Working with a large team of anthropologists, we aim to understand how people reason with spatial information. My research has focused on understanding how the spatial skills of remote hunter gatherer tribes in Namibia and the Yucatan peninsula differ from WEIRD (Western, educated, industrialized, rich and democratic) populations. I am interested in the influence of visual information in spatial reasoning and utilizing systematic changes in visual information to infer cognitive processes associated with visuospatial data.
The Morris water maze is a spatial abilities test adapted from the animal spatial cognition literature and has been studied in the context of sex differences in humans. This is because its standard design, which manipulates proximal (close) and distal (far) cues, applies to human navigation. However, virtual Morris water mazes test navigation skills on a scale that is vastly smaller than natural human navigation. Many researchers have argued that navigating in large and small scales is fundamentally different, and small-scale navigation might not simulate natural human navigation. Other work has suggested that navigation experience could influence spatial skills. To address the question of how individual differences influence navigational abilities in differently scaled environments, we employed both a large (146.4 meters in diameter) and a traditional (36.6 meters in diameter) scaled virtual Morris water maze along with a novel measure of navigation experience (lifetime mobility). We found sex differences on the small maze in the distal cue condition only, but in both cue-conditions on the large maze. Also, individual differences in navigation experience modulated navigation performance on the virtual water maze, showing that higher mobility was related to better performance with proximal cues for only females on the small maze, but for both males and females on the large maze.
Sex differences in range size and navigation are widely reported, with males traveling farther than females, being less spatially anxious, and in many studies navigating more effectively. One explanation holds that these differences are the result of sexual selection, with larger ranges conferring mating benefits on males, while another explanation focuses on greater parenting costs that large ranges impose on reproductive-aged females. We evaluated these arguments with data from a community of highly monogamous Maya farmers. Maya men and women do not differ in distance traveled over the region during the mate-seeking years, suggesting that mating competition does not affect range size in this monogamous population. However, men’s regional and daily travel increases after marriage, apparently in pursuit of resources that benefit families, whereas women reduce their daily travel after marriage. This suggests that parental effort is more important than mating effort in this population. Despite the relatively modest overall sex difference in mobility, Maya men were less spatially anxious than women, thought themselves to be better navigators, and pointed more accurately to distant locations. A structural equation model showed that the sex by marital status interaction had a direct effect on mobility, with a weaker indirect effect of sex on mobility mediated by navigational ability.
The fertility and parental care hypothesis interprets sex differences in some spatial-cognitive tasks as an adaptive mechanism to suppress women’s travel. In particular, the hypothesis argues that estrogens constrain travel during key reproductive periods by depressing women’s spatial-cognitive ability. Limiting travel reduces exposure to the dangers and caloric costs of navigating long distances into unfamiliar environments. Our study evaluates a collection of predictions drawn from the fertility and parental care hypothesis among the Twe and Himba people living in a remote region of Namibia. We find that nursing mothers travel more than women at any other stage of their reproductive career. This challenges the assumption that women limit travel during vulnerable and energetically demanding reproductive periods. In addition, we join previous studies in identifying a relationship between spatial ability and traveling among men, but not women. If spatial ability does not influence travel, hormonally induced changes in spatial ability cannot be used as a mechanism to reduce travel. Instead, it appears the fitness consequences of men’s travel is a more likely target for adaptive explanations of the sex differences in spatial ability, navigation, and range size.
See photographs from my field work below.