Learning the visuomotor transformation of virtual and real sliding levers: simple approximations of complex transformations

Abstract

Learning to operate a complex tool such as a sliding lever can be conceived as learning both a kinematic and a dynamic transformation. We investigated whether the presence of the dynamic transformation has an inhibitory or a facilitative effect on learning to control a sliding lever. Furthermore, we examined the characteristics of the internal model of the kinematic transformation of the lever in visual open-loop trials. In the experiment, one group of participants practiced with only the kinematic transformation of the lever (virtual lever), the other group practiced with both the kinematic and the dynamic transformation (physical lever). Visual feedback was continuously present during practice. Results showed only marginal differences between both groups in open-loop tests. This finding is likely to be related to the fact that in both groups a simplified approximation of the kinematic transformation was acquired, in particular a symmetry approximation. With such an approximation the target for the hand movement is derived from the visual target for the tip of the lever as the position which is symmetric around a sagittal axis.

A progression of approximations to internal models of complex visuo-motor transformations

“…This means that there is a novel relation of ones' own movements to their visually perceived consequences such as the location of the impact of the head of the hammer or the position of the cursor on the computer monitor. During recent years evidence has been accumulated which points to the existence of rapid discrete and slower continuous processes of adaptation (e.g., Abeele & Bock, 2001;Bock, Abeele, & Eversheim, 2003;Sülzenbrück & Heuer, 2009aWerner & Bock, 2010), which are perhaps related to discrete and continuous processes of motor planning (Ghez et al, 1997). Typically discrete processes approximate the visuo-motor transformation, and continuous processes incrementally increase the accuracy of the initial approximation.…”

Movement paths in operating hand-held tools: tests of distal-shift hypotheses

“…The adjustments of the final hand positions were inaccurate, but they were clearly present. The inaccuracy is not that remarkable because the internal model of the kinematic transformation of a sliding lever is of limited accuracy in general (e.g., Sülzenbrück and Heuer 2009, 2012. Even for the simple transverse movements, the required learning of position-dependent visuomotor gains is likely a challenging task (cf.…”

“…Referring to the previously mentioned limited accuracy of the internal model of the complex lever transformation (e.g., Sülzenbrück and Heuer 2009, 2012, it could be argued that especially such a complex tool as the sliding lever needs more time to be incorporated into the body schema and that with a less complex tool different results would have been obtained. Of course, longer training periods could perhaps change our pattern of results.…”

Mind and movement

“…In addition to intentions and to processes that are inaccessible to conscious awareness, there are processes and their outcomes that are accessible, though typically they are automatic. For example, Voigt (1933) described a fairly undifferentiated (Sülzenbrück, & Heuer, 2009a) awareness of jumps, which he-as a doctoral student of Otto Klemm and the Leipzig school of ''Ganzheitspsychologie''-characterizes as a motor Gestalt. But the motor Gestalt is fragile and can break up, e.g.…”

“…In addition, the inaccuracy of internal models can be systematic in that the model is a specific simplified approximation of the transformation. Figure 3 shows an example (Sülzenbrück, & Heuer, 2009a). Participants in that study had to learn to control the distal tip of a sliding lever by moving its proximal end with the hand, with the position of the distal tip of the lever being presented by a cursor on a monitor.…”