HOW THE IDENTIFICATION OF TARGET ACCELERATION IS AFFECTED BY MODES OF STARTING AND OF ENDING

It previously had been found that negatively accelerated visual motion may be identified more accurately than positively accelerated motion. An explanation was advanced in terms of the differential consequences of ‘missing’ the start of the motion. From this it was deduced that the difference in accuracy could be diminished by use of a lead‐in motion before the start of the portion to be judged. In the present experiment with twenty‐six adult human subjects, the prediction was upheld, as there was virtually equal accuracy with the moving onset for positively and negatively accelerated motion. However, the outcome was clear‐cut only when the motion ended with the target remaining stationary rather than disappearing from view. No explanation could be formulated for this interaction.