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Facial expressions are one of the most important ways to communicate our emotional state. In popular culture and in the scientific literature on face processing, the eye area is often conceived as a very important - if not the most important - cue for the recognition of facial expressions. In support of this, an underutilization of the eye area is often observed in clinical populations with a deficit in the recognition of facial expressions of emotions. Here, we used the Bubbles technique to verify which facial cue is the most important when it comes to discriminating between eight static and dynamic facial expressions (i.e., six basic emotions, pain and a neutral expression). We found that the mouth area is the most important cue for both static and dynamic facial expressions. We conducted an ideal observer analysis on the static expressions and determined that the mouth area is the most informative. However, we found an underutilization of the eye area by human participants in comparison to the ideal observer. We then demonstrated that the mouth area contains the most discriminative motions across expressions. We propose that the greater utilization of the mouth area by the human participants might come from remnants of the strategy the brain has developed with dynamic stimuli, and/or from a strategy whereby the most informative area is prioritized due to the limited capacity of the visuo-cognitive system., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The role of the corpus callosum in the inter-hemispheric integration of the visuo-spatial attention system, was investigated in patients with a total callosotomy or with an anterior callosal section. Subjects produced simple reaction times (RTs) to visual targets shown to the left or right visual hemifield. Preceding the target by an interval of 500 ms, arrow cues predicting the target location were shown left and right of the point of ocular fixation. For a majority of total and anterior callosotomy patients, results with valid focused cues (both arrows pointing to the target location) and with divided-attention cues (arrows pointing away from fixation) did not differ and both conditions produced shorter RTs than with neutral cues (equal signs). In contrast, neurologically intact subjects showed equal RTs with divided-attention and neutral cues, whereas valid focused cues produced reduced RTs relative to neutral cues. These results indicate that most split-brains, in contrast to normal observers, are capable of directing their attention to left and right visual field locations simultaneously, and therefore that each cerebral hemisphere controls its own visuo-spatial attention mechanism.

The processing of single characters in a pure alexic patient was studied in an attempt to identify the impairment responsible for his reading disorder. Observations from Experiments 1 to 4 suggested a deficit of identification of alphanumeric stimuli without any impairment affecting the elaboration of a structural description of visual stimulation. Experiment 5 indicated that the identification disorder results from a defect in the selective processes--activation and/or inhibition--that must come into play for achieving an appropriate match between a structural description of the stimulation and representations of the identities of known stimuli. The possible implications of this deficit in single-character identification for word reading are discussed.

We compared the speed at which visuo-spatial attention may be shifted from one stimulus to another as a function of the visual hemifield in which the items were displayed in a visual search task requiring serial processing. The increase in response time with the number of items displayed was similar for left- and right-hemifield presentations. This suggests that the rate at which visuo-spatial attention can be shifted from one stimulus to another during visual search does not differ between the cerebral hemispheres.