Thread by @niclas_kuper

Proud that my first paper as first author just got published in @ejpblog! It’s called “Resting Frontal EEG Asymmetry and Personality Traits: A Meta-analysis”. I worked on it with @w_kaeckenmester and Jan Wacker. I’ll explain what we found below! 1/12

onlinelibrary.wiley.com/doi/abs/10.100…

Frontal asymmetry describes the difference in brain activity between the left & right frontal cortex and is often measured in the resting state via EEG. It has been used in hundreds of studies as an indicator of motivation, emotion, and psychopathology. 2/12

Research has linked resting frontal asymmetry to personality traits, especially trait approach & withdrawal motivation (BAS & BIS). However, there have been replication issues & it was unclear whether these effects exist & what their magnitude is – so we did a #metaanalysis! 3/12

We included data from 79 independent samples with n = 5700 participants and examined the relationship between resting frontal asymmetry and five trait clusters: (1) Extraversion, (2) Neuroticism, (3) Impulsivity, (4) Anger, and (5) Defensiveness. 4/12

Overall, we found very small effects, especially for the most widely researched traits (see below). For Extraversion, Neuroticism, and Impulsivity, the total effects were not larger than r = .06. They were a bit larger for the other clusters, but limitations apply there. 5/12

The associations with Anger and Defensiveness were r = .12 & r = .21, respectively. However, especially the latter is based on very few studies & in general, there was evidence for publication bias. 6/12

Effect sizes from published studies were significantly larger and the overall effect size of unpublished studies was essentially zero. Adjusted effect size estimates using PET-PEESE and the three-parameter selection model were typically further reduced & all nonsignificant. 7/12

Results were similar when looking at more homogeneous sub-traits (e.g., agentic Extraversion) and the most frequently analyzed scales (BAS, BIS). In sum, we conclude that the validity of resting frontal asymmetry as a marker for personality is not supported. #measurement 8/12

For interested readers: The manuscript includes several analyses of methodological and other moderators (most n.s.). One moderator that did emerge as significant was journal impact factor – with larger effect sizes being published in higher IF journals. 9/12

We suggest that subsequent research on frontal asymmetry and personality should shift its focus away from resting FA towards examining FA as a state variable during contexts relevant to the respective trait. 10/12

Given that these effects “survived” in the literature for multiple decades, we end our discussion section with several suggestions on how to prevent this in subsequent research on state frontal asymmetry. 11/12

Studies should be pre-registered and highly powered. Furthermore, a systematic comparison of several methodological choices (e.g., reference scheme, electrode pair) is overdue #measurement. We think that large collaborative projects would be well-suited for this. 12/12