The effect of two “tranquillizers” on auditory discrimination and delayed response performance of monkeys

Five rhesus monkeys were tested on performance of an auditory discrimination and a delayed response test with a sliding scale of increasing difficulty after treatment with (a) 0·2 to 0·5 mgm./kgm. reserpine, (b) 150 mgm./kgm. meprobamate, (c) an equivalent saline injection, and (d) no treatment. Both drug treatments resulted in a severe deficit on the auditory discrimination and no change or improvement in delayed response performance. The auditory deficit was not due simply to an increased latency of response.

It is suggested that these results support the hypothesis that reserpine and meprobamate reduce the utilization of sensory information.     

Evidence of a single-channel decision mechanism limiting performance in a serial reaction task

An experiment is described in which the subject sat facing a display of two neon bulbs. When the left-hand bulb lit he pressed a key under his left hand, and when the right hand bulb lit he pressed a key under his right hand. The left-hand bulb gave brief flashes at random intervals averaging about 4 sec. The right-hand bulb gave a brief flash at regular intervals of about 4 sec.

The experiment repeats (the author believes for the first time) certain essential conditions of Vince's (1948, 1950) experiments and, following detailed scrutiny of every pair of responses, is taken as evidence for the following statements:—

(a) The response to a signal arriving during the reaction time to a former signal will be delayed by an amount approximately equal to the time elapsing between the arrival of the signal and the end of the reaction time to the former signal.

(b) An exception to this may occur when two signals arrive close together. In this case the two signals may be responded to as a single group.

(c) Delays can be occasioned by the monitoring of responses as well as by reactions to signals.

(d) “Grouping” of signal and monitoring may occur when a signal arrives close to the beginning of the movement made in response to a previous signal.

A survey is made of current theories in this field and suggestions given for further research.     

Temporal structure of letter groups and span of perception

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.     

What do sensory scales measure?

It is indeed an honour to have drawn Professor Stevens' fire (1964), in view of the magnitude of his research achievement in the field of sensory scaling. If I shall differ with him on certain of his conclusions, it is in full awareness of the debt we all owe him for the experimentation and thinking which has provided much of the factual basis and theoretical stimulus to further research and development in this area.

Professor Stevens (1960, 1964) advocates a psychophysical power law, while I have questioned it (Treisman, 1961, 1962, 1963a, 1963b, 1964a). I shall here examine the main points of disagreement lying behind these differing positions.     

Drive level effects on tasks of narrow and broad attention

Easterbrook (1959) has predicted that (a) performance on tasks involving the use of a wide range of cues will be impaired under high-drive conditions and that (b) performance on tasks requiring the use of only a narrow range of cues will be facilitated under such conditions.

Using the Porteus Maze Test, relatively clear evidence was obtained to support the first prediction. Using the Stroop Colour Word Interference Test some evidence was obtained in support of the second prediction.     

On knowing with which eye one is seeing

Experiments were performed to determine whether it is possible to discriminate which eye or eyes are being stimulated by a point source of light in a dark room when the subject is unaware which eye, if any, is occluded.

There were two stimulus conditions, (a) a continuous source of light, and (b) a flash. The results show that in these conditions discrimination is faulty and, in some instances, at chance level, although there is considerable individual variation. The implications of these results for the argument from transfer, as applied to after-effects, and the theory of depth perception are considered.     

Redundancy effects in short-term memory

Five experiments are reported whose purpose was to demonstrate that short-term memory is improved by redundancy within the material. In Experiment I “tune” containing two, three, four and five tones of differing frequencies had to be coded into digits 1-5, to indicate the order of the pitches in a tune. Performance on stimuli containing correlated amplitude and duration were compared with the uni-dimensional condition. Experiment II repeated I, but required intensity to be coded. Experiment III required pitch coding under three conditions including that when amplitude and frequency were uncorrelated, and compared the performance of musically trained sunjects with nonmusicians. Experiment IV repeated III, but subjects were informed of the relation between dimensions. Experiment V involved “shadowing” the tunes by whistling simultaneously with the stimulus.

