Semantic interference in a randomized naming task: effects of age, order, and category.

Lexical retrieval in production is a competitive process, requiring activation of a target word from semantic input and its selection from amongst coactivated items. Competitors are automatically primed through spreading activation within the lexicon, but competition may be increased by the prior presentation of related items: the semantic interference effect. This has been demonstrated in tasks in which pictures grouped by semantic category are compared to unrelated pictures (blocked naming) and in tasks involving successive naming of items from the same semantic category (continuous naming). Such highly structured tasks may not be representative of the processes at work under more natural word retrieval conditions. Therefore, we conducted a retrospective examination of naming latencies from a randomized picture naming task containing a wide variety of items and categories. Our large sample of adults, ranging in age from 22 to 89 years, also allowed us to test the hypothesis that older adults, who are particularly susceptible to word-retrieval problems, experience increased difficulty resolving competition among lexical items. Semantic interference effects were evident in the interaction between semantic category and order of presentation within a block-miscellaneous items were named more quickly, whereas related items were named more slowly. This interference effect did not vary with participant age, contrary to the hypothesis that older adults are more susceptible to semantic interference.