Visual scanpath training to emotional faces following severe traumatic brain injury: A single case design

Abstract

The visual scanpath to emotional facial expressions was recorded in BR, a 35-year-old male with chronic severe traumatic brain injury (TBI), both before and after he underwent intervention. The novel intervention paradigm combined visual scanpath training with verbal feedback and was implemented over a 3-month period using a single case design (AB) with one follow up session. At baseline BR's scanpath was restricted, characterised by gaze allocation primarily to salient facial features on the right side of the face stimulus. Following intervention his visual scanpath became more lateralised, although he continued to demonstrate an attentional bias to the right side of the face stimulus. This study is the first to demonstrate change in both the pattern and the position of the visual scanpath to emotional faces following intervention in a person with chronic severe TBI. In addition, these findings extend upon our previous work to suggest that modification of the visual scanpath through targeted facial feature training can support improved facial recognition performance in a person with severe TBI.

Keywords: Eye tracking; emotion; facial expression; facial expression recognition training; gaze; scanpath; traumatic brain injury; visual attention.

Figure 1.

Study Procedure. S = session; hr = hour.

Figure 2.

Intervention steps using a disgusted expression. A) Visual intervention: numbered prompts directed BR’s foveal fixations to salient facial features. 1 = left eye, 2 = nasion, 3 = right eye, 4 = mouth. B) Application to same facial expression. C) Verbal intervention with feedback. The emotional label appeared below the face for reinforcement. Note: interstimulus fixation marker and labels not shown.

Figure 3.

Areas of Interest (AOIs) shown superimposed onto a face stimulus. Note that the right AOI is on the right of the face stimulus and the left AOI is on the left of the face stimulus to align with how BR viewed the stimulus.

Figure 4.

A) Mean number and B) mean duration (ms) of fixations to each AOI across respective phases and sessions.

Figure 5.

Examples of BR’s visual scanpaths to emotional facial stimuli at baseline and follow up. Filled circles represent foveal fixations and white interconnecting lines represent saccades. Larger circles indicate longer fixation duration. A) Disgust, B) Surprise, C) Sad.