Acceptance of lack of closure: is it an index of advanced reasoning?

Lunzer reported data suggestive of a stage of cognitive development manifest between 9 and 11 years of age characterized by the ability to avoid drawing premature inferences when faced with ambiguity (i.e., accept lack of closure [ALC]). The present study sought to test this hypothesis. Inference tasks emphasizing ALC, memory, and hypothetico-deductive reasoning were administered to 67 males and 74 females (5-12 years in age). Although use of ALC increased with age, considerable use was evidenced on a simple task among 7-8-year-olds. On tasks hypothesized to place increasing demands on working memory, longer tasks were found to be more difficult. Marked improvement due to memory aids suggested that task difficulty results from limitations in working memory as predicted by Pascual-Leone's theory. Tasks requiring hypothetico-deductive reasoning were found to be most difficult. Performance was related to subject's spontaneous use of ALC. Lack of appropriate strategies was hypothesized to prevent solution rather than lack of logical competence. In conclusion, the relationship of ALC to age appears to be mediated by memory development rather than logical development.