Sex differences in visual-spatial working memory: A meta-analysis

Visual-spatial working memory measures are widely used in clinical and experimental settings. Furthermore, it has been argued that the male advantage in spatial abilities can be explained by a sex difference in visual-spatial working memory. Therefore, sex differences in visual-spatial working memory have important implication for research, theory, and practice, but they have yet to be quantified. The present meta-analysis quantified the magnitude of sex differences in visual-spatial working memory and examined variables that might moderate them. The analysis used a set of 180 effect sizes from healthy males and females drawn from 98 samples ranging in mean age from 3 to 86 years. Multilevel meta-analysis was used on the overall data set to account for non-independent effect sizes. The data also were analyzed in separate task subgroups by means of multilevel and mixed-effects models. Results showed a small but significant male advantage (mean d = 0.155, 95 % confidence interval = 0.087-0.223). All the tasks produced a male advantage, except for memory for location, where a female advantage emerged. Age of the participants was a significant moderator, indicating that sex differences in visual-spatial working memory appeared first in the 13-17 years age group. Removing memory for location tasks from the sample affected the pattern of significant moderators. The present results indicate a male advantage in visual-spatial working memory, although age and specific task modulate the magnitude and direction of the effects. Implications for clinical applications, cognitive model building, and experimental research are discussed.     

Sex differences among children on embedded tasks

100 8-yr.-old children (50 boys and 50 girls) were evaluated on the Children's Embedded Figures Test to determine whether there are differences in disembedding ability between boys and girls. Analysis indicated that the boys were superior to the girls on the test as a whole, but this superiority is the result of boys' greater ability to detect a triangular figure and not, on the contrary, their ability to detect the outline of a house.     

Sex differences in visual-spatial ability: The role of performance factors

Two studies were designed to explore the role of performance factors as sources of the frequently noted higher male scores on visual-spatial ability tests. In the first study, the mental rotations test (MRT) was administered to male and female college students of equally high quantitative ability (based on SAT math scores). Although males had significantly more correct responses on the test than did females, their advantage was eliminated when the ratio of correct responses to items attempted was used as the dependent measure. In the second study, the same test was administered to new groups of male and female college students. In this sample, the males had significantly higher SAT math scores. The MRT was administered under standard, timed conditions and under untimed conditions. Both raw and ratio scores were calculated. With SAT math score as the covariate, analyses of covariance indicated that males demonstrated higher performance in the timed, raw-score condition but not in the untimed or in the ratio-score conditions. The theoretical and social policy implications of these studies are discussed.     

Sex differences in attributions for sex-typed tasks1

Recent studies have indicated that males make more egotistical attributions than females, that is, males make more internal attributions for success and more external attributions for failure than females do. These sex differences in attributions were examined in terms of male/female differences in expectancies for success and ego-involvement in the tasks. Male and female subjects succeeded or failed on a masculine or a feminine task. It was found that males made more egotistical attributions than females on the masculine task, but females made more egotistical attributions than males on the feminine task. A covariance analysis revealed that these sex differences in attributions could be explained in terms of the differences between the males and females in expectancy for success and in ego-involvement. Finally, it was found that ego-involvement was a more important determinant of egotisical attributions in the present study than was expectancy.     

Sex differences in performance on three novel continuous response tasks

The Dynavision apparatus was used to assess psychomotor differences between men and women first-time users. Subjects, 50 men and 76 women, were tested on three 60-sec. Dynavision response tasks of graded difficulty. An analysis of variance with repeated measures indicated that men performed significantly better than women on all tasks. Performances on all tasks were also significantly different from each other within both sexes (p < or = .05). Furthermore, a significant interaction between sex and task was based on a greater drop in performance on the most complex task for women than for men.     

