Keywords

Approaching the first quarter of the twenty-first century, men and women exhibit only minor differences that could affect their academic performance. These similar educational outcomes are also observed in the university disciplines of health and natural sciences. For example, reviewing different meta-analyses, Hyde (2014) found an overall support for the gender similarities hypothesis. In other words, most of the variables analyzed (e.g., verbal performance, mathematics skills, self-esteem, academic self-concept, and leadership effectiveness) showed small to negligible differences between the sexes.

In contrast, few exceptions showing moderate to large sex differences were found (e.g., mental rotation in three-dimensions, sensation seeking, and physical aggression). Similarly, the comprehensive metasynthesis of 106 meta-analyses (over 12 million participants and 21,000 effects), by Zell et al. (2015), showed that the overall effect size of the difference between males and females in psychological traits was of d = 0.21, which represents a small size effect according to Cohen (1988). These meta-analyses support that university men and women tend to show similar academic abilities, including those needed to learn about health and natural sciences.

Nevertheless, as in Hyde (2014), the study by Zell et al. (2015) signaled a number of psychological traits that showed moderate to large gender or sex differences (e.g., mental rotation, aggression, and peer attachment). In this chapter, we consider one of those variables that challenged the gender similarities hypothesis, namely, mental rotation. We also include several related visuospatial processing tasks, as they are all involved in health and natural sciences achievement (see Castro-Alonso and Uttal this volume, Chap. 3).

Although these visuospatial tasks tend to show less marked sex differences than mental rotation instruments, they still show sex variations favoring men. This applies for both the spatial ability and the working memory tasks, jointly considered small-scale visuospatial processing abilities (see Castro-Alonso and Atit this volume, Chap. 2), where men usually outperform women.

For example, Stericker and LeVesconte (1982) showed that, among the introductory psychology students assessed, men outperformed women in all four spatial ability tests, including mental rotation with three-dimensional (3D) images, mental rotation with two-dimensional (2D) shapes, mental folding, and field independence. Also, in the meta-analysis of spatial and visual working memory tasks by Voyer et al. (2017), there was a small overall effect (d = 0.16) indicating the better performance of men compared to women in these tests.

Similarly, the study by Geiger and Litwiller (2005) with 63 university students (76% females) showed males performing better than females in a dual visuospatial task of working memory. Only the visual working memory test known as Object Location Memory shows women tending to outscore men (e.g., Eals and Silverman 1994).

The main goal of this chapter is to describe the existence of sex differences in the abilities described above as well as to provide examples to diminish them. The specific aims of this review are the following: (a) describe diverse degrees of sex differences, related to the different visuospatial abilities investigated; (b) provide sociocultural (nurture) and biological (nature) explanations for these sex differences; (c) show that visuospatial training could potentially help to diminish this gap; (d) discuss instructional implications for health and natural sciences; and (e) offer future research directions for the investigation of these sex differences in visuospatial processing.

4.1 Sex Differences in Different Visuospatial Processing Abilities

There are two research traditions concerning instruments to measure visuospatial processing abilities (see Hegarty et al. 2006). Firstly, we describe the abilities that belong to the literature about spatial ability, including mental rotation, mental folding, and field independence. Secondly, we address the abilities to solve visuospatial working memory tasks, including spatial working memory, visual working memory, and dual visuospatial tasks of working memory. These tasks are described in Castro-Alonso and Atit (this volume, Chap. 2). A summary of the expected directions and degrees of sex differences is provided in Table 4.1.

Table 4.1 Expected directions and degrees of sex differences for various visuospatial processing abilities
Full size table

4.1.1 Mental Rotation

Mental rotation was defined by Ekstrom et al. (1976) as the ability to perceive a whole figure and rotating it in mind. The spatial ability literature consistently shows that men have higher scores than women in common mental rotation instruments. The meta-analysis by Voyer et al. (1995) revealed an overall effect size of d = 0.56, and the meta-analysis by Linn and Petersen (1985) showed an average of d = 0.73. These values represent medium to large effect sizes favorable to males. These aggregated results have also been shown with specific mental rotation tests, which can be classified as 3D vs. 2D instruments. Following this distinction, the favorable outcomes for men tend to be larger with 3D as compared to 2D mental rotation tests (cf. Voyer and Jansen 2016).

Figure 4.1a shows an item from the Mental Rotations Test, a 3D mental rotation instrument, whereas Fig.4.1b depicts three questions from the Card Rotations Test, a 2D instrument (see also Castro-Alonso and Atit this volume, Chap. 2; Castro-Alonso et al. this volume-a, Chap. 8). Regarding the 3D mental rotation test in the figure, for every item, the participants must indicate which two figures from the given four on the right side are rotated versions of the shape on the left side. For the items of the 2D mental rotation test, the correct answer is to indicate which pictures are the same (S) as the given shape on the left side, only rotated versions, and which are different (D), meaning that they are rotated and mirror-reversed.

Fig. 4.1
figure 1

Examples of items of mental rotation instruments, requesting (a) 3D mental rotation, and (b) 2D mental rotation. The correct answer in each case is given. Note that these are not actual items, but adaptations

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The Mental Rotations Test has shown a male advantage in different populations, including: (a) medicine and anatomy students (Guillot et al. 2007; Vorstenbosch et al. 2013), (b) dentistry learners (Hegarty et al. 2009), (c) psychology students (Levinson et al. 2007; Terlecki and Newcombe 2005; Terlecki et al. 2008), (d) psychology and chemistry undergraduates (Hegarty 2018), (e) university students from various disciplines (Cherney 2008; Reilly et al. 2016), (f) undergraduates practicing sports and physical education (Jansen et al. 2016; Moreau et al. 2012), and (g) adults in general (Hegarty et al. 2006; Loftus et al. 2017).

Furthermore, in a large study (N > 240,000, 48% females) with data from 40 countries and seven self-identified ethnic groups attempting a short version of the Mental Rotations Test, Silverman et al. (2007) reported that the differences favoring males were observed in all countries and ethnicities, and the overall effect represented a medium size. In addition, Masters and Sanders (1993) conducted a meta-analysis of 14 studies of adults completing the Mental Rotations Test (N = 5,144; 58% females). In all of the 14 studies men outscored women, and the overall mean effect size was large (d = 0.90).

