The English language is made up of many words that are morphologically complex, that is, words that comprise two or more morphemes (e.g., golfer = golf + –er). The ten experiments reported in this thesis used visual lexical decision tasks to study the role of morphology in word recognition. Experiments 1–3 showed that masked priming for semantically opaque prime–target pairs (e.g., coaster–COAST) diminishes as the frequency of the prime increases and as the stimulus onset asynchrony (SOA)

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... ses. Priming for semantically transparent pairs (e.g., golfer–GOLF) and for form controls (e.g., turnip–TURN) appear to be largely unaffected by prime frequency and SOA. A prime-frequency effect also emerges for opaque pairs involving a prefix (e.g., mischief–CHIEF), as demonstrated by the results of Experiment 4. Experiment 5 examined interactions between stem frequency, affix productivity, and individual differences in language ability. It was found that words containing a relatively productive suffix (e.g., hopeful) exhibit a positive stem-frequency effect, whereas words containing a relatively unproductive suffix (e.g., herbal) do not. It was also found that the stem-frequency effect observed for the former is more pronounced in individuals with a semantic profile than in other individuals. Furthermore, the effect was shown, in Experiment 6, to survive a manipulation that promotes whole-word processing. Experiments 7–10 investigated the issues of affix productivity, affix type, and orthographic parsing. It was found that masked priming for transparent pairs is not moderated by affix productivity as long as the affix is at least somewhat productive (e.g., helpful–HELP, herbal–HERB). Priming is reduced, however, when an extremely unproductive affix is involved (e.g., bravado–BRAVE). Finally, it was observed that pseudowords prime their putative stems regardless of whether they end in a suffix or not (e.g., sportance–SPORT, sportain–SPORT), but that morphological priming is greater than form priming when a prefix is invol [...]