While providing basic notions about principles of nature and theories about how the world works, the schema both fosters and inhibits further learning. It is particularly good at promoting learning of refinement, whereby established expectations are confirmed and reinforced and responses made more subtle. However, learning of novelty is made less probable and more difficult by preset patterns of thought which limit an individual's range of cognitive adjustment. Thus, the schema encourages self-corrective, fine tuning of itself even in cases where it remains a basically maladaptive behavioral program.

The learning process can be broken down into two interrelated steps: assimilation and accommodation. Assimilation is the perception of stimuli and the incorporation of experience into an existing schema; it is accomplished by assigning an object or phenomenon to an established cognitive category, as defined by the individual's vocabulary. Accommodation is the change or modification of the schema due to the assimilation of new information. Minor adjustments and modifications of the schema are very common and occur with little or no awareness or emotional disturbance. The resulting schema is the individual's attempt to reorganize his experience into a system which provides both some assurance of predictability and a basic strategy for behavior.

However, as an individual matures, the presence of the schema tends to dominate the process of assimilation by defining perception in progressively restrictive terms and by the formation of attitudes which evaluate perceived data. Attitudes determine whether a given fact is construed favorably or unfavorably. This point is easily demonstrated by a play on a standard form of humor: "I have some good news and some bad news: the Yankees won last night". This is good news to Yankee fans, bad news to anti-Yankee fans, and not particularly amusing to anyone.

There are three factors which may contribute to the formation of attitudes. First of all, attitudes may be rooted in a person's need to know about the environment. Such attitudes are data based and provide a verbal knowledge system to which incoming bits of information are compared or contrasted. Attitudes may also be adopted because of externally applied social rewards and pressures of normative group influence. Finally, attitudes

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