Another 3D mental rotation test that shows these sex differences is the Purdue Visualization of Rotations. For example, in a meta-analysis of 40 studies (70 effect sizes), Maeda and Yoon (2013) observed that there was an overall medium effect size of g = 0.57 for men outperforming women. The meta-analysis also showed that the sex advantage for men was larger (g = 0.67) when a time limit was applied to the test. Not included in this meta-analysis, Bodner and Guay (1997) reported four studies with different chemistry students (N = 1,928). In all of these studies, men consistently outperformed women. More recently, Ferguson et al. (2015), investigating undergraduates (Study 3) and adults (Study 4), showed similar findings in a revised computer version of the test.

These sex effects have also been observed for 2D mental rotation instruments (but see Castro-Alonso et al. 2018b). For example, in an experiment with 95 introductory psychology undergraduates (72% females), Mayer and Massa (2003) reported that males outperformed females on the Card Rotations Test. Campos et al. (2004) investigated 129 university graduates of different ages (53% females) completing a mental rotation test with 2D shapes. Results showed an overall medium size effect (d = 0.49) for all ages, and a large effect (d = 0.84) for the youngest group of participants (< 41 years), always favorable to men.

When 3D and 2D mental rotation instruments are compared on a given study, usually the results favoring men are higher for the 3D tests. Three examples are provided in: (a) the study by Sanders et al. (1982) with 1,031 psychology undergraduates (65% females); (b) the report by Peters et al. (1995) with 101 participants (47% females); and (c) the study by Cherney (2008) with 61 university students (51% females). In these cases, men showed noticeably higher scores than women on the 3D test (the Mental Rotations Test), but not such large differences on the 2D test (the Card Rotations Test). Similar findings were reported by Roberts and Bell (2003) with 32 right-handed psychology undergraduates (50% females), and by Reilly et al. (2016) with 309 university students (66% females). In both studies, males outperformed females on the 3D instrument (the Mental Rotations Test) but not on the other tasks involving 2D mental rotations.

4.1.2 Mental Folding and Field Independence

As described by Ekstrom et al. (1976), mental folding (also called spatial visualization) requires mental rotation but also additional processing that involves serial operations and mental restructuring. Although mental folding can show sex differences, the effects are generally smaller than for mental rotation. For example, the meta-analyses by Linn and Petersen (1985) and by Voyer et al. (1995) reported small overall effect sizes favoring males over females (d = 0.13 and d = 0.19, respectively), which are smaller than the medium to large effect sizes reported for mental rotation (see Sect. 4.1.1).

The most common instrument for measuring mental folding is the Paper Folding Test. Sanchez and Wiley (2010) conducted a study with 96 psychology undergraduates (50% females), where the Paper Folding Test showed sex differences favoring men. Several reports have also shown favorable outcomes for men, but usually smaller in size when compared to mental rotation. For example, in an experiment by Peters et al. (1995), men outperformed women on the Mental Rotations Test (3D mental rotation), but not the Card Rotations Tests (2D mental rotation) nor the Paper Folding Test (mental folding). Also, the study with psychology undergraduates by Mayer and Massa (2003) showed that the sex differences favorable to men were larger in the Card Rotations Test than in the Paper Folding Test. Similarly, Stephenson and Halpern (2013) reported that 136 university students (52% females) presented larger sex effects for men on the Mental Rotation Test than on the Paper Folding Test. Lastly, Lord (1987) investigated 250 undergraduates (50% females) from both science and nonscience disciplines, and observed that the difference favoring males over females was about four times larger on a 3D mental rotation instrument (the Cube Comparisons Test) than on the Paper Folding Test.

Sex differences have also been investigated in other mental folding tests. For example, in a study by Nordvik and Amponsah (1998) with university students from fields of technology (N = 161, 42% females) and social science (N = 293, 77% females), participants were assessed on the Surface Development Test. In addition, the students were also measured in a 3D mental rotation instrument (Mental Rotations Test) and a 2D mental rotation test (Spatial Relations). Although men outperformed women on the three tests, the effects were the largest in the 3D mental rotation test (d = 0.85 for technology students and d = 1.06 for social science participants), followed by the 2D rotation instrument (d = 0.48 for technology and d = 0.41 for social science), and being smallest for the Surface Development Test of mental folding (d = 0.39: technology; d = 0.33: social science).

The last spatial ability presented here, field independence, requires perceiving a shape independently of its context (Witkin 1949). This ability can also show sex effects favoring men. For example, Guillot et al. (2007) investigated 184 students (29% females) attempting the field independence instrument known as the Group Embedded Figures Test. It was observed that males outperformed females in this test of spatial ability. Nevertheless, field independence, as mental folding, does not exhibit the large sex differences of mental rotation. On a sample of 221 adult participants (62% females), Hegarty et al. (2006) reported that the sex effects favoring men on the Mental Rotations Test were not observed for the Group Embedded Figures Test. Similarly, in the study by Reilly et al. (2016) with university students, men outperformed women only in the 3D mental rotation test, but not in the instruments measuring 2D mental rotation or the Group Embedded Figures Test. Analogously, the study by Lord (1987), which showed difference favoring men for a 3D mental rotation instrument (the Cube Comparisons Test) and a mental folding test (the Paper Folding Test), failed to show these sex effects on the field independence instrument called the Hidden Figures Test.

4.1.3 Spatial Working Memory

Spatial working memory is usually measured by tests that show visuospatial elements sequentially (cf. Darling et al. 2006). Voyer et al. (2017) conducted a meta-analysis of different spatial working memory tests, which included 48 samples and 69 effect sizes. It considered the Corsi Block Tapping Test and similar instruments involving location and sequencing. The meta-analysis revealed that men outperformed women with a small effect size (d = 0.18).

One study of this meta-analysis, conducted by Ruggiero et al. (2008), can be used to illustrate the sex differences in this Corsi test. In Experiment 2, 64 adult participants (50% females) attempted the traditional wooden version of the test and also a 2D mental rotations instrument. Results showed that both tasks presented sex differences favoring men, but they were smaller in the Corsi test than in the task of mental rotation. Thus, the trend with spatial abilities is also observed in spatial working memory tests, as they show smaller sex differences than mental rotation tasks.

In another study, Piccardi et al. (2008) investigated two different sizes of the Corsi test, with a sample of 75 undergraduate students (47% females). In the original version, an investigator tapped specific sequences of nine wooden block, and the students had to replicate these sequences. In the walking, large-size version, there were nine squares placed on the floor, which were stepped on in sequences, and the students had to walk and step on, following the series. It was observed that in both original and walk-size versions, men outperformed women.

