In his socio-relational framework of sex differences in the expression of emotion (i.e., the socio-relational framework of expressive behaviors [SRFB]), Vigil proposes that there should be gender differences in the processing of affective facial expressions, and he cites several specific examples of the ways in which males and females should differ in this domain. Here we focus on one in particular – sex differences in the detection of affective facial expressions and, in particular, whether there is evidence of such differences over the course of development.

Based on SRFB, Vigil claims that, because of their sensitivity to trustworthiness cues, females should detect affective facial expressions more quickly than males. The only exception might be in the detection of anger: since males should be particularly sensitive to dominance cues, they should detect angry facial expressions more quickly than females. The question of whether adults detect certain kinds of facial expressions more quickly than others has been of substantial interest to many researchers, making Vigil's claims easy to evaluate based on the existing literature.

Using a standard visual search paradigm, many researchers have examined the detection of threatening facial expressions, such as anger. However, with the exception of the few studies cited by Vigil, few report any gender differences. Most of these studies find that participants of both sexes are faster at identifying angry faces than happy faces overall (Calvo et al. Reference Calvo, Avero and Lundqvist2006; Esteves Reference Esteves1999; Fox et al. Reference Fox, Lester, Russo, Bowles, Pichler and Dutton2000; Gilboa-Schechtman et al. Reference Gilboa-Schechtman, Foa and Amir1999; Horstmann & Bauland Reference Horstmann and Bauland2006; Lundqvist & Öhman Reference Lundqvist and Öhman2005; Mather & Knight Reference Mather and Knight2006; Öhman et al. Reference Öhman, Lundqvist and Esteves2001; Schubo et al. Reference Schubo, Gendolla, Meinecke and Abele2006).

Although this research with adults offers no support for Vigil's theory, research with children might be particularly relevant to evaluating SRFB. Vigil's theory suggests an evolved or biological basis for gender differences in face detection, so it is possible that such differences would be apparent in childhood and even infancy. Recently, LoBue (Reference LoBue2009) examined the visual detection of several affective facial expressions (e.g., happy, sad, angry, fearful) in both preschool children and adults. Participants in a series of studies were asked to find the single instance of a given category in a 3 x 3 matrix of color photographs. For example, they might be asked to identify the single angry face among eight happy ones (or vice versa).

Consistent with the adult literature, both preschool children and adults were faster to detect facial expressions that depicted threat-relevant expressions (anger, fear) than non–threat-relevant expressions (happiness, sadness). In another series of studies, LoBue and DeLoache (Reference LoBue and DeLoache2008) reported that preschool children and adults were also faster at detecting pictures of threat-relevant animals (snakes) than non–threat-relevant ones (frogs or caterpillars). However, no gender differences were found in any of the experiments.

Despite the lack of significant sex differences, a slight advantage was apparent for female preschoolers in some of the studies. It is possible that the sample size in each study was too small (24 children in each study, 12 in each condition) for detecting subtle gender differences. Accordingly, we combined the data from all our visual search experiments to examine whether there was an overall advantage for females (data from LoBue Reference LoBue2009). There was in fact a significant effect of gender, indicating that girls detected the target faces more quickly than did boys. The advantage for females was stable across studies, and did not differ based on whether the target was threatening or non-threatening. Importantly, this advantage was significant only for the detection of affective facial expressions: When reanalyzing the data for the detection of snakes (data from LoBue & DeLoache Reference LoBue and DeLoache2008), there was no such advantage for girls.

These results indicate an advantage for young girls in the detection of affective facial expressions. Further, this advantage cannot be attributed to simple differences in motivation or compliance, since it was not found for the detection of non-facial stimuli. These results provide support for Vigil's claim that females should have an advantage over males in the detection of emotional facial expressions. However, Vigil's assertion that males should be particularly sensitive to threatening facial expressions was not supported – girls showed an advantage over boys across studies, regardless of whether or not the targets were threat-relevant.

While these findings provide some support for SRFB, whether there is a biological basis for these gender differences is still unclear. It is certainly possible that by preschool, children have developed gender differences in face processing based on experience. This question makes research with infants, who have less experience interacting with the relevant stimuli, critical for testing Vigil's hypothesis. Recently, LoBue and DeLoache (in press) did examine the detection of affective facial expressions in 8- to 14-month-olds, but found no gender differences. Further research in this area is needed in order to examine Vigil's claims more thoroughly.

Future research in other areas of development might also be informative for the SRFB. For example, Vigil suggests that females are better at posing affective facial expressions than are males. If so, this should also be true for children. Further, gender differences in infants' preferences for different kinds of faces might be an important consideration for future research. For example, Lutchmaya and Baron-Cohen (Reference Lutchmaya and Baron-Cohen2002) reported an important gender differences in 12-month-old infants' looking preferences. They found that when infants were presented with videos of moving cars or moving faces in a looking-preference experiment, infant boys preferred to look at the cars over faces, while infant girls preferred to look at faces over cars. This result supports Vigil's claims and may warrant further investigation.

In conclusion, developmental findings on gender differences in the detection of affective facial expressions provide partial support for Vigil's view that females should detect affective facial expressions more quickly than do males. Research with infants and young children could provide further information relevant to assessing the SRFB.