Temporal mechanisms underlying visual processing bias in peri-hand space.

The immediate space surrounding the hands has often been termed the peri-hand space (PHS), and is characterized by a smaller reaction time (RT), better detection, and enhanced accuracy for stimuli presented in this space, relative to those stimuli presented beyond this space. Such behavioral changes have been explained in terms of a biased allocation of cognitive resources such as perception, attention, and memory, for the efficient processing of information presented in the PHS. However, in two experiments, the current study shows that these cognitive biases seem to have an underlying temporal basis. The first experiment requires participants to perform a temporal bisection task, whereas the second experiment requires them to perform a verbal estimation task when stimuli are presented either near the hands or relatively far. Results from both experiments give evidence for slowing down of temporal mechanisms in the PHS - reflected in the form of temporal dilation for stimuli presented in the PHS relative to those presented further away. The slowing down of time in the PHS seems crucial in giving sufficient temporal allowance for the allocation of cognitive resources to prioritize the processing of information in the PHS. The findings are in line with the early anticipatory mechanisms associated with the PHS and seem to be driven by the switch/gate mechanism, and not the pacemaker component of the attentional gate model of time perception. Thus, the current study tries to integrate the theories of time perception with the peripersonal space literature.