Men and Women Exhibit a Differential Bias for Processing Movement versus Objects Robert F. McGivern1*, Brian Adams 1 , Robert J. Handa2, Jaime A. Pineda3 1 Department of Psychology, San Diego State University, San Diego, California, United States of America, 2 Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, United States of America, 3 Department of Cognitive Science and Neuroscience, University of California San Diego, La Jolla, California, United States of America Abstract Sex differences in many spatial and verbal tasks appear to reflect an inherent low-level processing bias for movement in males and objects in females. We explored this potential movement/object bias in men and women using a computer task that measured targeting performance and/or color recognition. The targeting task showed a ball moving vertically towards a horizontal line. Before reaching the line, the ball disappeared behind a masking screen, requiring the participant to imagine the movement vector and identify the intersection point. For the color recognition task, the ball briefly changed color before disappearing beneath the mask and participants were required only to identify the color shade. Results showed that targeting accuracy for slow and fast moving balls was significantly better in males compared to females. No sex difference was observed for color shade recognition. We also studied a third, dual attention task comprised of the first two, where the moving ball briefly changed color randomly just before passing beneath the masking screen. When the ball changed color, participants were required only to identify the color shade. If the ball didn’t change color, participants estimated the intersection point. Participants in this dual attention condition were first tested with the targeting and color tasks alone and showed results that were similar to the previous groups tested on a single task. However, under the dual attention condition, male accuracy in targeting, as well as color shade recognition, declined significantly compared to their performance when the tasks were tested alone. No significant changes were found in female performance. Finally, reaction times for targeting and color choices in both sexes correlated highly with ball speed, but not accuracy. Overall, these results provide evidence of a sex-related bias in processing objects versus movement, which may reflect sex differences in bottom up versus top-down analytical strategies. Citation: McGivern RF, Adams B, Handa RJ, Pineda JA (2012) Men and Women Exhibit a Differential Bias for Processing Movement versus Objects. PLoS ONE 7(3): e32238. doi:10.1371/journal.pone.0032238 Editor: Todd W. Troyer, University of Texas at San Antonio, United States of America Received July 27, 2011; Accepted January 25, 2012; Published March 14, 2012 Copyright: 2012 McGivern et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The work was supported in part by University of California San Diego Academic Senate Grant RJ145G (Pineda). No additional external funding was received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: mcgivern@sunstroke.sdsu.edu Introduction The majority of human cognitive sex differences are broadly categorized as ‘spatial’ or ‘verbal’ [1]. To what degree these differences arise from lower level perceptual processing is unknown, but functional studies of neurophysiological and behavioral sex differences in humans, as well as similarities in cognitive sex differences observed in humans and animals, suggest this possibility [2]. Below we review evidence that the kinds of spatial and verbal skills that show cognitive sex differences may involve differential processing of information involving the dorsal and ventral processing streams that are common to all mammals. Dorsal and ventral stream cortical processing provide a functional analysis of movement and object recognition, respec- tively. The dorsal stream provides the basis for conscious and unconscious knowledge of ‘where’ something is in visual space, as well as the tracking of object movement. Ventral stream processing provides information for conscious recognition of ‘what’ some- thing is, including its associated characteristics [3–4]. Both cortical streams operate in parallel, with some integration of movement and objects occurring in subdivisions of the dorsal stream that lies anatomically between the two classical pathways [5]. Spatial tasks showing reliable sex differences in men include targeting, maze learning, and dis-embedding tasks such as Rod and Frame and Embedded Figures [6–7], all of which involve processing of actual or abstract movement. Some corollaries to these sex differences are observed in animals. For instance, maze learning across species consistently favors males in environments that depend upon employing a cardinal orientation strategy [8– 10]. Similarly, targeting tasks that involve accuracy in throwing an object also favor males across species [11–14]. More complex tasks involving space relations, such as mental rotations, have no direct corollary in animals, but are proposed to partially rely on neural substrates associated with targeting skills [12]. In spite of the categorical label, verbal tasks that show sex differences are not easily related to differences in inherent linguistic ability since men and women exhibit similar writing skills, vocabulary, general fluency, and language and reading comprehension [13–14]. Instead, tasks in this category showing sex differences rely on verbal or written expression of knowledge related to objects (or events) and their associated characteristics. These include fluency in naming words beginning with a given letter, autobiographical and episodic memory, and communica- tion skills, all of which favor women [6][14]. The pattern suggests PLoS ONE | www.plosone.org 1 March 2012 | Volume 7 | Issue 3 | e32238