A Good Read

Theory of Mind is the human capacity to comprehend that other people hold beliefs and desires and that these may differ from one’s own beliefs and desires. The currently predominant view is that literary fiction —often described as narratives that focus on in-depth portrayals of subjects’ inner feelings and thoughts—can be linked to theory of mind processes, especially those that are involved in the understanding or simulation of the affective characteristics of the subjects. Kidd and Castano (p. 377, published online 3 October) provide experimental evidence that reading passages of literary fiction, in comparison to nonfiction or popular fiction, does indeed enhance the reader’s performance on theory of mind tasks.

Taking Out the Trash

The purpose of sleep remains mysterious. Using state-of-the-art in vivo two-photon imaging to directly compare two arousal states in the same mouse, Xie et al. (p. 373; see the Perspective by Herculano-Houzel) found that metabolic waste products of neural activity were cleared out of the sleeping brain at a faster rate than during the awake state. This finding suggests a mechanistic explanation for how sleep serves a restorative function, in addition to its well-described effects on memory consolidation.