Expectancies and memory retrieval in three-month-old infants.

The ability of 3-month-olds to acquire generalized expectancies of reward and the role of these expectancies in memory retrieval was assessed in 2 experiments. In both, infants learned to activate the components of a crib mobile by kicking and were trained with mobiles containing either the same (invariant) or different (variable) components in successive daily sessions. In Experiment 1, infants exhibited positive transfer over both the invariant and variable stimulus series. However, there was a trend toward disruption of retrieval when infants were tested with a familiar set of components following training on a variable stimulus series. In Experiment 2, infants were trained for 2 sessions with mobile components that either did or did not change between sessions. In a 24-hour retention test, mobile components that either continued or violated the serial order established during the preceding sessions were presented as retrieval cues. Infants again exhibited positive transfer over both variable and invariant series when the test stimulus was predicted by the serial order of training stimuli, but violations of either expected order produced a retention deficit. These results were interpreted as suggesting that very young infants develop generalized expectancies of reward that are based on the serial pattern in which events occur.