Feature-based attention spreads preferentially in an object-specific manner.

We studied the spreading of feature-based attention from attended to ignored motion fields (linear, circular, and combinations). When observers attended one of two superimposed motion fields on one side of the visual midline, sub-threshold priming by an ignored motion field was altered significantly on the opposite side of the midline. This attentional spreading was observed only when attended and ignored motion fields conformed to a complex global flow, not when they shared the same linear motion. These findings corroborate an earlier study (Festman & Braun, 2010), which obtained similar results with a complementary methodology. We conclude that feature-based attention is more complex than hitherto appreciated in that it spreads preferentially in an object-specific manner.