TY - JOUR
T1 - Modulating Fitts's Law
T2 - Perceiving targets at the last placeholder
AU - Radulescu, Petre V.
AU - Al-Aidroos, Naseem
AU - Adam, Jos J.
AU - Fischer, Martin H.
AU - Pratt, Jay
PY - 2011/5
Y1 - 2011/5
N2 - Fitts's Law predicts increasing movement times (MTs) with increasing movement amplitudes; however, when targets are placed in a structured perceptual array containing placeholders. MTs to targets in the last position are shorter than predicted. We conducted three experiments to determine if this modulation has a perceptual cause. Experiment 1, which used extremely diminished (three pixel) placeholders, showed that the modulation is not due to perceptual interference from neighboring placeholders. Experiment 2, which measured reaction times using a target detection task, showed that the modulation does not result from speeded perceptual processing at the last position of the array. Experiment 3, which measured accuracy using a masked letter-discrimination task, showed that the modulation does not result from the increased quality of perceptual representation at the last position of the array. Overall, these findings suggest that the changes in effectiveness of visual processing (less interference, speeded processing, and increased quality) at the last position in the perceptual array do not drive the modulation. Thus, while the locus of the Fitts's Law modulation appears to be in the movement planning stage, it is likely not due to perceptual mechanisms. (C) 2011 Elsevier B.V. All rights reserved.
AB - Fitts's Law predicts increasing movement times (MTs) with increasing movement amplitudes; however, when targets are placed in a structured perceptual array containing placeholders. MTs to targets in the last position are shorter than predicted. We conducted three experiments to determine if this modulation has a perceptual cause. Experiment 1, which used extremely diminished (three pixel) placeholders, showed that the modulation is not due to perceptual interference from neighboring placeholders. Experiment 2, which measured reaction times using a target detection task, showed that the modulation does not result from speeded perceptual processing at the last position of the array. Experiment 3, which measured accuracy using a masked letter-discrimination task, showed that the modulation does not result from the increased quality of perceptual representation at the last position of the array. Overall, these findings suggest that the changes in effectiveness of visual processing (less interference, speeded processing, and increased quality) at the last position in the perceptual array do not drive the modulation. Thus, while the locus of the Fitts's Law modulation appears to be in the movement planning stage, it is likely not due to perceptual mechanisms. (C) 2011 Elsevier B.V. All rights reserved.
U2 - 10.1016/j.actpsy.2011.03.005
DO - 10.1016/j.actpsy.2011.03.005
M3 - Article
C2 - 21474110
SN - 0001-6918
VL - 137
SP - 101
EP - 105
JO - Acta Psychologica
JF - Acta Psychologica
IS - 1
ER -