Affect can be best described as:

Affect is best described as the outward expression of emotions. It refers to the observable display of emotional states, such as facial expressions, body language, and tone of voice. This expression can indicate how someone is feeling internally, even if those internal feelings are not explicitly stated.

For instance, if a person is feeling happy, their affect might be joyful, which could be demonstrated through smiling, laughter, or animated speech. Conversely, if they are feeling sad, their affect may appear flat or withdrawn.

This definition emphasizes that affect is related to what can be seen or observed in a person's behavior, distinguishing it from personal feelings or thoughts, which may not always be visible to others. Stable emotional states, while they may influence affect, do not encapsulate the concept of outward expression, as affect can fluctuate based on external circumstances or interactions.