bluuebunny/crossref_metadata_2025 huggingface dataset:
An Apparatus for Presenting Continuously Varying Binocularly Disparate Views of an Apparently Single Object
Authors: Groman William
Published: March 2008

The perceptual effects of viewing continuously varying binocularly disparate views of a stimulus object under conditions in which convergence and accommodation are kept relatively constant and normal with respect to the target object have not been investigated.

Information regarding the effects of such stimulation should have relevance for problems of form and pattern perception, object constancy, and the perception of depth.

The apparatus to be described makes it possible to produce the stimulus conditions necessary for the study of this class of effects.
Subjective Hardness of Compliant Materials
Authors: Harper Roland , Stevens S. S.
Published: March 2008

The apparent hardness and softness of nine samples of compliant materials were scaled by direct magnitude estimation and by cross-modal matches to the apparent force exerted on a hand dynamometer and a finger dynamometer, and to the loudness of a band of white noise. The physical hardness (force/indentation) of the compliant specimens covered a range of more than 100 to 1, extending from a fairly soft sponge to a fairly hard block of rubber. The apparent hardness of the specimens was found to follow the psychophysical power law. Subjective hardness grows as the physical hardness raised to a power. The indicated exponent was about 0.8 for magnitude estimation, about 0.7 derived by calculation from handgrip matches, and about 0.6 derived by calculation from loudness matches.

Numerical estimates and cross-modal matches for softness gave functions that were approximately the reciprocal of the functions given for hardness. Hardness is a continuum on which there exists an upper threshold.
Subjective Expectancy and Choice Reaction Times
Authors: Mowbray G. H.
Published: March 2008

Previous findings suggested that selective response times might be affected both by the inter-stimulus interval and by the probability of occurrence of the stimulus for reaction. These two factors have been tested independently and have been found to influence reaction times in a fashion that an expectancy hypothesis would predict.
The Effect of Repetition of Items on Two Phases of Paired Associate Learning
Authors: Warr Peter B.
Published: March 2008

An investigation is reported in which the effect of repetition of items on two learning tasks is determined. These tasks are considered to be analogous to the response-learning and associative phases of paired associate learning. The findings tend to support the hypotheses under investigation, that response learning is an all-or-none occurrence and that the associative phase may be explained by the dual factor hypothesis.
Effects of Variation in the Warning Signal on Reaction Times of Severe Subnormals
Authors: Hermelin Beate
Published: March 2008

Reaction times of normal and subnormal subjects were compared, when a warning stimulus varied in modality as well as in its temporal relation to the RT signal. When the warning stimulus was in a different modality from the RT signal, reaction times were shorter than when both were in the same modality. Mongols, in contrast to the other subjects, responded relatively faster to light than to sound.

The effect of varying the time interval between warning and signal was linearly related to response speed. The results are discussed in respect to the comparative alerting effects of temporal relations between stimuli and their different modalities.
Peripheral Viewing and Simultaneous Contrast
Authors: Burgh Peter
Published: March 2008

An experiment was done to find the effect on simultaneous brightness contrast of viewing the test patches foveally or peripherally, at a distance of 3° or 6° from the fovea. It was found that contrast was greater in the periphery. It was also found that contrast increased with prolonged viewing of the display. A further experiment showed that blurring the test patches produced an increase in contrast.
Apparent Distance in a Horizontal Plane with Tactile-kinesthetic Stimuli
Authors: Davidon Robert S. , Cheng Mei-Fang Hsieh
Published: March 2008

In the study of active tactile-kinesthetic space perception apparent distance has been found to vary as a function of the direction of the line segment in a horizontal plane. The present data indicate that the error is not consistently related to the same frame of reference as the visual illusion. Rather, with movement of the extended arm to determine the relative distances between pairs of points, radial distances are overestimated in relation to tangential ones, whether parallel or perpendicular to the medial plane. Interpretations are in terms of kinesthetic stimulus patterns and the structure of perceptual representation.
The Effect of Somaesthetic and Acoustic Stimuli on the Threshold of Fusion of Paired Light Flashes in Human Subjects
Authors: Horn G. , Venables P. H.
Published: March 2008

