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. 2025 Mar 18;13(1):271.
doi: 10.1186/s40359-024-02218-2.

Facial emotion processing hemispheric bias is weakly associated with handedness, autistic traits and biological sex, but not age

B E Speranza  1 , M Do  2 , A T Hill  2 , P H Donaldson  2 , P G Enticott  2 , M Kirkovski  2   3
Affiliations

Facial emotion processing hemispheric bias is weakly associated with handedness, autistic traits and biological sex, but not age

B E Speranza et al. BMC Psychol. .

Abstract
in English, Spanish

Background: Right-hemisphere brain regions are strongly implicated in facial emotion processing (FEP), a phenomenon termed right-hemispheric bias. Variability in FEP hemispheric bias is thought to underpin differences in facial emotion recognition ability and has been associated with age, handedness, biological sex, and autistic traits. However, findings from research to date investigating factors associated with FEP hemispheric bias have been inconsistent.

Objective: To examine if FEP hemispheric bias can be predicted by individual factors such as age, biological sex, handedness, and autistic traits.

Methods: 427 adults recruited from the general population aged 18-67 years completed the Autism-spectrum Quotient. We also assessed covariates previously linked with FEP hemispheric bias including age, handedness, and biological sex. FEP hemispheric bias was indexed using laterality quotients calculated from a Chimeric Faces Task, where participants indicated which of two identical (but mirrored) half-emotional half-neutral (no emotion) chimeric faces were more emotive.

Results: Linear regression models revealed that (1) handedness predicted FEP hemispheric choice bias, (2) the attention switching Autism-spectrum Quotient subscale predicted FEP hemispheric reaction time bias, and (3) the imagination Autism-spectrum Quotient subscale predicted FEP hemispheric reaction time bias for males, but not females.

Conclusions: These findings indicate that the relationship between autistic traits and FEP hemispheric bias is nuanced. Additionally, handedness influences hemispheric bias effects during FEP. Future research should endeavour to investigate if FEP hemispheric bias is dependent on the emotion being observed and consider using more direct measures of hemispheric bias.

Right-handed people are more likely to exhibit a right-hemispheric bias during facial emotion processing than left-handed people.Levels of autistic traits related to attention switching may predict hemispheric bias during facial emotion processing.Levels of autistic traits related to imagination may predict hemispheric bias during facial emotion processing for males, but not females.The relationship between relevant demographic and individual characteristics and hemispheric bias during facial emotion processing is nuanced and may be affected by other factors that warrant investigation.Future research should utilise large, diverse samples, and employ various methodological approaches to ensure comprehensive investigation.

Keywords: Autism; Autistic traits; Emotion processing; Handedness; Hemispheric asymmetry; Hemispheric laterality; Hemispheric specialisation; Right-hemispheric bias; Social cognition.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This study was approved by the human research ethics committee of Deakin University (HEAG-H 187_2021), and in accordance with the Declaration of Helsinki. Informed consent was obtained from all participants. Consent for publication: Figure one contains an image modified from an open-access stimulus set, the racially diverse affective expression (RADIATE) face stimulus set. Upon collection of the images by the original authors who published the face stimulus set, all models from the RADIATE face stimulus set consented to be photographed and released their photos to be used for research and scientific purposes. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Example trial image. Note. Example of a given trial image presented to participants. In this example, if participants chose the top image (which contains the emotion in the left visual field) this would demonstrate a right hemispheric bias for facial emotion processing. Conversely, choosing the bottom face (with the emotion in the right visual field) would indicate a left hemispheric bias for facial emotion processing
Fig. 2
Fig. 2
Chimeric Faces Task Paradigm. Note.Each individual trial consisted of a fixation cross presented for 1 s, followed by the trial image presented until either (a) the participant made a response, or (b) 4.5 s had passed. This was followed by a 0.5 s inter-trial interval. Following this the next trial began
Fig. 3
Fig. 3
Scatterplots of significant regression findings. Note. Bivariate scatterplots, regression lines, and standard errors for (a) Edinburgh Handedness Inventory (EHI) and choice selection bias (laterality quotient 1); (b) Autism-Spectrum quotient – attention switching and reaction time bias (laterality quotient 2); and (c) Autism-Spectrum Quotient imagination*sex at birth interaction for reaction time bias (laterality quotient 2). All data points visually delineated by adding minor error/jitter
See this image and copyright information in PMC

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