It was concluded (a) that intercorrelation improves, but zero correlation impairs short-term memory; (b) that knowledge of the relation between dimensions improves performance in the correlated condition, but does not prevent impairment under zero correlation; and (c) the performance of musically trained subjects exceeds that of controls and is unaffected by the presence of a correlated or uncorrelated dimension.     

Acoustic similarity and interference in short-term recognition memory: Some results of a decision-theory analysis

The following three studies of single-probe recognition memory set out to show the effect on the signal-detectability measures of d' and β (Tanner and Swets, 1954) of variations in the acoustic similarity of interfering material, which may either precede or follow the item to be remembered (proactive or retroactive interference --PI or RI). The first experiment studies a situation employed by Wickelgren (1966a), who reported that acoustically similar RI substantially reduced d'. It is shown that this effect could have been due to biases in Wickelgren's original designs, and that when a bias-free design is used, the fall in d' is only of borderline significance.

To investigate this problem further, a design was evolved in which two items were presented for memorizing, which varied in acoustic similarity to each other, and (after a distracting task) a probe was presented with one of three questions: Was this the first item of the pair? Was it the second? or, Did it occur in either position? In the first case, recognition-memory with RI of varying acoustic similarity was being studied, and as in the first experiment, it was found that similarity slightly reduced d'. With the second question, PI effects were being studied, and here negligible differences were found. With the third type of question, a “location-free” test, no effects of similarity were found. The last result rules out Posner's (1967) “acid-bath” explanation of similarity effects in interference: an explanation in terms of “differentiation” (or “filtering”) was also invalidated by the results of a third experiment, in which the same effects were found even though similarity varied only between stimulus items and interference, and not between these and the probe. Wickelgren's (1966b) associative model appears to have least difficulty in accommodating these results, though even this needs certain ad hoc assumptions to be able to do so.     

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.     

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.     

Acquisition and extinction of a simple motor skill as a function of delay of knowledge of results

The present experiment demonstrates that the effects of delay of knowledge of results (KR) in a line drawing task depend upon the dependent variable which is considered and the original response tendency of the subjects. Delay of KR interfered with the acquisition of the correct response when number of correct responses is the dependent variable. When KR was omitted the immediate-KR group continued to make more correct responses than the delayed-KR group. However, there was a significant reduction in correct responses for both groups. When absolute error was the response measure there were no significant differences between immediate-and delayed-KR groups either during acquisition or extinction. Analysis of the type of response made during extinction suggested that the overshooting effect obtained by previous investigators may be typical of short responders trained under conditions of immediate reinforcement but not of those trained under delayed-KR.

Greenspoon and Foreman (1956) obtained clear cut evidence that the effectiveness of knowledge of results (KR) in a line drawing task varies inversely with the time delay between the response and KR. On the other hand, Bilodeau and Bilodeau (1958) were unable to demonstrate a similar effect in five different experiments. Bilodeau and Ryan (1960) hypothesized that the Greenspoon and Foreman findings could not be replicated and they did in fact obtain null results. However, Dyal (1965) has recently replicated the Greenspoon and Foreman results for the case of a 30 sec. delay interval.

The purpose of the present experiment is twofold: (a) to provide replication of Green-spoon and Foreman's study at the 20 sec. delay interval used by Bilodeau and Ryan, and (b) to determine the effect of elimination of KR on a simple motor response which has been formed on the basis of KR.     

Video tape recording: A provocative tool for the school psychologist

The video-tape recorder (VTR) is one of the newest and most versatile instruments available for collection of assessment and research data. It has been used by a psychological consultant to the schools (a) to collect observational data in order to complete referral information and formal test data, (b) to facilitate multiple consultation, and (c) to provide models for test administration for teachers or paraprofessionals. Innovative and imaginative use of the VTR is encouraged.     

