Unusual actions do not always trigger the mentalizing network.

Past fMRI research has demonstrated that to understand other people's behavior shown visually, the mirror network is strongly involved. However, the mentalizing network is also recruited when a visually presented action is unusual and/or when perceivers think explicitly about the intention. To further explore the conditions that trigger mentalizing activity, we replicated one of such studies (de Lange, Spronk, Willems, Toni, & Bekkering, 2008, Current Biology, 18, 454) under the minimal instruction to "view" pictures of unusual actions, without giving any "intention" instruction as in the original study. Contrary to earlier research, merely viewing unusual actions did not activate mentalizing areas. Instead, the dorsal anterior cingulate cortex was activated. We conclude that unusual actions are not sufficient by themselves to trigger mentalizing. In order to activate the mentalizing network without an intention instruction, a richer action context informative of the implausibility of the action might be a prerequisite.