The effect of interpolated motor activity on the short-term retention of movement distance and end-location

The effect of an interpolated movement on the recall of a blind, lever-positioning movement was assessed separately for the reproduction cues of distance and end-location. Both cues showed the context effect of assimilation, that is, the end-location of the interpolated movement caused directional biasing of the algebraic or constant error (CE) for location reproduction while the length of the interpolated movement caused similar directional biasing for distance reproduction. Variability about algebraic error (VE) was used to assess forgetting. There was no change in VE for location reproduction, and an increase in VE for distance reproduction was limited to the relatively large movements. Thus, an interpolated movement that does not have to be remembered does not cause interference with the retention of location information, but does cause some interference with the retention of distance information. The findings are discussed in relation to a model of motor short-term memory which incorporates both CE and VE.