Performance on Piagetian horizontality and verticality tasks: Sex-related differences in knowledge of relevant physical phenomena

College women consistently perform worse than college men on tasks devised by Piaget to assess children's horizontality and verticality concepts. To determine if these sex-related differences are due to inadequate knowledge of the behavior of water and plumb lines (performances) rather than to immature spatial concepts (competence), 80 male and 80 female college students in Study 1 received the tasks (a) with or without pictorial examples and (b) with or without a verbal rule concerning the relevant physical phenomena. As predicted, main effects for sex and rule were significant, although the pictorial example had no effect. Contrary to expectations, the rule did not lead females to perform as well as males. In Study 2, 80 male and 80 female college students received the tasks with or without the rule, but here the rule was presented more emphatically. Following the tasks proper, all Ss were asked to explain what rule (if any) they had used in answering. In the no-rule condition, males' and females' score distributions differed significantly, as did the types of explanations offered. In the rule condition, neither score distribution nor explanations differed significantly by sex. Results are consistent with a performance interpretation of females' difficulty on standard Piagetian tasks, and, taken with Study 1, demonstrate the importance of central rather than incidental presentation of the relevant information. (15 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).