The threshold of fusion of paired flashes of light was measured by determining the largest interval between two flashes of light at which they were reported as one and not as two flashes. When a weak electric shock to the skin was presented at the same time as the first flash, the threshold was increased compared to the threshold measured when the flashes were unaccompanied by a shock. As the interval between shock and first flash was increased up to 600 millisec, the effect diminished. A similar pattern of results was obtained using a click, instead of a shock as the additional stimulus. The effect on the two-flash threshold of varying click intensity was also studied. No retroactive effects of the shock on the two-flash threshold were observed.
A Chronometric Study of Some Relations between Sentences
Authors: Miller George A. , McKean Kathryn Ojemann
Published: March 2008

An attempt was made to study how people handle syntactic relations among English sentences by measuring the time required to convert one type of sentence into another. Preliminary results based on rate of work in a pencil-and-paper test are briefly summarized. More detailed data are given for an experiment in which subjects controlled the duration of presentation of the sentence they transformed. Presentation times were measured and compared with the presentation times when no transformation was required; the difference between these times was taken as a measure of the additional time required to perform the transformation. In such tasks, an active-passive difference requires more additional time than does an affirmative-negative difference; when both are involved the additional time required is approximately the sum for the two separately. Differences in verb constructions, however, all require about the same amount of time, and no additive relation is apparent. The relation of these results to the distinction between rules of formation and rules of transformation in descriptive linguistics is discussed.
A Re-examination of the Interrelations among Measures of Retention
Authors: Bahrick Harry P. , Bahrick Phyllis O.
Published: March 2008

The interrelations among measures of anticipation, recognition and savings are examined. It is shown that (a) the difficulty level of a recognition task can be above or below that of anticipation for the same material, and (b) the slope of retention curves based upon recognition measures may be more or less steep than the slope of curves based upon recall measures of the same material. Previous contrary conclusions reflect the exclusive use of easy recognition tests, and experimental designs in which the degree of learning is much greater for the recognition than for the recall task.
On the Relationship between Coding and the Ability to See what One is doing in a Sensori-motor Task
Authors: Leonard J. A.
Published: March 2008

In order to examine the possible interaction between different display-control relationships and the ability to look at what one is doing an experiment was carried out under four conditions: half the subjects were trained with a colour code display, the other half with a positional code; within each of these groups half the subjects were allowed to look at their hand while performing, and the others were not. It was found that the effect of not being allowed to look was larger with the colour code in the initial phase of training, and larger with the positional code in the final phase of training.
The Combination of Information from Different Sources
Authors: Davis R.
Published: March 2008

In this experiment subjects were presented with visual information from two different sources and were required to combine it in order to make the correct response. The time interval between the two signals was varied in two different ways (a) regularly and (b) randomly. Reaction times were measured from the moment of occurrence of the second signal. By this means the time course of the decision procedure involved in combining the information from the two sources was analysed.

Results indicate that subjects may deal with the situation in two ways (i) by means of a “perceptual” classification in which the individual elements are not analysed separately, or (ii) by means of an “intellectual” classification in which each signal is analysed sequentially. These two methods correspond to the experimental conditions of (a) regular intervals and (b) random intervals.

It is argued that when subjects use the latter strategy the results are consistent with the conception of the human operator as an intermittent analysing system.
The Effects of Context upon Speed of Reading, Eye Movements and Eye-voice Span
Authors: Morton John
Published: March 2008

Subjects read aloud 200-word passages of statistical approximations up to the 8th order. Their eye-movements were recorded together with a trace of the speech output. Speed of reading, using the syllable as the unit of measurement, increased up to the 5th order for slow readers. Fast readers, on the other hand, further increased their speed to the 6th order. This result had been predicted from a hypothesis that fast readers use contextual cues more efficiently.

Measures of the material in the eye-voice span showed an increase up to the 8th order. Fast readers had a larger material span than slow readers beyond the 5th order, a result paralleling the differences in speed increase. It is suggested that the eye-voice span measured in time is dependent upon the chosen reading speed and the material span.

