title: Rapid volitional control of apparent motion during percept generation.
abstract: How rapidly can one voluntarily influence percept generation? The time course of voluntary visual-spatial attention is well studied, but the time course of intentional control over percept generation is relatively unknown. We investigated the latter question using "one-shot" apparent motion. When a vertical or horizontal pair of squares is replaced by its 90º-rotated version, the bottom-up signal is ambiguous. From this ambiguous signal, it is known that people can intentionally generate a percept of rotation in a desired direction (clockwise or counterclockwise). To determine the time course of this intentional control, we instructed participants to voluntarily induce rotation in a precued direction (clockwise rotation when a high-pitched tone was heard, and counterclockwise rotation when a low-pitched tone was heard), and then to report the direction of rotation that was actually perceived. We varied the delay between the instructional cue and the rotated frame (cue-lead time) from 0 to 1,067 ms. Intentional control became more effective with longer cue-lead times (asymptotically effective at 533 ms). Notably, intentional control was reliable even with a zero cue-lead time; control experiments ruled out response bias and the development of an auditory-visual association as explanations. This demonstrates that people can interpret an auditory cue and intentionally generate a desired motion percept surprisingly rapidly, entirely within the subjectively instantaneous moment in which the visual system constructs a percept of apparent motion.
authors.affiliation: Northwestern University, Evanston, IL, USA, j-mossbridge@northwestern.edu.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Mossbridge
authors.forename: Laura
authors.initials: L
authors.lastname: Ortega
authors.forename: Marcia
authors.initials: M
authors.lastname: Grabowecky
authors.forename: Satoru
authors.initials: S
authors.lastname: Suzuki
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D003463:Cues; D006801:Humans; D009038:Motion; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology*; D012399:Rotation; D013028:Space Perception / Q000502:physiology*; D014836:Volition / Q000502:physiology*; D055815:Young Adult