Autism spectrum conditions (ASC) are characterised by social-emotional difficulties, such as problems identifying and understanding the emotional state of others. Research investigating emotion processing in ASC has provided mixed results to date. However, a number of studies have shown people with ASC have deficits processing negative basic emotions on both a behavioural and neural level, with intact processing of positive or neutral emotions.
Visual adaptation is a paradigm where participants constantly view a stimulus for a period of time. This then alters the neuronal firing associated with coding for that stimulus and, thus, alters subsequent perception of that stimulus. The alterations in perception are typically a deviation from the adapting stimuli in the opposite direction. For example, adaptation studies with basic emotions have shown that visually adapting to an emotion of one valence (e.g. negative) results in perceiving a neutral face as displaying the opposite valence (e.g. positive). This method can be used to probe underlying neural representations of the visual-perceptual world.
The current study investigated emotion processing differences related to autism using a visual adaptation paradigm. As autism is a spectrum condition, it is hypothesised that emotion processing deficits would be evident in subclinical individuals with a high degree of autism traits.
94 participants from the general population were recruited and assessed for the number of autism traits they possess using the Autism-Spectrum Quotient (AQ). Participants were assigned to either a ‘high’ or ‘low’ autism trait group based on their AQ scores, and basic emotion recognition ability was assessed. Participants then completed a visual adaptation task with images displaying basic emotions and anti-emotions created to be their perceptual. During adaptation, participants viewed an emotional expression for 30s before making a judgement regarding the expression shown on a briefly presented neutral expression test face. We expected those with high autism traits to show reduced adaptation effects compared to those with low autism traits when the perceptual after-effect involved a negative emotion representation, but no group differences when the after-effect involved positive emotions.
Results showed an interaction between Autism Trait Group and Adapting Emotion (F(1,92) = 5.25, p <.05). This was further explored to show that high autism trait participants had more difficulty versus those with low autism traits when perceiving an expression that would ordinarily appear negatively valenced following adaptation (t(90) = 2.01, p<.05; t(90) = 2.47, p < .05; t(90) = 2.47, p<.05). However, no group differences were evident for after-effect perceptions involving positive emotions (t(90) = -1.73, p>.05; t(90) =.62, p>.05). There were no group differences in the pre-adaptation emotion recognition task (all p’s>.05).
The results show that people with high autism traits have difficulties producing representations of negative emotional expressions, but not positive ones. These findings have implications for understanding basic emotion processing in the broader autism spectrum.
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