Selective attention to orientation and closure: An event-related potentialstudy

Event-related potentials (ERPs) were recorded when the subjects attended se lectively to stimuli in one visual field and responded to the targets inclu ding designated feature (orientation or closure) value. Attention to spatia l location elicited enlarged P1 and N1 at posterior electrodes contralatera l to the stimulus location, whereas selection to orientation or closure eli cited selection negativity (SN) and a late negative component (LNC). The se lection of spatial location was prior to the selection of orientation or cl osure. SN was elicited only by the stimuli in the attended visual field, su ggesting that the selection of orientation and closure are contingent on th e prior selection of location. Moreover, the onset latency of SN was earlie r for closure selection than for orientation selection, indicating that the processing of closure occurred earlier than the processing of orientation. The results are consistent with the early-selection theories of attention and provide psycho-physiological evidence for the topology theory of visual perception.