Which of the following is a manifestation of decreased positive affect?

The manifestation of decreased positive affect is most accurately represented by loss of interest. Positive affect refers to the experience of positive moods and emotions such as happiness, joy, and enthusiasm. When an individual experiences a decrease in positive affect, they may exhibit diminished interest or pleasure in activities that were previously enjoyable. This can be a hallmark symptom in various mental health conditions, such as depression, where the individual may withdraw from social engagement and have a marked disinterest in hobbies or everyday activities.

The other options, while they can be relevant to different emotional states, do not fit the definition of decreased positive affect as closely as loss of interest does. Excitability and restlessness may indicate increased emotional arousal or agitation rather than a decreased sense of positivity. Hostility may represent a negative affect rather than a lack of positive emotion, further distinguishing it from the concept of decreased positive affect.