Item and serial order retention in phonological short-term memory representations in relation to reading performance

This thesis focuses on item and serial order retention in verbal short-term memory (STM) of monolingual good and poor readers and typically developing bilingual children learning to read in a second language. One of the leading cognitive theories of dyslexia, i.e., the phonological deficit theory, postulates that individuals with dyslexia and poor readers have specific problems in the representation, storage, and/or retrieval of (a sequence of) speech sounds. It has been suggested that these poorly represented, stored, or retrieved phonological representations are at the core of their reading problems, as these representations are crucial for the establishment of associations between the orthographic and phonological representations of words, more particularly, by connections between the constituent phonemes and the corresponding graphemes. Support for this theory comes from evidence that individuals with dyslexia and poor readers perform particularly poorly in three phonological domains (phonological awareness, verbal STM, and lexical retrieval), which all involve the storage and retrieval of phonological information. Given that a phonological representation is a sequence of speech sounds, it involves several phonemic representations. Hence, both the identity of the individual speech sounds (item information) and their serial order (serial order information) are potentially important when processing phonological information. The strong research focus on the quality/accessibility of phonemic representations within the phonological deficit theory reflects an almost exclusive interest in the representation/retrieval of phonemes’ identity. However, an important but so far unanswered research question is whether phonemes’ serial order also plays a role in the adequate representation/retrieval of phonological representations. To address this question, we will examine item and serial order retention in verbal STM processing by means of a nonword repetition task (NRT). We will analyze the retention of phonemes and their relative serial order in a novel (but phonotactically well-formed) phoneme string. In contrast to traditional NRT studies, we will apply a unique scoring technique at the phoneme level, to study the effect of literacy on both the retention probability of phonemes’ identity and phonemes’ serial order.