Changes in children's categorization behavior between 15 and 21 months of age and the relation of these changes to developments in language, object permanence, and means-end understanding are reported. (PCB)

Recent studies on the biological development of the prefrontal cortex in rhesus monkeys are reviewed. These studies have elucidated the basic neural circuitry underlying the delayed-response function in adult nonhuman primates and suggest that a critical mass of cortical synapses is important for the emergence of this cognitive function. (BN)

Reports two experiments in which eight patients with organic memory disorders exhibited a pattern of search behavior that resembled mnemonmic precedence--the ability to retrieve an object at an initial location, but not at a new location. (HOD)

Investigates whether 6- to 12-month-old infants' exposure to the successful search behavior of a sibling in two object-concept tasks would enhance infants' subsequent performance on these tasks. (HOD)

Compares two types of semantic development (the acquisition of disappearance words and success-failure words) to performance on two types of cognitive tasks (object-permanence and means-ends tasks) among infants. (HOD)

Twenty-five infants were tested every two weeks on the AB Object Permanence Task, from the time they first reached for a hidden object until they were 12 months old. Results indicate that the AB provides an index of the ability to carry out an intention based on stored information despite a conflicting habitual tendency. (Author/RH)