EEG-based Identification of Evidence Accumulation Stages in Decision-Making

Abstract

Dating back to the 19th century, the discovery of processing stages has been of great interest to researchers in cognitive science. The goal of this paper is to demonstrate the validity of a recently developed method, hidden semi-Markov model multivariate pattern analysis (HsMM-MVPA), for discovering stages directly from EEG data, in contrast to classical reaction-time-based methods. To test the validity of stages discovered with the HsMM-MVPA method, we applied it to two relatively simple tasks where the interpretation of processing stages is straightforward. In these visual discrimination EEG data experiments, perceptual processing and decision difficulty were manipulated. The HsMM-MVPA revealed that participants progressed through five cognitive processing stages while performing these tasks. The brain activation of one of those stages was dependent on perceptual processing, whereas the brain activation and the duration of two other stages were dependent on decision difficulty. In addition, evidence accumulation models (EAMs) were used to assess to what extent the results of HsMM-MVPA are comparable to standard reaction-time-based methods. Consistent with the HsMM-MVPA results, EAMs showed that nondecision time varied with perceptual difficulty and drift rate varied with decision difficulty. Moreover, nondecision and decision time of the EAMs correlated highly with the first two and last three stages of the HsMM-MVPA, respectively, indicating that the HsMM-MVPA gives a more detailed description of stages discovered with this more classical method. The results demonstrate that cognitive stages can be robustly inferred with the HsMM-MVPA.

Discovering the Brain Stages of Lexical Decision: Behavioral Effects Originate from a Single Neural Decision Process

“…Second, in a previous study in which we experimentally manipulated decision difficulty, we saw a very similar bump-stage-bump pattern (Berberyan et al, 2021). In that study, the onset bump of the decision stage showed strong frontal negativity, and the end of the decision stage strong central-parietal positivity -highly resemblant of the current bump topologies of bumps 4 and 5.…”

“…This HsMM-MVPA method has been successfully applied to a range of cognitive tasks including associative memory recognition, arithmetic retrieval, and classical short-term memory tasks (Anderson et al, 2018(Anderson et al, , 2016Portoles, Borst, & van Vugt, 2018;van Maanen, Portoles, & Borst, in press;Walsh et al, 2017;Zhang, Borst, Kass, & Anderson, 2017;Zhang, van Vugt, Borst, & Anderson, 2018;Zhang, Walsh, et al, 2018). In a recent validation study, it was found that HsMM-MVPA allows for zooming into processes identified with RT-based methods by finding a range of corresponding cognitive stages (Berberyan, van Maanen, van Rijn, & Borst, 2021).…”

“…Our analysis started with the identification of good initial estimates for the parameters describing the bumps and gamma distributions, to avoid local maxima during subsequent EM estimations (Berberyan et al, 2021;Zhang, Walsh, et al, 2018). This was done by first fitting an HsMM model with the maximum number of bumps to the data (as bumps cannot overlap, this is the duration of the shortest trial divided by the 50-ms bump width).…”

The Discovery and Interpretation of Evidence Accumulation Stages

“…In a recent study, we found direct support for this assumption: we did two identical experiments, except that a decision rule was made more difficult in the second experiment. Here, we observed that the decision difficulty had a very clear effect on the duration of one of the stages (Berberyan et al 2021). This also indicated that stages are typically serial, even though the HsMM-MVPA does not enforce this.…”

“…We found that the duration of the penultimate stage was longer for the more difficult decision rule. Consequently the final stage was "pushed backwards" (Berberyan et al 2021), indicating that the onset of the final stage was triggered by an event in the penultimate stage, suggesting serial dependence.…”