In contrast, there are studies which could not indicate sex effects on the Corsi Block Tapping Test (e.g., Castro-Alonso et al. 2018b). For example, Kessels et al. (2000) investigated 140 adults (44% females), including 70 healthy participants and 70 patients with cerebral lesions, attempting the original test with nine wooden blocks. Although there was a slight tendency of men to remember more blocks than women (0.27 blocks), this difference was not significant. In the study by Woods et al. (2016), 189 adults (42% females) attempted a computerized test that involved clicking on ten 2D squared (as opposed to tapping on nine 3D wooden blocks in the traditional Corsi test). In this modern adaptation of the Corsi instrument, there were no significant sex differences in any of the metrics, including accuracy and reaction times.

There are other spatial working memory instruments, besides the Corsi test. For example, those following the n-back task paradigm. Voyer et al. (2017) performed a meta-analysis with eight samples and 19 effect sizes. Again, it was observed that men outperformed women with a small effect size (d = 0.20). A study from the meta-analysis that provides greater detail of these sex effects is the experiment with 36 psychology undergraduates (50% females) by Lejbak et al. (2011). They employed 2-back tasks of three different versions: verbal, object, and spatial tasks. When the sexes were compared, women were surpassed in the object and spatial versions, but there were no sex differences in the verbal format.

4.1.4 Visual Working Memory

Visual working memory is typically measured by instruments that show visuospatial elements simultaneously (cf. Darling et al. 2006). For visual working memory tests requiring memory for patterns, Voyer et al. (2017) performed a meta-analysis with 25 samples and 36 effect sizes, and observed that males outperformed females with a small effect size (d = 0.22).

Another example is the study by Bosco et al. (2004) with 107 psychology students. A visual working memory test was employed, based on the Visual Patterns Test by Della Sala et al. (1999). Also, the Corsi Block Tapping Test (spatial working memory) was included. Results showed that men outperformed women in both the visual and the spatial working memory tests. Similar findings were reported with the original version of the Visual Patterns Test. In this study by Della Sala et al. (1999), a sample of 345 participants (54% females) revealed sex difference favoring men over women, but the difference was small.

Other visual working memory instruments are those measuring object location memory (e.g., Eals and Silverman 1994; Epting and Overman 1998; cf. Hammond et al. 2019; Kessels et al. 1999), an ability to compare a stimulus visual display of elements to a test display and judge which elements have been moved between both displays (see an example in Fig. 4.2). These instruments show peculiar effects. In contrast to most of the findings of visuospatial processing tasks, in which men tend to show higher scores, the instruments of Object Location Memory tend to show the opposite direction of effects.

Fig. 4.2
figure 2

Adapted item from an Object Location Memory task, showing (a) stimulus display and (b) test display where the trees have been displaced. Note that this is not an actual item, but an adaptation

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For example, Voyer et al. (2007) conducted a meta-analysis of 86 effect sizes for object location memory tasks and observed an overall small effect size (d = 0.27) favorable to women. More currently, concerning simple location tasks (typically involving one object and short memorizing times), Voyer et al. (2017) reported a meta-analysis with nine samples and 26 effect sizes. It was also observed that in these less difficult location tasks, women outperformed men with a small to medium effect size (d = 0.35).

An important finding, not included in this meta-analysis, was provided in the large study (N > 245,000; 47% females) by Silverman et al. (2007), which collected data from participants attempting an Object Location Memory task in 40 countries and from seven self-identified ethnic groups. Results revealed significantly higher scores for the females of all the ethnicities and 35 of the 40 countries. The overall effect represented a small size (d = 0.31).

An explanation why women excel in these tasks is the verbal memory hypothesis, which predicts that the greater verbal ability of women (see Reilly et al. 2019) would allow them to add helpful verbal tags to the visuospatial test elements. For example, Choi and L’Hirondelle (2005) used novel tasks of object locations with 111 psychology undergraduates (55% females). One task employed images of nonsense object (difficult to verbally tag) and the other used images of ordinary objects (easy to verbally tag). In both tasks, participants had to memorize the display of images. After this, they had to replace each image in the right location, from memory. Also, verbal and visuospatial abilities were measured, and results showed that women excelled in the verbal instrument and men excelled in the visuospatial tests.

In the study, regarding the object location tasks, scores showed an interaction: Men presented higher scores with the nonsense objects, but females presented higher scores with the common objects. As predicted by the verbal memory hypothesis, women, who had a higher verbal score, might have relied more on verbally labeling the objects, and thus they achieved higher performance with the ordinary objects that were easier to tag. However, since the verbal strategy was less effective with nonsense objects, in this case, visuospatial processing was more effective. Consequently, men, who outperformed women in the other visuospatial tests, presented higher scores than women in the object location task with nonsense images.

In contrast, Lejbak et al. (2009), who investigated university students’ performance on a task memorizing pairs of elements on display, showed that women outperformed men, independently of the ease to tag the items verbally. In fact, the female advantage was observed in the three types of graphics shown in the items, including those easier to verbally label (everyday objects and familiar shapes) and those more difficult for this verbal strategy (uncommon shapes).

These different dependencies on verbal strategies could explain why object location tasks do not always show sex differences. An example of null sex effects is the study with 64 university students (50% females) by Postma et al. (2004), who showed no significant sex differences in the two object location memory formats tested, namely, the traditional pen-and-paper task and a computerized version. Similarly, in two experiments with undergraduates (50% females), Nairne et al. (2012) reported no sex differences in object location memory tasks showing 8 line drawing of either food elements (Experiment 1, N = 52) or animals (Experiment 2, N = 72). This nil sex effects were observed both when giving survival or no survival instructions to the participants (see also Castro-Alonso et al. this volume-c, Chap. 7). Similarly, in a study with 47 university students (57% females), in which Epting and Overman (1998) investigated sex differences and the effects of hormones on visuospatial tests, men outperformed women on the 2D mental rotation task, but there were no sex differences in the Object Location Memory test.

