Is speech alignment to talkers or tasks?

Speech alignment, or the tendency of individuals to subtly imitate each other's speaking styles, is often assessed by comparing a subject's baseline and shadowed utterances to a model's utterances, often through perceptual ratings. These types of comparisons provide information about the occurrence of a change in subject's speech, but they do not indicate that this change is toward the specific shadowed model. In three experiments, we investigated whether alignment is specific to a shadowed model. Experiment 1 involved the classic baseline-to-shadowed comparison, to confirm that subjects did, in fact, sound more like their model when they shadowed, relative to any preexisting similarities between a subject and a model. Experiment 2 tested whether subjects' utterances sounded more similar to the model whom they had shadowed or to another, unshadowed model. In Experiment 3, we examined whether subjects' utterances sounded more similar to the model whom they had shadowed or to another subject who had shadowed a different model. The results of all experiments revealed that subjects sounded more similar to the model whom they had shadowed. This suggests that shadowing-based speech alignment is not just a change, but a change in the direction of the shadowed model, specifically.