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doi: 10.1080/17470216408416384pmid: N/A
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.
Miller, George A.; McKean, Kathryn Ojemann
doi: 10.1080/17470216408416385pmid: N/A
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.
Broadbent, D. E.; Gregory, Margaret
doi: 10.1080/17470216408416386pmid: N/A
Recently Gray and Wedderburn showed that if a meaningful phrase of three words was presented together with three digits, in such a way that each ear received some items of each of the two types of material, it was no harder to recall the items grouped by type than it was to recall them grouped by ear. This finding is repeated and confirmed in several forms, culminating in the use of three letters of the alphabet and three digits as the six items presented. It is also shown, however, that even when all material is presented to one ear, it is harder to recall a list made up of alternate items of two classes than it is to recall the same items arranged as two successive sub-lists. Thus Gray and Wedderburn's result does not appear to reveal a situation in which alternation of attention between the ears is especially easy, but rather one in which continued attention to one ear is especially difficult because it requires alternation between classes of item.A further series of experiments showed that a reduction in the presentation rate of stimuli produced a much greater improvement in performance when the items were of two alternated classes than when the classes were left separate. Equally, a slow presentation rate is more helpful when alternation between ears is required than when each ear is to be dealt with separately. These results support the idea that attention takes time to shift; but require a separate kind of attention, to a class of item rather than to a source of stimulation.
Bahrick, Harry P.; Bahrick, Phyllis O.
doi: 10.1080/17470216408416387pmid: N/A
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.
doi: 10.1080/17470216408416388pmid: N/A
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.
doi: 10.1080/17470216408416389pmid: N/A
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.
doi: 10.1080/17470216408416390pmid: N/A
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.
doi: 10.1080/17470216408416391pmid: N/A
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.
Broadbent, D. E.; Gregory, Margaret
doi: 10.1080/17470216408416392pmid: N/A
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.
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