title: Visual layout modulates Fitts's law: the importance of first and last positions.
abstract: When a target in the last position of a structured visual array is aimed for, movement times (MTs) are shorter than predicted by Fitts's law (Adam, Mol, Pratt, & Fischer, 2006). That study, however, confounded relative target position with absolute target location. To determine whether target position does, indeed, produce changes in the speed-accuracy trade-off function, the present experiment manipulated relative target position (e.g., first or last) independently of absolute target location (e.g., nearest or farthest). This was accomplished by presenting connected placeholders at three adjacent locations from a set of five possible locations (i.e., the middle location could be the first, middle, or last placeholder position in an array). The results of a speeded manual-pointing task showed that relative position is important for Fitts's law; when absolute location was held constant, shorter MTs were found for last-position than for middle-position targets. In addition, a similar effect was found for first-position targets. These results suggest that Fitts's law holds within, but not between, relative target positions in visible structured arrays.
authors: Department of Psychology, University of Toronto, Toronto, Ontario, Canada. pratt@psych.utoronto.ca
authors: Jay
authors: J
authors: Pratt
authors: Jos J
authors: JJ
authors: Adam
authors: Martin H
authors: MH
authors: Fischer
mesh_terms: D006801:Humans; D009039:Motion Perception; D009068:Movement; D011584:Psychology / Q000379:methods*; D011930:Reaction Time; D014796:Visual Perception
references: Ergonomics. 1992 Feb;35(2):159-75
references: 1628609
references: Science. 1996 Sep 13;273(5281):1564-8
references: 8703221
references: J Mot Behav. 1985 Mar;17(1):77-95
references: 15140699
references: Ergonomics. 1991 Apr;34(4):397-406
references: 1860460
references: Psychol Sci. 2006 Sep;17(9):794-8
references: 16984297
references: Percept Psychophys. 1978 Jul;24(1):93-101
references: 693244
references: J Exp Psychol Hum Percept Perform. 2002 Jun;28(3):515-26
references: 12075885
references: Exp Brain Res. 2001 Jan;136(2):224-30
references: 11206284
references: Annu Rev Neurosci. 1992;15:167-91
references: 1575441
references: Psychon Bull Rev. 1994 Mar;1(1):29-55
references: 24203413
references: J Exp Psychol Gen. 1980 Dec;109(4):444-74
references: 6449531
references: J Mot Behav. 1973 Sep;5(3):175-8
references: 23961747
references: Aviat Space Environ Med. 2002 May;73(5):430-5
references: 12014601
references: J Neurophysiol. 2005 Sep;94(3):1861-8
references: 15917318
references: Exp Brain Res. 1994;98(3):535-41
references: 8056073
references: J Mot Behav. 1976 Jun;8(2):113-28
references: 23965141
references: Nature. 1970 Apr 11;226(5241):177-8
references: 5437004
references: J Exp Psychol Hum Percept Perform. 1990 May;16(2):248-67
references: 2142197
references: Behav Brain Sci. 1997 Jun;20(2):279-303; discussion 303-49
references: 10096999
references: J Exp Psychol. 1954 Jun;47(6):381-91
references: 13174710