What effect results in an observer being influenced by their initial perceptions of a subject?

The halo effect occurs when an observer's overall impression of a person or subject positively influences their evaluations of that subject’s specific traits or behaviors. For example, if someone perceives a person as friendly, they may also rate that person's other characteristics, such as intelligence or professionalism, more favorably, despite having little evidence to support those ratings. This cognitive bias demonstrates how initial perceptions can shape subsequent judgments, highlighting the powerful role of first impressions in perception and evaluation.

In contrast, observer bias refers to a more general tendency for an observer’s expectations to affect their observations and interpretations. Cognitive dissonance involves the mental discomfort experienced when new information conflicts with existing beliefs or values, leading to a motivation to resolve that discomfort. Confirmation bias is the tendency to seek out or give undue weight to information that confirms pre-existing beliefs while disregarding opposing evidence. Each of these concepts relates to perception and evaluation but focuses on different aspects of how biases can shape understanding. The halo effect specifically captures how initial positive impressions can color subsequent assessments, making it the most fitting choice for the question.