Development of Visual Selection in 3- to 9-Month-Olds: Evidence From Saccades to Previously Ignored Locations

Abstract

We examined changes in the efficiency of visual selection over the first postnatal year with an adapted version of a spatial negative priming paradigm. In this task, when a previously ignored location becomes the target to be selected, responses to it are impaired, providing a measure of visual selection. Oculomotor latencies to target selection were the dependent measure. Each trial consisted of a prime and a probe presentation, separated by a 67-, 200-, or 550-msec interstimulus interval (ISI), to test the efficiency of selection as a function of processing time. In the prime, the target was accompanied by a distractor item. In the probe, the target appeared either in the location formerly occupied by the distractor (repeated distractor trials) or in one of the other two locations (control trials). We tested 41 infants in each of 3 age groups (3, 6, and 9 months) on the three different ISIs. Nine-month-old infants' saccade latencies were slowed on repeated distractors relative to control trials, given sufficiently long ISIs. Saccade latencies in the youngest two age groups showed only facilitation on repeated distractor trials at short ISIs. These results suggest that visual selection efficiency is a function of the interaction of the processing limitations of a system with environmental conditions, in this case the time allotted for the selection process.

Figure 1

This schematic model depicts the theoretical time course of excitation and inhibition, beginning at display onset and proceeding postoffset, for both the target and distractor items. Adapted from Houghton and Tipper (1996), with permission from the publisher.

Figure 2

The two types of trials presented to infants. Each trial consisted of two presentations, a prime and a probe. In the repeated distractor probe display, the target appeared in a location occupied by the distractor in the prime. In the control probe display, the target appeared in one of the other possible locations outlined by the grid. The dashed lines represent the observer’s point of gaze. Adapted with permission from Amso and Johnson (2005).

Figure 3

Repeated distractor and control saccade latency data for infants in each of the three ISI conditions. Only 9-month-olds provided reliable evidence of spatial negative priming. Three- and 6-month-old infants showed only facilitation.

Figure 4

Proportion of looks to the distractor during the prime display. Three-month-olds looked reliably more often at the distractor than did either 6- or 9-month-old infants, suggesting greater susceptibility to interference.