An open issue is whether the weights are computed in isolation in the motion and shape sensitive regions or whether they are set through reciprocal interactions between these regions. The strong perceptual coupling between perceived shape and perceived motion suggests shape and motion are not processed independently. Using the perceptual evidence from both dimensions jointly may significantly increase the probability of a relevant interpretation of a visual scene (e.g., Weiss & Adelson,
1996; Bayerl & Neumann,
2007; Deneve, Latham, & Pouget,
2001), although perceptual evidence from one or the other dimension might be noisy and unreliable, and should be weighted accordingly. Several reasons plead in favor of interactions between both processing streams. Anatomical studies found dense reciprocal connections between dorsal and ventral regions in monkeys (Maunsell & Van Essen,
1983; DeYoe & Van Essen,
1988), and electrophysiology further provides evidence for interactions between the ventral and dorsal pathways (Verhoef, Vogels, & Janssen,
2010,
2011). In humans, connections between the ventral and dorsal stream have been described at various stages of the visual hierarchy (Sporns, Tononi, & Kotter,
2005; Ungerleider, Galkin, Desimone, & Gattass,
2008; Borra et al.,
2008; Borra, Ichinohe, Sato, Tanifuji, & Rockland,
2010), and psychophysical studies of structure-from-motion perception are also suggestive of interactions between the shape and motion pathways (e.g., Miskiewicz, Buffat, Paradis, & Lorenceau,
2008). In addition, fMRI studies found that 3D speed gradients elicited activity in ventral regions (Murray et al.,
2003; Paradis et al.,
2008), while static photographs with implied motion could elicit activity in dorsal regions (Kourtzi & Kanwisher
2000b; Krekelberg et al.,
2005), supporting the view that ventral and dorsal regions interact. In the present study, the opposite pattern of activity observed between the middle temporal area and the fusiform area is suggestive of a direct interaction between these two. However, the existence of causal influences between both areas remains unknown.