A recent study showed that viewing manipulable objects such as images of tools induces the neural activation of posterior parietal areas. This neural activation is observed even when visual awareness of the image is visually suppressed. (Fang and He, 2005 Nature Neuroscience 10 1380–1385; Almeida et al, 2010 Psychological Science 21 772–778). However, the specific visuomotor information in tool images that drives the activation of dorsal areas is still unclear. We measured priming effect of invisible tool prime (left or right handed orientation). Observers distinguished the orientation of target tools (appropriate for left vs right handed grip) briefly presented following visually suppressed primes (Experiment1). Also we measured the suppression time of tool images whose handle direction was presented in a left- or right-handed orientation. A dynamic noise pattern was presented to one of the observer's eyes at full contrast, while images of tools (left or right handed) were simultaneously presented to the left or right visual field of the other eye. The subjects were asked to respond to the appearance of any partial or full part of the test image (Experiment 2). Results showed that (1) observers responded faster in the congruent condition (the same orientation between prime and target) and (2) tool images shown in the right visual field took less time to gain dominance against the dynamic noise. These results suggest that even without overt recognition of presented tools, an object's affordance can be registered and processed in the brain. A recent study showed that viewing manipulable objects such as images of tools induces the neural activation of posterior parietal areas. This neural activation is observed even when visual awareness of the image is visually suppressed (Almeida et al., 2010 Psychological Science 21 772–778; Fang and He, 2005 Nature Neuroscience 10 1380–1385). However, the specific visuomotor information in tool images that drives the activation of dorsal areas is still unclear. We measured the priming effect of invisible tool prime (left or right handed orientation). Observers distinguished the orientation of target tools (appropriate for left vs. right handed grip) briefly presented following visually suppressed primes (Experiment 1). Also we measured the suppression time of tool images whose handle direction was presented in a left- or right-handed orientation. A dynamic noise pattern was presented to one of the observer's eyes at full contrast, while images of tools (left or right handed) were simultaneously presented to the left or right visual field of the other eye. The subjects were asked to respond to the appearance of any partial or full part of the test image (Experiment 2). Results showed that (1) observers responded faster in the congruent condition (the same orientation between prime and target) and (2) tool images shown in the right visual field took less time to gain dominance against the dynamic noise. These results suggest that even without overt recognition of presented tools, an object's affordance can be registered and processed in the brain.
