Non-holistic coding of objects in lateral occipital complex with and without attention.

A fundamental issue in visual cognition is whether high-level visual areas code objects in a part-based or a view-based (holistic) format. Previous behavioral and neuroimaging studies that examined the viewpoint invariance of object recognition have yielded ambiguous results, providing evidence for either type of representational format. A critical factor distinguishing the two formats could be the availability of attentional resources, as a number of priming studies have found greater viewpoint invariance for attended compared to unattended objects. It has therefore been suggested that the activation of part-based representations requires attention, whereas the activation of holistic representations occurs automatically irrespective of attention. Using functional magnetic resonance imaging in combination with a novel multivariate pattern analysis approach, the present study probed the format of object representations in human lateral occipital complex and its dependence on attention. We presented human participants with intact and half-split versions of objects that were either attended or unattended. Cross-classifying between intact and split objects, we found that the object-related information coded in activation patterns of intact objects is fully preserved in the patterns of split objects and vice versa. Importantly, the generalization between intact and split objects did not depend on attention. We conclude that lateral occipital complex codes objects in a non-holistic format, both in the presence and absence of attention.