Unexpected events disrupt visuomotor working memory and increase guessing.

When an unexpected event, such as a car horn honking, occurs in daily life, it often disrupts our train of thought. In the lab, this effect was recently modeled with a task in which verbal working memory (WM) was disrupted by unexpected auditory events (Wessel et al. in Nature Communications, 7, 11195, 2016). Here we tested whether this effect extends to a different type of WM-namely, visuomotor. We found that unexpected auditory events similarly decremented visuomotor WM. Moreover, this effect persisted for many more trials than had previously been shown for verbal WM, and the effect occurred for two different types of unexpected auditory events. Furthermore, we found that unexpected events decremented WM by decreasing the quantity, but not necessarily the quality, of items stored. These results showed an impact of unexpected events on visuomotor WM that was statistically robust and endured across time. They also showed that the effect was based on an increase in guessing, consistent with a neuroscience-inspired theory that unexpected events "wipe out" WM by stopping the ongoing maintenance of the trace. This new task paradigm is an excellent vehicle for further explorations of distractibility.