The abstraction and long-term retention of ill-defined categories by children

The acquisition, utilization, and long-term retention of ill-defined categories was assessed in 10.8-year-old children. Children initially classified 18 distorted form stimuli into three categories containing 3, 6, and 9 members, and then received transfer tests immediately following classification, one week later, and one month later. On the transfer tests, old, new, prototype, and unrelated forms were presented, and the subjects had available an optional junk category. The results showed that classification of new instances at all levels of distortion was unaffected by a month’s delay, with classification of the prototype and new instances strongly facilitated by increases in category size. The acquired breadth of these concepts was stable across the month’s delay. A comparison with adult performance in a highly similar task revealed no qualitative differences.