Tower of Hanoi and working memory in adult persons with intellectual disability

Persons with intellectual disability (ID) have been found to perform more p oorly than their mental age would suggest in the visuo-spatial problem solv ing task Tower of Hanoi (TOH). Inefficient performance has been assumed to be related to inability to use sophisticated problem solving strategies bec ause of restricted working memory capacity. In the present study, the TOH p erformance of adult persons with ID was found to be equal to that of fluid- intelligence-matched general children. However, persons with ID violated th e rules of the TOH more often, and needed more trials to solve the TOH prob lems than the children did. Visuo-spatial and executive working memory task s were significantly connected to the TOH performance of persons with ID, w hereas phonological working memory tasks were not. Poor inhibition ability was related to the poor performance of subjects with ID in the TOR We sugge st that for persons with ID, TOH performance is determined by individual di fferences in fluid intelligence, controlled attention, and inhibition abili ty. (C) 2001 Elsevier Science Ltd. All rights reserved.