The role of perception in generalization: Commentary on Zaman, Yu, and Verheyen (2023)

Stimulus generalization, or the transfer of learned responses between stimuli, is a critical ability for adaptation to everyday life. In a typical experiment, generalization is assessed by measuring responses to stimuli varying along a physical dimension. Variations in the gradient of learned responses are usually interpreted as differences in the underlying cognitive process of generalization. A recent study by Zaman, Yu, and Verheyen (2023) seeks to challenge this view, arguing that generalization is best modeled by perceptual factors and that individual differences in perception or ability to identify the stimuli are primary drivers of generalization. In this commentary, we outline issues in the methodology and analysis of Zaman et al.'s study and show that their key result is not robust to the addition of theoretically informed alternative models. We conclude that the evidence is not strong enough to support their conclusions regarding the primacy of perceptual processes in generalization. We propose some ways forward for researchers in this field attempting to understand the psychological mechanisms underlying individual differences in stimulus generalization. (PsycInfo Database Record (c) 2025 APA, all rights reserved).