From the eye-movement records there was no variation of the mean duration of fixation between passages, or between fast and slow readers. The average value was about 240 millisec. The number of both forward and regressive eye movements decreased with increase in contextual constraint up to the 5th or 6th order, i.e. with increase in speed of reading. Fast readers were superior to slow readers in both these respects. The effect of decreasing contextual constraint was to produce more regressive movements together with a slightly smaller mean saccade.
Left-right Differences in the Perception of Melodies
Authors: Kimura Doreen
Published: March 2008

Normal subjects were given two auditory tests, one consisting of spoken digits presented dichotically, the other of melodies presented dichotically. On the Digits test, the score for the right ear was higher than for the left (as previously established), and on the Melodies test the score for the left ear was higher than for the right. These findings were related to the different roles of the right and left hemispheres of the brain in verbal and nonverbal perception.
Accuracy of Recognition for Speech Presented to the Right and Left Ears
Authors: Broadbent D. E. , Gregory Margaret
Published: March 2008

Earlier reports by other authors had shown that recall of dichotically presented speech was better for words arriving at the right ear, while recognition of passages of music was better for music presented to the left ear. It seemed desirable to test recognition for speech, in order to show that the difference between materials rather than the difference in testing techniques was responsible for this disparity between ears.

Accordingly 18 men were presented with dichotic lists of digits, and then tested for recognition of the digits. There was no indication of an advantage for the left ear, but rather of the advantage for the right already established for recall of speech materials.
Immediate Memory and the “Perception” of Letter Sequences
Authors: Baddeley A. D.
Published: March 2008

It is suggested that the relationship observed by Miller, Bruner and Postman (1954) between the redundancy and the accuracy of reproduction of tachistoscopically presented letter sequences is not a perceptual effect as they suggest, but is due to the informational limitations of immediate memory. An experiment is performed which shows an exactly similar relationship between redundancy and number of letters correctly reproduced when exposure time is long enough for the subject to read out, and hence perceive, all the material with complete accuracy. It is concluded that the more redundant the letter sequence and the longer the exposure time, the more effectively the sequence can be coded and the better it will be recalled.
Induction of a Principle
Authors: Duncan Carl P.
Published: March 2008

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.
Overtraining, Transfer to Proprioceptive Control and Position Reversal
Authors: Mackintosh N. J.
Published: March 2008

If rats are overtrained on a visual discrimination they generally learn the reversal of the discrimination faster than non-overtrained rats. In position discriminations, however, this effect does not generally hold—indeed several investigators have found overtraining to retard position reversal. One of the important differences between the two types of problem seems to be the presence of irrelevant cues in visual discriminations, and their absence in position discriminations. It is suggested that a second important feature of position discriminations is that overtraining usually causes control of the maze running habit to be transferred from external to proprioceptive stimuli, and that successful reversal cannot normally occur until external control is re-established. In two experiments a study by Krechevsky and Honzik (1932) is repeated with certain modifications, with results that support this hypothesis; and a third experiment provides direct evidence of transfer to proprioceptive control in a T-maze. It is shown that this analysis will explain the apparently conflicting results of all recent position reversal experiments.
Study of the Single Channel Hypothesis and Input Regulation within a Continuous, Simultaneous Task Situation
Authors: Herman Louis M.
Published: March 2008

Subjects performed simultaneously on an auditory tracking and an auditory discrimination task, with each, task presented to a separate ear. Information transmitted on the tasks was measured as a function of ability to predict task characteristics, input information-rate, and input discriminability. Based on comparison of single-versus simultaneous-task performance, support was found for a single, central decision-type channel in information processing, having as one primary limit the rate at which information can be accepted. Discriminability of inputs also was found to be a limit on information processing rate. Although ability to predict a task's characteristics facilitated performance on that task, in this experiment it did not result in facilitation of performance on the second task. Relevance of these findings to certain aspects of Broadbent's information-processing model is discussed.
Secondary Reinforcement Value of Stimuli Associated with Shock Reduction
Authors: Lawler Edward E.
Published: March 2008

An experiment is described in which 32 rats were tested to determine if an escape box which had been previously associated with shock reduction had secondary reinforcement value. Subjects were tested in both a fear and a neutral situation. Significant secondary reinforcement effects were found in both situations. However, contary to expectations, greater secondary reinforcement effects were obtained in the neutral than in the fear situation.
Effect of Effort on Resistance to Extinction of the Bar-pressing Response
Authors: Quartermain David
Published: March 2008

This study was designed to obtain more information on the relation between effort and resistance to extinction when all subjects receive equal acquisition experience on each effort level at which the response is subsequently to be extinguished. Twenty-four subjects were given 120 reinforcements on each of three weighted bars of 5, 40 and 70 gm. They were then ordered into three groups, each extinguished on one effort level. Analysis of the number of responses emitted in six daily 20-min. extinction sessions showed that resistance to extinction was not related to the amount of effort expended in extinction.
The Influence of Stimulus Scale-interval upon the Assessment of Pain Threshold
Authors: Haslam Diana R.
Published: March 2008

An experiment concerning the influence of the scale of stimulus values upon the perception of heat-pain is reported in which it is found that the value of the threshold stimulus is dependent upon the size of the steps between successive stimuli.

