title: Corrections in saccade endpoints scale to the amplitude of target displacements in a double-step paradigm.
abstract: It is widely held that discrete goal-directed eye movements (saccades) are ballistic in nature because their durations are too short to allow for sensory-based online correction. Recent studies, however, have provided evidence that saccadic endpoints can be mediated via online corrections. Specifically, it has been reported that saccade trajectories adapt to the eccentricity of an unexpectedly perturbed target location (i.e., target 'jump' paradigm). If saccades are subject to online correction mechanisms, then the magnitude of such changes should scale to the amplitude of the target jump. To test this hypothesis, saccadic endpoints for trials on which the target jumped one of three amplitudes (Small: 2.5°, Medium: 5.0°, and Large: 7.5°; i.e., Jump trials) immediately after saccade onset were compared with the endpoints of trials in which the target location did not change (i.e., Reference trials). Results showed that primary saccade endpoints for Jump trials were longer than for Reference trials. Importantly, the magnitude of this increase in endpoint scaled with the amplitude of the target jump. Thus, these results support emerging and coalescent evidence that saccade trajectories are subject to online corrections.
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada; Department of Kinesiology, University of Maryland College Park, 2351 SPH Building, College Park, MD 20742-2611, USA.
authors.forename: Dovin
authors.initials: D
authors.lastname: Kiernan
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada; Centre for Motor Control, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada.
authors.forename: Gerome
authors.initials: G
authors.lastname: Manson
authors.affiliation: Centre for Motor Control, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada; School of Kinesiology, University of Western Ontario, Somerville House, University of Western Ontario, London, ON, N6G 2V4, Canada.
authors.forename: Matthew
authors.initials: M
authors.lastname: Heath
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada; Centre for Motor Control, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada.
authors.forename: Luc
authors.initials: L
authors.lastname: Tremblay
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada; Centre for Motor Control, University of Toronto, 55Harbord St., Toronto, Ontario, M5S 2W6, Canada. Electronic address: t.welsh@utoronto.ca.
authors.forename: Timothy N
authors.initials: TN
authors.lastname: Welsh
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time; D012438:Saccades; D055815:Young Adult
keywords: Feedback; Oculomotor; Online control; Saccades; Saccadic suppression; Target jump