A connectionist model of argument strength, which applies to arguments involving natural categories and unfamiliar predicates, was proposed by Sloman (1991). The model applies to arguments such as robins have sesamoid bones, therefore hawks have sesamoid bones. The model is based on the hypothesis that argument strength is related to the proportion of the conclusion category's features that are shared by the premise categories. The model assumes a two-stage process in which premises are first encoded by connecting the features of premise categories to the predicate. Conclusions are then tested by examining the degree of activation of the predicate upon presentation of the features of the conclusion category. The current work extends the domain of the model to arguments with familiar predicates which are nonexplainable in the sense that the relation between the category and predicate of each statement is difficult to explain. W e report an experiment which demonstrates that both of the phenomena observed with single-premise specific arguments involving unfamiliar predicates are also observed using nonexplainable predicates. W e also show that the feature-based model can fit quantitatively subjects' judgments of the strengdi of arguments with familiar but nonexplainable predicates.

Ail existing accounts of similarity assume that it is a function of matching and mismatching attributes between mental representations. However, Bassok and Medin (19%) found that the judged similarity of sentences does not necessarily reflect the degree of overlap between the properties of paired stimuli. Rather, similarity judgments are often mediated by a process of thematic integration and reflect the degree to which stimuli can be integrated into a common thematic scenario. We present results of a study which extend this surprising flnding by showing that it also applies to similarity ratings of objects and occurs whether or not subjects explain their judgments. Also, consistent with the Bassok and Medin findings, the tendency towards thematic integration was more pronounced when the paired stimulus shared few attributes--but was still an important factor in similarity judgments between objects which shared many attributes. We discuss the implications of these findings for models of cognitive processes which use similarity as an explanatory construct.

Many researchers have suggested that understanding novel noun phrases involves a process of conceptual combination in which people determine how two or more conceptsfittogether to form a new concept. One important way that people combine concepts is by property mapping, which involves asserting that a property of one concq)t is true of the other concept as in, "box that is striped" for "skunk box." A n experiment investigated the hypothesis that property mapping occurs by structural alignment in which mental representations are aligned or put into correspondence. T h e result of this process is primarily a set of matching elements (called commonalities) and a set of mismatching elements related to the commonalities (called alignable differences). The experiment compared property mapping definitions to the alignable differences listed by subjects in a comparison task which is known to involved structural alignment. Consistent with the hypothesis, there was a strong correspondence between property mapping definitions and alignable differences compared to another strategy in conceptual combination not thought to involve structural alignment (slot filling).