Hyperlexia in Chinese-speaking children : a behavioural study

Abstract

Hyperlexia is a language disorder featuring advanced reading aloud ability and deficit in language comprehension. Previous studies have found that hyperlexic children extensively use the Grapheme-Phoneme Correspondence (GPC) rule to read, and this reading pattern provides evidence for “reading without meaning” and supports the Dual-Route Cascade Model of reading aloud. However, in Chinese, the mapping between print and sound is opaque, and the GPC rule may not be a reliable strategy for reading aloud. Thus, it is unclear how Chinese-speaking hyperlexics perform in reading related skills, and how reading is achieved despite impaired semantics. The aim of this thesis is to investigate the reading pattern of Chinese-speaking children with hyperlexia in terms of their reading profile and the definition of hyperlexia, the meta-linguistic awareness skills in hyperlexic child that support reading aloud, and the role of semantics in the reading aloud process. Adopting a case study approach with case-control design, performance of hyperlexic cases were compared with typically developing and Autism Spectrum Disorder (ASD) control groups matched for chronological age and mental ability in order to understand how mental ability and ASD syndrome influence hyperlexic reading pattern. Study 1 examined the reading aloud and comprehension skills of six hyperlexic children speaking Chinese and identified four types of reading patterns, with higher reading ability and lower comprehension ability compared with chronological age being the most predominant type. Comparisons with the control groups suggest that the reading aloud ability of hyperlexic children is comparable to typically developing children matched for mental ability. Furthermore, the comprehension difficulty in hyperlexia may come from the ASD syndrome. Study 2 investigated the meta-linguistic awareness skills involved in the reading aloud of hyperlexic children. Tests on phonological, morphological and orthographic awareness skills were administered to one hyperlexic child with the predominant reading profile and control groups. Results found that the hyperlexic child did not demonstrate strength or weakness in phonological awareness skills, while having difficulties in morphological awareness and relied less on morphological awareness skill in reading compared with age-matched typically developing children. In addition, the hyperlexic child did not show advantages in the awareness of a character’s orthographic structure but had good lexical knowledge, which might be one of the reasons for their advanced reading ability. Study 3 examined whether hyperlexic reading depends on semantics using a word and nonword reading task and a picture-primed word reading task. Results found that reading accuracy and reaction time of hyperlexic children was influenced by the meaning of words, and the prior picture of different levels of semantic relationships. This finding differs from previous findings reported in alphabetic languages. Also, hyperlexic children are less efficient at rejecting irrelevant information during reading aloud. The results support the Parallel Distributed Processing model which argues that semantic activation is necessary in the reading aloud process. Taken together, hyperlexic reading in Chinese is supported by good lexical knowledge, and comprehension difficulties possibly come from the inefficiency in retrieving concepts. Furthermore, lack of significant difference between hyperlexic children and ASD control groups in semantic processing indicate hyperlexia might be one subtype of ASD reading pattern. Lastly, the studies did not find evidence for “reading without meaning” in Chinese-speaking hyperlexics suggesting for an opaque script, like Chinese, reading aloud must still activate semantics.