Sex differences and menstrual cycle effects in human spatial memory

A typical test of spatial memory requires subjects to relocate a number of objects in their original, previously studied positions. Tt has been argued that this rest includes multiple separate processing components (Postma, A ., De Haan, E.H.F., 1996. Quarterly Journal of Experimental Psychology 48A (1), 178-199. Postma, A.: Izendoorn, R., De Haan, E.H.F.,., 1998. Brain and Cognition 36, 334-345). One has to encode the precise positions occupied, assign the various objects to the correct (relative) locations, and achieve an integration of both types of spatial information. The present study exa mined the presence of sex differences and the role of hormonal factors for these selective components of spatial memory. A computerised, immediate (wo rking) memory version of the test was used, comparing 23 males and 34 femal es on three experimental conditions: positions only, object-to-position-ass ignment, and the combined condition, requiring integration of the other two components. In line with previous research (Postma et al., 1998) males sho wed a selective advantage for fine-grained, metric positional reconstructio n (i.e. positions-only). Interestingly, a within-subjects comparison in the females only revealed a menstrual cycle effect for exactly the same dimens ion of spatial memory. In the nonmenstrual phase, females were better than during menstruation. This dearly implies a role for sex hormones in spatial memory, even though a subsequent analysis of testosterone samples in saliv a did not reveal a significant correlation with measures of spatial memory in both males and females. (C) 1999 Elsevier Science Ltd. All rights reserv ed.