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Differentiating Speech Delay From Disorder: Does it Matter?

Dodd, Barbara

doi: 10.1097/TLD.0b013e318217b66a
Original Articles

Aim: The cognitive-linguistic abilities of 2 subgroups of children with speech impairment were compared to better understand underlying deficits that might influence effective intervention.

Methods: Two groups of 23 children, aged 3;3 to 5;6, performed executive function tasks assessing cognitive flexibility and nonverbal rule abstraction. Following the system of differential diagnosis of speech disorders first described by Dodd, Leahy, and Hambly (1989), one group was identified as having delayed speech development, as their non–age-appropriate speech error patterns were typical of younger children. The other group was diagnosed as disordered because children consistently used at least one speech error pattern atypical of any age group in an assessments' normative sample (Dodd, Zhu, Crosbie, Holm, & Ozanne, 2002).

Results and Conclusions: The disordered group performed less well than the delayed group: They had poorer cognitive flexibility and difficulty abstracting nonlinguistic rules. They made more consonant errors and different types of errors. The 2 groups did not differ on measures of language, vowel accuracy, or consistency of multiple productions of the same words. The findings suggest that different interventions, reflecting knowledge of underlying deficits, might benefit specific subgroups of children with speech impairment.

Department of Language and Communication Sciences, City University, London, United Kingdom.

Corresponding Author: Barbara Dodd, PhD, Department of Language and Communication Sciences, City University London, Northampton Square, London EC1V OHB, United Kingdom (e-mail:

The study reported was funded by the Australian Research Council Discovery Grants Scheme.

The willing cooperation of childcare centers, parents, and children is gratefully acknowledged. The author thanks Beth McIntosh, Sharon Crosbie, Aileen Wright, and Alison Holm for practical help and discussion.

© 2011 Lippincott Williams & Wilkins