title: The effect of the "rod-and-frame" illusion on grip planning in a sequential object manipulation task.
abstract: We investigated the effect of visual context (i.e., a visual illusion) on the planning of a sequential object manipulation task. Participants (n = 13) had to grasp a rod embedded in a "rod-and-frame" illusion and insert the rod-end into a tight hole in a pre-defined way. The grip type (defined by start posture, either pronated or supinated; and end posture, either comfortable or uncomfortable) used to grasp the rod was registered as a macroscopic variable of motor planning. Different rod orientations forced the participants to switch between grip types. As expected, most participants switched between pronated and supinated start postures, such that they ended the movement with a comfortable end posture. As it has been argued that planning is dependent on visual context information, we hypothesized that the visual illusion would affect the specific rod orientation at which participants would switch into a different grip type. This hypothesis was confirmed. More specifically, the illusion affected the critical spatial information that is used for action planning. Collectively, these findings are the first to show an effect of an illusion on motor planning in a sequential object manipulation task.
authors.affiliation: Nijmegen Institute for Cognition and Information (NICI), Radboud University Nijmegen, Montessorilaan 3, 6525 HR, Nijmegen, The Netherlands. c.craje@nici.ru.nl
authors.forename: Céline
authors.initials: C
authors.lastname: Crajé
authors.forename: John
authors.initials: J
authors.lastname: van der Kamp
authors.forename: Bert
authors.initials: B
authors.lastname: Steenbergen
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009042:Motivation; D009903:Optical Illusions / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011597:Psychomotor Performance / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology