Hypnotizability and "cognitive styles": a search for relationships.
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Cognition↗
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Results for “SIZE PERCEPTION”
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Clinical and experimental evidence that the pattern electroretinogram (PERG) is generated in more proximal retinal layers than the focal electroretinogram (FERG).
A TV monitor was used to evoke either a pattern ERG to a contrast-reversing checkerboard (PERG), or a focal ERG to alternate increases and decreases of luminance of the blank screen within a bright surround (FERG). Both responses are small (approx 2 microV) and fast (approx 50 msec to peak) and are similar in several other properties. However, they differ in timing and respond differently to changes in contrast. Each frame of a TV picture evokes a "raster ERG," even though the screen is blank. The response is focal and specific to a small central strip of the screen. It is simpler to record than the FERG, where the whole screen is flashing. Because the FERG summation area is about 4 deg, small squares (checks) reversing in contrast produce little luminance response. In 5 of 7 cases where the PERG is unilaterally reduced, the FERGs or raster responses were not affected. Thus clinical evidence also suggests that the PERG may be a separate phenomenon to the FERG and produced at a different site. Toxic, traumatic, congenital, and degenerative diseases of the optic nerve reduce the PERG. The comparison is most easily made in unilateral disease. Ten weeks after an optic nerve insult, the PERG becomes reduced in the affected eye as if retrograde degeneration was occurring. In 27 amblyopes of various types, the PERG was reduced in 23 where orthoptic treatment had failed. In 4 patients responding to treatment, PERGs of the amblyopic eye were as large as, or larger than, those of the fellow eye. The loss is greater with smaller checks. Retinal changes do occur after age 4 but so slowly that responses in heavily occluded eyes are not reduced. An additional level in the visual pathway is thus accessible to evoked potential investigation.
Amblyopia↗
Responses of the starburst amacrine cells to moving stimuli.
1. Rabbit retinas were isolated from the eye and incubated in the presence of 3H-choline. Samples of retina taken from a defined midperipheral eccentricity were spread over the domed end of a fiberoptic bundle that formed the floor of a superfusion chamber. The rate of release of labeled acetylcholine by the starburst amacrine cells was studied. 2. When the retina was stimulated by moving gratings, the cells vigorously increased their secretion of acetylcholine. Responses were observed when the bars were as small as 60 microns in width. Systematically varying the spatial and temporal frequency of stimulation revealed that temporal frequency was the dominant variable: the cells responded best to stimuli of 1-4 Hz, whether those stimuli were flashing lights, fine gratings moving slowly, or coarse gratings moving rapidly. 3. With temporal frequency constant, the cells' responses decreased as the spatial frequency of the grating increased. The decreased response to fine gratings is most likely due, at least in part, to lateral interactions that become stronger as the light and dark bars become more closely spaced. These could occur in either the outer or inner retina. 4. The velocity tuning curve for the starburst cells' release of acetylcholine matched fairly well the velocity tuning of ON-OFF directionally selective cells in the rabbit. It did not correspond at all well with the tuning curve for the ON directionally selective cells. If the ON cells receive input from the starburst cells, that input appears to be quite indirect.(ABSTRACT TRUNCATED AT 400 WORDS)
Acceleration↗
Orientational perception: 3. Orientational percept distortions in depersonalization.
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Depersonalization↗
The moon illusion: a test of the vestibular hypothesis under monocular viewing conditions.
The results of earlier monocular experiments on the moon illusion have been either negative or confounded. To test the role of vestibular function, 24 subjects made forced-choice distance comparisons between stimuli mounted in translucent tubes. The stimulus tube for standard distance could be positioned in three viewing angles (45 degrees up, horizontal, and 45 degrees down). A comparison tube adjustable for distance was mounted horizontally. There was a greater perception of depth in the downward looking condition. The relatively weak effects are discussed in terms of a two-hypothesis explanation of the real-life moon illusion and the poor cues for depth perception in monocular viewing.
