The influence of eye movements on perceived tone frequency: exploring pitch-space associations through psychophysics
Résumé
Saccades are known to influence the perception of various visual features, such as size or numerosity. When used in action-perception studies, these simple, reproducible and effortless movements allow for repeated testing and calculation of psychometric functions. This contrasts with the more complex actions used in the few previous studies investigating the impact of action on pitch perception. For example, one of them suggested that participants' verbal reports of tone frequency indicated pitch overestimation (underestimation) when they were walking upstairs (downstairs). However, in the absence of a control condition, it is impossible to rule out alternative explanations involving verbal associations (i.e., “high” vs. “low”) or the usual representation of pitch along a vertical mental line. For instance, standing upstairs could be sufficient to overestimate pitch.
To determine whether (eye) movements actually influence pitch perception, we measured the perceived pitch of pure tones in 28 participants using a psychophysical method (single stimuli). At the beginning of each trial, a central visual cue indicated the future location (top vs. bottom of the screen) of a saccade target. Immediately after this first cue, participants were presented with a tone of varying frequency that they were asked to judge. In a first experimental condition, they made a saccade to the target, whereas they maintained fixation on the center of the screen in a second condition.
Points of subjective equivalence differed according to the location of the visual stimulus : pitch was overestimated (underestimated) when this stimulus appeared at the top (bottom) of the screen. However, our results did not show an effect of saccade execution. Discrimination sensitivity remained constant across all conditions. These findings suggest that activation of pitch-space associations is sufficient to bias tone frequency estimation, while movement per se is not necessary.
Domaines
Sciences cognitivesOrigine | Fichiers produits par l'(les) auteur(s) |
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