The impact of augmented information on Visuo-motor adaptation in younger and older adults

Abstract

Background: Adjustment to a visuo-motor rotation is known to be affected by ageing. According to previous studies, theage-related differences primarily pertain to the use of strategic corrections and the generation of explicit knowledge onwhich strategic corrections are based, whereas the acquisition of an (implicit) internal model of the novel visuo-motortransformation is unaffected. The present study aimed to assess the impact of augmented information on the age-relatedvariation of visuo-motor adjustments.Methodology/Principal Findings: Participants performed aiming movements controlling a cursor on a computer screen.Visual feedback of direction of cursor motion was rotated 75u relative to the direction of hand motion. Participants had toadjust to this rotation in the presence and absence of an additional hand-movement target that explicitly depicted theinput-output relations of the visuo-motor transformation. An extensive set of tests was employed in order to disentanglethe contributions of different processes to visuo-motor adjustment. Results show that the augmented information failed toaffect the age-related variations of explicit knowledge, adaptive shifts, and aftereffects in a substantial way, whereas itclearly affected initial direction errors during practice and proprioceptive realignment.Conclusions: Contrary to expectations, older participants apparently made no use of the augmented information, whereasyounger participants used the additional movement target to reduce initial direction errors early during practice. However,after a first block of trials errors increased, indicating a neglect of the augmented information, and only slowly declinedthereafter. A hypothetical dual-task account of these findings is discussed. The use of the augmented information also led toa selective impairment of proprioceptive realignment in the younger group. The mere finding of proprioceptiverealignment in adaptation to a visuo-motor rotation in a computer-controlled setup is noteworthy since visual andproprioceptive information pertain to different objects. © 2010 Hegele, Heuer.