Feature-based attention promotes biological motion recognition.

Motion perception is important for visually segregating and identifying objects from their surroundings, but in some cases extracting motion cues can be taxing to the human attention system. We measured the strength of feature salience required for individuals to correctly judge three types of moving events: biological motion, coherent motion, and multiple object tracking. The motion animations were embedded within a larger Gabor grid and constructed such that motion was conveyed by a salient single-feature dimension (second order) or by alternating across equisalient feature dimensions (third order). In the single-feature displays, we found biological motion to require less difference in the Gabor features (relative to background) to yield equivalent task performance as the coherent motion or multiple object tracking. This main effect of feature magnitude may reflect the inherent salience of biological motion as a visual stimulus. In the alternating-feature displays, both the biological motion and coherent motion discriminations needed additional salience, as compared to the single-feature displays, to achieve threshold discrimination levels. Accuracy in the multiple object tracking task did not vary as a function of salience. Together, these findings demonstrate the effectiveness with which attention-based motion mechanisms operate in complex dynamic sequences and argue for a critical role of feature-based attention in promoting biological motion perception.