Spatial Memory Guides Attention before Object Recognition: Evidence from Lateralized N1pc Responses

Visual search is facilitated when targets reappear within invariant distractor layouts (contextual cueing). Although contextual cueing can bias attention within 150 msec, it remains unclear whether this guidance relies on global spatial configuration or requires object identity. We recorded ERPs while participants searched for targets in repeated versus novel arrays. Critically, each trial began with a placeholder display that conveyed only spatial configuration, preceding the search display by 500 msec. Following learning, targets were relocated and swapped their locations with a distractor in the opposite visual field, such that the overall search layouts remained unchanged. ERPs time-locked to placeholder onset revealed an early poster contralateral negativity (N1pc, 140-160 msec) for repeated contexts, despite the absence of target-specific object information. After relocation, this effect reversed polarity, indicating persistent orienting to the learned target location. A second N1pc, followed by N2pc and CDA, emerged only after search onset. These findings show that learned spatial structure rapidly guides attention, whereas effective selection requires additional processing of object information.