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Biomedical subjects

O Braddick

Publications and source records attributed to O Braddick.

72 records · Page 4Linked to original sources
PubMed1979

Contrast sensitivity of the human neonate measured by the visual evoked potential.

Visual evoked potentials (VEPs) were recorded from a total of 97 1- to 10-day-old infants, with phase-reversing sinusoidal grating stimuli. The grating contrast or spatial frequency for which 50% of infants gave a statistically significant VEP was taken as a measure of threshold. This procedure yielded an estimate of neonatal acuity of 0.85 cycles/degree and an optimal contrast threshold of 50%. VEPs from an older infant showed good agreement with behavioral measures of sensitivity on the same individual. Comparison of the neonatal VEP results with behavioral data from 5-week-old infants, suggests little change in visual performance over the first month of life.

Evoked Potentials↗
PubMed1978

Infant astigmatism measured by photorefraction.

Photorefraction of a sample of 93 infants of ages 1 day to 12 months showed that 63 percent of the subjects had astigmatism of 0.75 diopter or greater, and 12 percent greater than 2 diopters. Seventy percent of these astigmatisms were in the horizontal-vertical meridians. By comparison, only 8 percent of a sample of 26 adults tested by the same method showed astigmatism (all 0.75 to 1 diopter). The high incidence of infant astigmatism has implications for critical periods in human visual development and for infant acuity.

Adult↗
PubMed1976

Steroscopic discrimination in infants.

The ability to make discrimiations of binocular disparity was investigated in 2-month-old infnats by two methods: (a)fixation preference between patterns differing in the disparity they contained, and (b)recovery from habituation of high-amplitude sucking when there was a change in disparity in the visual reinforcer. The stimuli were random-dot steregrams. The results for both mthods indicated that at least some infants of this age could perform steroscopic discriminations and that both techniques were feasible for development for longitudinal studies of steroscopic vision.

Depth Perception↗
PubMedDate not supplied

Visual hyperacuity.

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Depth Perception↗