Early semantic activation in a semantic categorization task with masked primes: Cascaded or not?

• Masked word and nonword primes activate the semantic properties of neighbors in a semantic categorization task.
• This cascaded semantic activation occurs with relatively low orthographic overlap.
• This activation occurs despite the absence of reliable form priming (with word primes).
• This activation does not occur if there is no explicit requirement to categorize a target word.

The assumption that activation is cascaded implies that the semantic properties of all neighbors of the input word are activated to varying degrees. This assumption is tested using masked priming in a semantic categorization experiment, where the prime belongs to the same category as the target (a congruent prime), or to a different category (an incongruent prime). In Experiment 1, the prime was a nonword neighbor of an exemplar or non-exemplar of the category, and a clear congruence effect was produced, even though the orthographic overlap was fairly low (e.g., lucchibi-zucchini). In Experiment 2, the prime was a word neighbor (e.g., capable-cabbage), which eliminates the possibility that the prime was simply interpreted as equivalent to the nearest task-relevant word, but a congruence effect was still obtained. Experiment 3 replicated this effect. Experiments 4–6 investigated the possible role of the category using a two-alternative forced choice discrimination task, where the task was simply to guess which of two subsequently presented words was more similar in meaning to the masked word. Despite better than chance performance when the masked word was related to one of the alternatives, performance was at chance when the masked word was a neighbor of a word that was related to one of the alternatives, indicating that semantic activation is not normally cascaded. It is concluded that the categorization task fundamentally alters the way in which a masked word is processed.