In this paper we shall present a further development of a previously published theory concerning opinion influence processes in social groups (7). This further development has enabled us to extend the theory to deal with other areas, in addition to opinion formation, in which social comparison is important. Specifically, we shall develop below how the theory applies to the appraisal and evaluation of abilities as well as opinions. Such theories and hypotheses in the area of social psychology are frequently viewed in terms of how "plausible" they seem. "Plausibility" usually means whether or not the theory or hypothesis fits one's intuition or one's common sense. In this meaning much of the theory which is to be presented here is not" plausible ". The theory does, however, explain a considerable amount of data and leads to testable derivations. Three experiments, specifically designed to test predictions from this extension of the theory, have now been completed (5, 12, 19) . They all provide good corroboration. We will in the following pages develop the theory and present the relevant data. Hypothesis I: There exists, in the human organism, a drive to evaluate his opinions and his abilities. While opinions and abilities may, at first glance, seem to be quite different things, there is a close functional tie between them. They act together in the manner in which they affect behavior. A person's cognition (his opinions and beliefs) about the situation in which he exists and his appraisals of what he is capable of doing (his evaluation of his abilities) will together have bearing on his behavior. The holding of incorrect opinions and/or inaccurate appraisals of one's abilities can be punishing or even fatal in many situations. It is necessary, before we proceed, to clarify the distinction between opinions and evaluations of abilities since at first glance it may seem that one's evaluation of one's own ability is an opinion about it. Abilities are of course manifested only through performance which is assumed to depend upon the particular ability. The clarity of the manifestation or performance can vary from instances where there is no clear ordering criterion of the ability to instances where the performance which reflects the ability can be clearly ordered. In the former case, the evaluation of the ability does function like other opinions which are not directly testable in "objective reality'. For example, a person's evaluation of his ability to write poetry will depend to a large extent on the opinions which others have of his ability to write poetry. In cases where the criterion is unambiguous and can be clearly ordered, this furnishes an objective reality for the evaluation of one's ability so that it depends less on the opinions of other persons and depends more on actual comparison of one's performance with the performance of others. Thus, if a person evaluates his running ability, he will do so by comparing his time to run some distance with the times that other persons have taken. In the following pages, when we talk about evaluating an ability, we shall mean specifically the evaluation of that ability in situations where the performance is unambiguous and is known. Most situations in real life will, of course, present situations which are a mixture of opinion and ability evaluation. In a previous article (7) the author posited the existence of a drive to determine whether or not one's opinions were "correct". We are here stating that this same drive also produces behavior in people oriented toward obtaining an accurate appraisal of their abilities. The behavioral implication of the existence of such a drive is that we would expect to observe behaviour on the part of persons which enables them to ascertain whether or not their opinions are correct and also behavior which enables them accurately to evaluate their abilities. It is consequently * The development of this theory was aided by a grant from the Behavioral Sciences Division of the Ford Foundation. It is part of the research program of the Laboratory for Research in Social Relations.
Second, according to Festinger REF , people tend to evaluate their abilities (as the ones that students need to satisfy for the badge conditions) by comparing them with the abilities of others.
A Theory of Social Comparison Processes
Human Relations
Psychology