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Biomedical subjects

C Porac

Publications and source records attributed to C Porac.

52 records · Page 3Linked to original sources
PubMed1980

Life-span age trends in laterality.

Laterality of hand, foot, eye, and ear was measured in a sample of 1964 subjects, ranging in age from 8 to 100 years. Age trends were found, with hand, foot, and eye preference becoming more right-sided and ear preference becoming more left-sided with increasing age. Sex differences emerged in foot, eye, and ear preference but these did not systematically interact with the age variable. Several causal mechanisms are proposed but none can fully explain either the direction or the magnitude of the observed age changes. Thus, these data are most consistent with the view that the study of sidedness in humans should proceed with a consideration of a complex of underlying factors and individual difference variables.

Adolescent↗
PubMed1979

Normative data on hand position during writing.

It has been suggested that inverted versus upright handwriting position is an indicator of cerebral lateralization and the pattern of neuromotor control. Normative data on the prevalence of these handwriting positions was collected from 1758 subjects ranging in age from 10 to 75 years. Both age and sex differences in the prevalence of inverted handwriting positions were found.

Adolescent↗
PubMed1979

Heritability in visual-geometric illusions: a family study.

The Müller-Lyer and Ebbinghaus illusions were tested in 203 mother-father-offspring triads and 303 sibling pairs. Significant familial resemblances were found in all but the overestimated segment of the Ebbinghaus illusion. These results suggest that responses to visual-geometric illusions, mediated by optical or neural interactive mechanisms, show patterns of familial resemblance which may be based upon heritable factors.

Family↗
PubMed1979

Visual-geometric illusions: unisex phenomena.

The possibility of sex differences in responses to visual-geometric illusions was investigated with the use of forty-five illusion variants and a sample of 221 observers. No difference in illusion magnitude as a function of sex was found. A second experiment measured illusion decrement and transfer of decrement to other illusion configurations. Again there were no significant differences between male and female observers.

Female↗
PubMed1978

Iris pigmentation and visual-geometric illusions.

Blur or degrading of the retinal image has been shown to be a factor in the formation of visual-geometric illusions where intersecting line elements are present. Light irises allow more scattered light within the eye, which results in more image degradation than found in dark-eyed subjects. Measurements on 755 observers show that illusion magnitude varies as a function of iris pigmentation for a configuration with intersecting line elements (Müller-Lyer illusion), but not for a configuration devoid of such features (Ebbinghaus illusion).

Eye Color↗
PubMed1978

Sighting dominance and binocular rivalry.

Two experiments are reported that attempt to explore systematically the role of sighting dominance during binocular rivalry. Experiment 1 showed that the sighting eye tends to display longer total viewing time, and experiment 2 indicated that this asymmetry remained even when observers had increased experience with rivalrous stimulation. Additional analysis revealed that the average dominance period of the sighting eye was longer than that of the nonsighting eye, resulting in significant sequencing effects during the rivalry process.

Depth Perception↗
PubMed1977

Fifty centuries of right-handedness: the historical record.

A survey of more than 5000 years of art work, encompassing 1180 scorable instances of unimanual tool or weapon usage, revealed no systematic trends in hand usage. The right hand was used in an average of 93 percent of the cases, regardless of which historical era or geographic region was assessed.

Art↗
PubMed1977

The case for misapplied constancy scaling: depth associations elicited by illusion configurations.

It has been suggested that many visual-geometric illusions arise from inappropriate evocation of size-constancy by depth cues implicit in illusion configurations. Observers gave free association responses while viewing illusion figures. Analysis of these responses provides weak but consistent evidence for the elicitation of depth in the Sander parallelogram, Mueller-Lyer, Zoellner, and Ehrenfels variant of the Ponzo illusion. No evidence for depth is found in the normal form of the Ponzo, Poggendorff, and horizontal-vertical illusions, and the evidence is ambiguous in the Orbison configurations. These results indicate that depth processing may be evoked by some, but not all, classical illusion forms.

Cues↗
PubMed1976

The dominant eye.

Explore the source record for details and available documents.

Dominance, Cerebral↗
PubMed1975

Suppressive processes in binocular vision: ocular dominance and amblyopia.

Recent suggestsions linking suppression observed in amblyopia ex anopsia with that manifested in normal ocular dominance coordinations were experimentally tested. Training procedures which normally alleviate functional amblyopic suppression were shown to have similar results in alleviating the suppression of the nondominant eye in visually normal observers. Methodological and theoretical implications of these results are discussed.

Adult↗
PubMed1975

Is eye dominance a part of generalized laterality?

The laterality of eye and limb do not appear to be generally correlated as measured in 160 observers using a graded index. Sex differences emerge indicating more consistent eye and limb preferences as well as stronger eye dominance scores in male subjects. In addtiion, better consistency is found for right-eye dominants than for left. This pattern of results permits some inferences to be made about the role of the environment in determining the dominant eye and hand.

Dominance, Cerebral↗