Sex and Gender Differences

Sex and gender are among the most heavily investigated interindividual factors in all areas of psychology. Although sex and gender have been studied for more than a hundred years, there has been an explosion of theories and research in this area in the past several years. Whether psychological differences between men and women truly exist, and where they originate, is still under debate. Although the majority of experts would deny that sex and gender differences in mind and behavior are either purely biological or purely social in origin, it seems that the proportions attributable to nature and nurture are still being negotiated. New research takes into account biological and social factors, as well as the interaction between them, and addresses “the small difference” within a psychobiosocial approach. This topical issue integrates research on sex and gender differences from various psychological disciplines and emphasizes a psychobiosocial approach as a promising new perspective in this field.

In January 2005, Larry Summers, then president of Harvard University, gave a speech at the “Diversifying the Science and Engineering Workforce” conference held by the National Bureau of Economic Research in Cambridge, MA, that elicited a political and social earthquake. In his attempt to answer the question why women are underrepresented in top academic careers, he offered three potential explanations: (1) He argued that more young mothers than fathers are unwilling to spend 80 hr per week at work. (2) More boys than girls tend to be at the highest or lowest end of mathematical performance in high schools. Although boys and girls do not show significant differences in mean mathematical performance, a higher proportion of boys reveal extremely high mathematical aptitude, which might explain why women are underrepresented in the upper echelons of academic and professional life. (3) Finally, Summers admitted that discrimination at universities exists, including at Harvard University, but this may be less relevant because women are already underrepresented below the top level of academic leadership. His second point especially not only led to many attendees indignantly leaving the hall, but also revived a worldwide debate.

Is there empirical evidence for “innate” sex differences in cognitive abilities? Is there new empirical support for a biological basis for cognitive differences between men and women? What are the social factors that elicit or promote sex and gender differences? Although a lot of research has been done on these issues, many questions remain unanswered and an appraisal of new perspectives and new findings thus appears necessary from time to time (see, e.g., Schober, Reimann, & Wagner, 2004).

In light of this, the present topical issue “Sex and Gender Differences Revisited – New Perspectives and New Findings”, on the one hand, contains contemporary studies of sex differences in specific cognitive variables, focusing on some relevant biological and social factors underlying the “small difference,” and, on the other hand, presents new findings on mechanisms behind gender differences from more applied research on education, work, and science. Finally, it includes two opinion papers with the explicit aim of discussing new perspectives and possible reconciliations between very different research approaches to sex and gender.

Cognitive tests favoring men mainly include specific mathematical and spatial problems such as mental rotation, an ability that involves the ability to imagine and mentally manipulate 3D objects. Because mental rotation is particularly sex-sensitive so that men outperform women with effect sizes up to one standard deviation, sex differences in mental rotation are the focus of various psychological approaches.

Neuburger, Jansen, Heil, and Quaiser-Pohl (2012) focus on gender stereotypes and their effects on mental rotation performance in primary school children. Gender stereotype effects on cognitive abilities in general, and mental rotation in particular, have been reported before (e.g., Hausmann, Schoofs, Rosenthal, & Jordan, 2009). It has remained unclear, however, at what age gender stereotypes begin to affect cognitive behavior. Specifically, Neuburger and colleagues (2012) reveal that the male advantage in mental rotation disappears when children, at around 10 years of age, are told prior to experimental testing that girls are usually better at this task or that no differences between boys and girls exist in this task.

Beyond this experimental developmental perspective on gender stereotypes, Hirnstein, Freund, and Hausmann (2012) investigate effects of stereotypes on cognitive sex differences. While the majority of studies in this field have focused on cognitive domains in which men outperform women, far fewer studies have investigated whether gender stereotyping also affects men when men are seen as the vulnerable group. The authors conducted an experimental study in which the gender stereotype of adult women having better verbal abilities (verbal fluency) than men was activated in both male and female participants. Instead of a decline in men’s verbal fluency after confronting them with negative stereotypes about their sex’s verbal abilities (stereotype threat; Steele, 1997), both men and women performed significantly better on these tests when both sexes were stereotyped. While the detailed mechanisms are up for discussion, the results show that cognitive performance can change if individuals are aware that gender differences are being investigated. This strongly suggests that researchers in all psychological disciplines should be very careful with the way they frame their experimental tasks.

The extent to which sex differences in visuospatial abilities also account for sex differences in specific mathematical skills is investigated in children by Krinzinger, Wood, and Wilmes (2012). This study is based on the assumption that the use of spatial/conceptual strategies may be more advantageous for mathematical problem solving than verbal/syntactical strategies (Casey, Nuttal, & Benbow, 1995; Van Garderen, 2006). Although no sex differences in general spatial abilities were found, this study reveals that children’s attitudes toward mathematics (more positive in boys than in girls) and general spatial abilities predict multi-digit number processing. Visual-spatial working memory capacity is not a significant predictor. These results strongly suggest an interaction between specific (spatial) cognitive abilities and attitudes in children’s development of cognitive sex differences, which is in line with the psychobiosocial model. Moreover, Krinzinger and colleagues (2012) support the idea that sex differences in a specific task may be misclassified as a sex difference in mathematics, when in fact the task measures something else in addition or instead (Caplan, MacPherson, & Tobin, 1985), such as visuospatial abilities. This can obviously result in incorrect conclusions and overgeneralization of sex differences in specific cognitive domains.