Astronomical Phenomena↗
A zoom lens before the eyes during imagery: individual differences and strange, unexpected responses.
The research examined some aspects of an hypothetical involvement of the eyes in the process of imagery and the individual differences in the modulation of the imagery-perception interaction of 59 (7 male and 52 female) undergraduate students in psychology. The subjects were asked to image with open eyes and to project, looking through a zoom lens, the "mental" image onto a white screen. While the subject was imaging, the experimenter moved the lever of the zoom lens in the direction of an hypothetical enlargement. This movement evoked different classes of responses: 46% of the subjects had a loss, even if for a short time, of the image, 37% of the subjects observed a strange and unexpected enlargement of the mental image, 7% did not observe any change in imagery, and 10% had other responses. A psychophysiological discussion concerned the strange phenomena observed in this research that have not yet been explored enough.
Adult↗
Why is it easier to identify someone close than far away?
It is a matter of common sense that a person is easier to recognize when close than when far away. A possible explanation for why this happens begins with two observations. First, the human visual system, like many image-processing devices, can be viewed as a spatial filter that passes higher spatial frequencies, expressed in terms of cycles/degree, progressively more poorly. Second, as a face is moved farther from the observer, the face's image spatial frequency spectrum, expressed in terms of cycles/face, scales downward in a manner inversely proportional to distance. An implication of these two observations is that as a face moves away, progressively lower spatial frequencies, expressed in cycles/face--and therefore, progressively coarser facial details--are lost to the observer at a rate that is likewise inversely proportional to distance. We propose what we call the distance-as-filtering hypothesis, which is that these two observations are sufficient to explain the effect of distance on face processing. If the distance-as-filtering hypothesis is correct, one should be able to simulate the effect of seeing a face at some distance, D, by filtering the face so as to mimic its spatial frequency composition, expressed in terms of cycles/face, at that distance. In four experiments, we measured face perception at varying distances that were simulated either by filtering the face as just described or by shrinking the face so that it subtended the visual angle corresponding to the desired distance. The distance-as-filtering hypothesis was confirmed perfectly in two face perception tasks: assessing the informational content of the face and identifying celebrities. Data from the two tasks could be accounted for by assuming that they were mediated by different low-pass spatial filters within the human visual system that have the same general mathematical description but that differ in scale by a factor of approximately 0.75. We discuss our results in terms of (1) how they can be used to explain the effect of distance on visual processing, (2) what they tell us about face processing, (3) how they are related to "flexible spatial scale usage," as discussed by Schyns and colleagues, and (4) how they may be used in practical (e.g., legal) settings to demonstrate the loss of face information that occurs when a person is seen at a particular distance.
Discrimination Learning↗
On the dominance of unidimensional rules in unsupervised categorization.
In several experiments, observers tried to categorize stimuli constructed from two separable stimulus dimensions in the absence of any trial-by-trial feedback. In all of the experiments, the observers were told the number of categories (i.e., two), they were told that perfect accuracy was possible, and they were given extensive experience in the task (i.e., 800 trials). When the boundary separating the contrasting categories was unidimensional, the accuracy of all observers improved significantly over blocks (i.e., learning occurred), and all observers eventually responded optimally. When the optimal boundary was diagonal, none of the observers responded optimally. Instead they all used some sort of suboptimal unidimensional rule. In a separate feedback experiment, all observers responded optimally in the diagonal condition. These results contrast with those for supervised category learning; they support the hypothesis that in the absence of feedback, people are constrained to use unidimensional rules.
Adult↗
Comparison of the rates of associative change during acquisition and extinction.
Five experiments used a compound test procedure to compare the rate parameters for the associative changes resulting from reinforcement and nonreinforcement. Experiments 1 and 4, using a magazine-approach procedure in rats, found initial acquisition to proceed more rapidly but to generalize less broadly than extinction. Experiments 2 and 5 repeated these observations in an autoshaping preparation with pigeons. Experiment 3 found no evidence for differential disruption of acquisition and extinction in testing. These results were obtained in a test procedure that compares responding with stimulus compounds in order to remove the differences in overall performance, which have complicated inferences about associative changes in earlier experiments.
