On the failure to eliminate hypotheses in a conceptual task

This investigation examines the extent to which intelligent young adults seek (i) confirming evidence alone (enumerative induction) or (ii) confirming and discontinuing evidence (eliminative induction), in order to draw conclusions in a simple conceptual task. The experiment is designed so that use of confirming evidence alone will almost certainly lead to erroneous conclusions because (i) the correct concept is entailed by many more obvious ones, and (ii) the universe of possible instances (numbers) is infinite.

Six out of 29 subjects reached the correct conclusion without previous incorrect ones, 13 reached one incorrect conclusion, nine reached two or more incorrect conclusions, and one reached no conclusion. The results showed that those subjects, who reached two or more incorrect conclusions, were unable, or unwilling to test their hypotheses. The implications are discussed in relation to scientific thinking.     

Some implications of the logical calculus for empirical classes for social science methodology

An exposition of a calculus for empirical classes (CEC), one of the few attempts by logicians to deal with the problem of constructs and indicators, is presented. The CEC provides the groundwork for a formal structure for the situation in which individuals have a degree of membership in various classes rather than having either membership or nonmembership—a situation nearly always true in empirical research. The CEC is presented and its relation to various social science concepts is mentioned. An application of the CEC model to latent structure analysis (LSA) suggests alternatives to the local independence assumption including one called the local scale assumption, which has a close relation to a Guttman scale.     

The processing of positive and negative information

An affirmative statement which is known to be false and the complementary negative statement which is known to be true, provide the same information, i.e. that something is not the case. Similarly, an affirmative statement which is known to be true and the complementary negative statement which is known to be false, both imply that something is the case. (If P is false, not-P is true and if P is true, not-P is false.) Hence there are four kinds of statement (“conditions”): true affirmatives, false affirmatives, true negativee and false negatives, but only two kinds of information: positive and negative.

This experiment investigates the times taken to process information presented in these ways. The task was to select two alternative words which would make affirmative or negative conjunctive statements agree or conflict with given situations. The four conditions were presented six times in different serial orders, so that each occurred once in every block of four trials. The mean response times were: true affirmatives 8-99 sec, false affirmatives 11 19 sec., true negatives 12-58 sec, false negatives 15-17 sec. This order was the same at each of the six presentations of the conditions, the differences being significant at the 0 001 level in each case. There was a pronounced decline in errors (without knowledge of results) for three of the conditions. These results are discussed in relation to (i) the assumption of a positive set, established through a long learning process; (ii) the inferential nature of negative information in relation to experience; and (iii) the possible emotional effects of negative terms.