Although sex differences in specific spatial abilities are widely accepted, the study by Sänger, Schneider, Beste, and Wascher (2012) reveals that women do not necessarily show a general deficit in the processing of spatial information. However, in this electrophysiological study it was found that women are more distracted by irrelevant (spatial) cues, probably because women show a tendency to integrate (spatial) information more than men. In other words, the neurocognitive mechanisms that promote an augmented integration of information may be less efficient in situations in which relevant information is accompanied by irrelevant but salient information in the surroundings. It is also important to note that the results by Sänger and colleagues (2012) were not only observed behaviorally (error rates and response times) but there were also corresponding effects in an event-related electroencephalogram component (N2pc) that is assumed to reflect spatially selective attentional processing. It is generally assumed that, if sex differences in cognitive behavior are found, the neural correlate of this behavior should also be sexually differentiated. Although this is probably true, it should be borne in mind that male and female brain processes might differ even if no sex differences in (cognitive) behavior are found. In other words, neural correlates of cognitive processes can significantly differ between men and women, although the cognitive performance is almost identical between sexes (Cahill, 2006). For example, Jordan, Wüstenberg, Heinze, Peters, and Jäncke (2002) revealed overlapping but also different areas being activated in men and women during a mental rotation task, however, there were no differences in performance.

The above studies consider sex differences in cognitive variables at different ages and vary in their link to psychosocial variables. Braun, Peus, and Frey (2012) exclusively focus on the explanatory power of gender stereotypes and connected psychological mechanisms. Their study on possible negative consequences of attractiveness in female leaders confirmed gender-specific effects on followers’ trust and loyalty – but only for female followers and only when combined with a specific leadership style. In an extension to prior literature on this “beauty is beastly effect” (e.g., Braun & colleagues, 2012; Heilman & Stopeck, 1985), data indicate the relevance of powerful mediators. A differentiated view of moderating effects of this kind is necessary in order to understand the paucity of women in leadership positions.

Adding new insight into the determinants of this so-called “glass ceiling effect” (Lyness & Thompson, 1997) is a central aim of Jöstl, Bergsmann, Lüftenegger, Schober, and Spiel (2012). Their study is concerned with science as a field of careers, where a “leaky pipeline” for women is often diagnosed (see also Larry Summers’ statements above). The authors investigate young male and female scientists with regard to their research self-efficacy and the degree to which they are affected by the “impostor phenomenon” (IP). The IP integrates several motivational and cognitive characteristics and refers to objectively successful persons who fear that their deficits will be unmasked one day (e.g., Clance, 1985). The results show that the IP should be considered a psychological barrier for female university careers. This is the first study of the university context in German-speaking countries with the theoretical aim of testing the explanatory power of the integrating construct IP.

Beyond a more integrated perspective on individual variables, we also need new and integrated perspectives on the structural barriers faced by women (e.g., Oakley, 2000). Mutz, Bornmann, and Daniel (2012) investigate gender differences in science at a systemic level: They evaluate the peer-reviewing process of one of Austria’s biggest science funding sources (Austrian Science Fund – FWF) with regard to its gender fairness. In contrast to some previous studies on a possible gender bias in the review system and studies on individual differences described above, Mutz and colleagues (2012) found that sex and gender do not decisively matter in terms of the evaluation of research project proposals.

All aforementioned contributions of this topical issue are based on empirical studies and are focused on new findings on specific variables. They are thematically rather wide ranging, mostly following one specific research approach. Some researchers have already taken an integrative view and their results suggest why this is necessary. In contrast to these, the goal of Kaiser (2012) and Campbell (2012) is to explicitly elaborate new perspectives in research on gender and sex differences at a conceptual level. These two opinion papers discuss the integration of psychological, social, and biological approaches and traditions. Kaiser (2012) addresses reasons for and consequences of the difficulty of defining a clear-cut distinction between sex and gender – both terminologically and neurologically. The author suggests rethinking what is meant by male and female, especially in neuropsychological settings, and elaborates why this should be seen as the starting point for further research. Campbell’s contribution (2012) summarizes the contradictory positions of feminist and evolutionary psychology. The author reviews the sources of this conflict and identifies areas of convergence between them.

With the approach of identifying convergences, Campbell (2012) directly reflects on the basic aims of this topical issue. On the one hand, the present literature suggests that sex and gender differences still need to be investigated even after decades of research many questions remain open. On the other hand, an immense number of unconnected theories and evidence exist. Bearing this in mind, one clear issue becomes evident: Even if researchers on gender differences agree in principle on a complex interaction of biological, psychological, and social aspects (e.g., Ceci, Williams, & Barnett, 2009; Halpern, 2000), most research is so far conducted from only one of these perspectives. New approaches, realizing a systematic psychobiosocial approach, are therefore necessary as they can contribute substantially to a better understanding of sex and gender differences and their development (e.g., Hausmann, 2011).

So far, only a few studies have tried to realize this. This is perhaps understandable as this approach makes stringent demands on experimental designs and methods, and requires much more communication and coordination between different and very specialized (sub)disciplines than has been realized so far. In this sense, this topical issue can be a starting point by (a) presenting a number of studies that integrate different approaches and (b) being one of the rare topical issues in which researchers from psychological, biological, and social research traditions publish together.

But one final question remains: Was Larry Summers right when he said that there are innate sex differences in cognitive abilities that must be considered as one relevant explanation for deficits of gender equity in high positions? According to the present state of knowledge (as it is also presented in this topical issue), there seem to be differences between men and women in some specific cognitive abilities. However, for most of them, the magnitude of sex-related differences is usually quite small and they seem not necessarily relevant for daily life. Finding the reasons for the gender gap in many fields of daily life, such as the male dominance in academic leadership positions, seems to be complicated and we are far from understanding the full range of relevant mechanisms. But it is clear that we have to integrate knowledge from different disciplines and we have to find new perspectives by combining psychological, biological, and social approaches. This requires some changes in our present science culture of increasing specialization and differentiation. We hope this topical issue will encourage researchers of various psychological disciplines to contribute to this ambitious endeavor.