Human Movement Science xxx (2005) xxx–xxx www.elsevier.com/locate/humov 0167-9457/$ - see front matter  2005 Published by Elsevier B.V. doi:10.1016/j.humov.2005.12.001 UNCORRECTED PROOF HUMOV 946 No. of Pages 17; Model 1+ ARTICLE IN PRESS 28 December 2005 Disk Used Speed–accuracy trade-oVs in myocontrol Eric J. Fimbel a,b,¤ , Martin Lemay c , Martin Arguin b,d a Electrical Engineering Department, École de technologie supérieure, 1100 Notre Dame West, Montréal, Qué., Canada H3C 1K3 b Institut universitaire de gériatrie de Montréal, Canada c Department of Psychology, Université du Québec à Montréal, Canada d Department of Psychology, Université de Montréal, Canada Abstract Myoelectric (EMG) signals are used in assistive technology for prostheses, computer and domes- tic control. However, little is known about the capacity of controlling these signals. SpeciWcally, it is unclear whether myocontrol, i.e., the control of myoelectric signals, obeys the same laws as motor control. Neurologically intact adult participants performed pointing tasks with EMG signals cap- tured from the forehead or the hand in two modalities (sustained: stabilize the signal amplitude in the target; impulsion: produce an impulse and return to resting level). In the sustained modality, the time to reach the target (reach time) increased logarithmically with target amplitude, which is compatible with the predictions of Fitts’ law. The rate of failure was not signiWcantly aVected by target ampli- tude. In the impulsion modality, the reach time and the rate of failure followed a bow-shaped pattern as a function of target amplitude. Stabilization time in the sustained modality followed a convex (bow-shaped) pattern for the forehead and a concave pattern for the hand. This was the only signiW- cant eVect of electrode placement in this study. These Wndings suggest that myocontrol obeys laws that are distinct from those determining motor control, and that the muscular and intra-muscular synergies that produce EMG signals are speciWc of each pointing modality and target amplitude.  2005 Published by Elsevier B.V. Keywords: EMG; Reaching; Speed–accuracy; Fitts’ law; Motor control; Myocontrol * Corresponding author. Address: Electrical Engineering Department, École de technologie supérieure, 1100 Notre Dame West, Montréal, Qué., Canada H3C 1K3. Tel.: +1 514 396 8670; fax: +1 514 396 8684. E-mail address: eWmbel@ele.etsmtl.ca (E.J. Fimbel). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25