Abstract: This study investigated into the simple reaction time (RT) and event related potentials (ERPs) correlates of the scale of visual spatial attention. Fourteen participants performed a search task in which the search array was preceded by fixed cues of different sizes. The cue was a black circle varied in three different sizes randomly. The focuses of the circles were always at the center of the screen, avoiding the influence of spatial location. The RT with medium cue was longer than with small cue, and was shorter than with large cue. There were no amplitude modulations of both cue evoked and search array evoked P1 and N1 components with cue size. However, both amplitude and latency of P2 and N2 were significantly affected by cue size. The results showed: ①The P1 and N1 components under visual attention were related to the spatial location processes mainly. ②Cue evoked P2, N2 components were related to the size of attention range. ③The processes of spatial location information were earlier than other information in visual attention, which supported the theory that spatial selection is a prerequisite for correct processes of visual objects information.

Key words: visual attention, cues, attentive region size, visual search, event related potentials (ERPs)