Experimental disorientation in the horizontal plane

Twenty-eight subjects were examined on a visual matching task for their ability to maintain an orientation with respect to a particular direction in the horizontal plane following a voluntary rotary body movement through 180 degrees. Each subject was examined with respect to eight different directions.

Numerous gross errors occurred when visual information was reduced to the display of an arrow indicating a direction and a second arrow manipulated by the subject. The magnitude and distribution of the errors suggest that, under the conditions of this experiment, visual information as to direction in the horizontal plane is analysed according to the two horizontal dimensions defined by the sagittal and coronal planes of the head. In correcting for the rotary body movement, failure may occur with respect to either or both of these two dimensions. The frequency of a failure to make any correction at all (i.e. 180-degree errors) is consistent with independent failure in each of the two horizontal dimensions.

Failure is markedly more frequent in the fore-aft dimension than in the left-right dimension. It is suggested that this may be explained in terms of the ambiguous spatial significance of vertical disposition on the retina and the possibility of contamination between the two systems of conceptual analysis which identify the vertical and the fore-aft dimensions of visual space.

It is demonstrated that when minimal “landmarks” are provided they tend to be utilized as reference points in attempts to maintain orientation, even when the subject is aware that the “landmarks” are misleading. Such a use of “landmarks” does not suppress the previously mentioned mechanism of dimensional orientation.

The relevance of these results to normal human orientation is discussed.     

Training of fast tapping with reduction of kinaesthetic, tactile, visual and auditory sensations

Five subjects were trained to tap on a light Morse-key during nerve compression block. The training sessions lasted for 40 sec., with a 5 sec. rest after the first 20 sec. work period. The group learning curve reached 89.5 per cent. level of normal performance by the eighth training session. In the ninth, the testing session, subjects tapped with visual and auditory sense reduction superimposed on the kinaesthetic and tactile impariment of the training condition. Performance in the testing session reached 40.9 per cent. of normal.

The sixth subject was trained in the same task as the other five subjects, but the training condition included elimination of cues from all four sensory channels. He reached 79.09 per cent. of his normal tapping performance in the seventh session.

These results show that the motor skill of tapping can be relearned in the absence of kinaesthetic cues. Furthermore when the subject has no conscious knowledge of any peripheral sensory cues connected with the ongoing motor activity, learning can nevertheless take place. These findings lead to the hypothesis, that skilled motor activity can be monitored by central processes alone.

During the training sessions subjects showed a tendency of tapping in groups of gradually increasing length. It is hypothesized that increased number of taps forming a group gives an indication to the possible mode of action of these central processes.     

Selective noise disturbance of the information input in short-term memory

The present experiment was designed in order to investigate the effects of noise produced intermittently during the input stage of serially displayed visual materials (6-digit lists). These materials were to be memorized and subsequently reproduced on a specially designed keyboard. The four experimental conditions were the following: (1) quiet (Q);

(2) noise uninterrupted during the presentation of each list (CN);

(3) noise emitted simultaneously with each list element (500 ms) (ND);

(4) noise emitted in the interval (140 ms) between each element (NA).

Record was taken of the errors and omissions, of key response initiating times and of hand movement times. As an additional variable, subjects were required to estimate the annoyance induced by each of the four conditions. All noise conditions yielded more errors and omissions than the Q-condition, with the highest rates occurring in the two conditions where noise was superimposed on the digits. Close analysis of the errors showed that the primacy end of the lists was the most affected by noise, whereas keying speed for correct reproductions remained relatively unaffected.

On the other hand, when the speed variable was split into a decision and a motor component, it turned out that the more a condition was judged as annoying, the more the time for response decision was delayed, while the reverse occurred for keying movement times. The latter effect could possibly be ascribed to arousal induced by the three noise conditions. It is argued that noise is liable to affect differently the various components of a task performance, either directly by interference with the intake of pertinent information, or indirectly through induced annoyance or through noise modulated arousal.

They particularly would like to thank Dr M. Coltheart for his great help in the preparation of the definitive version of the paper.     

Memory for sentences: The subject superiority effect

Three experiments are reported on subject noun superiority in cued recall from S-V-O sentences. In Experiment I surface subjects were superior cues across a wide variety of conditions when the order of nouns/pronouns was matched in sentences and probes. The effect was less clear-cut in Experiment II, when cues and responses were confined to single key words.

