Protection of savings by reducing the salience of opposing errors.

When humans encounter the same perturbation twice, they typically adapt faster the second time, a phenomenon called savings. Studies have examined savings following adaptation to a gradually introduced perturbation, with mixed results. These inconsistencies might be caused by differences in how behavior returns to its baseline state during the 'washout' phase in between learning periods. To test this, participants controlled a cursor that was subject to a visual rotation in its motion direction. The rotation was applied during two learning periods, separated by a washout period where the rotation was removed abruptly, gradually, or without error feedback. We found that the type of error experienced during washout affected savings: abrupt washout with large errors eliminated savings, whereas gradual or no-feedback washout preserved it. Model-based analyses indicated these effects were driven by changes in error sensitivity suggesting that salient, opposing errors experienced during washout downregulate the response to error, nullifying savings.