Rodrigo Andrés Cárdenas

Masculine voices signal men's threat potential in forager and industrial societies

Humans and many non-human primates exhibit large sexual dimorphisms in vocalizations and vocal anatomy. In humans, same-sex competitors and potential mates attend to acoustic features of male vocalizations, but vocal masculinity especially increases perceptions of physical prowess. Yet, the information content of male vocalizations remains obscure. We therefore examined relationships between sexually dimorphic acoustic properties and mens threat potential. We first introduce a new measure of the structure of vocal formant frequencies, ‘formant position’ (Pf), which we show is more sexually dimorphic and more strongly related to height than is the most widely used measure of formant structure, ‘formant dispersion’, in both a US sample and a sample of Hadza foragers from Tanzania. We also show large sexual dimorphisms in the mean fundamental frequency (F0) and the within-utterance standard deviation in F0 (F0 − s.d.) in both samples. We then explore relationships between these acoustic parameters and mens body size, strength, testosterone and physical aggressiveness. Each acoustic parameter was related to at least one measure of male threat potential. The most dimorphic parameters, F0 and Pf, were most strongly related to body size in both samples. In the US sample, F0 predicted testosterone levels, Pf predicted upper body strength and F0 − s.d. predicted physical aggressiveness.

Salivary testosterone does not predict mental rotation performance in men or women

Multiple studies report relationships between circulating androgens and performance on sexually differentiated spatial cognitive tasks in human adults, yet other studies find no such relationships. Relatively small sample sizes are a likely source of some of these discrepancies. The present study thus tests for activational effects of testosterone (T) using a within-participants design by examining relationships between diurnal fluctuations in salivary T and performance on a male-biased spatial cognitive task (Mental Rotation Task) in the largest sample yet collected: 160 women and 177 men. T concentrations were unrelated to within-sex variation in mental rotation performance in both sexes. Further, between-session learning-related changes in performance were unrelated to T levels, and circadian changes in T were unrelated to changes in spatial performance in either sex. These results suggest that circulating T does not contribute substantially to sex differences in spatial ability in young men and women. By elimination, the contribution of androgens to sex differences in human performance on these tasks may be limited to earlier, organizational periods.

Why are infants held on the left? A test of the attention hypothesis with a doll, a book, and a bag

Most adults, especially women, hold infants and objects representing infants, such as dolls, preferentially on the left side. The attention hypothesis credits the effect to left-directed attention for perception of emotionally salient targets, faces being prime examples. Support comes from studies showing stronger left visual hemispace (LVH) biases in left-holders than right-holders on the Chimeric Faces Test (CFT), but control tests with non-social/emotional objects are needed. We therefore observed young women holding a doll, a book, and a bag, and compared their scores with their performance on the CFT. We also assessed their handedness to check on its possible role. Overall, only the doll elicited a significant side bias, with 57% of all holds on the left, 2% in the middle, and 41% on the right. On the CFT, only left-holders had an LVH bias, whereas right-holders had no bias in either direction. Only the doll-hold scores were consistently related to CFT scores, and for none of the objects was handedness related to side-of-hold.

Adults' preferences for side-of-hold as portrayed in paintings of the Madonna and Child

Most women hold infants on their left side. They do the same when depicted in works of art. Does the latter accurately reflect the real-life bias, the artists own aesthetic preference, or something else, such as the artists handedness, sex, direction of attentional bias, or even the artists own side-preference for holding infants? As a first step to finding out, we showed 272 young adults (85 men, 187 women) 20 pairs of paintings of the Madonna and Child, the original on one side, its mirror-reversal on the other, and asked which one they preferred. Along with assessing the effects of the variables already mentioned, we used equal numbers of paintings originally depicting left-holds and right-holds to control for the possible effects of differences between the paintings other than side-of-hold itself, such as in their colour scheme, background details, and the type of hold shown (e.g., cradle vs seated on lap). Each pair was presented twice, once with the original on the left, once on the right, for a total of 40 trials. Women and men alike more often preferred left-hold images, but the difference was significant only for women. Preferences were also stronger for original left-hold paintings than for the mirror-reversals of original right-hold paintings, suggesting that the originals differed in ways affecting preference beyond those we tried to control. Overall preference for left-hold images was enhanced when the images were on the viewers left. As for the other variables, they were for the most part unrelated to preferences. The reasons for the preference thus remain unclear but it is evidently affected by multiple variables, with at least some clearly different from those affecting side-of-hold preferences of real mothers holding real infants.

Do women's preferences for masculine voices shift across the ovulatory cycle?

Abstract Are estrous mate preference shifts robust? This question is the subject of controversy within human evolutionary sciences. For nearly two decades, mate preference shifts across the ovulatory cycle were considered an important feature of human sexual selection, directing womens attention toward mates with indicators of “good genes” in their fertile phase, when conception is possible. However, several recent studies on masculine faces, bodies and behaviors did not find evidence supporting this account, known as the good genes ovulatory shift hypothesis. Furthermore, evidence that preferences for masculine characteristics in mens voices are related to womens cycle phase and hormonal status is still equivocal. Here, we report two independent within‐subject studies from different labs with large sample sizes (N = 202 tested twice in Study 1; N = 157 tested four times in Study 2) investigating cycle shifts in womens preferences for masculine voices. In both studies, hormonal status was assessed directly using salivary assays of steroid hormones. We did not find evidence for effects of cycle phase, conception risk, or steroid hormone levels on womens preferences for masculine voices. Rather, our studies partially provide evidence for cycle shifts in womens general attraction to mens voices regardless of masculine characteristics. Womens relationship status and self‐reported stress did not moderate these findings, and the hormonal pattern that influences these shifts remains somewhat unclear. We consider how future work can clarify the mechanisms underlying psychological changes across the ovulatory cycle. HighlightsTested the robustness of ovulatory cycle shifts in women’s mate preferences for masculine voicesTwo large independent studies, using natural and manipulated stimuliEvaluated direct hormone assessments and moderator variablesNo evidence for cycle shifts in women’s preferences for vocal masculinityCycle shifts occurred for women’s attraction, regardless of voice masculinity, not moderated by relationship status or stress

Aesthetic preferences for direction of bias in artistic depictions of mothers holding infants

mal controls. In both cases, performance on the gambling task was clearly impaired, with a tendency for both children and adults to prefer less advantageous decks and to fail to improve their behavior throughout the task duration. For ADHD children, failure to perform the task was unrelated to any of two versions of the Stroop test. For psychopaths, gambling performance was marginally correlated to Stroop performance, but was very significantly correlated to the degree of psychopathy (assessed by the Hare’s psychopathy check list). Interestingly, these correlations were found in the control group as well. Taken together, these results suggest that ADHD children as well as adults with psychopathy tendencies have a dysfunction in brain reward mechanisms.