The final experiment showed that cue superiority depends on the cue which subjects learn to use in retrieving information from sentences, and can be reversed by brief training. Several other aspects of the results, including a contrast in recall and recognition patterns, suggest that subject cue superiority results from the way subjects process remembered sentences rather than from memory trace structure. It is suggested that failure to control the utilisation of cues for memory retrieval may account for the sometimes elusive nature of the subject superiority effect.     

A comparison of disconfirmatory, confirmatory and control strategies on Wason's 2-4-6 task

Attempts to instruct subjects to falsify on inference tasks designed to model scientific problem-solving have indicated that, in most cases, falsification does not lead to improved performance. The only study in which instructions to falsify did improve performance was done with groups, using a novel inference task. The present study is an attempt to replicate the success of falsification in the group study with subjects run individually on an inference task that has been used extensively in the literature: Wason's 2-4-6 problem. Each subject was run in one of three strategy conditions: confirmatory, disconfirmatory or control (no-strategy).

Results indicated that subjects in the disconfirmatory condition solved the 2-4-6 problem significantly more often than subjects in other conditions. The superior performance of disconfirmatory subjects was explained by the fact that they deliberately sought and obtained significantly more falsificatory information than subjects in other conditions.

The critical difference between this study and previous attempts to instruct individual subjects to falsify on the 2-4-6 task is that subjects in the present study were given no feedback as to whether their guesses were right or wrong until the experiment was over. The implications of this result for scientific problem-solving are discussed.     

The effects of position in a display upon problem solving

Sixty-four subjects, aged between 15 and 72 years were told how to carry out a problem-solving task, whose difficulty could be varied by changing the position of an index card in relation to a display and control.

The outstanding feature, particularly of the older group's performance was the repetition of the same two kinds of mistake. Their failure seemed mainly due to an inability to rid themselves of their wrong “solutions,” in spite of the constant information indicating the mistake at each position. Whilst these differences between the age groups were hot pronounced at the easiest task, they were at the most difficult.

It is suggested that: Firstly, the procedure of giving a subject the solution to a problem and observing how he reconciles his information with it, though only operating in a circumscribed area of problem-solving, is a genuine example of thinking, and, particularly where certain kinds of mistake can be predicted, it enables the experimenter to gain a more exact impression of what a subject is doing. Secondly, the manipulation of spatial contiguities lends itself to flexible and fairly precise measurement, and the principle might usefully be extended to other variables such as size, time intervals, colour, etc.     

The amount seen in brief exposures

The experiments reported are a series of attempts to test the consequences of assuming that a subject exposed to briefly presented tachistoscopic information does not have access to a visual image. The partial report procedure is examined under several conditions with the letter row cues immediately following stimulus exposure, and at different levels of cue delay.

The results of eye movement monitoring, and of instructing subjects where to look, agree with the guessing data of a previous experiment in showing a sharp decline in the number of letters correctly reported when the subject is looking at the wrong row, in conformity with the anticipative selection hypothesis. The result of varying the subject's uncertainty about what is to be reported is to vary the slope of the delay curve; with the implication that inefficient strategies of rehearsal, rather than visual image decay, are responsible for the reported delay effects.     

On the rate of gain of information

The analytical methods of information theory are applied to the data obtained in certain choice-reaction-time experiments. Two types of experiment were performed: (a) a conventional choice-reaction experiment, with various numbers of alternatives up to ten, and with a negligible proportion of errors, and (b) a ten-choice experiment in which the subjects deliberately reduced their reaction time by allowing themselves various proportions of errors.

The principal finding is that the rate of gain of information is, on the average, constant with respect to time, within the duration of one perceptual-motor act, and has a value of the order of five “bits” per second.

The distribution of reaction times among the ten stimuli in the second experiment is shown to be related to the objective uncertainty as to which response will be given to each stimulus. The distribution of reaction times among the responses is also related to the same uncertainty. This is further evidence that information is intimately concerned with reaction time.

Some possible conceptual models of the process are considered, but tests against the data are inconclusive.     

Channel-capacity, intelligibility and immediate memory

When subjects try to remember lists of digits played to them through pulse-modulated white noise the number of errors they make is greater than would be expected if digitrecognition errors and immediate memory errors were independent (Exp. 1).

A second experiment compared recall of digits in early list positions, when digits in subsequent list positions were presented through noise, and in clear. Digits in early positions were less well remembered when digits in later list positions had to be discriminated through noise.