Experimental finger dyspraxia

Subjects were required to perform discrete finger movements in accordance with a pre-arranged sequence of instructions. In all cases, any movement made by any finger was recorded by means of a constant-speed kymograph equipped with levers designed to record separately the movements of the individual fingers. This experiment was carried out under three conditions: (a) with no vision of the hand; (b) with direct vision of the hand; and (c) with the hand presented in mirror-image. It was found that, whereas deprivation of visual control was without effect on the efficiency of finger movements, presentation of the hand in mirror-image gave rise to significant increases in reaction time of three fingers and to an increase in the percentages of prior and substitute movements of other digits. Phenomena akin to depersonalisation were reported in some cases. It was also found that the rank order of mean reaction times of the five digits was approximately constant under all conditions and that the two fingers with the shortest reaction times were preceded by the fewest movements of other digits. These two digits were also the most frequently moved in advance when movements of other digits were requested and it is suggested that they have a certain “signpost function” in guiding identification of the remaining fingers. Some implications of these results for an understanding of “finger agnosia” are briefly indicated in an Appendix.     

Studies on sensory feedback: III the effects of display gain on tracking performance

Instrumentation is described which permits study of the effects of different forms of visual feedback display on the patterns of fine movement obtained from the extended human index finger when the subject is attempting to keep his finger at a fixed point in space. The task is a compensatory tracking task in which the only source of input to the system is the subject's own finger movement. The effects of increasing the gain (or amplification) of a proportional error signal on the pattern of finger movement was studied. Gains of 1, 2, 4, 10, 20 and 40 were studied with a group of 24 subjects. Increasing the gain of a proportional error signal resulted in a marked improvement in the ability of subjects to maintain their extended finger at a fixed point in space. As the gain of the error signal was increased, the subject's high-amplitude, low frequency errors were reduced, and there was a progressive appearance of high-frequency activity of low-amplitude, more accurately centred about the reference position in space. A total off-target area measure (integrated absolute error) showed marked decrease in scores as the amplification of the error signal was increased from 1 through 10. Beyond this gain there was no appreciable additional improvement in motor control, however no degradation of control was noted to characterize the group performance.

Exploratory studies were undertaken to permit comparison of the effects of increasing the gain of a proportional visual display with the effects of increasing the gain of non-proportional visual and auditory displays. An increase in the dominant-energy frequency was noted as the error signal gain was increased, independent of whether a proportional visual, or non-proportional visual or auditory display was used. This observation suggests that common mechanisms mediate the processing of the gain parameters of feedback displays, in some measure independent of the display form or the sensory modality used for presentation.     

Effects of feedback from active and passive body parts on spatial and temporal parameters in sensorimotor synchronization

Previous research on sensorimotor synchronization has manipulated the somatosensory information received from the tapping finger to investigate how feedback from an active effector affects temporal coordination. The current study explored the role of feedback from passive body parts in the regulation of spatiotemporal motor control parameters by employing a task that required finger tapping on one’s own skin at anatomical locations of varying tactile sensitivity. A motion capture system recorded participants’ movements as they synchronized with an auditory pacing signal by tapping with the right index finger on either their left index fingertip (Finger/Finger) or forearm (Finger/Forearm). Results indicated that tap timing was more variable, and movement amplitude was larger and more variable, when tapping on the finger than when tapping on the less sensitive forearm. Finger/Finger tapping may be impaired relative to Finger/Forearm tapping due to ambiguity arising through overlap in neural activity associated with tactile feedback from the active and the passive limb in the former. To compensate, the control system may strengthen the assignment of tap-related feedback to the active finger by generating correlated noise in movement kinematics and tap dynamics.     

I: Effect of delayed auditory feedback on speech and keytapping

The effects of delayed auditory feedback (DAF) on the performance of simple speech and keytapping tasks were compared. In the first experiment, each of the fourteen young adult subjects was asked to repeat the speech sound “b” in groups of three sounds. The subject heard his undelayed speech sounds through earphones. Under the delay condition, the speech sounds were delayed 244 millisec. before being returned to the subject's earphones. In the second experiment, each of the same subjects was asked to tap on a key in groups of three taps. The subjects heard an undelayed click through earphones each time they tapped on the key. Under the delay condition, the clicks were delayed 244 millisec. before being returned to the earphones. Graphic recordings were made of the time and intensity characteristics of tapping under both conditions.

