Specificity of Learning in a Video-Aiming Task: Modifying the Salience of Dynamic Visual Cues Christelle Robin Lucette Toussaint Yannick Blandin Laboratoire Performance, Motricité & Cognition Poitiers, France ABSTRACT. The authors investigated whether the salience of dynamic visual information in a video-aiming task mediates the specificity of practice. Thirty participants practiced video-aiming movements in a full-vision, a weak-vision, or a target-only condi- tion before being transferred to the target-only condition without knowledge of results. The full- and weak-vision conditions result- ed in less endpoint bias and variability in acquisition than did the target-only condition. Going from acquisition to transfer resulted in a large increase in endpoint variability for the full-vision group but not for the weak-vision or target-only groups. Kinematic analysis revealed that weak dynamic visual cues do not mask the processing of other sources of afferent information; unlike strong visual cues, weak visual cues help individuals calibrate less salient sources of afferent information, such as proprioception. Key words: motor control, motor learning, specificity of practice, video aiming, visual feedback nvestigators have suggested that learning is specific to the source or sources of sensory information that optimize per- formance during practice. For both manual and video-aiming tasks specifically, researchers have proposed that participants determine early in practice the source or sources of afferent information more likely to ensure optimal accuracy and pos- sibly process that source exclusively, to the detriment of all other sources of information (Coull, Tremblay, & Elliott, 2001; Proteau, 1992, 1995; Proteau & Carnahan, 2001; Soucy & Proteau, 2001; Tremblay & Proteau, 1998). That proposition has received support from two recurrent observa- tions made in both manual and video-aiming tasks. First, regardless of the amount of practice, aiming accuracy remained better in a full-vision condition than in a condition in which only static visual cues were available (starting base and target; hereafter called target-only condition). Second, withdrawing dynamic visual information (vision of the hand or of a cursor representing it on a video screen while it pro- gressed toward the target) in a transfer test resulted in a large increase in aiming bias and variability, again regardless of the previous amount of practice in the full-vision condition. Thus, according to the specificity of practice hypothesis, rel- atively early or even late in practice, the dynamic visual information available in those tasks dominates other sources of sensory information, ensuring endpoint accuracy. The dominance of visual afferent information may result either or both from its higher saliency and from the fact that such information allows better aiming accuracy than do other sources of afferent information, as observed in the just-cited research. Our objective in the present study was to determine whether making dynamic visual information less salient would reduce its dominance over other sources of afferent information in ensuring endpoint accuracy of video-aiming movements. One possible, although indirect, way that an experi- menter can achieve that goal is to increase the size of the target that participants are aiming for so that they can reach it successfully in a target-only condition. With that goal in mind, Proteau and Isabelle (2002) had participants aim at small (4 mm) or large (50 mm) targets in either a full-vision or a target-only condition. Contrary to their expectation, the results indicated that withdrawing visual afferent informa- tion in a transfer test had similarly deleterious effects regardless of target size. Considering that at the end of prac- tice, participants in the target-only condition were able to hit the target in only 60% of the trials, it is not surprising that participants in the full-vision condition still relied heav- ily on dynamic visual information to ensure accuracy of Correspondence address: Luc Proteau, Département de kinési- ologie, Université de Montréal, P.O. Box 6128 Station Downtown, Montréal H3C 3J7, Canada. E-mail address: luc.proteau@ umontreal.ca 367 Journal of Motor Behavior, 2005, Vol. 37, No. 5, 367–376 I Luc Proteau Département de kinésiologie Université de Montréal Québec, Canada