Acoustic Stimulation↗
Blind spot "fixation" in normal eyes: implications for eccentric viewing in bilateral macular disease.
Normal subjects were trained to look to the side of a small, flickering target in order to make this target disappear within the physiological blind spot of the right eye. Subsequently, subjects aimed the eye more eccentrically when the target was nearer and less eccentrically when the target was farther than when it was at the training distance of 1.5 m. Thus, the eccentric eye aiming of our subjects represented a compromise between looking to the side of the target by a constant visual angle and by a constant lateral extent. We propose that patients who lose central vision bilaterally may similarly err in trying to aim the diseased macula to one side of targets by a constant visual angle, impeding their ability to use a single, nonfoveal region effectively.
Distance Perception↗
Rod persistence on a partial-report task with scotopic and photopic backgrounds.
Two experiments were undertaken to demonstrate the participation of the rod system under certain stimulus conditions on the partial-report task of iconic memory. In Experiment 1, scotopically matched letter arrays of differing wavelength produced equivalent partial-report superiority but only if relatively large letters and a long cue delay were employed. In Experiment 2, variable photopic backgrounds were employed in contrast to the constant dark background used in the first experiment. For constant luminance targets, photopically matched red and blue-green backgrounds of 5 ftL (15.9 cd/m2) did not produce equivalent partial-report performance. Partial-report superiority was evident at much longer cue delays with the red background. This was attributed to the minimal stimulation of the rod system by this long wavelength background. However, if an intense adaptation field that saturated the rod system were interposed between stimulus trials, the photopically matched backgrounds then produced equivalent partial-report performance at all cue delays.
Color Perception↗
Coarse blobs or fine edges? Evidence that information diagnosticity changes the perception of complex visual stimuli.
Efficient categorizations of complex visual stimuli require effective encodings of their distinctive properties. However, the question remains of how processes of object and scene categorization use the information associated with different perceptual spatial scales. The psychophysics of scale perception suggests that recognition uses coarse blobs before fine scale edges, because the former is perceptually available before the latter. Although possible, this perceptually determined scenario neglects the nature of the task the recognition system must solve. If different spatial scales transmit different information about the input, an identical scene might be flexibly encoded and perceived at the scale that optimizes information for the considered task-i.e., the diagnostic scale. This paper tests the hypothesis that scale diagnosticity can determine scale selection for recognition. Experiment 1 tested whether coarse and fine spatial scales were both available at the onset of scene categorization. The second experiment tested that the selection of one scale could change depending on the diagnostic information present at this scale. The third and fourth experiments investigated whether scale-specific cues were independently processed, or whether they perceptually cooperated in the recognition of the input scene. Results suggest that a mandatory low-level registration of multiple spatial scales promotes flexible scene encodings, perceptions, and categorizations.
Adult↗
Inertia tensor and weight-percept models of length perception by static holding.
S. J. Lederman, S. R. Ganeshan, and R. E. Ellis (1996) reported an experiment demonstrating that for occluded rods of equal mass and length but different diameters length perception by static holding was larger for rods of smaller diameter. They concluded that participants inferred length from illusory weight percepts. However, rods of equal mass and length that differ in diameter also differ in the eigenvalues of their respective inertia tensors. In the present experiments, the authors manipulated the diameters (Experiment 1) and the inertial eigenvalues (Experiments 4 and 5) of statically held objects. As has been shown with wielded objects, perceived length was a function of the eigenvalues. Additional experiments failed to confirm the expectation from the weight-percept model that perceived length maps to the estimated weight (Experiments 2 and 3). Physical quantities, not psychological quantities, seem to explain length perception by static holding.
Adult↗
Perception of enclosure effects of architectural surfaces in a large scale interior space.
