Story of Psychology - Morton Hunt [234]
Nor can they proceed systematically when tackling a problem with several variables. One of Piaget’s most productive tests was his pendulum problem. He would show a child a weight hanging from a string and demonstrate how to vary the length of the string, the amount of weight suspended by it, how to release the weight from different heights, and how to push it with different degrees of force. Then he would ask the child to figure out what factor or factors (length, weight, height, and force, singly or together) affected the pendulum’s rate of swinging. Pre-operational children made no plan of action; they tried different things at random, often varying several factors at once, making many incorrect observations, and reaching wrong conclusions. Operational children, though more systematic and accurate, still made frequent mistakes owing to illogical thinking. One ten-year-old boy tried changing the length of the string and concluded correctly that a pendulum swings slower when the string is longer. Then he compared the effect of a hundred-gram weight on a long string against that of a fifty-gram weight on a short string and concluded incorrectly that the pendulum also swings slower when the weight is greater.18
Formal operations (12 and up): In the final stage of development, children become capable of thinking about abstract relationships, like ratio and probability. They grasp syllogistic reasoning, cope with algebra, and begin to comprehend the elements of scientific thought and methodology. They can formulate hypotheses, concoct theories, and systematically examine the possibilities in a puzzle, mystery, or scientific problem. They play a game like Twenty Questions methodically, starting with broad questions and narrowing down the field of possibilities; until this stage their questions skipped from broad areas to narrow ones and back to broad ones, or overlapped, or were repetitive.
More important, they can now think not only about the concrete world but about possibilities, probabilities, and improbabilities, about the future, about justice, and values. As Piaget and his longtime collaborator, Bärbel Inhelder, say:
The great novelty of this stage is that by means of a differentiation of form and content the subject becomes capable of reasoning correctly about propositions he does not believe, or at least not yet; that is, propositions he considers pure hypotheses. He becomes capable of drawing the necessary conclusions from truths which are merely possible.19
Jerome Kagan has called Piaget’s analysis of the fundamentally new cognitive powers of adolescence “one of the most original ideas in any theory of human nature” and the source of “insights about adolescent behavior that challenge traditional explanations.” For one thing, it helps us understand the rise in the suicide rate in the teen years: the ability to think about hypothetical situations and know when one has exhausted all solution possibilities enables the adolescent to tell himself (rightly or wrongly) that he has tried or examined all ways of solving some personal problem and that none will work. For another, the ability to perceive inconsistencies within his own beliefs or those he is told to believe helps explain the rebelliousness, anger, and anxiety of the adolescent. Among the common and deeply troubling inconsistencies: conflicting values about teenage sex (it is immoral and risky, yet to abstain may seem “hung up” and abnormal); conflicting perceptions of the teenager’s relation to his parents (he