In a third experiment prose passages were played to subjects who subsequently answered questions about their factual content. Judged by this technique recall of the first half of a prose passage is less accurate if the second half must be heard through noise than if the entire passage is heard through a good fidelity system. These results together are interpreted as demonstrations that increased difficulty of recognition of speech through noise may interfere with other activities, (conveniently termed “rehearsal”) which may be necessary to efficiently retain data in memory.     

The effect of lack of sleep on visual watch-keeping

Sixteen subjects performed a test of visual watch-keeping twice, at the same hour of the same day of successive weeks. The test lasted 40 min. On one of these occasions the test was done after normal sleep the previous night; signals were detected at a steady rate throughout. On the other occasion the subjects had no sleep the previous night; they passed the time in innocuous leisure activities. Here a similar level of performance was maintained for the first 20 min. of the test. After this the rate of signal detection declined steadily. In the final quarter of the test the rate was roughly one third that of the first quarter.

Signals missed were divided into three categories, (u) signals missed while watching the display, (b) signals missed while not watching, and, (c) signals missed while asleep. Lack of sleep produced increases in all three of these categories.

These results support previous suggestions that a test has to be prolonged before performance is affected by moderate loss of sleep; they also suggest that it is the simpler, or perhaps the more predictable, tests which are more affected.     

An experimental study qn the fitness of signs to words

This experiment, following Rartlett's Picture-writing, was designed to show : how much agreement there would be in the choice of a sign as the most fitting in connection with a word; whether the reasons given for a choice of sign mould vary greatly, and would be rationalizations rather than a primary ground for so choosing; and whether the chosen signs were more easily recalled than the not-chosen.

Six cards were shown to the subject, 011 each of which was one word aiid two signs. The signs were not intended to represent any object, although none was arbitrary. The subject had to choose the more appropriate sign and give the reason for his choice. Afterwards he had to reproduce all the signs.

Agrcement in choosing one of the signs of each pair was surprisingly high, although the reasons varied considerably. The chosen signs were reproduced more accurately and frequently, the reproductions showing the conventionalizing effect of the reasons given.

Choice of a sign as most fitting seemed to depend upon certain formal structural qualities of a general character. The most fitting sign for a verbal setting seemed to combine a conventional structure with simplicity and regularity of design. Linking these results with those of an experiment of Harrower's, it is considered possible that a method may here be available for exploring forms of mental organization not so far tapped by standard intelligence tests.     

Visual factors in auditory localization

Previous experiments showing the importance of visual factors in auditory localization are shown to have been insufficiently quantitative.

In the first Experiment, bells were rung and lights shone on the same or different vectors, eleven subjects indicating which bell had rung. In the second Experiment, a puff of steam was seen to issue from a kettle whistle with no whistling sound, while similar whistles were sounded by compressed air on that or another vector. Twenty-one subjects cooperated.

The addition of a visual stimulus at 0° deviation increased the percentage of correct responses significantly in the second, and insignificantly in the first experiment. At 20°-30° deviation the proportion of naive responses to the visual cue was 43 per cent. in the first and 97 per cent, in the second experiment. At greater angular deviations, the proportion of naive responses fell to chance level in the first, but remained significant in the second experiment, even at 90°. The “visuo-auditory threshold” was found to be 20°-30°, but might be much larger if there were more grounds for supposing the two stimuli to be from the same source in space.     

Frustration and stereotyped behaviour in human subjects

The investigation was designed to show the effects upon behaviour of three different durations of frustration, and two degrees of motivation during the frustrating period. Frustration was induced in 144 subjects by setting them the task of “learning” an insoluble temporal maze; they had to record their responses by pressing on one or other of two morse-type keys. Its effect was measured in terms of:

(1) The time taken to learn a soluble maze introduced, without the subjects' knowing it, by changing the system of “rewarding” responses from one based on chance to one based on the constant repetition of a pattern requiring the responses: Left—Right—Right, for its solution.

(2) The tendency for the subjects to show stereotypy of behaviour by responding on the same key for a number of trials in succession without reaching a solution.

(3) The pressure exerted on the response keys, which was taken to be a measure of vacillation.

Predictions that the time taken to learn the soluble task, and the stereotypy, would increase in direct relation to the duration of the frustrating period and the degree of motivation were tested.

