Multiple dimensions of relatedness among words

Words can be similar with respect to form (viz., spelling, pronunciation), meaning, or both form and meaning. In three lexical decision experiments (48 ms forward masked, 116 ms, and 250 ms SOAs), targets (e.g., FLOAT) followed prime words related by form only (e.g., COAT), meaning only (e.g., SWIM), or form and meaning (e.g., BOAT). BOAT–FLOAT and SWIM–FLOAT type pairs showed reduced target decision latencies relative to unrelated controls when primes were unmasked, but not when they were masked, and the magnitude of facilitation increased with increasing prime duration. By contrast, COAT–FLOAT type pairs produced significant inhibition at the shorter two prime durations. In all three experiments, including at the shortest SOA, (BOAT–FLOAT) pairs that shared form and meaning differed from COAT–FLOAT type pairs that shared only form. We discuss the similarity of the BOAT–FLOAT pattern to that of morphological facilitation and argue that if the same mechanism underlies both outcomes then activation of a shared morphemic representation need not underlie morphological facilitation.