The effect of explicitly varying the proportion of “same” and “different” responses on sex differences in the Shepard and Metzler mental rotation task

The mental rotation of three-dimensional objects is consistently identified as the most salient cognitive sex difference in humans. The Shepard and Metzler task (1971) requires participants to rotate an object in their “mind's eye” and then compare the shape to a second object to identify if the two objects can be aligned in an identical orientation (warranting a “same” response) or represent mirror image shapes of one another (warranting a “different” response). The mental rotation task not only involves a rotational component but also nonrotational components such as comparison and decision making. Recent research has suggested that the sex difference in mental rotation resides in the nonrotational aspects of “different” decisions specifically. This experiment examined this proposal by varying the proportion of “different” decisions across conditions. Participants were ether exposed to the traditional format (50:50 same/different) or a bias towards (75:25) or away from (25:75) different responses. Contrary to previous research, the sex difference was found to reside in “same” responses that required a greater degree of rotation when assessing error rates in mental rotation. Sex differences in mental rotation error rates were particularly sensitive to the rotational aspect of same responses, not rotational aspects of different responses nor nonrotational aspects of both same and different responses. For reaction time, however, a sex difference emerged in the nonrotational aspects of the task. The bias described here affected these nonrotational aspects of the task, but not the rotational aspects, in line with prediction. A second study reran the experiment without making the bias explicit. Under this implicit bias, no sex differences were identified between conditions.     

Perturbations of Human Posture

Leg muscle EMG responses and cerebral evoked potentials (CP), elicited by perturbations of stance while on a treadmill with split belts, were analyzed in order to study the relationship between compensatory leg muscle responses and afferent input to supraspinal centers. Various conditions of perturbation were used to establish the extent to which compensatory EMG responses and CPs show congruent behavior. Four different treadmill acceleration rates were applied in three different conditions (unilateral perturbation, directed forward or backward; bilateral perturbation, directed forward or backward; and opposing bilateral perturbation). EMG responses and CPs showed parallel increases in amplitude with increasing displacement velocity. The EMG responses showed distinct differences, predominantly in the response amplitude, between the different perturbation conditions, whereas the CPs were affected only to a minor degree. Tibialis anterior EMG responses were more closely related to the CP following forward perturbation than the corresponding gastrocnemius responses were to the CP following backward perturbation.

We conclude that the EMG responses are more closely related than the CPs to displacement parameters and suggest that this is due to the further spinal processing of the afferent input needed to generate an appropriate EMG response. The closer relationship between the tibialis anterior response and CP may reflect a predominant central representation and control of tibialis anterior activation in the regulation of posture. The functional implications of these findings are discussed.     

Is there a "special relationship" between unconscious emotions and visual imagery? Evidence from a mental rotation test

There is an increasing interest in the relationship between imagery and emotion (e.g., Holmes & Mathews, 2005). The present research examined whether unconscious emotions affect visual imagery. In particular, participants were invited to perform a mental rotation test following subliminal presentation of happy, sad and neutral expressions. This study revealed an increase in mental rotation abilities after unconscious visual processing of emotional expressions. Altogether, these findings support the hypothesis of a bidirectional relationship between imagery and emotions.     

Dissociating the effects of angular disparity and image similarity in mental rotation and object recognition

Performance is often impaired linearly with increasing angular disparity between two objects in tasks that measure mental rotation or object recognition. But increased angular disparity is often accompanied by changes in the similarity between views of an object, confounding the impact of the two factors in these tasks. We examined separately the effects of angular disparity and image similarity on handedness (to test mental rotation) and identity (to test object recognition) judgments with 3-D novel objects. When similarity was approximately equated, an effect of angular disparity was only found for handedness but not identity judgments. With a fixed angular disparity, performance was better for similar than dissimilar image pairs in both tasks, with a larger effect for identity than handedness judgments. Our results suggest that mental rotation involves mental transformation procedures that depend on angular disparity, but that object recognition is predominately dependent on the similarity of image features.     

