The abstract below is of a paper (here) in the Proceedings of the Royal Society, Synchronization of spontaneous eyeblinks while viewing video stories, by N. Tamami and others.

Blinks are generally suppressed during a task that requires visual attention and tend to occur immediately before or after the task when the timing of its onset and offset are explicitly given. During the viewing of video stories, blinks are expected to occur at explicit breaks such as scene changes. However, given that the scene length is unpredictable, there should also be appropriate timing for blinking within a scene to prevent temporal loss of critical visual information. Here, we show that spontaneous blinks were highly synchronized between and within subjects when they viewed the same short video stories, but were not explicitly tied to the scene breaks. Synchronized blinks occurred during scenes that required less attention such as at the conclusion of an action, during the absence of the main character, during a long shot and during repeated presentations of a similar scene. In contrast, blink synchronization was not observed when subjects viewed a background video or when they listened to a story read aloud. The results suggest that humans share a mechanism for controlling the timing of blinks that searches for an implicit timing that is appropriate to minimize the chance of losing critical information while viewing a stream of visual events.

By and large we are not conscious of our blinks, although we can attend to them for short periods. Nor do we usually have conscious intentions to blink. It appears that a good deal of comprehension is needed to control the timing of blinks and the knowledge would usually be used in the blinking system before that comprehension entered consciousness.