Abstract
Looking at a pair of objects is easy when automatic grouping mechanisms bind these
objects together, but visual exploration can also be more flexible. It is possible to mentally
“re-group” two objects that are not only separate but belong to different pairs of objects.
“Re-grouping” is in conflict with automatic grouping, since it entails a separation of each
item from the set it belongs to. This ability appears to be impaired in patients with schizophrenia.
Here we check if this impairment is selective, which would suggest a dissociation
between grouping and “re-grouping,” or if it impacts on usual, automatic grouping, which
would call for a better understanding of the interactions between automatic grouping and
“re-grouping.” Sixteen outpatients with schizophrenia and healthy controls had to identify
two identical and contiguous target figures within a display of circles and squares alternating
around a fixation point. Eye-tracking was used to check central fixation. The target pair
could be located in the same or separate hemifields. Identical figures were grouped by a
connector (grouped automatically) or not (to be re-grouped). Attention modulation of automatic
grouping was tested by manipulating the proportion of connected and unconnected
targets, thus prompting subjects to focalize on either connected or unconnected pairs.
Both groups were sensitive to automatic grouping in most conditions, but patients were
unusually slowed down for connected targets while focalizing on unconnected pairs. In
addition, this unusual effect occurred only when targets were presented within the same
hemifield. Patients and controls differed on this asymmetry between within- and acrosshemifield
presentation, suggesting that patients with schizophrenia do not re-group figures
in the same way as controls do.We discuss possible implications on how “re-grouping”
ties in with ongoing, automatic perception in healthy volunteers.