The results are analysed in the light of a paper by Brown and Cane (1959) in which they point out that the value of a sensory threshold yielded by the Limiting Method is mathematically dependent upon the size of the steps between successive values of the variable stimulus. The threshold values reported here are found to be dependent on the step-size between stimuli to a greater extent than that which would be predicted by Brown and Cane.

In view of these results, an attempt is made to explain the wide variety of pain threshold values reported in the literature.
Counter Displacement in the Visual Figural After-effect
Authors: Prysiazniuk A. W. , Kelm Harold
Published: March 2008

In this study an attempt is made to specify the conditions under which counter displacement (test contour displaced toward the inspection contour) will occur. Three experiments are described in which different lengths of inspection of the test-(T-) figure are given following short and long inspections of the inspection-(I-) figure. In Experiment I, after partial dissipation of the figural after-effect (FAE), a period of continuous inspection of the T-figure was employed. In Experiments II and III distributed inspection of the T-figure was given by increasing the number of measurements of the FAE. In all experiments counter displacement was evident. The results were consistent with an interpretation of counter displacement offered earlier by the authors.
Expectancy and Intermittency
Authors: Davis R.
Published: March 2008

When a human subject responds to the second of two closely succeeding stimuli, his reaction time to the second stimulus tends to increase sharply as the interstimulus interval decreases. Controversy has centred on the issue of whether this increase is mainly due to the effects of the first stimulus in producing some kind of block in the central analysing systems or whether it is mainly due to the temporal uncertainty of the second signal, as determined by the distribution of interstimulus intervals used.

By substituting for the first stimulus a spontaneous response on the part of the subject and holding the distribution of interstimulus intervals constant, it is shown that the delays in responding to the succeeding signal are eliminated, even at intervals as short as 50 millisec. This is interpreted as evidence in support of the intermittency hypothesis and as a clear indication that the increase in reaction times normally observed is not a result of the distribution of interstimulus intervals.
The Beneficial Effects of Meprobamate on Delayed Response Performance in the Frontal Monkey
Authors: Weiskrantz L. , Gross C. G. , Baltzer V.
Published: March 2008

Previous studies of antagonistic treatments on delayed response performance by frontal monkeys suffer from a logical flaw in that the treatments may also improve the performance of normal monkeys. In a previous study (Gross and Weiskrantz, 1961) we have shown that meprobamate is without effect on delayed response in normal monkeys, but it does severely depress their discrimination performance. In the current study meprobamate is shown to produce a significant improvement in delayed response in each of three frontal monkeys. Nembutal is also effective. Various interpretations of the results are discussed, the view being favoured that the frontal monkey suffers from an excessive and inappropriately ordered intake of sensory information.
Delayed Auditory Feedback and Shadowing
Authors: Yates Aubrey J.
Published: March 2008

On the basis of speech disturbance under binaural DAF, groups of subjects of high and low susceptibility were formed. Both groups were required to shadow messages presented under four conditions: single message presented binaurally; message presented to one ear with either white noise, an irrelevant message, or delayed feedback of the repetitition of the message, presented to the contralateral ear. For both groups the number of errors (omitted words) increased significantly in the irrelevant message and the delayed feedback conditions as compared with the binaural or white noise conditions. There was no difference between the susceptible and non-susceptible groups in the binaural and white noise conditions, but the susceptible group showed a much larger increase in the irrelevant message and delayed feedback conditions. Implications of these findings for theories of DAF are discussed.
Short-term Temporal Changes in Free Recall
Authors: Postman Leo , Phillips Laura W.
Published: March 2008

An experimental study of short-term memory for lists of familiar English words is reported. Lists of 10, 20, and 30 unrelated words were presented at a 1-sec. rate. Retention was measured by free recall after intervals of 0, 15 and 30 sec. A counting task was used to prevent rehearsal during the retention interval. The absolute level of recall increased with length of list whereas the percentages retained showed the reverse trend. The recall scores decreased steadily as a function of retention interval, with the rates of forgetting comparable for the three lengths of list. The decline in the amount recalled was due in large measure to the loss of the terminal items in the list. Consequently, the pronounced recency effect present on the immediate test of recall was progressively reduced as a function of time. By contrast retention of the initial part of the list was relatively stable. These variations in rate of forgetting are attributed to differences among serial positions in susceptibility to proactive inhibition.
Iterative Techniques for Unbiased Rating Scales
Authors: Pollack Irwin
Published: March 2008

