The effect of biological motion on oculomotor response might result from the activation of a specific neuronal pathway for biological motion processing (Grossman et al.,
2005,
2000; Saygin,
2007; Saygin et al.,
2004). Evidence from single neuron recordings suggests that the region of the superior temporal sulcus (STS) of the macaque monkey is specifically involved in the perception of biological motion. The network dedicated to biological motion perception is partially independent of the low-level motion perception network (first- and second-order motion). Indeed, in humans, disruption of the motion-sensitive, middle temporal area (MT) did not affect the perception of biological motion (Billino et al.,
2009; Saygin,
2007; Vaina et al.,
1990), whereas a lesion in MT reduced low-level motion perception (Komatsu & Wurtz,
1989) and impaired smooth pursuit eye movements in monkeys (Dursteler & Wurtz,
1988; Newsome et al.,
1985). Similarly, psychophysics testing of the low-level motion perception network (speed discrimination, coherent motion detection, etc.) showed that processing of motion degraded with age (Gilmore, Wenk, Naylor, & Stuve,
1992; Norman, Ross, Hawkes, & Long,
2003; Sekuler, Hutman, & Owsley,
1980; Warren, Blackwell, & Morris,
1989), whereas the perception of biological motion did not (Billino, Bremmer, & Gegenfurtner,
2008a; Norman, Payton, Long, & Hawkes,
2004). In contrast, the third-order motion processing system, which is strongly influenced by attention (Lu & Sperling,
2001), was necessary for perceiving biological motion (Garcia & Grossman,
2008). For instance, patient studies demonstrated that lesions in the parietal lobe degraded third-order and biological motion perception, while low-level motion perception remained intact (Battelli, Cavanagh, & Thornton,
2003; Billino et al.,
2009). In sum, there are at least two different motion processing pathways: the classical one, which involves area V5/MT (Born & Bradley,
2005) and a second, which might rely on the STS area (Barraclough, Xiao, Oram, & Perrett,
2006; Perrett et al.,
1985) and be subservient to biological motion perception. The relative independence of the biological motion and low-level motion perception networks, together with our results, suggests that the biological motion perception pathway might directly influence the smooth pursuit network (Ilg & Thier,
2008).