Making Sense of Randomness " Implicit Encoding as a Basis for Judgment

People attempting to generate random sequences usually produce more alternations than expected by chance. They also judge overalternating sequences as maximally random. In this article, the authors review findings, implications, and explanatory mechanisms concerning subjective randomness. The authors next present the general approach of the mathematical theory of complexity, which identifies the length of the shortest program for reproducing a sequence with its degree of randomness. They describe three experiments, based on mean group responses, indicating that the perceived randomness of a sequence is better predicted by various measures of its encoding difficulty than by its objective randomness. These results seem to imply that in accordance with the complexity view, judging the extent of a sequence's randomness is based on an attempt to mentally encode it. The experience of randomness may result when this attempt fails. Judging a situation as more or less random is often the key to important cognitions and behaviors. Perceiving a situation as nonchance calls for explanations, and it marks the onset of inductive inference (Lopes, 1982). Lawful environments encourage a coping orientation. One may try to control a situation by predicting its outcome, replicating, changing, or even by avoiding it. In contrast, there seems to be no point in patterning our behavior in a random environment. Although people feel that they know what they mean when speaking of randomness (Kac, 1983) and they communicate in everyday and professional affairs using their shared intuitive understanding of the term, it.is one of the most elusive concepts in mathematics. Randomness resists easy or precise definition, nor is there a decisive test for determining its presence (Ayton, Hunt, & Wright, 1989, 1991; Chaitin, 1975; Falk, 1991; Lopes, 1982; Pollatsek & Konold, 1991; Wagenaar, 1972a, 1991; Zabell, 1992). Attempted definitions of randomness involvo intricate philosophical and mathematical problems (Ayer, 1965;