Infant learning and long-term memory at 6 months: a confirming analysis

In three experiments, we tested the generality and validity of prior evidence of delayed recognition, memory reactivation, and retrieval specificity at 6 months of age using a new operant task. In Experiment 1, the forgetting function was found to be 2 weeks but not 3, the same as previously obtained using the mobile conjugate reinforcement task. In Experiment 2, a reactivation treatment with the original cue (train set) in the original context (room in the home) recovered the memory but was ineffective when either was changed. These results also confirmed prior findings but expanded the manipulation of context to include the place where training occurred. Following a reactivation treatment, infants in Experiment 3a failed to recognize the original cue in a different context, as before, but generalized to a different cue in the original context. Because the latter test condition was novel, a comparison group was trained in the mobile task and tested with a different mobile in the original context 1 day after a reactivation treatment (Experiment 3b); this group failed to recognize the mobile. The disparity in these outcomes was attributed to the salience of features common to the two train sets. Taken together, these findings demonstrate that, for the same parameters of training and testing, memory performance at 6 months is task-independent.