Perceptual history influences neural responses to face and body postures

The interpretation of a visual scene is profoundly influenced by information other than that in current visual input. One important source of information is the perceptual history, ie specific visual patterns that were on the retina in the immediate past. We provide direct evidence that the response selectivity of a substantial number of cells in the anterior part of the superior temporal sulcus (STSa) of the macaque monkey to the sight of static head and body postures under natural viewing is controlled by the sight of immediately preceding body actions. The cells responded vigorously to the sight of a face or body posture that followed a particular action, but not when it followed other actions. The effective action or posture presented in isolation or in different sequences failed to produce a response. We argue that the 'vocabulary' of actions and body postures coded for by single STSa cells is much larger than previously thought, encompassing also specific action - posture sequences. Our results demonstrate that cells in temporal cortex could support the understanding of natural body actions, which are continuous and complex sequences of postures with linking movements, and could support the formation of expectations about impending behaviour of others.