4.1.5 Dual Visuospatial Tasks of Working Memory

As most of the evidence gravitates toward mental rotation favoring men and object location memory favoring women, there is less research showing sex differences with instruments such as dual visuospatial tasks of working memory. As described in Castro-Alonso and Atit (this volume, Chap. 2), dual tasks of working memory include two tasks (see also Castro-Alonso et al. 2018a). The main one is a memory task, in which different memory elements are shown in order, and they must be remembered in the order of presentation. The secondary task, which is interspaced between the memory task, is the processing task, where a Yes/No answer is usually expected (e.g., “Is this visual equation logical?”). Different standard tests use a diversity of memory and processing stimuli (see Castro-Alonso et al. this volume-a, Chap. 8). Here, we briefly describe two studies that employed visuospatial stimuli and investigated sex differences.

Investigating a large sample (N > 5,500) of participants, Redick et al. (2012) measured sex differences in the Symmetry Span Task. In this test, the memory task involves remembering where the filled square was positioned in a pattern of empty squares. The typical processing task is to judge whether different patterns of squares are symmetrical or not. Results for the memory task showed a small sex effect (d = 0.26) favoring men. For the processing component, there were no sex differences. Analogously, Geiger and Litwiller (2005) investigated 63 university students (76% females) attempting cognitive tasks. Results on a dual visuospatial task with rotated and mirror-reversed letters were favorable to men in the memory task.

In conclusion, several visuospatial processing tests show a different degree of sex influence. The tasks more favorable to men are mental rotations, notably 3D mental rotation tasks. However, the whole spectrum of visuospatial processing tasks is more favorable to men. The only exception where women tend to outscore men is in the visual working memory tasks of object location memory. Explanations for these sex differences in visuospatial processing are provided next.

4.2 Sociocultural and Biological Explanations

As described by Halpern (2006), explanations about sex differences on cognitive abilities are generally rooted in a false dichotomy of sociocultural vs. biological causes. For example, a myth about sex differences in visuospatial processing abilities tends to give precedence of fixed biological factors over malleable social variables (see Newcombe and Stieff 2011). Similarly, sex differences in other cognitive variables also show research streams that favor one pole over the other (see Eagly and Wood 2013). However, any cognitive performance is caused by biological variables influencing sociocultural experiences, which also shape back the biological factors. Thus, is a complex integrative mechanism where both sociocultural and biological roles are involved (see also Levine et al. 2016).

Nevertheless, the dichotomy is persistent among researchers because an alternative integrative approach would require interdisciplinarity, which is more difficult than dealing with the causes separately (see Eagly and Wood 2013). As such, although both nurture (socioculture) and nature (biology) causes should be considered together for a robust explanation of sex differences on visuospatial processing abilities, the evidence tends to be disaggregated into the poles. For this reason, we will also consider them separately here. Starting with sociocultural causes of sex differences in visuospatial processing, we will describe visuospatial experience (Sect. 4.2.1) and stereotype threat (Sect. 4.2.2). After this, we will address the biological cause of hormones (Sect. 4.2.3).

4.2.1 Visuospatial Experience

A greater and richer visuospatial experience for men than for women could be a sociocultural explanation for the sex differences observed in mental rotations and other visuospatial processing tasks. Although the evidence is generally correlational, it supports that better outcomes on visuospatial processing tests as an adult can be at least partially explained by a rich visuospatial experience from young ages. As shown in Table 4.2, we grouped these experiences as: (a) sports and hobbies, (b) toys and games, and (c) computers and videogames.

Table 4.2 Types and examples of visuospatial activities influencing sex differences
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Addressing the type of sports and hobbies, Newcombe et al. (1983) developed a survey for high school and university students regarding participation in different spatial activities. The survey included 81 spatial activities: 40 regarded as masculine (e.g., basketball and carpentry), 21 considered feminine (e.g., ballet and knitting), and 20 considered neutral (e.g., volleyball and photography). Nazareth et al. (2013) conducted a mediation analysis to investigate if these sports and hobbies experienced when teenagers could help to explain the performance as adults on the Mental Rotations Test. Results indicated that being a man predicted successful performance on the 3D test. Notably, it was also observed that this model presented a better fit when the variable number of previous masculine spatial activities was included.

In addition to the type of spatial sport and hobby practiced, there are indications that any experience with sports and hobbies is more effective for cognitive processing than a sedentary lifestyle (see Castro-Alonso et al. this volume-c, Chap. 7; but see Jansen et al. 2016). For example, Voyer and Jansen (2017) conducted a meta-analysis of 33 samples and 62 effect sizes, to investigate the relationship between: (a) music and sports experience, and (b) tests of spatial ability. They observed an overall small to medium effect (d = 0.38), in which individuals with extensive practice in activities such as combat sports, gymnastics, dance, and music, showed higher spatial ability scores than subjects with no motor expertise.

Considering the type of toys and games, Jirout and Newcombe (2015) studied a large sample (N = 847) of 4- to 7-year-old children, in which spatial ability was assessed with a standard pen-and-paper instrument. In addition, the parents reported how frequently their children played with various categories of toys and games. Results indicated that boys outperformed girls in the spatial ability test, after controlling for several cognitive variables. It was also observed that boys were reported as playing more frequently than girls in the following two categories: (a) bicycles, scooters, skateboards, and swings; and (b) blocks, puzzles, and board games. Levine et al. (2005) investigated 547 school students (50% females) from different socioeconomic backgrounds. The study showed that boys and girls from lower status showed equally low scores on a mental rotation task. In contrast, at higher socioeconomic backgrounds, where the scores were higher for all, boys outperformed girls. As suggested in the study, these findings supported that wealthier boys could have access to more expensive toys and games promoting spatial skills, as compared to poorer boys. It was assumed that girls, even from the higher socioeconomic status, were less involved in these somewhat expensive spatial activities with toys and games.

Recently, Moè et al. (2018) examined Mental Rotations Tests performance in 176 university students (54% females) from either science (chemistry, physics, mathematics) or nonscience (education, languages, philosophy) disciplines. The participants also rated their childhood preference for spatial toys (e.g., blocks and puzzles) and non-spatial toys (e.g., puppets and board games). Results showed that the females showing the highest mental rotation scores were those in science disciplines and those who had played with spatial toys.

Regarding the possible influence of computers and videogames, the review by Verdine et al. (2014) is broad enough to include these virtual experiences and the spatial toys and games just described. As such, the study reviewed different spatial activities that were effective in promoting the visuospatial abilities of young children, both at home and in preschool. These activities included spatial digital platforms and videogames, construction blocks, and jigsaw puzzles.