Three iterative techniques for neutralizing the effects of stimulus bias in category rating experiments were examined with a wide variety of stimulus variables. Under all conditions examined, the iterative techniques quickly led to a stable category estimation. This result was obtained for stimulus variables with strong measurement properties, e.g. length and weight; for stimulus variables with only ordinal properties, e.g. emery papers; and for stimulus variables with only nominal properties, where an ordered set is obtained only in the course of the category scaling, e.g. female profiles.
Comparative Analysis of Proprioception in Left and Right Arms
Authors: Wyke Maria
Published: March 2008

Using the “kinaesthetic memory for the target” technique, differences in the accuracy of pointing to a target with the right and left arms are analysed. The effect of rotation of the head to left and right upon this process is also studied.

With the head normally orientated, it was found that pointing with the right arm is significantly better than with the left. Accuracy of pointing is greater with the target directly in front of the body than when it lies to either left or right side.

When the head is rotated, the direction of the pointing error is inversely related to the direction of rotation.

The study suggests that the precision of control over arm (in the absence of vision) is related to the varying ability of individual subjects to correlate limb movements with the prevailing orientation of the body, especially of the head and neck. This is additional to the influences of genetically-determined handedness and of the sensory input from the moving limb.
Acquisition and Extinction of a Simple Motor Skill as a Function of Delay of Knowledge of Results
Authors: Dyal James A. , Wilson Wayne J. , Berry Kenneth K.
Published: March 2008

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.
Visual Discrimination of Shape by Humans. II: (I) Matrix Figures and (II) Minimal Area Changes
Authors: Butler J.
Published: March 2008

Two experiments are described in which an attempt was made systematically to vary two dimensional shapes according to a pre-arranged design. In the first, subjects were presented tachistoscopically with pairs of “reflexive matrix figures” whose members were either horizontally or vertically orientated; and it was found that reaction times to horizontal pairs were faster than to vertical ones, a result that is in keeping with previous findings. In the second experiment two ensembles were devised that were alike in every respect save that one group was extended or reduced vertically while the other varied horizontally. Performance was better on the vertically orientated ensemble. These findings are briefly related to former studies and the pre-eminence of vertical symmetry is underlined.
Predictability and Immediate Memory for Consonant Sequences
Authors: Baddeley A. D. , Conrad R. , Hull A. J.
Published: March 2008

Two measures which have been shown to predict the ease of learning trigrams, namely log letter frequency and sequential predictability, were applied to data from an experiment on short term memory. This involved the immediate recall of 120 six-letter consonant sequences which were presented visually one letter at a time. A significant correlation was found between the probability that a given sequence would be recalled correctly and both its mean log letter frequency (r = 0.308, p < 0.001), and its mean predictability (r = 0.393, p < 0.001). Partial correlation showed only a marginally significant effect of log letter frequency when predictability was partialled out (r = 0.161, 0.05 < p < 0.1). With log letter frequency partialled out, however, a reliable correlation between predictability and recall score remained (r = 0.300, p < 0.001).
The Effect of Overlearning on Transfer of Training
Authors: Holborn Stephen , Boe Erling E.
Published: March 2008

The effect of overlearning on transfer of training on the A-B:A-Br* paradigm was studied in paired-associate learning with meaningful material (adjective pairs). One group of subjects was trained to criterion on list A-B, and two additional groups were given 100 per cent and 200 per cent overlearning on list A-B. Rate of learning list A-Br was found to be directly related to amount of overlearning. Negative transfer on list A-Br was found for errors with the criterion group, while positive transfer was found for the 100 per cent and 200 per cent overlearning groups. The results were consistent with previous paired-associate experiments, and with results of some maze, reversal learning experiments with infrahuman subjects.
Studies on Sensory Feedback: III the Effects of Display Gain on Tracking Performance
Authors: Chase Richard Allen , Cullen John K. , Openshaw Joseph W. , Sullivan Scott Alexander
Published: March 2008

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.
The Limits of Over-constancy
Authors: Joynson R. B. , Newson L. John , May D. S.
Published: March 2008

