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In two studies [a pilot (12 7- to 10-yr.-olds) and a main study (100 8- to 12-yr.-olds)] hyperactive and normal children were compared on the ability to estimate time intervals ranging from 7 to 60 sec. The differences between estimated and elapsed time were larger for hyperactives than for normals, with the differences between the groups increasing with the length of the interval to be estimated.
An investigation into the composite or colinear form of the Müller-Lyer illusion, with one shaft adjustable by subjects, was carried out using black-on-white and CRT displays. Three fin-angle and two fin-length conditions were examined for both configurations of this figure, i.e., arrow-headed and feather-headed standards. Adaptations of the Müller-Lyer figure were also studied. Framing effects influenced the extent of this illusion. A highly consistent illusion error for balanced-field conditions, based on the formula k L cos A can be predicted which relates closely to previous experimenters' observed illusory errors and gives a remarkably simple explanation for this illusion.
Previous studies have shown that subjects could acquire a prismatic aftereffect contingent on the direction of gaze. Other studies have shown that subjects could acquire two simultaneous aftereffects with multiple cues. In the present study 12 subjects practiced alternately under two opposite 20-diopter lateral displacements and displayed two gaze-contingent aftereffects.
The purpose of the present experiment was to test the hypothesis that flat surface information for the plane of projection is the essential difference between ordinary and pictorial perception. Adults were asked to make relative size judgments of pairs of squares and triangles placed and pictured at various distances. The conditions were: real scene controls, life-size slides and prints, and real scenes viewed through clear glass, textured glass, a screen and a 50-mm lens. The error rate was significantly lower with real scenes than with either slides or prints which did not differ. The control data for real scenes were used for comparison to test for the effects of interposed flat surfaces on size judgments of real scenes. Viewing real scenes through either a clear glass pane or a 50-mm lens increased the error rate two and one-half times that of the controls for real scenes. Neither textured glass nor a screen significantly affected error rate. Results were interpreted as supporting the hypothesis that information about a flat surface for the plane of projection is the critical variable determining the special character of picture perception.
This study demonstrates that auras can be produced under laboratory conditions and explained by the principles of afterimages and border contrast phenomena.
This experiment investigated prism adaptation as influenced by performing a secondary task during the adapting and by the gender of the subject. Experimental subjects (10 males and 10 females) performed a secondary force-production task with the left hand, while adapting to prismatic displacement with the right (target-pointing). Control subjects (n = 20) were not required to perform the force-production task. While male subjects were not influenced by the secondary task manipulation, female subjects exhibited less adaptation. Since males' and females' performance did not differ on the secondary force-production task, it is unlikely that this finding can be explained by differential primary vs secondary task tradeoffs.
This study examined the effects of three conditions of movement (active, passive, and eye movement only) combined with two conditions of vision (sight and no sight of the body) on visual-motor adjustment to a familiar but optically rearranged environment. A total of 175 male college students were subjects. Each subject wore a pair of 25-diopter prism glasses while performing one of seven possible tasks. Visual-motor adjustment was measured by means of a mirror-box test administered prior to, and immediately following, performance of a 15-min. treatment session. Analysis of covariance indicated significant main effects for vision and a significant interaction between conditions of movement and vision. The actively moving subjects with sight of their bodies made significantly greater visual-motor adjustment to the optically rearranged environment than those in any of the other conditions investigated. The fact that non-moving subjects made small but significant adjustment was unexpected and remains unexplained.
20 male and 20 female adults, matched by age, read under conditions of normal and 113-, 152-, 200-, 253-, 307-, and 347-msec. delayed auditory feedback. Disfluency counts were correlated with delayed auditory feedback reactions which were changes in disfluencies under delay conditions. Pearson product-moment and Spearman's rbos were negative and significant for delay times of 113, 153, 200, and 253 msec. The Pearson product-moment correlation for 307 msec. was also negative and significant. Two groups of 11 adults were selected from the original sample on the basis of high and low initial disfluency counts. Their reactions to delayed auditory feedback were compared, using a 2-way analysis of variance with repeated measures (groups X delay times). Both main effects were significant but not their interaction.
