Affect (which is generally pronounced with the emphasis on the ‘a’ at the start of the word) is a term used in psychology to describe how we outwardly display our emotional state, that is, how we are feeling.
Affect is how we communicate non-verbally, (for example our eyes opening wide with surprise). In normal development we learn about affect naturally – we don’t have to be taught it explicitly.
When we are babies we learn very quickly that a frown or some indication of disapproval, from our parent (or another principal carer as we get a little older) indicates a boundary. A smile, however, or a warm touch, informs us that we are included. We then learn that we can, in turn, influence our environment and those around us with our facial expressions, body posture and movement. (This non-verbal, two-way knowledge flow is vital for our development and is the principal reason why affect is a root foundation).
I read somewhere once that 70% of communication is non-verbal. I’m not sure if that is true, but if it is, most of the communication happens through affect. Of course, communication between children who have not yet learned how to talk is virtually all affect-based as they read each other’s intentions without much (if any) conscious awareness or verbal communication.
Sometimes people who are described in lacking in affect may be diagnosed by medical model practitioners with a psychiatric condition such as psychosis, schizophrenia or autism.
That is, they may not show their feelings (for example, sadness, or happiness) in a situation where, typically, someone considered to be a normal person would.
Apart from observing small children playing, watching old black and white silent films, particularly comedies – there are a lot of them on Youtube – is a good way of observing affect. In the early days of film, everything had to be conveyed to the audience non-verbally, through what actors and actresses were feeling, so they exaggerated their expressions and gesticulations accordingly.