Moving beyond single words: Dissociating levels of linguistic representation in short-term memory (STM)

This study assessed the role of semantic, phonological, and grammatical levels of representation in short-term list recall through a 2 (meaningfulness) × 2 (phonological similarity) ×2 (grammaticality) manipulation. Dutch subjects (Experiment 1-2) and English subjects (Experiment 3-4) and seven aphasic patients (Experiment 5) were required to recall lists consisting of adjective-noun word-pairs. Within each list, meaningfulness was manipulated by pairing adjectives and nouns in a meaningful or non-meaningful way; phonological similarity was manipulated through the degree of phonological overlap between words; grammaticality was manipulated through the order of the adjective and noun within each word pair in English (e.g., “salty mea”´ vs. “meat salty”) and through morphological agreement in Dutch. Overall, subjects showed better recall for words in the meaningful, phonologically-dissimilar, and grammatical conditions. Moreover, by relating these main effects to subjects' phonological and semantic STM capacity, we found that subjects with better phonological STM were less affected by the meaningfulness manipulation, while subjects with better semantic STM were less affected by the phonological manipulations. These results demonstrated that there are multiple routes to group information in STM via the combinatorial constraints afforded by language, and subjects might benefit from additional cues when memory load is high in certain level(s)