film techniques - Subconsciously influencing the audience with embedded single frames

No, its is not considered a filming technique to do this, at least not an effective technique.

It is a bit of an urban legend that subliminal messages are effective. Subliminal stimuli are sensory stimuli that are below a threshold of being consciously perceived - in the context of movies these are usually thought of as single frames spliced into the scene. Classically these are usually thought of in the context of advertising - "Eat more popcorn" - but you could conceive of them being used to influence the audiences response to the movie.

However studies of subliminal stimuli have not really shown that they are effective, and they continue to be an urban legend, alongside the idea that they are somehow 'banned' by regulatory authorities. For more reading on this see the following wikipedia page, and a snopes page on the urban legend. The snopes page highlights that basis of the urban legend was was a falsified scientific study from the 1950's, which has never been replicated, and the legend has been repeated as fact in other media, such as an episode of Columbo from 1973.

The only movie that I can consider using something inspired by this technique is Fight Club, where very brief images including the Tyler Durden character were spliced into the movie before the character was introduced. However these images were several frames long and deliberately long enough to show as 'glitches' for the audience to see, clearly not subliminal. Later in the movie Tyler also describes how, when working as a movie projectionist, he used to splice single frames of pornography into family movies. The use of (almost) subliminal images in the movie are used to hint that the character is somehow not entirely real, but it is also a bit of an 'easter egg' buried in the movie.