Generalization and transfer of contextual cues in motor learning

In our everyday life, we’re constantly adjusting our movements to deal with different situations. It’s a bit like having an inner map for each type of movement we need to make. And we’re constantly creating new maps or updating old ones based on what our senses are telling us. So far, a lot of research has been looking at what these sensory cues are like. In our study, we wanted to see if and how these sensory cues can be applied in new situations or to different body parts.

Imagine you’re trying to reach for something, but there’s a force pushing your hand off course. We call this a ‘force field’. In our experiment, we trained people to make two-part movements. First, they would make a ‘premovement’ that acted as a cue, and then they would make a targeted reach that was pushed off course by one of two force fields going in opposite directions. The direction of the premovement was uniquely connected to the direction of the force field, so they could learn two different internal ‘maps’ at the same time.

After this, we tested how well these cues worked when we changed the direction of the premovement, and when we asked people to use their other hand. What we found was pretty interesting. The cues seemed to work best for premovements that were close to the ones they’d been trained on, and not so well for movements that were very different. It was kind of like there was a zone around the trained movement where the cues worked well.

If the force fields were different strengths, the stronger one had a bigger impact on how the cues worked. We also found that the patterns of how well these cues worked could be transferred to the other hand. But it wasn’t like there was a simple on-off switch for each internal map. Instead, it seemed like the brain was blending different maps based on how similar the current movement was to the ones they’d been trained on. This gave us new insights into how our bodies learn to adapt to different conditions and situations.