Area-threshold relations at controlled retinal locations in 1-month-old infants.
A fixation-and-flash technique has been developed to provide control over the retinal eccentricities of stimuli presented to infant subjects, to within a few degrees of visual angle. The technique is a variant of forced-choice preferential looking (FPL). An adult observer triggers presentation of the test stimulus when she judges that the infant is fixating a centrally located fixation target. The stimuli are short in relation to the infant's refixation latency. Auxiliary experiments confirmed that on most trials the stimuli fell within +/- 4 degrees of the designated eccentricity. Test fields of two sizes, 3.1 and 17 degrees, were presented to 1-month-old infants at one of four retinal locations, 9, 18, 27 and 36 degrees eccentric. The infants' data show a perfect area-intensity tradeoff at all four locations. Adult control subjects showed summation over areas of only 1-2 degrees. The results are discussed in relation to other evidence of coarse spatial processing in human infants and other immature mammalian systems.
D000328:Adult; D003623:Dark Adaptation; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D007223:Infant; D008297:Male; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*