Mental rotation with abstract and embodied objects as stimuli: evidence from event-related potential (ERP).

This study investigated sex differences in performance and neuronal activity in a mental rotation task with abstract and embodied figures. Fifty-eight participants (26 females and 32 males) completed a chronometric mental rotation task with cube figures, human figures, and body postures. The results are straightforward: depending on angular disparity, participants had a faster reaction time and a higher accuracy rate for embodied stimuli compared to cube figures. The electroencephalogram (EEG) activity pattern showed a higher negative amplitude modulation in the frontal electrodes for females compared to males during the late (400-600 ms) time interval. From 200 to 400 ms after stimulus onset, there was a different activation pattern in the parietal and central electrodes, whereas frontal electrodes did not show differences between embodied and abstract stimuli. From 400 to 600 ms after stimulus onset, there was a different pattern in the central and frontal electrodes but not in the parietal areas for embodied figures in compared to cube figures. Concluding, even though there were no sex differences in the behavioral data, the EEG data did show alterations at the late time interval. Thus, the disparate results regarding sex differences that depend on the type of analysis (behavioral versus neurophysiological) should be more thoroughly investigated. Furthermore, the difference in processing embodied stimuli in an object-based mental rotation task could be confirmed in EEG activity pattern for the first time.