Effects of left frontal lesions on the selection of context-appropriate meanings

The present study examined the role of the left frontal cortex in strategic aspects of semantic processing. Participants were tested in a semantic priming task involving the meaning access of ambiguous and unambiguous words. Patients with left or bilateral frontal lesions failed to develop semantic facilitation of context-appropriate homograph meanings relative to age-matched controls and patients with right frontal lesions who produced more facilitation than controls. When the ambiguous words, however, were replaced by unambiguous words, patients with left frontal lesions improved to normal levels of semantic priming. This pattern of results seems difficult to explain in terms of a problem to access semantic information per se or to use contextual cues. The findings are, however, consistent with a deficit in selecting context-appropriate meanings in the presence of competing meanings.