Do first and last letters carry more weight in the mechanism behind word familiarity?

Previous research has suggested a role of letter location information in familiarity-detection that occurs with word stimuli, but no studies have yet investigated whether certain letter positions are weighted more heavily in the feature-based mechanism behind word familiarity-detection. Based on psycholinguistic research suggesting that first and last letters are weighted more heavily than interior letters when it comes to reading words, we investigated whether first and last letters carry more weight in the mechanism behind word familiarity that results from feature familiarization in a list-learning paradigm. In two experiments, participants studied word fragments (e.g., RA_ _ _ _OP) and later rated the familiarity of complete words (e.g., RAINDROP). We varied whether the first and last or only interior letters were present at study. Participants consistently rated test words whose fragments went unidentified at study as more familiar when the first and last letters had been studied than when only interior letters had been studied. This suggests that first and last letters contribute more strongly to the word familiarity signal than interior letters.