Contextual facilitation in plaid patterns remains constrained by component-level collinearity

Contextual facilitation is typically studied with simple gratings, in which detection is improved by collinear flankers depending on their spatial and temporal relationship to the target. The present study examined whether this framework generalizes to plaid stimuli, which contain multiple orientation components and may engage more integrated structural representations. Across seven experiments, target structure, flanker configuration, and temporal arrangement were manipulated using gratings and plaids. Facilitation remained closely tied to the presence of a collinear component rather than emerging as a general property of plaid stimuli. When plaid structure was introduced into either the target or the flankers, facilitation depended more on component-level collinear relationships than on global plaid structure. Flanker effectiveness was better predicted by component-level collinearity than by overall plaid structure, and stable stimulus onset asynchrony tuning emerged only for selected contextual configurations. Although longer presentation duration broadened facilitation for plaid targets, the magnitude of facilitation still depended on flanker orientation. Together, these findings indicate that contextual facilitation in plaid-related displays remains constrained primarily by component-level collinearity rather than by emergent plaid structure. Plaid stimuli therefore provide a useful extension of traditional grating-based paradigms for distinguishing component-based and composite-level influences on spatial interactions.