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Biomedical subjects

G W Bronson

Publications and source records attributed to G W Bronson.

9 recordsLinked to original sources
PubMed1994

Infant's transitions toward adult-like scanning.

Visual scanning patterns of 6-13-week-old infants are derived from some 50 half-minute assessments in which the infants viewed static geometric figures. Measures include fixation dwell-times, saccade lengths, and the choices and sequences of saccadic targets. From the patterns of change across 3 age periods, it appears that as infants grow older an initial salience-guided scanning increasingly is replaced by volitional control over the choice of saccadic targets. The change tentatively is attributed to neural developments within later stages of the infant visual system.

Age Factors↗
PubMed1991

Infant differences in rate of visual encoding.

To clarify the basis for infant differences in rate of visual encoding, the eye movements of a sample of 9 12-week-old infants were recorded throughout an encoding experiment. Results showed that the more slowly encoding infants scanned less extensively over the stimulus, often spent extended intervals in the continuous inspection of one part of the figure, and frequently engaged in prolonged fixations. A second experiment provided comparable scanning data from a sample of 9 2-week-old infants. There were significant age differences in the manner of visual scanning, and the scanning style of the more slowly encoding 12-week-old infants proved to be more like that of the younger infants. Possible explanations for both the between-age and within-age differences are proposed.

Age Factors↗
PubMed1990

The accurate calibration of infants' scanning records.

The visual scanning characteristics of 10 infants were assessed repeatedly over the 2- to 14-week age period, using a bright-pupil/corneal reflection technique. The present report focuses on the calibration process--a procedure by which stimulus figures are mapped onto the raw scanning data. It is concluded that the major calibration parameters vary significantly among infants, and therefore separate calibration data must be collected on each infant if errors on the order of several degrees of visual angle are to be avoided. Moreover, it was found that infants' saccades often are not directed accurately toward the attracting stimulus, and hence repeated calibration trials are required for the precise determination of parameter values. After about 6 weeks of age, the parameter values established for a given infant remained largely invariant. During the initial weeks of life, however, parameter values occasionally changed, apparently because very young infants sometimes will center the image of an attracting stimulus about some extrafoveal location. This raises an additional complexity when interpreting the scanning records of very young infants.

Age Factors↗
PubMed1990

Changes in infants' visual scanning across the 2- to 14-week age period.

The characteristics of visual scanning over the 2- to 14-week age period were examined through repeated assessments conducted on a sample of 10 infants. Scanning patterns were measured using a bright-pupil corneal reflex system, and the stimuli consisted of various sets of static, moving, or flickering geometric figures. There appear to be a number of age-related changes in the dominant mode of visual scanning. At the youngest ages the infants' scanning often proved unrelated to the locations of the stimulus contours, and in instances where a stimulus figure was in fact attended the infants typically centered their regard on a single prominent feature. In contrast, as the infants grew older they more consistently directed their saccades toward stimulus contours, became increasingly disposed to scan between different stimulus features, and directed their saccades with increased accuracy. When a stimulus was flickering, however, the infants' scanning characteristics reverted to those typically found at younger ages. The mechanisms which might account for the effects of age and of stimulus quality on visual scanning are considered.

Age Factors↗
PubMed1977

On the distinction between fear and wariness.

The study seeks to illuminate the mechanisms that mediate avoidant reactions in young humans. 40 babies repeatedly were observed throughout their second year in a variety of mildly challenging situations, and then again in a series of follow-up assessments at age 3 1/2. Analysis of the covariance patterns among the repeated measurements supports positing 2 distinct types of avoidant mechanism--an inclination to be "wary" of the unfamilar, and a proclivity to be "fearful" after exposure to a mildly difficult situation. Each type of phenomena constituted an independent source of individual differences. Behaviors that differed as a result of prior experience proved fairly predictive of future social orientations; variations in initial wariness did not.

Adaptation, Psychological↗