| Abstract: | In an adaptation of usual experimental techniques for studying the performance of a subject who has to discover a well-defined concept, two theories were independently tested. It was found that Bourne's set of inference operations (Bourne 1974; Salatas and Bourne 1974) predicted fairly well the relative difficulty for the connectives studied (inclusive disjunctive, alternative denial, joint denial, exclusive, exclusive disjunctive) for a stimulus population based on three-valued dimensions but not for a four-valued stimulus population. Reaction times gathered after the subject made no further classification errors fitted the decision-tree structures developed by Hunt et al. (1966). Inspection of the hypotheses subjects made about the rule, revealed two possible major reasoning obstacles: the introduction of a negative attribute and the notion of exception i.e. when the assignment of an attribute in one class depends on another attribute whereas in another class it does not. |