Sex differences in genetic and environmental effects on aggression

The aim of the present study was to investigate the genetic and environmental factors influencing teacher and parental rated aggression in boys and girls, asking whether the magnitude of these effects is similar across rater and sex. The study is part of an ongoing nationwide twin‐family study of behavioral development and health habits carried out in Finland. The sample consisted of 1651 twin pairs (264 monozygotic male, 300 monozygotic female, 292 dizygotic male, 278 dizygotic female, and 517 dizygotic opposite‐sex twin pairs), representing subsets of five 11‐ to 12‐year‐old twin cohorts (b. 1983–1987). The data were collected using the teacher and parental rating forms of the Multidimensional Peer Nomination Inventory. Structural equation models of sex‐limitation assessed sex differences in genetic and environmental influences on aggression. The results suggested significant genetic, common environmental, and specific environmental effects on aggression in both boys and girls, but the best fitting model differed depending on the informant. For both ratings, boys showed lower levels of heritability and higher levels of common environment than girls. In addition, the teacher rating data also suggested the presence of either sex‐specific common environmental effects or sex‐specific genetic effects. Support is provided also for sibling contrast effects, either at the behavioral level or as a rater bias. Aggr. Behav. 29:55–68, 2003. © 2003 Wiley‐Liss, Inc.     

Sex differences in unfamiliar face identification: evidence from matching tasks

Research on sex differences in face recognition has reported mixed results, on balance suggesting an advantage for female observers. However, it is not clear whether this advantage is specific to face processing or reflects a more general superiority effect in episodic memory. The current study therefore examined sex differences with a face-matching task that eliminates memory demands. Across two experiments, female but not male observers showed an own-sex advantage on match trials, in which two pictures have to be identified as the same person. This advantage was present for whole faces and when only the internal or external facial features were shown. Female observers were also more accurate in these three conditions on mismatch encounters, in which two photographs have to be identified as different people, but this reflects a more general effect that is present for male and female faces. These findings converge with claims of a female advantage in face recognition and demonstrate that this effect persists when memory demands are eliminated.     

Two- vs. three-dimensional presentation of mental rotation tasks: Sex differences and effects of training on performance and brain activation

The well-documented sex difference in mental rotation favoring males has been shown to emerge only for 2-dimensional presentations of 3-dimensional objects, but not with actual 3-dimensional objects or with virtual reality presentations of 3-dimensional objects. Training studies using computer games with mental rotation-related content have demonstrated training effects on mental rotation performance. Here, we studied the combined effect of a two-week mental rotation (MR) training on 2-dimensional vs. 3-dimensional presentations of a classic Shepard–Metzler task (presented in a pretest–training–posttest design) and their accompanying cortical activation patterns assessed via EEG in a sample of 38 male and 39 female adolescents of about 15 years of age. Analysis of one performance parameter (reaction times) displayed only main effects of dimensionality (with shorter RTs on the 3D vs. 2D version of the MR task) and of training (significant shortening of RTs), but no significant sex difference. Analysis of the other performance parameter (scores) in the MR task revealed a sex difference favoring males that first, appeared only in the 2D version, but not in the 3D version of the MR task and, secondly, diminished after training. Neurophysiologically we observed a complex sex × dimensionality × training × hemisphere interaction showing that the hypothesized decrease of brain activation (increase in neural efficiency) with training emerged for males in both 2D and 3D conditions, whereas for females this decrease was found only in the 3D but not with the 2D version of the MR task.     

Contextual interference effects with two tasks

The present study was intended to test whether the standard contextual interference effect would be observed when only two patterns were practiced in blocked or random schedules of multisegment movement tasks rather than three patterns which is the norm. In line with the basic effect, Blocked learners' performance was closer to ideal during acquisition, but Random learners had smaller errors at 24-hr. retention. In addition, random learners had better recall of the details of the patterns they had practiced. Learners' predictions of retention performance did not match the group differences actually observed.     

Sex differences and effects of aging on visuomotor coordination.