空间能力测验及其研究应用

空间能力所表现出的个体差异一直是空间能力研究中的热点问题,在研究中所使用的测验也多种多样。二维空间能力测验主要包括标准心理旋转测验及其多种变式;三维空间能力测验则是运用虚拟现实技术针对动态空间定位与位置学习等空间能力开发出的新型测验。这些测验主要用于探讨空间能力个体差异的影响因素。本文在介绍测验的同时总结了空间能力个体差异研究的结果并提出展望。     

The influence of juggling on mental rotation performance in children with spina bifida

This study examined the influence of juggling training on mental rotation ability in children with spina bifida. Children between the ages of 8 and 12 solved a chronometric mental rotation test. Half of the children received juggling training (EG) over an 8week time period; the other half did not receive training (CG). Afterwards, all participants completed the mental rotation test again. Children of the EG showed a significant decrease in reaction time and an increase in mental rotation speed compared to the control group. This indicates that juggling improves the rotation in the mental rotation process in children with spina bifida.     

The relationship between mental rotation and arithmetic: do number line estimation,working memory,or place-value concept matter?

Mental rotation is positively related to arithmetic ability; however, the mechanism underlying this relationship remains unclear. The possible roles of working memory, place-value concept, and number line estimation in the correlation between mental rotation and whole-number computation were investigated. One hundred and fifty-five first-grade students were tested to determine their mental rotation ability, arithmetic ability, and non-verbal intelligence. One year later, their working memory, place-value concept, number line estimation, and overall arithmetic ability were assessed. After controlling for age, gender, and prior arithmetic ability, we found that mental rotation uniquely predicted arithmetic ability after one year. Further mediation analyses demonstrated that number line estimation significantly mediated the relationship between mental rotation and arithmetic ability. In contrast, neither working memory nor place-value concept significantly mediated the relationship between mental rotation and arithmetic ability. This study highlights that mental number line estimation is the most important element explaining the influence of a dynamic spatial skill, that is, mental rotation, on arithmetic ability among young Chinese children.     

Two Routes to Expertise in Mental Rotation

The ability to imagine objects undergoing rotation (mental rotation) improves markedly with practice, but an explanation of this plasticity remains controversial. Some researchers propose that practice speeds up the rate of a general‐purpose rotation algorithm. Others maintain that performance improvements arise through the adoption of a new cognitive strategy—repeated exposure leads to rapid retrieval from memory of the required response to familiar mental rotation stimuli. In two experiments we provide support for an integrated explanation of practice effects in mental rotation by combining behavioral and EEG measures in a way that provides more rigorous inference than is available from either measure alone. Before practice, participants displayed two well‐established signatures of mental rotation: Both response time and EEG negativity increased linearly with rotation angle. After extensive practice with a small set of stimuli, both signatures of mental rotation had all but disappeared. In contrast, after the same amount of practice with a much larger set both signatures remained, even though performance improved markedly. Taken together, these results constitute a reversed association, which cannot arise from variation in a single cause, and so they provide compelling evidence for the existence of two routes to expertise in mental rotation. We also found novel evidence that practice with the large but not the small stimulus set increased the magnitude of an early visual evoked potential, suggesting increased rotation speed is enabled by improved efficiency in extracting three‐dimensional information from two‐dimensional stimuli.     

Sex differences in neural efficiency: Are they due to the stereotype threat effect?

The neural efficiency hypothesis postulates a more efficient use of brain resources in more intelligent people as compared to less intelligent ones. However, this relationship was found to be moderated by sex and task content. While the phenomenon of neural efficiency was previously supported for men when performing visuo-spatial tasks it occurred for women only when performing verbal tasks. One possible explanation for this finding could be provided by the well-studied phenomenon called stereotype threat. Stereotype threat arises when a negative stereotype of one’s own group is made salient and can result in behavior that confirms the stereotype. Overall, 32 boys and 31 girls of varying intellectual ability were tested with a mental rotation task, either under a stereotype exposure or a no-stereotype exposure condition while measuring their EEG. The behavioral results show that an activated negative stereotype not necessarily hampers the performance of girls. Physiologically, a confirmation of the neural efficiency phenomenon was only obtained for boys working under a no-stereotype exposure condition. This result pattern replicates previous findings without threat and thus suggests that sex differences in neural efficiency during visuo-spatial tasks may not be due to the stereotype threat effect.