Abstract
Purpose: :
It is known that individuals with a traumatic brain injury (TBI) have difficulty interpreting facial expressions of emotion. Despite this, there lacks an exploration of the visual scan path to emotional facial expressions in this population. The purpose of this study was to investigate the visual scan path to emotional facial stimuli in individuals with a severe TBI.
Methods: :
Four male participants (mean age + SD: 30.3 + 8.2 years) with a severe TBI (PTA > 14 days) who were at least 2 years post-injury (mean time + SD: 12.8.+ 7.8 years) were matched for age (p = 0.86) and gender with 4 healthy controls (31.3 + 7.3 years). Participants’ eye movements were recorded using the Tobii 1750 binocular infrared eye tracker while they viewed coloured pictures of 18 static emotional faces. The faces portrayed six universal expressions of emotion (i.e., sad, happy, angry, disgusted, anxious, surprised) taken from the Matsumoto & Ekman (2004) JACFEE set. Each emotion was shown 3 times. Groups were compared with respect to accuracy in labeling the emotional facial expression, reaction time, number and duration of fixations to internal (i.e., eyes, nose, mouth) and external (all other) regions of the stimuli.
Results: :
TBI participants were less accurate than controls in labeling the faces, yielding an average of 12.3/18 faces correct, compared with 15.5/18 for controls (p = 0.05). TBI participants also took significantly longer to identify the faces (p = 0.04). Control participants fixated more frequently (p = 0.001) and for longer periods of time (p = 0.002) on internal facial features. This pattern was not evident for TBI participants who demonstrated no significant difference in the number (p = 0.338) or duration of fixations (p = 0.304) to internal versus external regions of the face.
Conclusions: :
The visual scan path to emotional facial expressions appears to be significantly impaired following a severe TBI. Attentional allocation appears more dispersed in this patient population and less concentrated on internal (i.e., salient) facial features.
Keywords: face perception • eye movements • visual search