Why do eye-blinks activate during conversation? We manipulated informational content and communicative intent exchanged within dyads. By comparison to a silent situation, both emitters and receivers increased their blink rate when the former delivered a treasure hunt route to the latter. When the previously known route was repeated, or when the alphabet was reeled off within the same dyads, the receiver did not increase the rate, although the emitter did. The emitter’s rate increased as well when formulating the route not vocally but silently in an inner voice; none reacted when the emitter was really silent. Therefore, the high rates of spontaneous blinking commonly observed during a conversation can be explained outside of a bilateral communication function. It seems primarily related to individual cognitive processing of afferent or efferent information. The speaker blinks when handling the speech; the listener blinks only when taking heed of a useful content.