Sample results from Agam et al. 2005

The images at the left show 20 stimuli and corresponding responses from a study of delayed imitation (Agam, Bullock and Sekuler, Journal of Neurophysiology, 2005). On each trial, a human subject first watched as a disc moved over an irregular, unpredictable path, and then tried to reproduce that path from memory. Because only the disc's momentary position was visible at a moment, the subject had to knit together the trajectory's successive segments in the mind's eye. Imitations were produced by drawing with a stylus on a graphics tablet. In each panel, the stimulus model is shown by the yellow tracing, and the corresponding imitation is shown by the blue. The model and and imitation share the same starting location. This is the point in each panel at which the two traces are coincident. Note that as an imitation proceeded from its starting point, the imitation's fidelity to the model tends to degrade, sometimes dramatically. This is powerful evidence that a complex imitation exhibits a serial-position effect akin to that for other memory-dependent processes. Note also that in some cases, although the imitation preserves the overall gist of the model, discrepancies between the two suggest that details are clearly lost from memory.