Another example is the meta-analysis by Cai et al. (2017) investigating sex differences on attitudes toward technology. This analysis of 87 comparisons (50 studies from the years 1997 to 2014), revealed small but significant effect sizes for belief (believing in the positive uses of technology) and self-efficacy (confidence in one’s ability to use technology) favoring men over women. This men’s higher technology self-efficacy may be partially explained by the findings of Drabowicz (2014) from adolescents of 39 countries completing the Program for International Student Assessment (PISA). Results of these questionnaires revealed that boys reported more frequent computer use than girls.

Roberts and Bell (2000) tested 44 psychology university students (52% females) attempting a computer mental rotation task with 2D shapes. In addition to researching sex differences, the authors assessed if familiarization with the computer influenced mental rotation performance. As expected, in the group that had not been familiarized with the computer before the test, males were faster than females on the mental rotation computer test. However, in the group that had time to know the computer, there were no sex differences on the computer mental rotations. As discussed by the authors, being knowledgeable with computers may have been more critical for this 2D computer task than being capable of mental rotation.

To include a study with other visuospatial processing abilities, the meta-analysis for different visuospatial tasks conducted by Voyer et al. (2017) showed that computerized tests drove the small overall effect size that favored men. When comparing computer-based versus pen-and-paper tests, it was reported that only the computer instruments produced significant effects, as the paper tests produced no sex differences. In other words, women were more challenged by the computer tasks.

4.2.2 Stereotype Threat

As reviewed in Spencer et al. (2016), in a stereotype threat situation, the affected person (e.g., Woman A) tries to avoid confirming a negative stereotype (e.g., women are bad at maths). In attempting to disconfirm the stereotype, this overthinking taxes working memory beyond its limits, resulting in a final negative result (e.g., Woman A having a bad math score). The stereotype threat literature dealing with sex effects was arguably started by Spencer et al. (1999) with females’ underperformance in mathematical tasks (see also Nguyen and Ryan 2008).

Later research tackled related tasks demanding visuospatial abilities, as these have also the label of being difficult to women. An example of more confidence in spatial processing in men than in women is the meta-analysis by Syzmanowicz and Furnham (2011) studying 10,689 participants (57% females) self-estimating their spatial intelligence. Analyzing 56 comparisons, the overall effect size was medium (d = 0.43) for men outperforming women.

Due to this confidence of men in their visuospatial abilities, sex stereotypes about these abilities tend to be harmful to women only. Sometimes, by just being in a threat scenario, such as in a mixed-sex location attempting a spatial test, women are negatively affected. This would be an implicit sex threat situation. In contrast, giving framing instructions before the spatial test, in other words, giving indications that men perform better, results in an explicit threat situation. As shown in Table 4.3, we categorized sex stereotype threats by these two degrees.

Table 4.3 Degrees of sex stereotype threats and examples of framing instructions that could trigger these effects
Full size table

Implicit framing instructions involve mentioning the sex of the participants before a visuospatial test but not giving an explicit comment on which sex generally performs better on the task. For example, McGlone and Aronson (2006) investigated 90 undergraduates (50% females) attempting the Mental Rotations Test after a brief questionnaire had emphasized their sex. Results on the rotation task showed that priming to consider their sex impaired women and was beneficial for men.

Implicit threats can also be activated by the stimuli used in the visuospatial tests. For example, stimuli perceived as masculine could induce a greater implicit threat scenario than feminine or neutral stimuli. For an example with children, Ruthsatz et al. (2017) reported that 144 fourth graders (47% females) rated cube figures in a mental rotation test as male-stereotyped and pellet figures as female-stereotyped. The results showed the prediction for an implicit threat situation: Boys solely outperformed girls in tasks with the “masculine” cube figures rotated in depth, while there was no significant sex difference with the “feminine” pellet-figure items.

Although less investigated than for mental rotation, there are also stereotype effects with other visuospatial tasks. For example, regarding field independence, in a study with 166 (50% females) undergraduates, Drążkowski et al. (2017) assessed the participants’ performance in the Group Embedded Figures Test. Notably, the authors compared field independence between participants who wrote down their sex either before or after attempting the test. Even such a minor intervention as reporting the sex beforehand was sufficient to elicit negative stereotypes in women, as they showed lower scores than men who reported their sex previously. In contrast, there were no significant differences in field independence when the sex was reported after the spatial ability test.

In contrast, an explicit sex threat involves, for example, mentioning which sex tend to show better performance on a specific visuospatial task. In a study with 114 adults (52% females), Hausmann et al. (2009) employed instruments to measure mental rotations in 3D (the Mental Rotations Tests) and 2D (the Mirror Pictures Test). Crucially, participants in the experimental condition read a description of a person’s capacities (e.g., “…can rotate abstract objects mentally…”; “…can imagine common objects from different perspectives”) and estimated the probability that the person was male or female. (In contrast, the control group estimated probabilities of being a North American or a European). For the experimental group with the sex stereotype activation, all participants tended to attribute spatial abilities more to males than to females. Moreover, this stereotype activation led men to increase and women to decrease their performance on the more difficult 3D mental rotation test, but this sex difference was not observed for the easier 2D mental rotation task.

Another example is from Heil et al. (2012), who studied the Mental Rotations Test performance of 300 adults (50% females) randomly assigned into three different stereotyping conditions, according to the instructions given before the task. In the men are better condition, the instructions for the Mental Rotation Test indicated that usually men scored higher on the test. In the neutral control condition, there was no indication of sexes affecting performance. In the women are better group, it was indicated that usually women scored higher than men. Although results showed that in all three groups men outperformed women, the effects were in the expected directions due to the framing instructions. The largest sex effect favoring men was in the men are better condition (d = 1.17), followed by the control group (d = 0.86), and followed by the women are better condition (d = 0.27, non-significant).

To explain stereotype threat effects, the depletion of working memory is a straightforward rationale, as it resonates with the cognitive load theory methods for avoiding working memory overload (see Castro-Alonso et al. this volume-b, Chap. 5). As defined by Hobfoll (1989) in the conservation of resources model for stress, the threat of losing valuable resources, such as academic reputation and self-esteem, is a stressful event. In this case, this psychological stress, in form of negative thoughts during spatial tasks in women, reduces available working memory to deal with the tasks.

