J. J. Buchanan

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Emergence of postural patterns as a function of vision and translation frequency. We examined the frequency characteristics of human postural coordination and the role of visual information in this coordination. Eight healthy adults maintained balance in stance during sinusoidal support surface translations (12 cm peak to peak) in the anterior-posterior(More)
Bimanual 1:1 coordination patterns other than in-phase (0 degrees ) and anti-phase (180 degrees ) have proven difficult to perform even with extended practice. The difficulty has been attributed to phase attraction that draws the coordination between the limbs towards the bimanual patterns of in-phase and anti-phase and variability associated with the(More)
Subjects performed two patterns of coordination between the elbow and wrist joints of the right arm: 1) wrist flexion synchronized with elbow flexion and wrist extension with elbow extension (homologous muscle groups); and 2) wrist extension synchronized with elbow flexion and wrist flexion with elbow extension (non-homologous muscle groups). As a(More)
Two experiments were conducted to determine if multi-frequency (2:1 and 3:2) coordination between the limbs is enhanced when integrated feedback is provided in the form of Lissajous plots, attention demands are reduced, and attempts to consciously coordinate the limbs are not encouraged. To determine the influence of vision of the limbs, covered and(More)
Two experiments addressed the issue of discrete and cyclical units as possible basic units of action that might be used to construct complex actions based on task constraints. The experiments examined the influence of low and high accuracy constraints on the end-effector's motion in rhythmical aiming movements. Both experiments utilized a Fitts-type task(More)
An aiming task was used to identify the processes whereby the motor system adapted a repetitive aiming action to systematic changes in ID (ID = log2 (2A/W), Fitts in J Exp Psychol 47:381–391, 1954) within a single trial. Task ID was scaled in a trial by moving the outside edge of two stationary targets to produce nine different target IDs in a trail. The ID(More)
The coordination dynamics (e.g., stability, loss of stability, switching) of multijoint arm movements are studied as a function of forearm rotation. Rhythmical coordination of flexion and extension of the right elbow and wrist was examined under the following conditions: (1) forearm supine (forearm angle 0°), simultaneous coordination of wrist flexion/elbow(More)
The target width of a single target in a two-target reciprocal aiming task was scaled from small (ID = 5.85) to large (ID = 2.85) and large-to-small within individual trials with movement amplitude fixed. Scaling target width produced a transition in the end-effector's dynamics and based on a measure of movement harmonicity, the transition was sensitive to(More)
The purpose of the present experiment was to observe the performance of participants attempting to produce a 1:1 bimanual coordination pattern with 90° relative phase between the arms when feedback concerning the movement of the two limbs was integrated within a Lissajous plot and when this information was withdrawn. One group was paced with an auditory(More)
The coordination dynamics of learning and transfer were studied in a single limb multijoint task requiring rhythmic elbow and wrist motions. Participants were required to learn a continuous 90° relative phase pattern between the elbow and wrist such that an angle-angle plot of elbow and wrist motion produced a circle with a diameter of 80°. Joint motion was(More)