CENTER FOR RESEARCH IN
COGNITION & NEUROSCIENCES/ConnexConnex

Gestalt psychology argued that the whole is different from the sum of the parts. Wholes were considered primary in perceptual experience, even determining what the parts are. How to reconcile this position with what we now know about the visual brain, in terms of a hierarchy of processing layers from low-level features to integrated object representations at the higher level? What exactly are the relationships between parts and wholes then? I will argue that there are different types of “Gestalts” with their own relationships between parts and wholes, both in visual experience and in their neural encoding. Some Gestalts seem to be encoded in low-level areas based on feedback from higher-order regions. Other Gestalts seem to be encoded in higher-level areas, while the parts are encoded in lower-level areas. In some cases, this happens without suppression of the parts (“preservative Gestalts”); in others, with suppression of the parts (“eliminative Gestalts”). I will describe three studies from our own lab to illustrate these different types of Gestalts. In one study, we investigated the visibility of color changes to moving dots making up a biological motion walker, and showed a clear relationship between the “goodness” of the whole and the “badness” of the parts. In a second study, we investigated the neural basis of the “configural-superiority effect” by means of fMRI decoding, and found a neural configural-superiority effect in shape-selective regions but not in low-level retinotopic areas, where decoding of parts was more pronounced. In a third study, we asked observers to indicate whether they perceived an ambiguous stimulus locally or globally while we recorded fMRI activity in lower and higher cortical areas, and found suppression of activity in V1 in the presence of a global percept. Together, these findings support the general conclusion that not all Gestalts are equal, while the specific conceptual refinements made may help to motivate further research to better understand the mechanisms of how parts and wholes are encoded in the visual cortical hierarchy.