Sentences like “The athlete jumped for 20 minutes / jogged for 2 years.” engender an iterative meaning that is well understood yet morpho-syntactically unsupported—a case manifesting “meaning underspecification.” We argue that such underspecified meaning results from a costly meaning search in the sentential context by evaluating (a) the conventional event duration denoted by the verb, (b) the interval length denoted by the for-adverbial, and (c) the discourse context if there is one. In a naturalness-rating questionnaire and a self- paced reading experiment, we crossed two verb types (Punctual: jump / Durative: jog) and the interval-lengths denoted by for-adverbials (Short: for 20 minutes / Long: for 2 years). In addition, we investigated the impact of individuals’ cognitive styles indexed by autistic tendency on real-time meaning computation. Results showed that, in the absence of discourse context, (i) the harder a specific meaning could be determined from sentential context, the less natural the sentence was perceived, (ii) all sentences with underspecified meaning engendered significantly longer reading times regardless of verb type. Moreover, (iii) individuals with higher autistic tendency lingered significantly longer at the sentence-final region, likely reflecting a difficulty in information integration or a tendency towards deliberative reasoning. These findings suggest that meaning comprehension is lexically-guided and context-constraining, while the online processing profile vary with individuals’ autistic tendency.