Microsoft has filed patents for systems that can scan online activity, including facial expressions captured in video conversations, to detect a user’s emotions in order to match online advertisements with their moods.

A recently surfaced patent application describes pairing advertisers with users in a particular emotional state.

This would see weight-loss ads matched with unhappy people (who are more likely to want to change their lifestyle) and electronic ads with happy people (who are more likely to spend).

The user’s mood is assessed by facial expressions, speech patterns, browsing history, webpage content, searches, emails, instant messages, and online games on all “computing devices.”

Advertisers are matched people who are either “positive, happy, confused, neutral, negative, angry or sad,” according to the patent. Degrees of emotion can vary — a user can be “very angry” or “slightly angry” — as well as the duration of the emotion. Advertisers can target people “happy for one hour” or “happy for 24 hours.”

The patent appears to be a variation on a theme. Earlier this year another Microsoft patent for a similar idea outlined a system that would tailor search engine results according to social media posts and activity.