An exploratory study of arm-reach reaction time and eye-hand coordination

The study examined the time taken to reach and touch keys positioned both within and just outside the traditional reach envelope, as well as within and just outside the region of easy visibility, defined as being within a 30 degrees cone centered on the line of sight. Movements were required from a start key positioned in front of the subject to a response key positioned at one of 140 positions, defined by seven heights (from 360 to 1080 mm above the seat reference point (SRP), five angles (in vertical planes positioned from 30 degrees across the body to 90 degrees ipsilaterally) and four radii (from 200 mm closer to the body than the normal reach boundary to 100 mm further away than the normal reach boundary). The time taken was divided into detection time (the time from illumination of response signal to release of start key), and movement time (the time from release of start key to contact with response key). Results suggested that the visual cone should be extended downwards, as detection time increased rapidly to keys positioned outside the visual cone upwards, but not in the downwards direction. In general, responses to keys positioned anywhere that was both within the reach envelope and also within the visual cone took approximately the same time, from 371 to 420 ms. Movement time increased with distance moved, but disproportionately so, up to 595 ms, when movement was required to positions that were at one or more of the extremes of height, angle or radius.