Speech discrimination and phonological working memory in children with ADHD

This study examined phonological working memory and speech discrimination a mong children with attention-deficit-hyperactivity disorder (ADHD) with and without motor problems. Forty-one children were assigned to three groups; children with ADHD (N=9), children with ADHD plus developmental coordinatio n disorder (ADHD+, N=13), and age-matched control children (N=19), The subj ects' ability to classify stimulus pairs was examined in two experiments. T he first experiment required subjects to discriminate pairs of monosyllabic stimuli with contrasting consonants to test speech discrimination without using a working-memory load. In the second protocol, subjects were exposed to two- to five-syllabic non-word pairs with contrasting vowels in order to test speech discrimination with a working-memory load. The subjects classi fied the pairs as being either the same or different in both experiments. N o significant differences were found between the subject groups in the disc rimination task with monosyllables. When exposed to the two- to five-syllab ic stimuli, the ADHD+ group scored significantly lower than both other grou ps. This was attributed to a higher sensitivity to working-memory load. Som e possible explanations of this effect are discussed.