It was found that, while there was an immediate increase in both the time taken to learn the soluble task and the stereotypy after a short period of frustration, a point was reached under conditions of prolonged frustration after which no further increase occurred and some adjustment to the situation was shown.

Some confirmation of the effect of increase in motivation in the direction predicted was obtained in all cases, but the differences were not statistically significant. The rankings of the subjects according to the time taken to learn the soluble task and the degree of stereotypy were found to be closely correlated. A definite tendency towards increased vacillation of response was seen in many of the records during the period when frustration might have been expected to have been at its peak.

These findings are discussed in relation to Maier's theory of frustration and to Selye's concept of a “general adaptation syndrome.” The latter theory is more suitable for the interpretation of the results of the present investigation.     

Studies in olfactory acuity. I: Measurement of olfactory thresholds in the rat

The capacity of the rat to respond to olfactory cues has been studied in three experimental situations: (i) an elevated Y-maze, (ii) a rectangular choice apparatus in which extraneous environmental cues were present, and (iii) a circular choice apparatus from which such cues were either excluded or randomized.

No rat showed any sign of learning on the Y-maze even after extensive training and the application of electric shock as deterrent for error.

Some rats succeeded in performing an olfactory discrimination in the rectangular choice apparatus but learning was retarded, and in some cases inhibited, by the counter-influence of non-olfactory factors.

All rats readily learned an identical discrimination when shielded from such cues in the circular choice apparatus which provides a satisfactory medium both for training and for the study of olfactory acuity.

Differences in the behaviour of rats on these three types of apparatus suggest first, that the formation of learned habits based on olfaction depends on the close contiguity of stimulus and reward, and second that the sense of smell possesses weak orientating properties by comparison with those exerted by other modalities. The findings thus help to explain differences in the ease or di+culty uith which olfactory discriminations have been established by earlier workers.     

What does a man do after he makes an error? an analysis of response programming

When people make errors during continuous tasks they temporarily pause and then slow down. One line of explanation has been that they monitor feedback to detect errors, that they may make incidental responses when errors occur (e.g. they may swear) and that they may pause to analyse their errors. In all these cases they may be assumed to act as single channel information processing systems of limited capacity, and to be unable to recognise any new signal until these processes have been completed.

Analysis of response after errors shows that this cannot be the case. Responses after errors are inaccurate, but are not slow when they require the subject to make the response which he should have made on the previous trial (i.e. to make an error correction response). Subjects thus must recognise new signals as soon as they occur. The present results require a new model of error detection and correction, and a model for response programming and priming.     

Information relevance, working memory, and the consideration of alternatives

People routinely focus on one hypothesis and avoid consideration of alternative hypotheses on problems requiring decisions between possible states of the world--for example, on the “pseudodiagnosticity” task (Doherty, Mynatt, Tweney, & Schiavo, 1979). In order to account for behaviour on such “inference” problems, it is proposed that people can hold in working memory, and operate upon, but one alternative at a time, and that they have a bias to test the hypothesis they think true. In addition to being an ex post facto explanation of data selection in inference tasks, this conceptualization predicts that there are situations in which people will consider alternatives. These are:

1. “action” problems, where the alternatives are possible courses of action;

2. “inference” problems, in which evidence favours an alternative hypothesis.

Experiment 1 tested the first prediction. Subjects were given action or inference problems, each with two alternatives and two items of data relevant to each alternative. They received probabilistic information about the relation between one datum and one alternative and picked one value from among the other three possible pairs of such relations. Two findings emerged; (1) a strong tendency to select information about only one alternative with inferences; and (2) a strong tendency, compared to inferences, to select information about both alternatives with actions.

Experiment 2 tested the second prediction. It was predicted that data suggesting that one alternative was incorrect would lead many subjects to consider, and select information about, the other alternative. For actions, it was predicted that this manipulation would have no effect. Again the data were as predicted.     

Immediate memory in dialling performance with and without simple rehearsal

This experiment was designed to explore the effects of simple rehearsal on immediate memory in telephone dialling performance in a sample of 36 men aged 45 to 60 for whom data on intelligence, vocabulary, emotional stability and occupation were available.

The eight-digit messages were the same as those previously used by Conrad in a study of telephone operators which compared performance on dialling and keysender equipment. Using a Latin square design, subjects were required to dial 10 eight-digit messages in each of six conditions (three with auditory and three with visual presentation). Dialling was carried out (1) immediately the message had been presented; (2) after it had been once vocally rehearsed by the subject; (3) after it had been written down while being vocally rehearsed. A complete record was obtained of all performances, at rehearsal and at dialling.

