Representational Momentum

Under appropriate conditions an observer's memory for the final position of an abruptly halted object is distorted in the direction of the represented motion.

Demonstrating RM

In a classic representational momentum experiment, subjects are presented with a series of static inducing displays sampled from a path of motion (e.g. 3 rectangles at successive 17° rotations about the rectangle's center), and instructed to remember the last position. The subjects are then tested by asking them to decide if an additional stimulus (e.g. a fourth rectangle), presented at either the same orientation as the last inducing stimulus or slightly further or back along the implied path, was in fact at the same orientation as the last inducing display. Subjects are much less likely to reject forward than backward distractors.

In the example simulation on this page, the test position is in fact further along the path of motion than the last stimulus position!

Technical Notes

The simulation above is implemented using The Netscape 2.0 "animated GIF" feature. A version using JAVA is also available. Note that the constraints of raster displays and a network environment imply that timing and positioning for the demonstration are less precise than in an actual experiment. To maximize the momentum effect

given these inducing stimuli, we would use stimulus durations of perhaps 250ms, interstimulus intervals after first and second stimuli of perhaps 250ms, and a retention interval before the test stimulus of about 300ms.

By the way, an inducing stimulus of 3 rotated rectangles is not the most powerful way to produce RM. Try continuous linear motion of a directional (arrow-like) cartoon creature, e.g. a fish with a big tail.