The organization of verbs in the mental lexicon

It has been proposed in recent years that the mental lexicon for verbs is organized into class-inclusion hierarchies (Fellbaum, 1998a; Miller & Fellbaum, 1991). This dissertation used four different paradigms to examine experimentally the validity of that proposal. Taken together the results of those studies provide only partial support for the hierarchical model.; Experiment 1, which used a lexical decision task to investigate the criterial asymmetry among semantically related verbs, yielded results consistent with the hierarchical model. The obtained semantic facilitation was asymmetric---semantically related subordinate verbs primed midlevel targets, whereas superordinate primes did not. However, the observed asymmetry was confined to verbs from two specific hierarchical levels and did not generalize to other superordinate relations within the semantic field.; Experiment 2 used pair-wise similarity ratings to elucidate the internal structure of verb semantic fields. For some semantic fields both the pattern of obtained similarity ratings and the MDS solutions derived from similarity ratings agreed with the hierarchical view. However, the MDS solutions for some of the semantic fields could not be explained in terms of hierarchical organization. Experiment 3 introduced SIMBEL (SIMilarity By ELimination)---a novel experimental paradigm conducive to studying concepts believed to have a graded internal structure. The order of elimination as well as the MDS solutions based on derived similarity revealed the typicality effect (i.e., some verbs were considered more typical of the category than the others) for many (but not all) semantic fields.; Finally, in Experiment 4 participants produced highly diverse and disparate solutions when asked to generate a verb hierarchy from a set of semantically related verbs. In particular, there was considerable disagreement among participants regarding the placement of more specific verbs (i.e., those located lower in the hierarchy).; The results suggest that the hierarchical model does not apply universally to all semantic fields in the mental lexicon for verbs.