly occurring signal detected.

The results indicated that (1) variation in signal rates did not produce differences in detection, (2) no difference in detection occurred over hours of watch, (3) detection and deprivation level were linearly related (Y = 4.1408X + 3.9900), (4) low motivation (8-hr. deprivation) performance was lower (f < 0.01) than high motivation (24-hr. deprivation) for comparable signal frequencies, and (5) the temporal course of a 1.78 mg./kg. dosage of chloropromazine and detection efficiency was found to be logarithmic (Y = 78.33 log X—19.08).
Binocular Rivalry and the Contrast at Contours
Authors: Whittle Paul
Published: March 2008

Binocular rivalry was recorded between various achromatic figures in or near the foveae. For a pair of intersecting contours, one in the field of each eye, it was found that the percentage of time for which a contour was dominant at the point of intersection increased with the contrast at that contour, and also with average luminance when contrast was constant. Further, for 1° circles in corresponding positions in the two fields, one darker than its surround and one lighter, the same results were obtained. Various auxiliary results, on rate of rivalry, eye-dominance, the occasional mixture of the rivalling stimuli, and binocular lustre, are given. Finally the relationship between predominance in rivalry and perceived brightness is discussed.
Length of Experimental Session as a Parameter of Response Rate under a Non-discriminated
Authors: Schedule Avoidance , Hurwitz H. M. B.
Published: March 2008

Following the stabilization of response rate under an avoidance schedule which was defined by two temporal parameters, the shock-shock interval and the interval by which each response postponed the onset of shock, the length of the experimental session was changed. It was found that after the subjects had been exposed to a longer session of avoidance schedule, their rates of response were considerably increased without a corresponding reduction in the number of shocks received.

In recent years considerable use has been made of an avoidance training technique in which the performance of the response functions to postpone the onset of an aversive stimulus, usually shock, by a fixed period. In the absence of the required response the aversive stimulus is programmed to occur at regular intervals. Experiments by Sidman (1953) have shown that the critical independent variable controlling the rate of avoidance response, is the shock postponement interval (R*S). All other things being equal, the rat in the lever pressing situation will respond at a rate which is inversely related to the R*S interval, low intervals generating high response rates and high intervals generating low response rates. However, under very low values of R*S, the response rate may break down altogether. The animal then receives shock at the rate determined by the shock-shock interval parameter.

As a result of an apparatus failure, Sidman, Herrnstein and Conrad (1957) discovered that the response rate can also be increased by occasionally shocking the animal in spite of its avoidance responses. An apparatus failure has also been responsible for the isolation of yet another parameter of response rate in the shock-postponement avoidance situation and is reported here. Briefly, it was found that a change in the duration of an experimental session influences the response rate on subsequent sessions.