The purpose of this study was to examine the effects of aging on men and women in processing information required to reproduce direction and distance on a visuomotor task. Subjects (45 men and 45 women) selected from three age groups (25-34 yr., 45-54 yr., 65-74 yr.) were required to estimate blindly the exact criterion location of a target-point they had identified under one of the following conditions: visual, kinesthetic, and visuokinesthetic. Errors in direction (degrees) and in distance (cm) were recorded. The analysis of the total variability in responding (E) indicated that the women of the 65- to 74-yr. age group were significantly less accurate in estimating distance than were the men of the two older age groups (45 to 54 yr., 65 to 74 yr.) and less accurate than were the women of the 25- to 34-yr. age group. No significant differences in estimating distance were found among the three age groups of men. No significant differences for direction were found between men and women.     

Sex differences in psychological effects of exercise

The purpose of this study was to investigate sex differences in psychological effects of exercise on university students. University students (73 female and 65 male) were randomly assigned to experimental and control groups by equating sex in each group. The experimental group participated in step dance sessions of 50 min per day, 3 days per week for 10 weeks with 60-80% of their heart rate reserves. Throughout the 10-week period, the lecture control group was told not to participate in any organized or structured exercise and participated in a lecture that was about the physiological and psychological benefits of exercise. Self-concept, belief in external control, and trait anxiety of the groups were measured before and after the exercise program. A significant improvement in the psychological variables after the exercise program and more improvement for female exercise participants were expected. Analysis revealed no significant initial differences in self-concept, belief in external control, and trait anxiety between the two groups or between males and females, other than family and moral/ethical self. Repeated measures analysis of variance revealed that exercise led to less belief in external control and significant improvement in physical self and identity dimensions of self-concept for the experimental group compared to the control group. However, there was no significant difference in trait anxiety between the two groups after exercise (p>.05). Analysis also revealed that changes in belief in external control, trait anxiety, and self-concept did not differ with regard to sex. Males and females showed no difference in their improvement on trait anxiety, belief in external control, and most dimensions of self-concept during the 10 weeks. Only changes in personal and physical self throughout 10-week period were different for males and females. Exerciser males improved their personal self and physical self scores more than female exercisers and male and female nonexercisers throughout the 10-week period (p<.05).     

Expectancy and visual-spatial attention: effects on perceptual quality

When we expect important stimuli at a particular spatial location, how does our perceptual sensitivity change over space? Subjects were cued to expect a target stimulus at one location and then required to perform one of the following tasks at that and three other locations: luminance detection, brightness discrimination, orientation discrimination, or form discrimination. The analysis of subjects' performance according to signal detection theory revealed changes in both sensitivity and bias for each of these tasks. Sensitivity was maximally enhanced at the location where a target stimulus was expected and generally decreased with distance from that location. Factors that influenced the gradient of sensitivity were (a) the type of task performed and (b) the spatial distribution of the stimuli. Sensitivity fell off more steeply over distance for orientation and form discrimination than for luminance detection and brightness discrimination. In addition, it fell off more steeply when stimuli were near each other than when they were farther apart.     

Age and visual field differences in computing visual-spatial relations.

Age and brain hemispheric differences in visual-spatial performance were investigated using 2 versions of categorical and coordinate (metric) spatial relations tasks. Thirty-two young adults (M = 19.2 years) and 32 older adults (M = 68.8 years) participated. An overall age-related decrement in computing visual-spatial relations was obtained for lateralized presentations and when items were presented centrally. In contrast to some previous findings, there was no evidence to suggest differential aging of the right hemisphere in computing visual-spatial relations.     