A number of studies have led to the generalization that there is a tendency to “overconstancy” in the perception of size. The experiments reported here suggest that over-estimation is limited to objects subtending angles of approximately 2° or less, and that objects subtending greater angles are judged fairly accurately. This raises the possibility that foveal diameter (approximately 2°) is involved.
The Nature of the Age Decrement in Performance on Dichotic Listening Tasks
Authors: Craik F. I. M.
Published: March 2008

Previous experimental work has shown that when subjects of different ages are presented with a series of dichotic digits (as two simultaneous half-sets, one to each ear) there is an age decrement in the reproduction of the second half-set. It has been suggested that this result is due to the second half-set being involved in a short-term storage process and that this process declines in efficiency with age.

It seemed equally possible however that the result was due to perceptual or attentional factors rather than memory factors. Two experiments were thus carried out in an attempt to specify the nature of the decrement. In the first, instructions as to which half-set to reproduce first were given before presentation of the digits. In the second experiment attention was equally divided between the ears by giving these instructions after presentation. An analysis of types of error in the first experiment suggested that attentional factors were more important but from a similar analysis in the second experiment it was concluded that memory factors were largely responsible for the age decrement.
Similarity and Intrusions in Short-term Memory for Consonant-vowel Digrams
Authors: Wickelgren Wayne A.
Published: March 2008

Subjects listened to lists of six consonant-vowel digrams presented at the rate of 0·8 sec./digram and copied them as they were being presented. Immediately after finishing copying the list, they attempted ordered recall of the six digrams. The digrams in each list were chosen from a population of eight digrams consisting of all digrams that can be constructed from the consonants “f” and “n,” the vowels “ā” and “Ō,” and the two orders “CV” and “VC.” Intrusions tended to be similar to the presented digram, and the frequency of an intrusion was a monotonic increasing function of degree of similarity to the presented digram. The ordering of intrusion frequency for each similarity type was from greatest to least: +−+ (same consonant, different vowel, same order), + + −, − + +, − + −, + − −, − − +, − − −. The findings indicate that forgetting is not all-or-none, that digrams are coded in terms of phonemes, and that initial vs. terminal position is a distinctive feature of consonants, but not vowels, in short-term memory.
Position Reversal Training in the Virginia Opossum: Evidence for the Acquisition of a Learning Set
Authors: Friedman Herbert , Marshall David A.
Published: March 2008

To obtain an estimate of the learning ability of opossums, five tame ones were trained on a series of position reversals to a criterion. With 4 trials per day there was no consistent improvement over a series of 15 reversals. When each daily session was increased to as many trials as needed to reach criterion, errors dropped sharply, indicating the formation of a position learning set. Upon return to 4 trials per day, 3 of 4 animals continued to perform with few errors, showing transfer of learning set. Opossums do more poorly than rats on this task, which is in agreement with the relative phyletic level of the two species.
The Effect of Anxiety on Food Intake in the Rat
Authors: Strongman Kenneth T.
Published: March 2008

Three levels of anxiety were induced experimentally in rats. With hunger drive held constant, the effects of anxiety on the intake of food which had either a positive or negative incentive value were observed and compared. The results for the intake of food with positive incentive value showed eating to be increased above control level by a low level of anxiety, and slightly decreased by medium and high levels. On the other hand, a direct relationship was observed between level of anxiety and suppression of the intake of food with a negative incentive value. These findings were shown to be inconsistent with previous explanations of similar effects in terms of an interaction between relevant and irrelevant drives. An alternative explanation in terms of incentive was offered.
Temporal Factors in Pattern Vision
Authors: Fiorentini Adriana , Mackay D. M.
Published: March 2008

A sequence of uncorrelated randomly patterned visual stimuli (“visual noise”) is normally seen as a field of particles in “Brownian motion.” When each frame of the sequence is followed by a blank flash superimposed on the same region of the visual field, the apparent structure of the noise field is strikingly altered, its form varying with the time interval between frame and flash. At a critical interval, many dots seem to cohere, to form maggot-like objects.

Some of the factors determining this critical interval have been studied. They include the brightness, repetition frequency and exposure duration of the noise field, and the distance of its retinal image from the fovea.

The critical interval for “perceptual blanking” is quite different from that for the “maggot effect,” but the two show a suggestively similar dependence upon the duty cycle of the noise display.

