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Delphine Pins, Muriel Boucart, Marc-Etienne Meyer, Foucher Jack; Automatic object identification in a peceptual matching paradigm : An fMRI study. Journal of Vision 2001;1(3):95. doi: 10.1167/1.3.95.
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Previous data (Boucart & al., 1995, J. of Exp. Psychol.: HPP, 21:584; Boucart & Humphreys, 1997, Perception, 26:1197) have suggested that there is automatic access to object identity when observers attend to a physical property of the form of an object (requiring processing of the global configuration ; e.g., the orientation of the main axis) and no semantic processing when subjects attend to a surface property of an object (requiring only a local processing ; e.g., colour, luminance…). We examined this automatic access to object identity in an fMRI study. We evaluated whether, in addition to neural areas associated with decisions to specific perceptual properties, areas associated with access to semantic information were activated when tasks demanded processing of global configuration. Two perceptual matching tasks were used. In an orientation-matching task, subjects had to match the reference and target stimuli on the basis of their global orientation (vertical versus horizontal). In a colour-matching task, subjects had to match the reference and target stimuli on the basis of their outline colour (blue versus green). These two tasks were compared with control tasks (boxcar paradigm) in which pictures were replaced by oriented (or coloured) rectangles. Results showed activation of areas 18–19 for both colour and orientation, with a predominance of the left hemisphere for colour and the right for orientation. More importantly, activation of the temporal area 37, involved in overt semantic judgements (Buchel & al., 1998, Nature, 394:274) occurred in the orientation decision task and not in the colour decision task. This result suggests that automatic access to object identity, in a task that does not require semantic processing, activates the same brain area as overt processing of semantic information.
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