rationalskepticism.org

Hassett et al, 2008 wrote:Abstract

Socialization processes, parents, or peers encouraging play with gender specific toys are thought to be the primary force shaping sex differences in toy preference. A contrast in view is that toy preferences reflect biologically determined preferences for specific activities facilitated by specific toys. Sex differences in juvenile activities, such as rough and tumble play, peer preferences, and infant interest, share similarities in humans and monkeys. Thus if activity preferences shape toy preferences, male and female monkeys may show toy preferences similar to those seen in boys and girls. We compared the interactions of 34 rhesus monkeys, living within a 135 monkey troop, with human wheeled toys and plush toys. Male monkeys, like boys, showed consistent and strong preferences for wheeled toys, while female monkeys, like girls, showed greater variability in preferences. Thus, the magnitude of preference for wheeled over plush toys differed significantly between males and females. The similarities to human findings demonstrate that such preferences can develop without explicit gendered socialization. We offer the hypothesis that toy preferences reflect hormonally influenced behavioral and cognitive biases which are sculpted by social processes into the sex differences seen in monkeys and humans.

Alexander & Hines, 2002 wrote:Abstract

Sex differences in children’s toy preferences are thought by many to arise from gender socialization. However, evidence from patients with endocrine disorders suggests that biological factors during early development (e.g., levels of androgens) are influential. In this study, we found that vervet monkeys (Cercopithecus aethiops sabaeus) show sex differences in toy preferences similar to those documented previously in children. The percent of contact time with toys typically preferred by boys (a car and a ball) was greater in male vervets (n = 33) than in female vervets (n = 30) (P < .05), whereas the percent of contact time with toys typically preferred by girls (a doll and a pot) was greater in female vervets than in male vervets (P < .01). In contrast, contact time with toys preferred equally by boys and girls (a picture book and a stuffed dog) was comparable in male and female vervets. The results suggest that sexually differentiated object preferences arose early in human evolution, prior to the emergence of a distinct hominid lineage. This implies that sexually dimorphic preferences for features (e.g., color, shape, movement) may have evolved from differential selection pressures based on the different behavioral roles of males and females, and that evolved object feature preferences may contribute to present day sexually dimorphic toy preferences in children.

We know of at least two other examples of male–female cognitive differences that resemble the interesting pattern that appears in the toy choice data of Hassett et al. (2008): visual recognition memory (McGivern et al., 1997) and spatial navigation (e.g., Sandstrom et al., 1998; Williams et al., 1990;Williams and Meck, 1991). In both of these cognitive domains, females appear to process information comprehensively, while males appear to select and respond to only certain types of information. For example, when visual recognition memory for male-oriented objects (e.g., drawings of balls, bikes, sports equipment, and motor vehicles), female oriented objects (e.g., drawings of human and animal figures, cooking and sewing items, girls' clothing) or random objects (e.g., drawings of household items, office objects, furniture) was assessed in children and adults, females performed equally well when presented with all three types of stimuli, and males only performed as well as females when the objects were male-oriented (McGivern et al., 1997). These data are particularly striking because the authors ruled out a language-based explanation of their findings by including a more difficult task in which a single neutral object differed only in its internal pattern; thus, these objects would be difficult to name. While the performance of all subjects for this task was very poor compared to memory of nameable objects, females still outperformed males. These findings suggest that this sex difference in recognition memory may be the result of differences in visual attention. Male bias to attend to male-oriented objects may account for their increased performance only on this category of objects.

Males, but not females, also show strong selectivity in information processing of spatial information. When a navigation task may be solved by using either local or distal cues, male rats (e.g., Brown and Moore, 1997; Sava and Markus, 2005; Suzuki et al., 1980) and rhesus monkeys (Herman and Wallen, 2007) tend to use distal cues, while females are able to use either type of cue (Herman and Wallen, 2007; Tropp and Markus, 2001), suggesting that females may be more likely to attend to both types of information while males focus on one type of cue. This difference can also be seen if rats' use of spatial information is probed after male and female rats reach equal asymptotic performance on a radial-arm maze task (Williams et al., 1990). Female rats are not disrupted in performance if either landmark (e.g., the computer, experimenter, cart with cages) or geometry (e.g., the rectangular room shape) is removed or obscured. However, males are completely reliant on room geometry; their performance is severely disrupted if the room shape is obscured, even if large salient landmarks in the room remain to guide navigation. In this case, it appears that for males, the Euclidian properties (i.e., angles and distances) that define the environmental landscape (e.g., test room) overshadow the large salient landmarks, and are the default information for spatial navigation, while females appear to process both environmental geometry and landmark cues comprehensively, and can use either set of cues to navigate. Interestingly, these effects are organized by perinatal hormone exposure, as males castrated at birth rely on both landmarks and geometry similar to adult ovariectomized females; and neonatally estrogen treated females show reliance on geometry, just like adult castrated males (Williams et al., 1990). Thus while circulating hormones may further alter navigation strategies (e.g., Korol, 2004), they are not required for these sex differences in cue use.