Duration of
preceding motion
Click on:

The duration of the preceding motion has a strong effect on the direction of the high-phi jump. When the duration is below 75-150 ms (the exact limit varies from one observer to the next), the jump is seen in the same direction as the preceding motion; for longer durations, the jump is seen in the opposite direction.

When you click on one of the "Brief" buttons above, the texture rotates by only 1°, and then immediately switches to a new random texture. The tiny 1° rotation is perceived as a much larger jump, reported by most observers between 10° and 60°. Although the amplitude of the jump is highly amplified, its direction is always the same as that of the tiny rotation that preceded it. On the other hand, if the preceding rotation last longer, the jump is in the opposite direction, as can be seen by clicking the "Long" buttons.