title: Smooth pursuit eye movements with imaginary targets defined by extrafoveal cues.
abstract: Initiation of smooth pursuit eye movements was studied using imaginary targets defined by pairs of small spots ("cues") moving together in step-ramp motion. The arrangement of cues and imaginary target were either "two-sided"--cues far apart and imaginary target midway between, or "one-sided"--cues 4 deg apart and imaginary target to one side of the cue pair. (1) Pursuit of two-sided stimuli was much better than pursuit of one-sided stimuli and was often as good as pursuit of a real foveal target. (2) Experiments with various cue configurations suggest an attribute required for vigorous pursuit: "foveal enclosure". Configuration information is available to the pursuit system immediately after the onset of motion. (3) Pursuit of imaginary targets is markedly degraded by a background; the effect is strongest for a background at the fovea and weaker for an eccentric background, including one at the cue location.
authors.affiliation: Schnurmacher Institute for Vision Research, State University of New York, State College of Optometry, New York 10010.
authors.forename: H J
authors.initials: HJ
authors.lastname: Wyatt
authors.forename: J
authors.initials: J
authors.lastname: Pola
authors.forename: B
authors.initials: B
authors.lastname: Fortune
authors.forename: M
authors.initials: M
authors.lastname: Posner
mesh_terms: D003463:Cues; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D005584:Fovea Centralis / Q000502:physiology; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology; D011698:Pursuit, Smooth / Q000502:physiology*; D012438:Saccades / Q000502:physiology; D013997:Time Factors