Employing explicit threat instructions, Schmader and Johns (2003, Experiment 1) tested the working memory depletion hypothesis. In the experiment, 59 psychology undergraduates (47% females) completed maths working memory tests either in non-threat or threat conditions. In the non-threat condition, the instructions given for the working memory test did not indicate that sex influenced performance. In the threat group, the working memory test was described as related to sex differences and maths ability, known to be favorable to men. In the non-threat condition, there was no difference in performance on the working memory test between men and women, but in the threat condition, women (but not men) showed lower scores on the working memory test. These findings support that stereotype threat is at least partially caused by a reduction in total working memory capacity available to process a cognitive task (see also Schmader et al. 2008).

4.2.3 Hormones

A natural cause to explain sex differences in visuospatial abilities is that men and women have distinct types and levels of hormones, such as males’ testosterone. In the visuospatial processing research literature, the effects of hormones can be classified according to the age of the participants. The studies can involve prenatal individuals (organizational effects) or developed participants, such as adults (activational effects). Organizational effects influence the in utero development of cognitive structures, which more permanently would affect visuospatial processing abilities. In contrast, activational effects depend on fluctuating levels of hormones in adults and tend to be less irreversible.

As shown in Table 4.4, a consistent effect with samples of prenatal individuals is that testosterone tends to enable women in visuospatial tasks. This finding has been observed in two of the three types of studies described here, namely, fetal levels and twins. In other words, research with fetal hormone levels and twin comparisons are more conclusive for women than for men. For the third category of prenatal studies, medical conditions, the effects are positive for both sexes.

Table 4.4 Age of participants, types of studies, and effect for hormones influencing sex differences
Full size table

In contrast, for adult participants, the effects are more difficult to interpret, and the different types of studies show conflicting evidence. In other words, the types termed here as: (a) testosterone measured, (b) testosterone administered, and (c) estradiol measured are not giving a conclusive picture, yet (see also Quaiser-Pohl et al. 2016).

An example of prenatal research measuring fetal hormone levels is given by Grimshaw et al. (1995). The authors used data from fetal testosterone levels of 60 participants (48% females) to investigate if these prenatal levels affected later mental rotation performance. When the participants had turned 7 years, they were required to perform a computer 2D mental rotation task with cartoon illustrations of bears. As expected, it was observed that girls who had previously higher prenatal testosterone did the mental rotations faster than girls with lower testosterone levels. But, for boys, the results were in the unexpected opposite direction, as higher fetal testosterone was related to slower rates of mental rotation.

More conclusive evidence can be obtained with larger samples, usually employed in the second type of prenatal studies, those with twins. Investigating 804 young adult twins (59% females), Vuoksimaa et al. (2010) tested if the sex of the co-twin in prenatal development would affect later adult performance on the Mental Rotations Test. This investigation tested the prenatal masculinization hypothesis, which assumes that there can be an intrauterine exchange in testosterone between twins, and that females are exposed to the testosterone from their male co-twins. Consistent with the hypothesis, results revealed that females with male co-twins showed higher scores in the Mental Rotations Test as adults, as compared to females with female co-twins. For males, there were no significant differences between having a male or a female co-twin. Also, males with male co-twins scored higher in mental rotations than females with female co-twins. Moreover, regression analyses showed that the greater performance of females with male co-twins over females with female co-twins was not influenced by environmental factors, including gestational age and videogame experience.

Similarly, Heil et al. (2011, Experiment 1) investigated the scores in the Mental Rotations Test of adult women with a high school degree, and observed that, from the 200 twins analyzed, the 100 females with a male co-twin outperformed those 100 with a female co-twin. Critically to discard environmental factors, these females with a male co-twin presented higher mental rotation scores than 100 control females (non-twins) who were raised with a slightly older brother.

In short, both fetal levels and twins’ studies tend to show that testosterone enables women performance in visuospatial tasks (e.g., mental rotation). The research involving medical developmental conditions also shows this enabling effect in women, but it also shows disabling effects in men with low testosterone. For example, Resnick et al. (1986) investigated 25 patients (68% females) with congenital adrenal hyperplasia, a medical condition that exposed them to abnormally high levels of testosterone during development. A battery of cognitive tests was used, including measures of mental rotation, mental folding, and field independence. Results showed that women with the medical condition outperformed unaffected control women on the Mental Rotations Test, the Card Rotations Test, and the Hidden Patterns Test. Similarly, Berenbaum et al. (2012) observed that women with congenital adrenal hyperplasia preferred significantly more traditional male activities and presented significantly higher scores on the Mental Rotations Test, compared to women without this condition.

Analogous to this medical condition in which women produce more testosterone, Hier and Crowley (1982) investigated men with the developmental condition of idiopathic hypogonadotropic hypogonadism, who present a lack of androgenization likely mediated by testosterone deficiency. In the study, 19 of these adult men with low testosterone levels were compared in three verbal and three spatial tests to 19 adult men with regular concentrations of the hormone. It was observed that performance on the verbal tests was equivalent between participants, but in the three spatial tests (including one instrument of mental rotation and one of field independence) the scores were lower in the groups of men with low testosterone.

Describing adult samples, the evidence with these participants includes studies in which circulating levels of testosterone were measured, and these concentrations were correlated with visuospatial processing performance. For example, with an adult sample of 114 participants (52% females), Hausmann et al. (2009) reported that free levels of testosterone (measured from the saliva) were the best predictors for men’s performance in 3D and 2D mental rotation tasks. However, this predictive effect was not observed in women.

In a longitudinal study with 17 adult participants (41% females), Courvoisier et al. (2013) investigated if performance in the Mental Rotations Test was influenced by cyclic variation of hormone levels, for both men and women, over the lapse of 2 months. It was observed that the relationship between testosterone and mental rotation speed was different between the sexes: reaction times were slowest at medium concentrations of testosterone for males, whereas they were slowest at high concentrations of testosterone for females. Notably, after mental rotation training for 2 months, the hormones did not remain predicting performance. In other words, the effects of hormones were less important than those of training.

The second group of adult studies concerns the administration of testosterone. In the experiment by Aleman et al. (2004), 26 right-handed adult females received sublingually either testosterone or placebo, and 5 h later attempted the Mental Rotations Test. Results showed that testosterone caused higher mental rotations than placebo. To conclude from these two types of adult research, when measuring testosterone, the results suggest that the hormone is not as helpful as when the hormone is administered. This is somewhat contradictory.

