A comparison of children's performance on two recognition memory tasks: delayed nonmatch-to-sample versus visual paired-comparison.

Although 4- to 6-month-old children have a significant tendency to look at new stimuli in a visual paired-comparison task (VPC), they have difficulty in consistently choosing novel objects in a delayed nonmatch-to-sample task (DNMS). To evaluate which factors could account for this difficulty, we tested human infants (10-107 months) and adults (17-25 years) in a DNMS task while monitoring eye fixations. The results indicated that children at all ages reliably looked at (VPC scores) or chose (DNMS scores) the new stimuli about 60% of the time, indicating that both tasks measure visual recognition memory. A videotape analysis of visual attention revealed that children younger than 22 months, but not older children, spent significantly more time visually exploring the objects rather than looking at the food reward under it. Although this visual attraction to objects in children younger than 22 months of age may have impaired the formation of stimulus-reinforcer association needed to solve the DNMS task, this was not the case for older children, since beyond 22 months of age children consistently looked at the reward while displacing the objects. These results suggest that other cognitive abilities required by the DNMS task may not be fully functional even in children 22 months and older.