Sex differences in chronic stress effects on memory in rats

Recent studies in rodent models and in humans have shown that the status of both the gonadal and adrenal axes (hypothalamic-pituitary-gonadal, HPG and hypothalamic-pituitary-adrenal, HPA, respectively) can influence learning and memory function. In this article, the effects of activating the HPA axis (stress) on performance of memory tasks in rats are reviewed. More importantly, results are presented which show that chronic stress has a different impact on performance of these tasks depending upon the sex of the rat. These observations are novel and potentially important since few studies, animal or human, have utilized females as subjects in studies of the stress response. Sex differences in the effects of chronic stress on memory were investigated in rats using an object recognition task and two spatial memory tasks, radial arm maze and object location. Given the same chronic stress--21 days of restraint for 6 h each day--males were impaired in all of the memory tests while females showed enhanced performance of the spatial memory tasks and no changes in object recognition performance. Levels of neurotransmitters and metabolites were measured in brain areas important for cognition in the subjects in order to determine neural systems that may respond to stress and mediate the cognitive responses. These results show that responses of monoamine and amino acid containing neural systems may contribute to or underlie sex differences in stress effects on cognition. Stress decreased dopaminergic activity in the frontal cortex and amygdala of males but not females; whereas, in CA3 of the hippocampus, stress increased levels of 5-HT and norepinephrine in females, but not males, and increased GABA in males, but not females. Finally, a possible role for estradiol in mediating sexually differentiated responses to stress was examined. Behavioral and neurochemical evaluations in ovariectomized, stressed females, with or without estrogen replacement, suggest that sex differences in response to stress are influenced by both the organizing and activating effects of estradiol. A few, recent studies in humans, that show sexually dimorphic relationships between chronic stress and cognition, are also highlighted. These results in humans are consistent with the pattern of results in rats. Clearly, further studies are necessary to substantiate sex differences in stress effects on memory function in humans and to understand mechanisms whereby estrogen may influence the stress response in rats. Nonetheless, recent studies show sexually differentiated cognitive responses to chronic stress and underline the importance of considering the sex/gender of subjects when studying the stress response.     

Sex differences in the correlation of memory span with scan and other episodic memory tasks

Three studies of the relationship between memory span and other measures of memory and information processing are reported here. These other measures included memory scanning rate, the short- and long-term components of free recall, and word recognition from long-term memory. All three studies produced evidence for a sex difference in the correlation of these tasks with memory span. The first study produced a partial replication of Chiang and Atkinson's report (Memory & Cognition, 1976, 4,661–667) of a sex difference: for males, span and scanning rate were unrelated, while for females they were positively correlated. The second study showed that span and the primary memory component of free recall had a modest positive correlation for females but not for males, while span was unrelated to measures of secondary or long-term memory for females but was consistently positively related for males. In the third study, recognition accuracy and span were uncorrelated for females, but positively correlated for males. Finally, a reanalysis of data from a large-scale study by Underwood, Baruch, and Malmi (Journal of Experimental Psychology: General, 1978, 107, 393–419) also showed evidence of similar sex differences. Sex differences involving the correlation of memory span with other cognitive test performances seem quite general and need to be taken account of in the analyses of individual differences in memory and cognitive processes. A tentative theory is presented to account for the differences found in these studies.     

Sex differences in early childhood, adolescence, and adulthood on cognitive tasks that rely on orbital prefrontal cortex

Through the use of several tests of cognition we have documented sex differences in young children, adolescents, and adults on tasks that rely on the integrity of the orbital prefrontal cortex. In children under three years of age, males performed with significantly fewer errors than did females on tests of object reversals. No significant sex differences were found in older children, despite the use of a more challenging object reversal task. Sex differences were also found in adolescents and adults on the Iowa Gambling Task. On this decision-making task, in contrast to males, females appear to be responding to different elements of the task. Discussion of the implications for these findings is presented.     

Sex differences and estropausal phase effects on water maze performance in aged rats

An age-related decline in memory has been reported in male rats; however, there are few studies that have addressed these changes in aged female rats. In young female rats, hormonal cycles influence behavior. By the age of 22 months most female rats have not had regular hormonal cycles for at least 9 months. In the current study we examined how the hormonal status (persistent estrus and pseudo-pregnant) of the aged (22-24 months) female rat (Long Evans) influenced performance on a spatial version of the Morris water maze and compared this to aged male rats. Aged females in persistent estrus showed better performance on the water maze than both aged females that were pseudopregnant and aged males. Thus, postestropausal hormonal status may influence the course of aging in females.