Semantic interference during blocked-cyclic naming: Evidence from aphasia

Nonaphasic speakers are known to take longer to name pictures when they are blocked by semantic category and repeated multiple times. We replicated this "semantic blocking effect" in older controls and showed that in aphasia, the effect is manifested in increased error rates when naming semantically homogeneous, compared to mixed blocks. We further showed that semantic blocking affects Broca's aphasics more than a matched group of NonBrocas, and that the effect increases with repetition of the blocked sets. Error analysis undermines the inhibition-based account of the blocking effect by showing that errors arise from competition among increasingly activated items within the homogeneous set. The consequent slowing of naming latencies is due at least in part to the intervention of a controlled selection mechanism, and the disruption of this mechanism in anterior aphasia accounts for the increase in error vulnerability. (c) 2005 Elsevier Inc. All rights reserved.