Negative affect, emotional expression, and forgetting in young infants.

Ss were trained for 3 days to move an overhead mobile containing 10 objects, changed to 2 objects during the 3rd session. The change resulted in crying in half of the Ss. A retention test was given 1 or 7 days later. Measures of facial expressions during nonreinforcement phases at the outset of each session showed that interest was the predominant expression. Interest decreased and surprise increased during the 3rd session and continued into the 4th sesson for Ss in the 1-day retention group. When shifted to the 2-object mobile, criers exhibited decreasing interest and increasing anger and sadness as their state escalated toward crying. Consistent with earlier research, all Ss showed retention at 1 day, but only noncriers exhibited retention at 7 days. Criers displayed significantly more anger than noncriers during the 1- but not the 7-day retention test