Are there Hemispheric Differences in Visual Processes that Utilize Gestalt Principles?

Hemispheric differences in the visual system have been well-established, although their exact
nature remains under study (Hellige 1990). Thus far, research has focused on the perception of
whole objects or scenes. Van Kleeck and Kosslyn (1989) investigated the possibility of
lateralization for Gestalt principles using an embedded figures task. They^ found an effect of
lateralization, that parts of figures fitting Gestalt breaks were more quickly identified by the right
than the left hemisphere. They concluded that Gestalt processing is lateralized to the right
hemisphere. In this study, two experiments were conducted to more closely investigate this
claim. The first experiment focused on the Gestalt principle of grouping by proximity using dot
lattices. No effects of lateralization were found. In the second experiment, concentric circles of
Gabor patches were used to test grouping by orientation. This did not result in any main effects
of hemisphere, but in reaction time, those stimuli with the probe located in central vision created
a large decrease in reaction time for the right hemisphere, while probes in the periphery caused a
greater increase for the right hemisphere than the left. This seems to indicate that not all Gestalt
principles are processed preferentially in the right hemisphere, but some Gestalt principles do
show the same lateralization as found by Van Kleeck and Kosslyn.