It was found that with auditory serial presentation, immediate vocal rehearsal and immediate dialling are equally good and both superior to dialling which followed vocal rehearsal. With visual simultaneous presentation, immediate vocal rehearsal is clearly superior to dialling with or without rehearsal, which do not differ. Performance after written-down rehearsal was the worst in both modes of presentation.

A non-linear relationship between intelligence and performance was found, and acute individual differences in performance were observed among the subjects of the highest intelligence.     

Variations in reflex blink-rate during visual-motor tasks

The influence of the performance of various tasks on the reflex blink rate has been investigated repeatedly, but the results obtained have been somewhat contradictory. More recently, it has been suggested that the reflex blink rate may be a considerable factor in the accuracy with which visual-motor tasks are performed. The aim of the present experiment was to attempt to obtain further evidence on both these questions.

The experiment was carried out in two parts. The main part was done in the laboratory, while a validating experiment was carried out on the road. In the laboratory, subjects were required t o steer a pencil along a moving track which varied in difficulty. The difficulty of the response was varied by using a direct control on some trials and a velocity control on others. Blink rate, errors, and control measurements were recorded throughout. In the road experiment, cine films were taken of the driver's eyes while driving in heavy traffic and in open country.

The results of both experiments show:

(a) That there are marked individual differences in blink rate, the relative order of which is maintained in spite of variations in the actual blink rate.

(b) That there is no relationship between the accuracy with which a particular individual carries out a task of this sort and his blink rate. The rapid “blinker” is no more and no less likely to be accurate than the infrequeiit I “blinker.”

(c) That the actual blink rate for all individuals varies inversely with the difficulty of the task and the amount of control movement necessary. The blink rate decreases as the necessity for detailed visual control of movement increases. Blink rates when driving a car in heavy traffic, or when steering along an oscillating track, are considerably lower than when driving in open country or when following a straight track.

(d) That the adjustment of the blink rate to the difficulty of the task is achieved not only by an alteration in overall blink rate, but also by a change in the distribution of blinking. The blink rate is approximately constant under constant conditions, but when the task is varying in difficulty, blinking occurs just before and just after periods of maximum difficulty, but is completely inhibited during the periods of maximum difficulty itself.     

Variations in blink rate during non-visual tasks

A total of fifty-five subjects were tested in three experimental situations. Blinking was recorded electrically, and related to various features of the three non-visual tasks. A new type of suction electrode was developed for this purpose.

It was found that blink rate fell below the normal resting rate during the learning of a stylus maze, and during a special audio-tracking task. During pauses between each trial, blink rate was above the resting rate.

There was a significant tendency for those subjects who showed the greatest difference in blink rate during the trials and the pauses between each trial to make the fewest errors per run of the stylus maze.

In the audio-tracking task the subjects followed a changing note with a second oscillator. Blink rate was found to be inversely related to the rate of change of the course tone.     

Induction of a principle

Two experiments are reported in which student subjects attempted to discover a principle obtaining among pairs of numbers and letters. In the first experiment, subjects were more successful when they were free to select whatever number-letter pairs they wished than if they were restricted in whole or in part to pairs specified by the experimenter. In the second experiment, subjects who did discover the principle were compared to those who did not. Successful subjects were shown to be slightly more systematic in their approach to the task, to work at a faster pace, to write down more positive instances, and to have a much stronger tendency to vary only one variable of the task at a time.

Wason (1960) reported a study in which subjects tried to discover a principle applying to instances each of which consisted of three numbers. He discovered that subjects mostly showed enumerative rather than eliminative induction, i.e. they made little use of instances that would have enabled them to eliminate wrong hypotheses. Wetherick (1962) found that by modifying Wason's procedure in certain ways, enumerative behaviour was reduced and the subject's chance of discovering the principle was increased. Elimination of hypotheses remained infrequent.

In the Wason study, the subject was free to write down, for each instance, any three numbers he wished, i.e. his choice of instances was not restricted in any way. This may account in part for the behaviour Wason observed. In the first experiment to be reported here, the subject is restricted, in various degrees, in his choice of instances, to determine whether the principle is discovered more (or less) readily under such restriction.