Stimulus discriminability may bias value-based probabilistic learning

Iris Schutte, Heleen A. Slagter, Anne G.E. Collins, Michael J. Frank, J. Leon Kenemans

Research output: Contribution to JournalArticleAcademicpeer-review


Reinforcement learning tasks are often used to assess participants' tendency to learn more from the positive or more from the negative consequences of one's action. However, this assessment often requires comparison in learning performance across different task conditions, which may differ in the relative salience or discriminability of the stimuli associated with more and less rewarding outcomes, respectively. To address this issue, in a first set of studies, participants were subjected to two versions of a common probabilistic learning task. The two versions differed with respect to the stimulus (Hiragana) characters associated with reward probability. The assignment of character to reward probability was fixed within version but reversed between versions. We found that performance was highly influenced by task version, which could be explained by the relative perceptual discriminability of characters assigned to high or low reward probabilities, as assessed by a separate discrimination experiment. Participants were more reliable in selecting rewarding characters that were more discriminable, leading to differences in learning curves and their sensitivity to reward probability. This difference in experienced reinforcement history was accompanied by performance biases in a test phase assessing ability to learn from positive vs. negative outcomes. In a subsequent large-scale web-based experiment, this impact of task version on learning and test measures was replicated and extended. Collectively, these findings imply a key role for perceptual factors in guiding reward learning and underscore the need to control stimulus discriminability when making inferences about individual differences in reinforcement learning.

Original languageEnglish
Article numbere0176205
JournalPLoS ONE
Issue number5
Publication statusPublished - 1 May 2017
Externally publishedYes


Experiment 1 and 2 were supported by a grant from the Netherlands Organization for Scientific Research awarded to LK (grant nr: 404-10-318). Experiment 3 was supported by a grant from the National Science Foundation awarded to MF (NSF grant, nr 1460604). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. There was no additional external funding received for this study.

FundersFunder number
Directorate for Social, Behavioral and Economic Sciences1460604


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