The study of lexical aspect is one of the linguistic fields that has aroused most interest over the past 50 years. However, the psychological reality of the lexical aspect is a question that still remains unresolved. Empirical evidence is needed to account for the fact that speakers set cognitive differences among aspectual classes, as well as how they structure these categories. Moreover, the relation between aspect and polysemy has to be empirically proved. Specifically, we argue that analyzing the macro-aspectual distinction between states and events (dynamic situations and non-dynamic situations) is a crucial point, since this generic distinction underlies all eventive classifications that have been proposed. This paper presents the design, application and findings of a self-paced reading experiment that consists of an empirical evaluation of the processing cost of verbal dynamicity in Spanish. The experiment is based on two main hypotheses: firstly, it is predicted that in Spanish prototypical eventive verbs, being semantically more complex, will be processed longer than prototypical stative verbs, as Gennari and Poepple (2003) have demonstrated for English. Secondly, above and beyond this first hypothesis, it is predicted that, coherently, aspectually different meanings of a polysemic verb (i.e. senses) will also show differences in processing time precisely because of their different aspectual type. (Contains 2 tables, 6 charts, and 5 notes.)