Abstract
During binocular rivalry, the relative dominance times of the two competing images are influenced by both low level image factors as well as high level object properties. In a previous study (He & Liu, VSS 2010), we demonstrated that for rivalry between faces and words, there was a face advantage for left visual field presentation and a word advantage for right visual field presentation. This is due to the fact that face and word representations are biased towards the right hemisphere and left occipitotemporal cortex respectively. In the current study, we went beyond the previous correlational observation and investigated potential causal effects from lateralized tDCS stimulations. While observers viewed centrally presented streams of faces and words engaged in binocular rivalry, tDCS (anodal or cathodal) was applied to the left or right occipitotemporal cortex. Results from 11 participants show that, compared to the sham condition, right occipitotemporal anodal tDCS significantly increased the relative dominance durations of faces over words, while cathodal tDCS significantly reduced the relative face dominance. However, left occipitotemporal tDCS had little effect on their relative dominance durations. In addition to the effect on relative dominance, Anodal, but not cathodal, tDCS of either left or right occipitotemporal sites led to more rapid rivalry switching. Together, our results suggest that tDCS could selectively strengthen or weaken high level representations of visual inputs, and causally modulate rivalry competition at an earlier stage through recurrent processing. Additionally, anodal tDCS likely increased neuronal excitability and noise levels, leading to more frequent rivalry switching.