The present study was designed to investigate possible residual effects of delayed auditory feedback on paragraph readings performed by normal speaking college students. No residual effect was shown under any of the experimental conditions employed.
Two experiments assessed the effect of hypnotically suggested arm anesthesia on adaptation to displacing prisms. In Study 1, 30 highly susceptible subjects adapted to prisms by pointing at a visual target for 2 min. with their hypnotically anesthetized dominant arm. Suggestion and hypnosis were then "lifted," and subjects were randomly assigned to three groups: subjects in one group were asked to move the hand slowly during the posttest (slow motion); those in a second group were told that hypnotic anesthesia would enable them to overcome displacement aftereffects (hypothesis informed); the remaining subjects (controls) were given no special instructions. During posttesting, all groups showed a significant displacement aftereffect, with no differences occurring between groups. Study 2 followed the same procedure except that during adaptation the usual target was removed and subjects pointed towards a homogeneous backboard. 20 highly susceptible subjects were assigned to an hypothesis-informed or control group immediately before posttesting. All subjects showed a significant displacement aftereffect. Both studies provide further evidence that hypnotic suggestions do not influence automatic perceptual processes. The results of Exp. 2 contradict the suggestion that hypnotic limb anesthesia eliminates the displacement aftereffect when the target is removed during adaptation trials.
Earlier papers showed that the relative impairment in response to faces and facial expressions shown by right-brain-damaged subjects was reduced by using blurred stimuli. Reanalysis of these data supports the hypothesis of differential hemispheric sensitivity to spatial frequency of inputs and shows processing of expressions partially depends on the processing of faces.
To compare the influence of the projected retinal size and of the figure size on the perception of the horizontal-vertical illusion, the target size, the viewing distance, and the slant of an illusion figure were varied. In the first experiment the illusion produced by two figures of the same object size but of different retinal size was compared with that of two figures projecting the same retinal size but differing in object size. The illusion diminished when the size of the retinal projection was increased, whereas a change in figure size did not change the illusion. In Exp. II the illusion figure was tilted backwards which reduced the retinal projection of the 'vertical' figure limb. The illusion decreased and became negative as a function of the retinal projection, but this decrease was relatively small compared with the reduction of the retinal image. The results are interpreted as supporting a retinal origin as an explanation of the illusion. Although there is strong evidence for size-constancy scaling in a tilted figure, constancy scaling is considered of minor importance as a determinant of the usual illusion.
Using the duration of the spiral aftereffect as an index of motion perception, the presence of high spatial frequencies inhibited perceived motion for 12 observers.
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All night sleep electroencephalograms were recorded in 10 healthy adults for 2 nights. On the second night all subjects were requested to be at the laboratory 5 hr. before their usual bedtime and were submitted to the same routine for performance on several visuomotor tasks; experimental subjects were required to use visual inverting prisms upon their arrival and during the performance of the tasks. Subjects were awakened 10 min. after each paradoxical sleep episode for dream collection. Dream content was significantly affected by the use of the inverting prisms: the presleep tasks and day-time activities were more frequently incorporated into the dreams of the experimental subjects. The dreams of the experimental group were more active and vividness was evaluated as lower by them than by the control subjects.
Eyeblinking during autokinetic movement observed by one subject living in the up-down inverted visual world, was investigated. The subject wore frame-spectacles (without prisms) for the first two days and then wore up-down inverting spectacles (with prisms) for the next four days, followed by the resumption of the former frame-spectacles for one day. Eyeblinks during autokinetic movement were measured by using vertical EOG. Analysis showed (1) the occurrence of eyeblinking during autokinetic movement was not influenced by living in the up-down inverted visual world; (2) the frequency of eyeblinking during autokinetic movement significantly decreased with successive days of observation.
The movement of a hand or fingers and locomotion of the body by a subject wearing prisms which inverted his visual world were investigated. A subject wore frame-spectacles (without prisms) for the first two days and then wore up-down inverting spectacles (with prisms) for the next four days, followed by wearing the former frame-spectacles again for one day. Measurements were made of skill on star-drawing, pegboard tests, and on zigzag-walking and walking up and down stairs. There were no differences on the five measures during acquisition for the four tasks, which suggests smooth progress of prism-adaptation by this man.
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