Chimeric Face Task

Background

The Chimeric Face Test (CFT) is a behavioral task used to assess hemispheric asymmetry (lateralization) in emotional processing by presenting split faces. Participants are shown composite images—half-emotional/half-neutral—and asked to select the "happier" face, generally revealing a right-hemisphere dominance for emotion by preferring left-side emotional expressions.

While the general concept of using split-face images to study perception dates back to Werner Wolff in 1933, it was later formalized into a standardized behavioral test to measure brain lateralization by Jerre Levy and colleagues in the 1980s. The CFT is included in the Behavioural Laterality Battery (BLB), a free online test battery published by Adam J. Parker and colleagues in 2020 - this test battery is also provided in the Millisecond Library (Inquisit BLB).

The Millisecond CFT is based on-, and uses chimeric stimuli provided by the BLB.

Task Procedure

Participants view chimeric faces (different emotion on left and right side of face) as well as control images (same emotion on both sides of the face) for a short duration (500ms) and have to select from 4 possible emotion buttons (anger, disgust, happiness, sadness) to report the emotion that they experienced as the strongest one displayed. They have 1sec to respond.

The test stimuli set consists of 16 stimuli: Each of the four emotions (anger, disgust, happiness, sadness) is paired with the others (including itself for control items), so that each emotion is presented left four times. Participants work through two repetitions of this set for a total of 32 trials. The order of the stimuli is determined randomly. A short practice block with two different emotions (surprise,fear) precedes the test block.

What it Measures

The Chimeric Face Test (CFT) is a behavioral measure of hemispheric asymmetry (lateralization) in emotional processing.

Psychological domains

• Brain Lateralization: The principle that specific cognitive functions are dominant in either the left or right hemisphere of the brain
• Emotion Processing: The perception, interpretation and responding to emotional stimuli

Main Performance Metrics

• LateralizationRatio: a ratio that compares (correctly) left selected emotions to (correctly) right selected emotions; measure of overall emotion lateralization

Psychiatric Conditions

CFT performance has been found to be impaired in the following patient groups

• Traumatic Brain Injury (TBI)
• Schizophrenia
• Autism Spectrum Disorder
• Mood Disorders

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Chimeric Face Task.

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Burt, D. M. & Perrett, D. I. (1997). Perceptual asymmetries in judgements of facial attractiveness, age, gender, speech and expression. Neuropsychologia, 35, 685-693. https://doi.org/10.1016/S0028-3932(96)00111-X

Innes, R. B., Burt, D. M., Birch, Y. K. & Hausmann, M. (2016). A leftward bias however you look at it: Revisiting the emotional chimeric face task as a tool for measuring emotion lateralization. Laterality, 21, 643-661. https://doi.org/10.1080/1357650X.2015.1117095

Adam J. Parker , Zoe V. J. Woodhead , Paul A. Thompson & Dorothy V. M. Bishop (2020): Assessing the reliability of an online behavioural laterality battery: A pre-registered study, Laterality, DOI: 10.1080/1357650X.2020.1859526 To link to this article: https://doi.org/10.1080/1357650X.2020.1859526