Effect of Time Constraint in Exploring Spatial Differences With Balanced Allocation of Performance Factors in a Redrawn Mental Rotation Test

To achieve a comprehensive and unbiased measurement, a mental rotation test (MRT) (cube form) was redrawn and administered with influential performance factors, namely, time constraint, item type, angular disparity, and rotation/flipping. Item type, angular disparity, and rotation/flipping were systematically balanced into the items of the redrawn Pentomino-MRT, and two time-constraint conditions were randomly assigned to 813 Grade 4 to 6 primary students when administering the test. Children of these ages are of investigative interest because they are at crucial stages of spatial ability development and are at an age where associated gender differences emerge. The study demonstrates that spatial gender differences can be detected in Grade 4, are more marked in Grade 5, and become stable in Grade 6. The importance of time constraint is acknowledged in how and at what grade gender differences emerge under the conditions of the performance factors investigated. In particular, the performance of girls reminds us to focus on their spatial ability development if later STEM-related field participation is of concern.

Pupillometry as a measure of cognitive load in mental rotation tasks with abstract and embodied figures

We investigated sex differences in behavioral performance and cognitive load in chronometric mental rotation tasks with abstract and embodied figures. Eighty participants (44 females and 36 males) completed 126 items, which included cube figures, body postures, and human figures, which were all comparable in shape and color. Reaction time, accuracy, and cognitive load, measured by changes in pupil dilation, were analyzed. As a function of angular disparity, participants showed shorter reaction times and higher accuracy rates for embodied stimuli than cube figures. Changes in pupil dilation showed a similar pattern, indicating that mental rotation of embodied figures caused less cognitive load to solve the task. No sex differences appeared in any of the measurements.

Does mental rotation emulate motor processes? An electrophysiological study of objects and body parts

Several arguments suggest that mental rotation (MR) and motor planning may share embodied neural mechanisms, but the overlap between cognitive processes recruited during MR of objects and body parts is not well established. We here used high-density EEG to examine the cognitive similarity between MR of non-manipulable objects (chairs) and bodily stimuli (hands). We selected chairs because they may appear in a recognizable left-right orientation and are not automatically associated with a manual action. Participants had identical response options for both types of stimuli, and they gave responses orally in order to prevent possible interference with motor imagery. MR of hands and chairs generated very similar behavioral responses, time-courses and neural sources of evoked-response potentials (ERPs). ERP segmentation analysis revealed distinct time windows during which differential effects of stimulus type and angular disparity were observed. An early period (90-160 ms) differentiated only between stimulus types, and was associated with occipito-temporal activity. A later period (290-330 ms) revealed strong effects of angular disparity, associated with electrical sources in the right angular gyrus and primary motor/somatosensory cortex. These data suggest that spatial transformation processes and motor planning are recruited simultaneously, supporting the involvement of motor emulation processes in MR.

Mental rotation of sequentially presented 3D figures: sex and sex hormones related differences in behavioural and ERP measures

Mental rotation of 3D objects demonstrates one of the largest sex differences. We investigated sex and sex hormones-related differences in behaviour and event related potentials (ERP) using a modified Shepard and Metzler task composed of sequentially presented 3D figures in 29 men and 32 women. We demonstrated a significant increase in response time and decrease in both accuracy and positivity of the parietal ERP with increasing angular disparity between the figures. Higher angular disparity evoked an increase of global field power (GFP) from 270 to 460 ms and different activation topographies from 470 to 583 ms with lower parietal, but higher left frontal positivity. Flatter slopes in higher angular disparity condition suggest distinct strategies being implemented depending on the difficulty of the rotation. Men performed the task more accurately than women. Performance accuracy in women tended to be negatively related to estradiol while the response time tended to increase with increasing progesterone. There were no associations with testosterone. Women demonstrated higher GFP and an increased positivity over the parietal scalp area, while men showed higher activation in the left frontal cortex. Together these findings indicate dynamic angular disparity- and sex-related differences in brain activity during mental rotation of 3D figures.

Does Children’s Left Hemisphere Lateralization During Mental Rotation Depend Upon the Stimulus Material?

Recent publications suggest that there is a developmental-based change of lateralization of brain activity during mental rotation from left to bilateral. But it is an open question whether this left hemisphere activation could also be observed with stimuli other than characters. To test this, behavioral data and event-related potentials (ERPs) were measured in 28 children, 28 juveniles, and 28 adults during a mental rotation task with animal drawings. The results showed that reaction times (RTs) and error rates decreased with the increasing age of the participants. Furthermore, RTs and error rates increased with increasing angular disparity. An unlateralized ERP amplitude modulation at parietal electrodes as a function of angular disparity was present in all age groups. These results contrast former studies revealing a left lateralization in children when characters were used as stimuli for mental rotation. Left hemisphere activation is therefore not a general developmental trend; rather, it is suggested that it might be a correlate of written language acquisition.

Dynamic Changes in the Mental Rotation Network Revealed by Pattern Recognition Analysis of fMRI Data

We investigated the temporal dynamics and changes in connectivity in the mental rotation network through the application of spatio-temporal support vector machines (SVMs). The spatio-temporal SVM [Mourao-Miranda, J., Friston, K. J., et al. (2007). Dynamic discrimination analysis: A spatial-temporal SVM. Neuroimage, 36, 88–99] is a pattern recognition approach that is suitable for investigating dynamic changes in the brain network during a complex mental task. It does not require a model describing each component of the task and the precise shape of the BOLD impulse response. By defining a time window including a cognitive event, one can use spatio-temporal fMRI observations from two cognitive states to train the SVM. During the training, the SVM finds the discriminating pattern between the two states and produces a discriminating weight vector encompassing both voxels and time (i.e., spatio-temporal maps). We showed that by applying spatio-temporal SVM to an event-related mental rotation experiment, it is possible to discriminate between different degrees of angular disparity (0° vs. 20°, 0° vs. 60°, and 0° vs. 100°), and the discrimination accuracy is correlated with the difference in angular disparity between the conditions. For the comparison with highest accuracy (0° vs. 100°), we evaluated how the most discriminating areas (visual regions, parietal regions, supplementary, and premotor areas) change their behavior over time. The frontal premotor regions became highly discriminating earlier than the superior parietal cortex. There seems to be a parcellation of the parietal regions with an earlier discrimination of the inferior parietal lobe in the mental rotation in relation to the superior parietal. The SVM also identified a network of regions that had a decrease in BOLD responses during the 100° condition in relation to the 0° condition (posterior cingulate, frontal, and superior temporal gyrus). This network was also highly discriminating between the two conditions. In addition, we investigated changes in functional connectivity between the most discriminating areas identified by the spatio-temporal SVM. We observed an increase in functional connectivity between almost all areas activated during the 100° condition (bilateral inferior and superior parietal lobe, bilateral premotor area, and SMA) but not between the areas that showed a decrease in BOLD response during the 100° condition.