Revisiting the Relationship Between the Processing of Gaze Direction and the Processing of Facial Expression

There is mixed evidence on the nature of the relationship between the perception of gaze direction and the perception of facial expressions. Major support for shared processing of gaze and expression comes from behavioral studies that showed that observers cannot process expression or gaze and ignore irrelevant variations in the other dimension. However, these studies have not considered the role of head orientation, which is known to play a key role in the processing of gaze direction. In a series of experiments, the relationship between the processing of expression and gaze was tested both with head orientation held constant and with head orientation varied between trials, making it a relevant source of information for computing gaze direction. Results show that when head orientation varied between trials, the processing of facial expression was not interfered with gaze direction, and conversely, the processing of gaze could be made without being interfered from irrelevant variations in expression. These findings suggest that the processing of gaze and the processing of expression are not functionally interconnected as was previously assumed.