We investigated whether individuals with Williams Syndrome (WS) produce language with a bias towards statistical properties of word combinations rather than grammatical rules, resulting in an overuse of holistically stored, familiar phrases. We analysed continuous speech samples from English children with WS (n = 12), typically developing (TD) controls matched on chronological age (n = 15) and TD controls matched on language age (n = 14). Alongside word count, utterance length, grammatical complexity, and morphosyntactic errors, we measured familiarity of expressions by computing collocation strength of each word combination. The WS group produced stronger collocations than both control groups. Moreover, the WS group produced fewer complex sentences, shorter utterances, and more frequent function words than chronological-age matched controls. Language in WS may appear more typical than it is because familiar, holistically processed expressions mask grammatical and other difficulties.

Artificial grammar learning is an empirical paradigm that investigates basic pattern and structural processing in different populations. It can inform how higher cognitive functions, such as language use, take place. Our study used artificial grammar learning to assess how children with Williams syndrome (WS; n = 16) extract patterns in structured sequences of synthetic speech, how they compare to typically developing (TD) children (n = 60), and how prosodic cues affect learning. The TD group was divided into a group whose nonverbal abilities were within the range of the WS group, and a group whose chronological age was within the range of the WS group. TD children relied mainly on rule-based generalization when making judgments about sequence acceptability, whereas children with WS relied on familiarity with specific stimulus combinations. The TD participants whose nonverbal abilities were similar to the WS group showed less evidence of relying on grammaticality than TD participants whose chronological age was similar to the WS group. In absence of prosodic cues, the children with WS did not demonstrate evidence of learning. Results suggest that, in WS children, the transition to rule-based processing in language does not keep pace with TD children and may be an indication of differences in neurocognitive mechanisms.

The aim of this study was to compare the prosodic profiles of English- and Spanish-speaking children with Williams syndrome (WS), examining cross-linguistic differences. Two groups of children with WS, English and Spanish, of similar chronological and nonverbal mental age, were compared on performance in expressive and receptive prosodic tasks from the Profiling Elements of Prosody in Speech–Communication Battery in its English or Spanish version. Differences between the English and Spanish WS groups were found regarding the understanding of affect through prosodic means, using prosody to make words more prominent, and imitating different prosodic patterns. Such differences between the two WS groups on function prosody tasks mirrored the cross-linguistic differences already reported in typically developing children.