Philip Salapatek

Developmental changes in the scanning of faces by young infants.

6 1-month-old infants and 6 2-month-old infants each viewed 3 faces (his mothers, a strange womans, and a strange mans) while his eye movements were recorded by corneal photography. The 1-month-olds fixated away from the faces most of the time, and they looked at their mothers even less often than at the strangers. When they did fixate a face, they usually chose a limited portion of the perimeter. By constrast, 2-month-olds fixated the faces most of the time, looked at more features, and were more likely to look at internal features, especially the eyes. This scanning resembles that reported previously for 2-dimensional shapes, although in some respects it appears unique to faces.

Saccadic localization of visual targets by the very young human infant

The direction, latency, and form of the 1- and 2-month-old human infant’s saccadic eye movements toward peripheral targets were investigated. Infants of both ages reliably executed a directionally appropriate first saccade toward a peripheral target introduced as far as 30 deg from the line of sight along the horizontal and both diagonal axes, but only to 10 deg along the vertical axis. The presence of a second target in the central visual field reduced the probability of peripheral target localization. A significant inverse relation was found between target distance from the line of sight and probability of initiating a directionally appropriate saccade. Electro-oculography revealed that latency to first saccade, although highly variable, was less than 500 msec on a significant proportion of trials. Unlike the adult, the first saccade to target was grossly hypometric and was followed by one or more saccades of approximately equal amplitude to the first.

Contrast sensitivity function of the infant visual system.

Abstract The response of the human infant visual system to sinewave gratings of various spatial frequencies was measured. The contrast sensitivity functions obtained are an estimate of the spatial information available to the infant. Evidence for lateral inhibitory processing was found. The implications of the results for the development of form perception are discussed

The visual response of the human newborn to linear contour

Abstract The visual response of 16 newborn infants to a black-white edge and to a blank homogeneous field was recorded by corneal-reflection photography. Each infant was presented the edge once in a vertical orientation, to the left or right of center, and once in a horizontal orientation, above or below center. Vertical edges clearly attracted the newborns gaze but horizontal edges appeared to have no effect whatsoever. Various interpretations are offered for the greater attractiveness of vertical edges and some preliminary data on scanning patterns are discussed.

The coordination of eye and head movements during early infancy: a selective review.

A review of work dealing with the human infants ability to use coordinated eye and head movements is presented. Primary emphasis is given to performance under two conditions: (1) the shifting of fixation to a visual stimulus in the periphery; and (2) the use of eye movements to maintain fixation by compensating for the effects of externally imposed head movements.

Prolonged investigation of a plane geometric triangle by the human newborn

Abstract Five human newborns were presented with a plane geometric triangle repeatedly on the same day and across days. Eye fixations and eye movements to within approximately ±3–4° were recorded by means of corneal photography. There were marked individual differences in the form of visual scanning on the figure. Some infants consistently oriented towards only a single feature while others alternated between single and multiple feature selection. Postnatal age or exposure alone did not appear to guarantee either response.

The effect of change in a stimulus sequence on P300

In past studies, the P300 amplitude of the ERP has been found to be enhanced for infrequent, unpredictable and/or task-relevant eliciting events. A fourth factor, namely the physical change between two consecutive stimuli in event sequences used, has often been confounded with frequency, predictability and relevance. The current study examined whether change also increases the P300 amplitude. Fourteen adults viewed sequences of slides in which predictability, task (counting) and change varied within subject. ERP was recorded at Cz, Pz, Oz and Fz. P300 amplitudes were significantly larger: (1) for unpredictable than for predictable events, (2) for counted than for non-counted stimuli, and (3) for stimulus change rather than no stimulus change. The change effect interacting with counting suggested that P300 amplitude may be particularly increased by stimulus changes imbedded within only certain cognitive tasks.

The 4-month-old infant’s perception of holograms and real objects: A demonstration of equivalence

Three experiments were conducted to determine whether 4-month-old infants perceive and respond to holograms as real objects. Infants in the first experiment failed to differentiate between a hologram of a toy car and the real car from which the hologram was constructed. In a second and third experiment, infants responded to holograms of two objects as they did to the real objects. The implications of using holograms in the study of early perceptual development are discussed.