It was hypothesized that the perceived enclosure effect of spaces would be dependent upon the explicitness of presented architectural surfaces according to the 1961-1970 model of Thiel. It was also hypothesized that the contribution of the surfaces would adhere to theoretical weights proposed by Thiel. It was further hypothesized that the perceived contribution of the surfaces to enclosure would be similar for men and women. 20 women and 10 men were presented 24 line drawings in one-point, eye-level perspective of the same furnished and occupied interior space. The line drawings differed only in the absence or presence of floor, wall, or ceiling surfaces. On an initial task the spaces represented by the drawings were ordered by the subjects from least enclosed (most open) to most enclosed (least open). In a second task the surfaces in a diagram were ranked according to their relative importance in determining the perception of the enclosing effect. The hypotheses were confirmed, and so provided support for the model that the explicitness of perceived surfaces contribute differentially to the perception of the openness of an environment.
Adolescent↗
Obese individuals' perception of body image.
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Analysis of Variance↗
Effects of nonspatial selective and divided visual attention on fMRI BOLD responses.
Using an uncertainty paradigm and functional magnetic resonance imaging (fMRI) we studied the effect of nonspatial selective and divided visual attention on the activity of specific areas of human extrastriate visual cortex. The stimuli were single ovals that differed from an implicit standard oval in either colour or width. The subjects' task was to classify the current stimulus as one of two possible alternatives per stimulus dimension. Three different experimental conditions were conducted: "colour-certainty", "shape-certainty" and "uncertainty". In all experimental conditions, the stimulus differed in only one stimulus dimension per trial. In the two certainty conditions, the subjects knew in advance which dimension this would be. During the uncertainty condition they had no such previous knowledge and had to monitor both dimensions simultaneously. Statistical analysis of the fMRI data (with SPM2) revealed a modest effect of the attended stimulus dimension on the neural activity in colour sensitive area V4 (more activity during attention to colour) and in shape sensitive area LOC (more activity during attention to shape). Furthermore, cortical areas known to be related to attention and working memory processes (e.g., lateral prefrontal and posterior parietal cortex) exhibit higher activity during the condition of divided attention ("uncertainty") than during that of selective attention ("certainty").
Adult↗
Laterality patterns in young fluent readers.
Neuropsychological profiles of kindergarten children who were reading fluently with understanding were compared with those of both chronological age controls and reading level controls. Finger tapping, dichotic listening, and nonverbal intersensory tasks succeeded in differentiating the two kindergarten groups, but not the kindergarten readers and the older reading level controls. Correlations among the measures were significant only for the young fluent readers, with greater bilaterality of both fine motor and linguistic functions being associated with better intersensory skills, indicating qualitative differences in central nervous system organization. Neuropsychological predisposition to early acquisition of reading is suggested.
Auditory Perception↗
Parallel networks operating across attentional deployment and motion processing: a multi-seed partial least squares fMRI study.
Anticipatory deployment of attention may operate through networks of brain areas that modulate the representations of to-be-attended items in advance of their occurrence through top-down control. Luks and Simpson (2004) (Luks, T.L., Simpson, G.V., 2004. Preparatory deployment of attention to motion activates higher order motion-processing brain regions. NeuroImage 22, 1515-1522) found activations in both control areas and sensory areas during anticipatory deployment of attention to visual motion in the absence of stimuli. In the present follow-up analysis, we tested which network activity during anticipatory deployment of attention is functionally connected with task-related network activity during subsequent selective processing of motion stimuli. Following a cue (anticipatory phase), participants monitored a sequence of complex motion stimuli for a target motion pattern (task phase). We analyzed fMR signal using a partial least squares analysis with previously identified cue- and motion-related voxels as seed regions. The method identified two networks that covaried with the activity of seed regions during the cue and motion-stimulus-processing phases of the task. We suggest that the first network, involving ventral intraparietal sulcus, superior parietal lobule and motor areas, is related to anticipatory and sustained visuomotor attention. Operating in parallel to this visuomotor attention network, there is a second network, involving visual occipital areas, frontal areas as well as angular and supramarginal gyri, that may underlie anticipatory and sustained visual attention processes.
Adult↗