ABSTRACT
In this study we investigated the influence of hemispace, movement direction, and type of movement on distractor interference in selective reaching. Participants reached for a green target while ignoring a simultaneously presented red distractor. In Experiment 1 participants performed rightward or leftward movements within the right or the left hemispace using their dominant (i.e., right) hand. Reaction times, movement times, and percentage errors were recorded. Results showed significant interference effects in movement time, not in reaction time. Importantly, movement time interference was found to be smaller for leftward than for rightward movements. However, in Experiment 1, movement direction was confounded with type of movement (i.e., abduction vs. adduction). In Experiment 2 we disentangled these two factors by having participants perform rightward and leftward movements with right and left hands. Results indicated again that leftward movements were less prone to distractor interference than rightward movements, regardless of the responding hand. This phenomenon is interpreted in terms of a left hemisphere superiority in online feedback-processing during goal-directed movements in right-handers.
Subject(s)
Attention , Color Perception , Functional Laterality , Orientation , Pattern Recognition, Visual , Psychomotor Performance , Adult , Dominance, Cerebral , Feedback, Psychological , Female , Humans , Male , Reaction TimeABSTRACT
The authors investigated distracter effects on the kinematics of reaching movements to determine when during reaching responses (reaction time, time to peak velocity, time after peak velocity, or peak velocity) distracter interference occurred and how target-distracter separation affected the locus of interference. Participants moved a pen on a digitizing tablet toward a target appearing with or without a distracter. With a small target-distracter separation, distracter interference occurred during time after peak velocity (similar amounts of interference from near and far distracters). With a large target-distracter separation, distracter interference occurred during time to peak velocity (more interference from near compared to far distracters). The results demonstrated that target-distracter separation is an important determinant of the locus of distracter interference.
Subject(s)
Attention , Movement , Adolescent , Adult , Biomechanical Phenomena , Female , Hand , Humans , Male , Reaction Time , Task Performance and AnalysisABSTRACT
In the present experiment, the authors sought to differentiate between a distance and a grouping explanation for the symmetric versus asymmetric patterns of distractor interference in selective reaching. Participants (N = 16) pointed to a green target that appeared either with or without a red distractor. Target-distractor separation was manipulated within an array of 5 closely grouped stimulus boxes, and distractor interference (difference in performance between trials with and trials without a distractor) was measured in reaction time, movement time, percentage errors, and movement endpoints. Small distances (5 mm) between target and distractor yielded a symmetric pattern of interference, whereas large distances (20 mm) yielded an asymmetric pattern, with more interference from near than from far distractors. Those findings support the distance account of distractor interference and refute the grouping account.
Subject(s)
Attention/physiology , Choice Behavior , Distance Perception , Perceptual Masking/physiology , Psychomotor Performance , Adult , Female , Humans , Male , Reaction TimeABSTRACT
Students participated in 3 experiments investigating the use of environment- and action-centered reference frames in selective reaching. They pointed to a green target appearing either with or without a red distractor. Target-distractor distance was manipulated, and distractor interference (difference between distractor trials and no-distractor trials) was measured in reaction time, movement time, and movement endpoint. Target-distractor distance determined the dominant frame of reference. Small distances evoked an environment-centered framework that encoded targets within an external context. Large distances evoked an action-centered framework that encoded targets relative to the start position of the hand. Results support the hypothesis that the brain represents spatial information in multiple frames of reference, with the dominant frame of reference being dependent on the task demands.