The changes which occurred in speech and keytapping under DAF were qualitatively the same and consisted of increases in intensity and unit-to-unit time of both taps and speech sounds. When performing under DAF, the subjects also exhibited a tendency to repeat more sounds or to tap more times than had been requested. The percentage of change in intensity and time characteristics for speech and keytapping performances which occurred under DAF were not significantly different for the two motor systems. The amount of change in speech performance under DAF did not correlate significantly with the amount of change in keytapping performance.     

Studies in Spaced and Massed Learning: III. Paired-Associate and Serial Learning

An experiment on paired-associate learning was carried out to test Hovland's prediction that spaced practice should be more advantageous than massed if the order of presenting the pairs of nonsense syllables were fixed.

In the results, spaced and massed practice showed little difference in learning efficiency. Hovland's prediction was not confirmed.

In a previous experiment of this series of studies it had been found that spaced practice was more efficient than massed in serial learning when syllables of “low-meaningfulness” value were used; but that there was little difference in efficiency between the two forms of distribution when “high-meaningfulness” syllables were used. The results of the two experiments naturally suggested that, as regards the relative efficiency of spaced and massed practice, paired-associate learning of low-meaningfulness syllables differed from serial learning of similar syllables, but matched serial learning of high-meaningfulness syllables. It seems justifiable to draw the conclusion that the relative efficiency of spaced and massed practice is different in paired-associate and serial learning, not because remote associations can be formed in the one case and not in the other, as Hovland (1939a, 1939b) assumed; but because the organization of the material and the learning processes are different in the two forms of learning.     

The suppression of visualization by reading

Four experiments are described which demonstrate a conflict between reading verbal messages and imagining the spatial relations described by those messages. Listening to the same messages did not produce comparable interference with visualization. The conflict between reading and visualizing was obtained even when the subject previously had seen the referent of the message. In contrast, when the subject was induced to treat the messages as rote strings of words instead of visualizing their referents, reading was a more effective means of presentation than was listening.

Two interpretations of these results were proposed. (a) Visualization and reading compete of the use of neural pathways specialized for visual perception. (b) The process of reading hinders the conversion of input material into any non-verabl form; that is, reading forces the subject to deal with information in a more exclusively verbal form than does listening. It was suggested that regardless of interpretation this method provides a means of investigating the internal processes underlying concrete verbal reference.     

Response elimination without performance

Hungry rats were taught to press a lever in order to obtain a small quantity of food. It has been shown that the strength of the lever-pressing response can be reduced by allowing the animals to explore the box without finding food. This result conflicts with a simple reactive-inhibition theory of forgetting and response-elimination. Three possible explanations have been considered: (a) that the failure to find food changed the motivational condition of the animal; (b) that a conditioned drive, associated with the food-box, underwent extinction; (c) that a genuine response extinction occurred, and that this could be accounted for in terms of a principle of reaction-chain acquisition and extinction which differs in important respects from Skinner's (1938) and Hull's (1954) principles of conditioning.     

Goal-directed aiming under restricted viewing conditions with confirmatory sensory feedback

A substantial body of research has examined the speed-accuracy tradeoff captured by Fitts’ law, demonstrating increases in movement time that occur as aiming tasks are made more difficult by decreasing target width and/or increasing the distance between targets. Yet, serial aiming movements guided by internal spatial representations, rather than by visual views of targets have not been examined in this manner, and the value of confirmatory feedback via different sensory modalities within this paradigm is unknown. Here we examined goal-directed serial aiming movements (tapping back and forth between two targets), wherein targets were visually unavailable during the task. However, confirmatory feedback (auditory, haptic, visual, and bimodal combinations of each) was delivered upon each target acquisition, in a counterbalanced, within-subjects design. Each participant performed the aiming task with their pointer finger, represented within an immersive virtual environment as a 1 cm white sphere, while wearing a head-mounted display. Despite visual target occlusion, movement times increased in accordance with Fitts’ law. Though Fitts’ law captured performance for each of the sensory feedback conditions, the slopes differed. The effect of increasing difficulty on movement times was least influential in the haptic condition, suggesting more efficient processing of confirmatory haptic feedback during aiming movements guided by internal spatial representations.