The A-not-B Error: Object Permanence and Infant Working Memory

Between roughly 8 and 12 months, infants pass through one of the most famous demonstrations in developmental psychology: shown a toy hidden repeatedly at location A, then watched it hidden at a new location B, they often still reach back to A. This simulator models that classic Piagetian "A-not-B error" as a competition between an exponentially decaying working-memory trace for the object's new hiding place and a learned reaching habit toward the old one, following the working-memory-plus-habit account developed by Adele Diamond and later formalised by Yuko Munakata's connectionist models. Adjust the simulated infant's age, the delay before it is allowed to search, and how many times it previously found the toy at A, then run trials and watch the live memory and habit gauges race to decide — correctly at B, or perseveratively at A — exactly as real infants do in the lab.