To this confusing picture, the studies in which the hormone estradiol is measured do not help to reach an overall conclusion. For example, an experiment with 70 undergraduates (56% females) conducted by Hampson and Morley (2013) investigated the effects of estradiol on females. Taking salivary samples, a group with higher blood levels of estradiol was compared to a group with lower levels of the hormone. For the Mental Rotations Test, the group with lower estradiol concentrations presented higher outcomes. In contrast, for a visual working memory task, the females with higher estradiol presented higher results.

In short, the effects of hormones, particularly in adult participants, seem to be less conclusive than those of spatial experience or sex stereotype threats. In addition, as the longitudinal study by Courvoisier et al. (2013) showed, there are other variables more influential to visuospatial performance than hormone levels, such as training, described next.

4.3 Visuospatial Training to Reduce Sex Differences

Among the spatial ability myths described by Newcombe and Stieff (2011), one was that spatial ability is fixed. This myth assumes that spatial ability is genetically transmitted and cannot be modified with sociocultural experiences. However, as we described in the previous section, the evidence suggests that both biological and sociocultural factors play a role in visuospatial processing. For example, the recent meta-analysis of twin studies by King et al. (2019), in which 42 effect sizes were included, showed that, although visuospatial processing was largely heritable (biological), it was also dependent on environmental and sociocultural factors (although to a smaller extent).

Hence, as explained by Newcombe and Stieff (2011), spatial ability is not fixed, because it can be improved with training (see also Uttal et al. 2013). Moreover, this training can also be transferred to related spatial tasks (see Castro-Alonso and Uttal this volume, Chap. 3). More important for this review, visuospatial training could potentially reduce the sex gap unfavorable to women (see Levine et al. 2016).

Visuospatial training can take many forms. Examples of formal educational activities that are recommended by Wai and Kell (2017) to train visuospatial processing in health and natural science contexts include: (a) exploring 3D phenomena with science models, (b) doing manipulations and laboratory activities, and (c) analyzing 2D images and graphs. Informal activities recommended by Reilly et al. (2017) are: (a) sports, (b) model building, (c) construction blocks, and (d) computer games. Next, we describe studies in which several of these training activities did or did not reduce the sex differences that were observed before training.

4.3.1 Reducing the Sex Differences

Addressing mental rotation, Provo et al. (2002) reported that a course of canine anatomy was effective in reducing the sex gap in first-year veterinary students. The authors observed that men showed higher scores before the intervention in a test of 3D mental rotation, and that this sex difference disappeared by the end of the anatomy course, showing that women improved more than men with this kind of training. Recently, the experiment with 611 medicine university students (65% females) by Guimarães et al. (2019) investigated the effects of virtual human anatomy training on Mental Rotations Test performance. When comparing the tests scores obtained before and after the training, it was observed that post-training performance was higher and that the sex differences favoring men before the treatment had disappeared after the anatomy training.

Feng et al. (2007, Experiment 2) investigated 20 undergraduates (70% females) playing videogames for a total training of 10 h (during less than 4 weeks). It was observed that training with action videogames increased performance on standard tests of mental rotation and spatial attention. Notably, these positive effects were higher for women than for men.

Regarding research with several tasks, Wright et al. (2008) investigated 31 adults (55% females) practicing computer 3D mental rotation and mental folding, in 21 training sessions once daily. In addition to a training effect and a smaller but significant transfer effect between the two visuospatial tasks, it was also observed that the initial sex differences disappeared by the end of training. Also, Stericker and LeVesconte (1982) trained 45 psychology participants (53% females) with three different standard instruments, respectively measuring 3D mental rotation, mental folding, and field independence. The training consisted of six weekly sessions devoted to approximately 20 min per test. After the training, the students improved their original scores in all the tests, compared to a control condition. Notably, the original men advantage observed in the tests before training disappeared after the six sessions.

Lord (1987) examined 120 science undergraduates (approximately 50% women) attempting a 3D mental rotation task (the Cube Comparisons Test), a mental folding test (the Paper Folding Test), and an instrument of field independence (the Hidden Figures Test). A one-semester training that involved weekly spatial exercises proved to be adequate for mental rotation and mental folding, but not for field independence. Furthermore, the effects were higher in women, so the gender gap in mental rotation and mental folding, unfavorable to women at the start, was reduced after the training.

The last example also concerns field independence. Goldstein and Chance (1965) investigated training effects of 26 undergraduates (50% females) completing the Embedded Figures Test. At the onset, men outperformed women on this instrument. However, when finishing the training of eight blocks of trials, women improved more than men, producing that the sex differences disappeared.

4.3.2 Not Reducing the Sex Differences

About mental rotation, Peters et al. (1995) reported a study with 27 university students (70% females) from fields of science (biological and physical science, and engineering) and non-science (arts, social sciences, and humanities). The participants practiced the Mental Rotations Test once weekly, for a total training of 4 weeks. It was observed that men significantly outperformed women on the test. Also, although training was effective in significantly improving the scores for the participants, it was equally effective for both sexes, so it could not diminish the original differences favoring men.

Terlecki et al. (2008) invited 180 psychology undergraduates (66% women) among the highest and lowest scorers on a survey of computer and videogame expertise (see Terlecki and Newcombe 2005) to participate in a videogame spatial training program. For 12 weeks, the spatial condition practiced with 3D and 2D versions of the videogame Tetris™, whereas the non-spatial control condition practiced with the card videogame of Solitaire. Results showed that the spatial condition was effective in increasing the scores on the Mental Rotations Test. However, the original sex gap between men and women was not significantly closed, and this null result was not affected by the participants’ experiences with computers and videogames.

Concerning various abilities, Okagaki and Frensch (1994, Experiment 1) investigated the effects of 12 training sessions (6 h in total) with the videogame of Tetris on three pen-and-paper visuospatial processing tests: (a) the Cube Comparisons Test of 3D mental rotation, (b) the Card Rotations Test of 2D mental rotation, and (c) the Form Board Test of mental folding. The study, conducted on 57 introductory psychology undergraduates (51% females) inexperienced in Tetris, revealed initial sex differences favoring males in the three visuospatial tests and Tetris performance. After the 6 h of videogame training, only males’ scores on the Cube Comparisons Test and the Form Board Test improved, but females did not improve in any test. These results showed an enlargement of the initial sex gap unfavorable to the females for these instruments of mental rotation and mental folding.

