Twelve participants were trained to be experts at identifying a set of `Greebles', novel objects that, like faces, all share a common spatial configuration. Tests comparing expert with novice performance revealed: (1) a surprising mix of generalizability and specificity in expert object recognition processes; and (2) that expertise is a multi-faceted phenomenon, neither adequately described by a single term nor adequately assessed by a single task. Greeble recognition by a simple neural-network model is also evaluated, and the model is found to account surprisingly well for both generalization and individuation using a single set of processes and representations. 1998 Elsevier Science Ltd. All rights reserved. Keywords: Configural encoding; Face recognition; Neural networks; Object categorization; Perceptual expertise 1. Introduction Are the mechanisms used by perceivers as they become increasingly familiar with an object class the same as those used by perceivers when they first en...

this article, reporting the results of multiple psychophysical experiments during the acquisition of expertise with novel objects. To leverage these methods, our approach combines psychophysical assessment with neuroimaging techniques in two ways. First, the psychophysical procedure we used to train participants to expertise was the same as that used in a recent neuroimaging study, in which activity for Greebles in the fusiform face area (FFA) increased with expertise (Gauthier, Tarr, Anderson, Skudlarski, & Gore, 1999; half of the 10 participants in the present study also participated in this earlier fMRI study). Second, we correlated behavioral measures of expertise acquisition with concurrent neural changes in these same participants

tegories, and our results also establish the importance of manipulating task requirements when evaluating a `neural module' hypothesis. Addresses: *Psychology, Yale University, PO Box 208205, New Haven, Connecticut 06520-8205, USA. + Diagnostic Radiology, Yale University School of Medicine, PO Box 208042, New Haven, Connecticut 06520-8042, USA. # Cognitive and Linguistic Sciences, Brown University, Box 1978, Providence, RI 02912, USA. Correspondence: Isabel Gauthier E-mail: isabel.gauthier@yale.edu Current Biology 1997, 7: 645-651. Background The neural processes that underlie recognition of a face, rather than another object, could be special in at least two ways: they may require unique perceptual processing and/or engage a specific region of the brain [1-2]. Several behavioral studies suggest, however, that a common mechanism is used to process faces and non-face objects when experimental conditions are carefully matched [3-5

Functional magnetic resonance imaging was used to compare brain activation associated with basic-level #e.g., BIRD# and subordinate-level #e.g., EAGLE# processing for both visual and semantic judgments. We localized the putative face area for eleven subjects, who also performed visual matching judgments for pictures and aurally-presented words. The middle fusiform and occipital gyri were recruited for subordinate minus basic visual judgments, re#ecting additional perceptual processing. When the face area was localized individually for each subject, analyses in the middle fusiform gyri revealed that subordinate-level processing activated the individual's face area. We propose that what is unique about the way faces engage this region is the focal spatial distribution of the activation rather than the recruitment of the face area per se. Eight subjects also performed semantic judgments on aurally-presented basic- and subordinate-level words. The parahippocampal gyri were more activated f...

infinite set of images to a relatively small number of known objects and categories. It is a problem that the human visual system routinely and effortlessly solves. How the mammalian brain solves the problem of visual recognition has been a topic of study since the early days of cognitive science. David Hubel and Torsten Wiesel (1959) received the Nobel Prize for their discovery of organized columns of orientation-tuned neurons in cat visual cortex. This critical result appeared to capture an important facet of visual processing---a visual system that is sensitive to edges (boundaries between regions of light and dark) positioned at different orientations in space. Once the particular orientations of edges are known, it seemed only a small step to "connect the dots"---joining edges into more complex descriptions of object shape. Edge-based representations appeared ideal for recognition: shape defining edges often capture the critical features of objects and remain rela

In humans and many other primates, the visual system plays the major role in object recognition. But objects can also be recognized through haptic exploration, which uses our sense of touch. Nonetheless, it has been argued that the haptic system makes use of ‘visual’ processing to construct a representation of the object. To investigate possible interactions between the visual and haptic systems, we used functional magnetic resonance imaging to measure the effects of cross-modal haptic-to-visual priming on brain activation. Subjects studied three-dimensional novel clay objects either visually or haptically before entering the scanner. During scanning, subjects viewed visually primed, haptically primed, and non-primed objects. They also haptically explored non-primed objects. Visual and haptic exploration of non-primed objects produced significant activation in several brain regions, and produced overlapping activation in the middle occipital area (MO). Viewing visually and haptically primed objects produced more activation than viewing non-primed objects in both area MO and the lateral occipital area (LO). In summary, haptic exploration of novel three-dimensional objects produced activation, not only in somatosensory cortex, but also in areas of the occipital cortex associated with visual processing. Furthermore, previous haptic experience with these objects enhanced activation in visual areas when these same objects were subsequently viewed. Taken together, these results suggest that the object-representation systems of the ventral visual pathway are exploited for haptic object perception. © 2002 Elsevier

Theories of object recognition often assume that only one representation scheme is used within one visual-processing pathway. Versatility of the visual system comes from having multiple visual-processing pathways, each specialized in a different category of objects. We propose a theoretically simpler alternative, capable of explaining the same set of data and more. A single primary visual-processing pathway, loosely modular, is assumed. Memory modules are attached to sites along this pathway. Object-identity decision is made independently at each site. A site's response time is a monotonic-decreasing function of its confidence regarding its decision. An observer's response is the first-arriving response from any site. The effective representation(s) of such a system, determined empirically, can appear to be specialized for different tasks and stimuli, consistent with recent clinical and functional-imaging findings. This, however, merely reflects a decision being made at its appropriate level of abstraction. The system itself is intrinsically flexible and adaptive.

this paper, we present a new approach to semantic access of a database of images by asking for the presence of certain objects; this is known as object-related image retrieval

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It is current dogma that neurons in primary visual cortex extract local edges from the scene, from which later visual areas reconstruct more meaningful shapes. Recent neuroimaging studies, however, have shown V1 modulations by the degree of structure in the image (shape). These V1 modulations due to the level of shape coherence have been explained in one of two possible ways: due to changes in image statistics or shape-based perceptual influences from higher visual areas. Here we compare both hypotheses using stimuli composed of Gabor arrays constructed to form circular shapes that can be successively degraded by manipulating the orientations of individual Gabors while maintaining local and global statistics. In a first experiment we confirm that V1 responses are inversely correlated with the degree of structure in the image. In a second experiment, stimulus predictions are compared based upon the degree of circular shape or change in the image statistic varied (orientation variance) in the image. We find that these V1 modulations to shape change are correlated with low-level changes in orientation contrast rather than shape perception per se. 2