The Effect of Word Length on Immediate Serial Recall Depends on Phonological Complexity, Not Articulatory Duration

Immediate recall for sequences of short words is better than for sequences of long words. This word-length effect has been thought to depend on the spoken duration of the words (Baddeley, Thomson, & Buchanan, 1975) or their phonological complexity (Caplan, Rochon, & Waters, 1992). In Finnish both vowel and consonant quantity distinguish between words. Long phonemes behave like phoneme repetitions. In Experiment 1, subjects were presented with auditory lists of three kinds of pseudowords based on Finnish phonotactics: short CVCV-structures (e.g. / tepa/), long two-syllable items with long phonemes (e.g. / te: p: a/), and long three-syllable items with CVCVCV structures (e.g. / tepalo/). Although both kinds of long stimuli (of identical spoken length) took longer to read, only three-syllable items were more difficult to remember than the short stimuli. Experiment 2 contrasted the effect of number of syllables with number of different phonemes. The long two-syllable items were replaced by two-syllable items of equal spoken duration but containing six different phonemes (e.g. / tiempa/). These two-syllable items were as difficult to recall as were the three-syllable items. Experiment 3 controlled for the possibility that long stimuli might be rehearsed in a shorter form. It is concluded that aspects of phonological complexity are critical for word-length effects. Implications of this finding for working memory theory are discussed, and future work based on multi-layered phonological representations is proposed.