Effect of reinforcement on infants' performance in a preferential looking acuity task.

Two experiments examined the effect of reinforcement on infants' performance in a preferential looking acuity task. In experiment 1, performance of 3- and 5-month-old infants was assessed under three conditions. In one condition, reinforcement was contingent upon performance. In another, no reinforcement was provided. In the last condition, reinforcement was provided, but it was not contingent upon performance. Similar performance was observed in all three conditions. In experiment 2, 7-month-olds were tested in the first and second conditions. No differences in performance were observed between these two groups. Thus, the reinforcement used in preferential looking measurements does not appear to improve performance significantly for 3- to 7-month-old infants. Several interpretations of these results are presented. The most plausible is that performance under nonreinforced conditions is already nearly optimal, so the addition of reinforcement has little impact. General implications for estimates of infant visual sensitivity in the laboratory and clinic are discussed.