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Participants made perceptual judgments about the length of, and manual aiming movements to the opposite end of, formerly visible Müller-Lyer stimuli. The Müller-Lyer illusion affected both perceptual judgments and aiming amplitude. Manipulations of stimulus duration (10 ms or 3,000 ms) and memory delay length (10 ms or 3,000 ms) had no impact on the(More)
Over the past decade there has been a great deal of controversy regarding the relative impact of visual illusions on cognitive judgments and the control of goal-directed action. We report the results of two experiments indicating that perceptual biases associated with the Müller-Lyer illusion involve a misjudgment of amplitude/extent while aiming biases(More)
Sharing a drink or passing a tool to another person is frequently done in our daily lives. However, a second thought is rarely given about how the object should be handed; instead we pay attention to other factors (e.g., the company). This interaction (handing a tool to someone) is interesting, since it may give insight to how motor intentions are(More)
We examined the planning and control of goal-directed aiming movements in young adults with autism. Participants performed rapid manual aiming movements to one of two targets. We manipulated the difficulty of the planning and control process by varying both target size and amplitude of the movements. Consistent with previous research, participants with(More)
Over the last decade, there has been an interest in the impact of visual illusions on the control of action. Much of this work has been motivated by Milner and Goodale's two visual system model of visual processing. This model is based on a hypothesized dissociation between cognitive judgments and the visual control of action. It holds that action is immune(More)
Adam, Mol, Pratt, and Fischer (2006) reported what they termed "a violation of Fitts's Law" - when participants aimed to targets in an array, movement times (MTs) to the last target location (highest index of difficulty (ID)) were shorter than predicted by Fitts's Law. Based on the results of subsequent studies in which placeholders were present either(More)
Two experiments explored how individuals with and without autism plan and reprogram movements. Participants were given partial or complete information regarding the location of the upcoming manual movement. In Experiment 1, direct information specified the hand or direction of the upcoming movement. These results replicated previous reports that(More)
Two experiments investigated how persons with and without autism plan manual aiming movements when advance information is direct and when strategic planning is required. In Experiment 1 advance information about hand, direction, and/or movement amplitude was manipulated. Reaction times suggested both groups adopted a hierarchical pattern of movement(More)
PURPOSE Since previous testing of the Challenge Module revealed that response scales should assess performance speed as well as skill accomplishment, this study sought to develop empirically based dual-criterion (accomplishment and time) response options. METHODS Challenge items were tested with a convenience sample of 34 children who were typically(More)