Although the halo effect is one of the oldest
and most widely known of psychological phenomena,surprisingly little is known about its
nature. The halo effect is generally defined as the influence of a global evaluation on evaluations of individual attributes of a person, but this definition is imprecise with respect to the strength and character of the influence. At one extreme, the halo effect might be due
simply to an extrapolation from a general impression to unknown attributes. Global evaluations might color presumptions about specific traits or influence interpretation of the meaning or affective value of ambiguous trait information. Thus, if we like a person, we
often assume that those attributes of the person about which we know little are also favorable.
(Politicians often seem to capitalize on this tendency by appearing warm and friendly
but saying little about the issues.)