It is of some neurological interest that the phenomenon is not appreciably visible with dichoptic mixing of noise and blank stimuli.
An Adjacency Effect in Free Recall
Authors: Jensen Arthur R.
Published: March 2008

An adjacency effect was demonstrated at a high level of significance in the free recall, by 123 subjects, of a list of 40 high-frequency nouns presented in varying order on successive trials. The phenomenon referred to as the adjacency effect consists of the fact that when a subject is given repeated trials of study and free recall of a list of words (always presented in a different order), the probability of recalling a given item is greater when the item is presented temporally adjacent to an item which is already learned (as evidenced by recall on the previous trial) than when the item stands temporally between other items which are not yet learned. The enhancement of recall is greater when the item is presented between two previously learned items. The implications of the adjacency effect for verbal learning theory, particularly for the serial-position effect in serial learning and the concepts of interference and neural consolidation, are discussed.
Input Restriction and Immediate Memory Decay in Normal and Subnormal Children
Authors: O'connor N. , Hermelin Beate
Published: March 2008

Twelve imbeciles and 12 normals, matched for their digit memory span, were presented with three digit numbers successively and simultaneously. Seven speeds of presentation were used. Each simultaneous speed of presentation had a corresponding successive speed. Subjects were required to recall digits on the conclusion of presentation of each number. Each performance was scored as the number of errors for each digit. With simultaneous presentations the difference between the groups was significant only at fast presentation speed, where the normals were significantly better than the imbeciles. Imbeciles improved at slow speeds and became as good as normals. In the case of successive presentations differences between groups occur only in relation to the second digit, which the normals remember better than the subnormals. Both groups remember the first digit worst as rates of presentation become progressively slower. Results are explained in terms of input restriction and of memory trace decay.
Intra-List Differences in Short-Term Memory
Authors: Howe M. J. A.
Published: March 2008

Subjects attempted to recall lists of nine consonants immediately after presentation. Using various recall orders it was found that recall of part of a list interfered with retention of the other parts, memory for items presented early in a list being less affected by such interference than was that for later items. Since this result was not obtained when rate of presentation was increased, it is suggested that rehearsal contributed to the greater stability of early items.
The Effect of Instructions on the Apparent Reversal of Rotary Motion in Depth
Authors: Power R. P.
Published: March 2008

This study concerns experimental investigation of the effect of instructions on the apparent reversal of rotary motion in depth. It was found that subjects instructed to report apparent reversals of an elliptical shape signalled more reversals than subjects who were instructed to report the non-occurrence of reversals. This difference increased over four trials. When the stimulus object was a trapezium window instructions to report reversals led to a higher rate of reversals than did instructions to report non-occurrence, but this difference did not increase significantly over trials.
Cdk11 is a RanGTP-dependent microtubule stabilization factor that regulates spindle assembly rate
Authors: Yokoyama Hideki , Gruss Oliver J. , Rybina Sofia , Caudron Maïwen , Schelder Malgorzata , Wilm Matthias , Mattaj Iain W. , Karsenti Eric
Published: March 2008

Production of Ran–guanosine triphosphate (GTP) around chromosomes induces local nucleation and plus end stabilization of microtubules (MTs). The nuclear protein TPX2 is required for RanGTP-dependent MT nucleation. To find the MT stabilizer, we affinity purify nuclear localization signal (NLS)–containing proteins from Xenopus laevis egg extracts. This NLS protein fraction contains the MT stabilization activity. After further purification, we used mass spectrometry to identify proteins in active fractions, including cyclin-dependent kinase 11 (Cdk11). Cdk11 localizes on spindle poles and MTs in Xenopus culture cells and egg extracts. Recombinant Cdk11 demonstrates RanGTP-dependent MT stabilization activity, whereas a kinase-dead mutant does not. Inactivation of Cdk11 in egg extracts blocks RanGTP-dependent MT stabilization and dramatically decreases the spindle assembly rate. Simultaneous depletion of TPX2 completely inhibits centrosome-dependent spindle assembly. Our results indicate that Cdk11 is responsible for RanGTP-dependent MT stabilization around chromosomes and that this local stabilization is essential for normal rates of spindle assembly and spindle function.
The Caenorhabditis elegans nephrocystins act as global modifiers of cilium structure
Authors: Jauregui Andrew R. , Nguyen Ken C.Q. , Hall David H. , Barr Maureen M.
Published: March 2008

