Brief report: perception of genuine and posed smiles by individuals with autism

Abstract

Individuals with autism are impaired in the recognition of fear, which may be due to their reduced tendency to look at the eyes. Here we investigated another potential perceptual and social consequence of reduced eye fixation. The eye region of the face is critical for identifying genuine, or sincere, smiles. We therefore investigated this ability in adults with autism. We used eye-tracking to measure gaze behaviour to faces displaying posed and genuine smiles. Adults with autism were impaired on the posed/genuine smile task and looked at the eyes significantly less than did controls. Also, within the autism group, task performance correlated with social interaction ability. We conclude that reduced eye contact in autism leads to reduced ability to discriminate genuine from posed smiles with downstream effects on social interaction.

Figure 1

sample images of a genuine smile (left), and a posed smile (right) from the stimulus set. Gaze points that fell within the boxes were used to calculate gaze time to the eye region or the mouth region. From Miles & Johnston (2006). Adapted with permission.

Figure 2

mean scores of the autism group and the control group in the Smiles condition (discriminating a genuine from a posed smile), and in the Control condition (discriminating a happy from a neutral face). Participants with autism scored lower than controls in the Smiles condition (p = 0.035, 1-tailed).

Figure 3. mean score in the Smiles and Control conditions for each participant with autism plotted against his or her RSI score (a higher RSI score indicates greater social impairment), r = -0.469, p = 0.049.

Figure 4

eyegaze data from the autism and control groups, showing the percentage of gaze time within the eye and mouth regions in the Smiles condition. There was a significant interaction between participant group and facial region (p = 0.010). An analysis of simple effects showed the autism group spent less time than controls looking at the eye region (p = 0.033). The difference for the mouth region approached significance (p = 0.065).

Figure 5

eyegaze data from the autism and control groups, showing the percentage of fixations made to the eye and mouth regions in the Smiles condition. There was a significant interaction between participant group and facial region (p = 0.016). An analysis of simple effects showed the autism group made fewer fixations than controls to the eye region (p = 0.048). There was a trend towards a difference for the mouth region (p = 0.055, 1-tailed).