Development of preterm and full-term infant ability on AB, recall memory, transparent barrier detour, and means-end tasks.

10 preterm and 10 full-term infants were tested longitudinally from 28 to 60 weeks of age on a modified version of the AB task, a nonreaching AB task, a Barrier Detour task, a Means-End task, and Perseveration in the Means-End task. Results show that age-corrected (age since conception) premature infants tolerated longer delays than full-term infants on the modified and nonreaching AB tasks. However, when compared by chronological age (age since birth), there were no group differences on either the reaching or nonreaching AB task. No group differences were found on Barrier Detour, Means-End, or Perseveration in either the age-corrected or chronological age comparisons. The results suggest that the function that mediates modified AB performance is one of memory and not of perseveration or means-end ability. Further, these findings suggest that current proposals about brain development based on single samples of infants may be tenuous. Finally, the results of this study suggest that development of the brain structure(s) that mediate modified AB performance is strongly influenced by experience in the postnatal environment.