How you feel influences what you see, it is not just what you see that influences how you feel; a top down approach to understanding the visual system.
Affective Circumplex: Affect can vary in terms of valence (positive/negative) and arousal (high/low).
A great analogy for understanding how affect (the experience of an emotion) influences perception is to think of affect as a spotlight, or a source of “attention” that sheds light on the external world. This is known as a top-down process because the cortical and sub cortical levels of the brain directly influence what one externally experiences. This is opposed to a bottom-up process wherein external stimuli influences processing in the brain (an example of this process would be hearing something hit the floor behind you and immediately shifting your attention to that object). The brain uses both of these processes interchangeably, but it has only been recently that a top-down understanding of the visual system (a system that has classically been believed to be primarily regulated by external stimuli and how such stimuli influence attention) has been accepted. Many studies by Lisa Feldman Barrett and the Interdisciplinary Affective Sciences lab at Northeastern University seem to have proved strong evidence against the popular claim that the bottom-up system is the sole means by which perception can be influenced. More