A conclusion from the visuospatial training studies is not straightforward, as there is evidence showing that the initial sex gap favorable to men: (a) reduces, (b) continues, and (c) enlarges. Although various encouraging results support visuospatial training as an effective strategy to reduce the sex gap, the different visuospatial tasks and training regimes do not show yet consistent findings.

4.4 Discussion

There are many different abilities controlled by the visuospatial processing components of working memory. These different visuospatial abilities show different directions and degrees of sex differences. Although they generally favor men, the ability known as object location memory is usually performed better by women. For most of the other visuospatial skills, in which men excel, mental rotation and mainly 3D mental rotation show the most consistent differences favoring males.

There are sociocultural (nurture) and biological (nature) causes to explain these differences. One sociocultural explanation for these differences favoring men is visuospatial experience, because men generally practice with spatial sports, hobbies, toys, and videogames more often than women. Another sociocultural reason is stereotype threat, as only females are disadvantaged in visuospatial testing situations where they do not want to fail. By overthinking to avoid confirming the stereotype that women are bad in visuospatial abilities, they may fail in the tests due to working memory overload. A biological explanation for these sex differences involves the different hormones that male and female produce, notably testosterone.

Visuospatial training could be a powerful method to reduce the sex gap unfavorable to women. Many different visuospatial activities, which can be included in formal and informal educational settings, have shown positive effects for diminishing the gap. For example, training with visuospatial tests, spatial toys, science activities, and videogames show encouraging findings. However, there are also negative findings in which visuospatial training is not as effective to favor women over men.

4.4.1 Instructional Implications for Health and Natural Sciences

A first instructional implication is that educators (e.g., lecturers and instructors) should be aware that visuospatial processing could be influenced by sex, sex stereotypes, and science stereotypes. Consequently, educators should encourage visuospatial training and visuospatial activities in the classroom (see Newcombe 2016; Wai and Kell 2017), as a way to circumvent these sex and stereotype effects.

A second implication, related to the first, stems from the fact that different visuospatial tasks will show different sex influence. Similarly, different visuospatial tasks will be required to learn about different health and natural science topics (cf. Castro-Alonso et al. 2019a). As such, educators should focus their efforts on training the most relevant visuospatial task for the science content or discipline involved.

A third implication regards stereotype threat. As suggested by Levine et al. (2016), the instructional efforts should concentrate on reducing the susceptibility to these negative stereotypes. For example, female students should see female models excelling in visuospatial tasks, as women role models are pivotal in health and natural sciences (e.g., Miller et al. 2015; Rochon et al. 2016; Young et al. 2013). Also, students should be made aware of the stereotype threats effects that could impair their visuospatial and science achievement.

A fourth implication, linked to the previous, also regards stereotype threat. In this case, the awareness is for educators. They should be aware of the implicit stereotype threat that they might be transferring to their students (cf. Rosenthal and Jacobson 1968). In consequence, the stereotypes that teachers and instructors enforce or alleviate will affect students’ visuospatial performance and learning in the science fields.

A fifth implication is for parents, coaches, and educators in general who oversee young children. They should encourage these children to be involved in visuospatial sports and hobbies, as these activities provide positive effects on health and cognition.

4.4.2 Future Research Directions

We now note some future directions that research into sex differences and visuospatial processing might follow. The first direction concerns also investigating the effects of gender, and not only sex differences. As described in Torgrimson and Minson (2005), the primary difference between the two constructs is that sex is biological, and gender is more related to sociocultural representations. For example, future research could recruit males (sex variable) and compare individuals with different self-identities (gender variable, e.g., Reilly et al. 2016) attempting 3D mental rotations.

Secondly, as Choi and L’Hirondelle (2005) reported different sex outcomes on Object Location Memory due to verbal strategies, these could also be investigated in other visuospatial processing tests. For example, as described in Castro-Alonso et al. (this volume-a, Chap. 8), instruments such as the Corsi Block Tapping Test or the Visual Patterns Test can be programmed to show a number on each element to memorize. These numbers could be used as verbal labels to remember better the sequences or patterns of the tests. Whether these verbal strategies are more helpful to women or men could be investigated.

In third place, a promising approach would be to integrate sociocultural as well as biological research questions in one design to investigate the interacting effects of both possible reasons. Although Eagly and Wood (2013) note that this approach is difficult because it involves interdisciplinary research, we believe that its potential makes the attempts worthwhile.

As a fourth possible direction, we consider the influence of computer and videogame experience on sex differences. For example, research on instructional simulations and videogames about science (see Castro-Alonso and Fiorella this volume, Chap. 6) are promising future directions for sex effects and visuospatial processing. Similarly, particular learning scenarios that need visuospatial processing, such as learning health and natural sciences from visualizations, could also be studied (see Castro-Alonso et al. this volume-b, Chap. 5). For example, learning from instructional visualizations is influenced by sex or gender and visuospatial processing (e.g., Castro-Alonso et al. 2019b; Wong et al. 2015, 2018).

A fifth direction concerns sex stereotype threats. Future research could investigate if different degrees of threats, such as implicit versus explicit framing instructions, have different results on the visuospatial performance of the same population. Also, the effects of sex threats could be compared between different visuospatial processing abilities. For example, spatial working memory and object location tasks could be analyzed. Also, because working memory depletion can partially explain these adverse stereotyping effects, the duration and cognitive loads involved in this depletion (e.g., Chen et al. 2018) could also be investigated.

A sixth direction involves training effects on the different visuospatial processing abilities. For example, the favorable training effects for women on mental rotation seem to be larger than for field independence. Different training activities, such as videogaming versus sports, are also encouraging new directions for inquiry.

4.4.3 Conclusion

Sex differences in visuospatial abilities are harmful to the underperforming sex, as these abilities are needed to learn and flourish in the fields of health and natural sciences. Despite mental rotation consistently showing a sex difference favoring men, not all visuospatial abilities show the same direction and degree of effects. In contrast to the small to moderate differences favorable to men in most of the visuospatial abilities, Object Location Memory is usually performed better by women. Explanations for these differences are typically classified as sociocultural or biological, ranging from previous visuospatial experience to hormonal factors. As experience is a well-documented explanation, a way forward to diminish these sex gaps is to promote activities and experiences that can train the visuospatial abilities, such as sports, toy manipulations, and videogames. The goal is that visuospatial training and other solutions help both women and men to improve in the areas of health and natural sciences.