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Erik W. Cheries, Laurie R. Santos, Brian J. Scholl; Units of Visual Identification in Rhesus Macaques (Macaca mulatta): Objects or Unbound Visual Features?. Journal of Vision 2004;4(8):819. doi: 10.1167/4.8.819.
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© ARVO (1962-2015); The Authors (2016-present)
An essential task for the visual system is to structure the incoming wash of unbound visual features into coherent object representations. To date, this process has been explored in two independent research programs. Behavioral research has explored when and how infants and nonhuman primates will use featural information to individuate and identify objects across occlusion, but has not directly demonstrated that such features are bound to the objects in question. Research in psychophysics and neuroscience, in contrast, has focused on the details of how and when the binding process itself occurs, but has not demonstrated that information about binding is used for in the service of other higher-level decisions. Here we try to bring these two research programs closer together, by exploring whether rhesus monkeys will use bound object representations in addition to individual unbound features to identify persisting objects over time and occlusion. Subjects observed a stage containing two stationary objects which could differ in both color and shape. After 3 repeated identical presentations (separated by the addition and removal of a screen), a final display was uncovered introducing two objects that had changed shape (e.g. green and yellow circles had changed to green and yellow triangles); changed color (e.g. a green circle and triangle had changed to a yellow circle and triangle); swapped a single feature (e.g. a green circle and yellow triangle had changed to a green triangle and yellow circle); or didn't change at all. The subjects dishabituated to all actual changes. Because the ‘feature swap’ condition did not introduce any new features into the display, dishabituation here demonstrates that the color and shape features were bound together into coherent objects which the subjects identified over time and occlusion. These results provide the first evidence to date that feature binding is used in monkeys' dynamic object identification.
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