This effect might be due either to sensory or cognitive factors. Since all stimuli were faces, in this experiment the asymmetry cannot be ascribed to a generic effect of face processing. Indeed, the literature on face recognition does not support the evidence of a right lateralization for the P1 response, but, rather, a bilateral distribution is often reported (when P1 is considered, see Table 1). Furthermore, in studies involving visual-spatial or selective attention tasks, the P1 component is often described as larger at the right than the left occipital lateral sites both for space orienting (e.g., [29]) and processing of global configurations (e.g., [30]). In addition, P1 is always right-lateralized in response to low spatial frequency patterns even in passive viewing conditions [31,32]. For these reasons, we cannot discuss the P1 right lateralization as an index of a hemispheric dominance for face processing.
