Are individual differences in lexical and coarticulatory biases linked across speech tasks?

Individuals vary in their tendency to be biased by lexical and coarticulatory information during speech perception, though the sources of these differences remain debated. One suggestion is that lexical and coarticulatory bias trade-off with each other due to differences in processing style. This study explores the nature of this individual variation through three speech sound categorization tasks: one where both lexical and coarticulatory biases are present simultaneously for the /s-ʃ/ sibilants, a replication of Lai, Wade, and Tamminga [(2022) Linguist. Vanguard 8, 29-39]; the second where only lexical bias is present for /ɛ/-/ɪ/ vowels; and finally /d/-/g/ stops following /r/ or /l/ coarticulatory biasing contexts. Across 89 native Canadian English listeners, we replicated the within-task trade-off between lexical and coarticulatory effects (r = -0.19), weaker but consistent with Lai, Wade, and Tamminga [(2022) Linguist. Vanguard 8, 29-39]. There was no evidence for a trade-off across tasks; a joint Bayesian model that estimated individual-level correlations across tasks showed that lexical and coarticulatory effects were not credibly related. Participants' consistency in categorizing the acoustic continuum (effect of continuum step) was consistent across tasks. Overall, the findings suggest that while trade-off patterns can be replicated within specific tasks, they are not robust across tasks, indicating possible task-specific effects or contrast-specific perceptual strategies.