Reviewing Evidence for the Perception-Action Model From Garner Interference

It is a widely accepted notion that visual information in the brain is processed via two parallel but separate cortical pathways, the ventral stream for visual perception and the dorsal stream for visuomotor actions. Perception-action dissociations from behavioral experiments are often cited as supportive evidence and one such example is Garner interference: It is assumed that perceptual/ventrally processed tasks suffer Garner interference, while visuomotor/dorsally processed tasks are immune to it (Ganel & Goodale, 2003). Ideally, this dissociation is demonstrated by comparing manual size estimation (assumed ventrally processed) with grasping (assumed dorsally processed). However, few studies actually made this comparison. We addressed this empirical shortage with two improved replications, yielding smaller effects of Garner interference in manual estimation than previous studies reported. In two subsequent experiments, we attempted to modulate Garner interference by manipulating the temporal profile of participants' responses, building on previous work (Hesse & Schenk, 2013) and extending it to manual estimation. We conclude with a literature review covering all relevant studies on Garner interference. Contrary to previous claims, the currently available evidence for a perception-action dissociation from Garner interference is insufficient to support a ventral-dorsal dissociation.