Grange, JA and Schuch, S (2022) A spurious correlation between difference scores in evidence-accumulation model parameters. Behavior Research Methods. ISSN 1554-351X

[thumbnail of Manuscript (Revision 2).pdf]
Manuscript (Revision 2).pdf - Accepted Version

Download (4MB) | Preview
[thumbnail of s13428-022-01956-8.pdf]
s13428-022-01956-8.pdf - Published Version

Download (1MB) | Preview


Evidence-accumulation models are a useful tool for investigating the cognitive processes that give rise to behavioural data patterns in reaction times (RTs) and error rates. In their simplest form, evidence-accumulation models include three parameters: The average rate of evidence accumulation over time (drift rate) and the amount of evidence that needs to be accumulated before a response becomes selected (boundary) both characterise the response-selection process; a third parameter summarises all processes before and after the response-selection process (non-decision time). Researchers often compute experimental effects as simple difference scores between two within-subject conditions and such difference scores can also be computed on model parameters. In the present paper, we report spurious correlations between such model parameter difference scores, both in empirical data and in computer simulations. The most pronounced spurious effect is a negative correlation between boundary difference and non-decision difference, which amounts to r = - .70 or larger. In the simulations, we only observed this spurious negative correlation when either (a) there was no true difference in model parameters between simulated experimental conditions, or (b) only drift rate was manipulated between simulated experimental conditions; when a true difference existed in boundary separation, non-decision time, or all three main parameters, the correlation disappeared. We suggest that care should be taken when using evidence-accumulation model difference scores for correlational approaches because the parameter difference scores can correlate in the absence of any true inter-individual differences at the population level.

Item Type: Article
Additional Information: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit
Subjects: R Medicine > R Medicine (General) > R735 Medical education. Medical schools. Research
Divisions: Faculty of Natural Sciences > School of Psychology
Related URLs:
Depositing User: Symplectic
Date Deposited: 07 Feb 2023 09:07
Last Modified: 07 Feb 2023 09:07

Actions (login required)

View Item
View Item