Infant long-term retention of a visual discrimination

333 INFANT LONG-TERM RETENTION OF A VISUAL DISCRIMINATION Marjorie Carroll, Jeffrey Fagen, Adriana France, and Jennifer Byrnes Department of Psychology, St. Johns University, Jamaica, NY 11432 In their everyday functioning, infants are continually confronted with a multitude of stimuli in their environment. Their ability to effectively discriminate and use features of stimuli as cues for adaptive behavior has repeatedly been demonstrated by researchers interested in discrimination learning in infancy. However, despite the fact that extended learning is basic to most theories of child development, the retention of acquired discriminations by infants has received little attention. In the present study, the mobile conjugate reinforcement task was used to investigate the long-term retention of an acquired visual discrimination by 3-month-old infants. In the first training session, all infants learned to produce movement of an overhead mobile (Sl) by kicking one of their feet. During a second training session, the infants received alternating presentations of two mobiles (Sl and S2). During this session, two mobile stands were used, each positioned on either side of the crib. One was designated as the active stand and was always associated with reinforcement; the other stand served as the inactive stand, that is, when the mobile was on that stand it never moved in response to the infants’ kicks. For the experimental group, this constituted the discrimination training phase because S 1 (S +) was associated with reinforcement whereas no reinforcement was available in the presence of S2 (S-). During this period, the control group received contingent reinforcement in the presence of both mobiles. Retention was assessed 1, 3, or 5 days following completion of discrimination training. Consistent with previous infant discrimination learning research, the experimental group responded more in the presence of S+ than S-. No evidence of differential responding was observed in the control group. Unexpectedly, retention of the discrimination was not observed at any of the retention intervals (1, 3, and 5 days). Further, not only did the infants in the experimental group fail to continue to respond differentially to the two mobiles at any of the retention intervals, they also did not demonstrate retention of the footkick-mobile movement contingency at 1 and 3 days. However, at 5 days following discrimination training, these infants exhibited good retention of the contingency. It is hypothesized that the infants in the experimental group learned how to “solve” the discrimination based on positional rather than stimulus-based information. Because the infants did not have to attend to the specific details of either mobile in order to solve the discrimination, these details may not have become part of their memory for the discrimination. Thus, when presented with a nonmoving mobile on the inactive stand during the retention test, the memory that was cued was that their kicks would be ineffective. However, at 5 days, the memory of the discrimination phase had faded and the memory of the contingency was accessible. Although the control group showed retention of the contingency at 1 and 3 days, they failed to demonstrate retention at 5 days. It is hypothesized that the training experience of Session 2 modified the original training memory causing it to be less accessible at a longer retention interval.