Search PubMed⌕ Search

Biomedical subjects

A Yonas

Publications and source records attributed to A Yonas.

27 records · Page 2Linked to original sources
PubMed1982

Infants' sensitivity to familiar size as information for distance.

2 experiments tested the effectiveness of familiar size as information for perceived distance. In Experiment 1, under monocular viewing conditions, adults judged the distances to large and small (34.2 cm and 16.9 cm high) photographs of faces and to large and small checkerboard ovals equal to the faces in size. Familiar size influenced subjects' distance estimates. The small faces were judged to be more than twice the distance of the large faces. No significant difference was found between the judged distances to large and small checkerboards. In Experiment 2, the same displays were presented to 5- and 7-month-old infants. Faces were viewed either monocularly or binocularly; checkerboards were viewed monocularly. Duration of reaching was observed as a measure of perceived distance. 7-month-olds gave clear evidence of sensitivity to familiar size. In the monocular-face condition, the difference in duration of reaching to the large and small faces was significantly larger than in either the binocular-face condition or the monocular-checkerboard condition. This indicates that infants were not simply reaching to large faces or large objects without regard to spatial information. Rather, these results indicate that they perceived the large faces to be within reach and the small faces to be beyond reach in the monocular condition. 5-month-olds failed to provide evidence of sensitivity to familiar size.

Age Factors↗
PubMed1979

The role of frames of reference in the development of responsiveness to shading information.

The use of frames of reference in interpreting shading information in pictures was studied with children from 3 to 8 years of age. After learning to discriminate tactually between a convexity and a concavity, the subjects were presented a photograph of the convexity and the concavity in which the only information for differential shape was provided by the relationship between the orientation of the shading on the shapes and the frames of reference. By changing the position of the subject's head, rotating the display, and changing the location of the source of illumination, the relevance of egocentric, environmental, and lighting-specified frames of reference was manipulated. Children in this age range were found to be sensitive to shading information for depth, both when that information was specified by only a single frame of reference and when all three frames of reference were relevant. Differences in the responsiveness to individual frames of reference were found: the egocentric (head-retina) frame of reference was most effective, followed by the environmental reference frame, and finally by the frame of reference based on the location of the light source in the space surrounding the photograph. Responsiveness to the environmental and lighting-based frames of reference increased with age, while responsiveness to the egocentric frame of reference was high for all age groups and did not increase with age.

Child↗
PubMed1978

Development of sensitivity to pictorial depth.

Sensitivity to static pictorial information for depth develops between 22 and 26 weeks of age. When conflicting binocular and surface-texture information was minimized, 26- to 30-week-old infants directed their reaching to the apparently closer side of a photograph of a window rotated in depth. Younger infants, from 20 to 22 weeks of age, did not direct their reaching to the pictorially nearer side of the display but did reach with a high degree of directionality when presented with a real window rotated in depth.

Behavior↗
PubMed1978

The effects of the reader's skill and the difficulty of the text on the perceptual span in reading.

Development of the perceptual span in reading was investigated by varying the availability of graphic information in the periphery of vision. Low-ability eighth-grade readers, high-ability eighth-grade readers, and skilled adult readers read texts presented in a normal prose format, with a single space between words, and texts typed with 13 letter spaces between words. It was found that removing peripheral information by wide spacing improved comprehension for low-ability eighth graders but did not affect their overall reading efficiency (the number of questions answered correctly per minute of reading time). Wide spacing decreased the reading efficiency of high-ability eighth-grade readers and skilled adult readers. In addition, the texts were of two levels of difficulty. It was hypothesized that subjects would employ a larger span of perception with the easy text. Surprisingly, the wide spacing of words did not produce greater decrement fo reading efficiency with the easy text. The findings thus suggest that the perceptual span may increase as reading skill develops but does not change under the influence of momentary task variables.

Achievement↗
PubMed1978

Development of sensitivity to information provided by cast shadows in pictures.

The shadow cast by an object in a two-dimensional picture can specify for the observer the spatial relations between that object and its surroundings, and also the shape and size of the object itself. Some sensitivity to this information is present even in three-year-old children. Experiment 1 provided evidence that three- and four-year-old children can rely on the shape of the shadow cast by an object to judge the shape of the object. In experiment 2, with adults and three- and four-year-old children, the location of the shadow cast by an object influenced the perceived depth and height off the ground plane of the object. Although even the three-year-old children were sensitive to the location of the cast shadows, there was evidence of improvement with age in judging the distance and size of the object. The three-year-olds were not able to judge the object's size when the location of the cast shadow provided the only differential information for size. In contrast, they were significantly better in judging size when the location of the object, rather than the location of the shadow, was varied.

Adult↗
PubMed1976

Radial localization of odors by human newborns.

To study sensitivity to radial location of an odor source, 20 human newborns, ranging from 16 to 130 hours of age, were presented with a small amount of ammonium hydroxide. The odor source was placed near the nose slightly to the left or right of midline, with its position randomized over repeated trails. Direction of headturn with respect to the odor location and diffuse motor activity were scored from the videotape recordings of the newborns' behavior. It was found that as a group, the newborns turned away from the odor source more frequently than they turned toward it. The tendency to turn away from the odor was stronger in infants who displayed less motor activity after the response. Newborns also exhibited a right bias in the direction of the head movements. It is concluded that a spatially appropriate avoidance response is present in the neonate and that the newborn is innately sensitive to the radial location of an odor.

Female↗