Reproduction of Seen Actions: Stimulus-Selective Learning

Abstract

Subjects observed and reproduced abstract, irregular stimulus models generated by the steady movement of a disk across two-dimensional paths. The paths comprised 3 to 7 randomly oriented linear segments linked head-to-foot. Reproductions were expressed by moving a stylus over the surface of a graphics tablet while the disk was tracing its trajectory (concurrent reproduction), or soon after the disk had finished (delayed reproduction). For both concurrent and delayed conditions, fidelity of reproduction fell with increasing number of segments in the model. Overall quality of reproduction did not differ between the two conditions. When a few models were repeated, interspersed among non-repeated ones, performance improved but only when reproduction was delayed. This improvement was stimulus-selective, not a general improvement with practice. Two additional experiments showed that (i) memory for a seen model is well preserved for at least 6 s, with relatively modest need for rehearsal, and (ii) successful reproduction is possible with remarkably little information having been extracted from key points in the model's trajectory.

Chunking and Compound Cueing of Movement Sequences: Learning, Retention, and Transfer

“…Each segment was 1.5° of visual angle long and its presentation (the movement across the screen) took 500 msec. To prevent illusory distortions of the linear paths (Sekuler, Siddiqui, Goyal, & Rajan, 2003), successive segments were separated by a 500-msec. pause in the disc's movement.…”

Gesture Imitation in Schizophrenia

“…Increasing WM demand resulted in reduced imitation accuracy, especially in older adults. 21 Findings from these studies 21,22 suggest that WM affects imitation performance. Weeks and colleagues 23 investigated imitation of hand shapes both while the stimulus image was displayedonlineandafter a delay.…”

“…Solid evidence points to deficits in guidance of behavior by WM or internal representation in schizophrenia 14,19,20 and such deficits could undermine imitation, especially in sequencing. Two studies investigated the role of WM load and delay in imitation accuracy 21,22 using a series of quasi-random dot movements in healthy adults. Increasing WM demand resulted in reduced imitation accuracy, especially in older adults.…”

A new method to evaluate order and accuracy of inaccurately and incompletely reproduced movement sequences

“…Imitation learning has been studied with sequences of connected pen strokes (Agam, Galperin, Gold, & Sekuler, 2007;Sekuler, Siddiqui, Goyal, & Rajan, 2003). Most likely this task involves different control strategies than our pen-up pointing task (Desmurget, Jordan, Prablanc, & Jeannerod, 1997).…”