A longitudinal study of visual expectation and reaction time in the first year of life.

Developmental change and stability of visual expectation and reaction times (RT) were examined at 5, 7, and 12 months in a longitudinal sample of term and preterm infants (birthweight <1,750 g). Using the traditional 200-ms cut-point to separate anticipatory from reactive saccades, RTs (and their standard deviations) declined markedly over age, whereas anticipations increased. Those infants who had faster RTs were more likely to anticipate upcoming events and were more attentive (fewer trials off-task and less response variability). Crossage stability was modest for most measures from 5 to 7 and 7 to 12 months, but rarely significant from 5 to 12 months. When the cut-point was lowered to 150 ms (to accommodate recent concerns that the higher cut-point may misclassify some true RTs as anticipations), the age-related increase in anticipations disappeared. Thus, although the results indicate marked increases in processing speed with age, evidence for increasing anticipations is equivocal. Findings were similar for preterm and term infants.