Nephronophthisis (NPHP) is the most common genetic cause of end-stage renal disease in children and young adults. In Chlamydomonas reinhardtii, Caenorhabditis elegans, and mammals, the NPHP1 and NPHP4 gene products nephrocystin-1 and nephrocystin-4 localize to basal bodies or ciliary transition zones (TZs), but their function in this location remains unknown. We show here that loss of C. elegans NPHP-1 and NPHP-4 from TZs is tolerated in developing cilia but causes changes in localization of specific ciliary components and a broad range of subtle axonemal ultrastructural defects. In amphid channel cilia, nphp-4 mutations cause B tubule defects that further disrupt intraflagellar transport (IFT). We propose that NPHP-1 and NPHP-4 act globally at the TZ to regulate ciliary access of the IFT machinery, axonemal structural components, and signaling molecules, and that perturbing this balance results in cell type–specific phenotypes.
Repair of injured plasma membrane by rapid Ca2+-dependent endocytosis
Authors: Idone Vincent , Tam Christina , Goss John W. , Toomre Derek , Pypaert Marc , Andrews Norma W.
Published: March 2008

Ca2+ influx through plasma membrane lesions triggers a rapid repair process that was previously shown to require the exocytosis of lysosomal organelles (Reddy, A., E. Caler, and N. Andrews. 2001. Cell. 106:157–169). However, how exocytosis leads to membrane resealing has remained obscure, particularly for stable lesions caused by pore-forming proteins. In this study, we show that Ca2+-dependent resealing after permeabilization with the bacterial toxin streptolysin O (SLO) requires endocytosis via a novel pathway that removes SLO-containing pores from the plasma membrane. We also find that endocytosis is similarly required to repair lesions formed in mechanically wounded cells. Inhibition of lesion endocytosis (by sterol depletion) inhibits repair, whereas enhancement of endocytosis through disruption of the actin cytoskeleton facilitates resealing. Thus, endocytosis promotes wound resealing by removing lesions from the plasma membrane. These findings provide an important new insight into how cells protect themselves not only from mechanical injury but also from microbial toxins and pore-forming proteins produced by the immune system.
Regulation of Mih1/Cdc25 by protein phosphatase 2A and casein kinase 1
Authors: Pal Gayatri , Paraz Maria T.Z. , Kellogg Douglas R.
Published: March 2008

The Cdc25 phosphatase promotes entry into mitosis by removing cyclin-dependent kinase 1 (Cdk1) inhibitory phosphorylation. Previous work suggested that Cdc25 is activated by Cdk1 in a positive feedback loop promoting entry into mitosis; however, it has remained unclear how the feedback loop is initiated. To learn more about the mechanisms that regulate entry into mitosis, we have characterized the function and regulation of Mih1, the budding yeast homologue of Cdc25. We found that Mih1 is hyperphosphorylated early in the cell cycle and is dephosphorylated as cells enter mitosis. Casein kinase 1 is responsible for most of the hyperphosphorylation of Mih1, whereas protein phosphatase 2A associated with Cdc55 dephosphorylates Mih1. Cdk1 appears to directly phosphorylate Mih1 and is required for initiation of Mih1 dephosphorylation as cells enter mitosis. Collectively, these observations suggest that Mih1 regulation is achieved by a balance of opposing kinase and phosphatase activities. Because casein kinase 1 is associated with sites of polar growth, it may regulate Mih1 as part of a signaling mechanism that links successful completion of growth-related events to cell cycle progression.
Peering deeply inside the branch
Authors: Cai Liang , Bear James E.
Published: March 2008

The actin-related protein 2/3 (Arp2/3) story has captivated the cytoskeleton community for over a decade. Not only does this complex nucleate new actin filaments, but it also anchors them into a dendritic meshwork that is used in many cellular contexts such as lamellipodial protrusion, endosome rocketing, and the movement of pathogens. One key piece of this puzzle that has been missing is a detailed structure of the Arp2/3-actin branch. Using electron tomography and computational docking, Rouiller et al. (Rouiller, I., X.-P. Xu, K.J. Amann, C. Egile, S. Nickell, D. Nicastro, R. Li, T.D. Pollard, N. Volkmann, and D. Hanein. 2008. J. Cell Biol. 180:887–895) present an elegant and intriguing structure of the Arp2/3 complex–mediated actin branch.