Speech lateralization and attention/executive functions in a Finnish family with specific language impairment (SLI).

Hemisphere lateralization for speech perception was investigated in a Finnish family with specific language impairment. We used dichotic presentations of consonant-vowel (CV) syllables, consisting of the six stop-consonants paired with the vowel /a/, under three different attentional instructions. The dichotic listening technique means that two different speech stimuli are presented simultaneously, one in each ear. Left hemisphere dominance for speech perception is assessed from a preference for the right ear stimulus. Response accuracy was compared in five members, over three generations, of a family with SLI with 5 healthy control subjects. The dichotic listening task was performed under three different instructions, to attend only to the right ear stimulus, to attend only to the left ear stimulus, or with no instruction about attention. The subjects indicated orally which of the six CV-syllables they heard on each trial. There were 36 dichotic presentations of the CV-syllables for each instruction. The CV-syllables were played from a CD with digitized stimuli. The results showed no difference between the groups during the no instruction condition, indicating normal speech lateralization in the SLI group. However, the SLI group was deficient in modifying the ear advantage through focused attention to the left ear, thus indicating an attentional/executive deficit in addition to a deficit in left hemisphere lateralization. It is concluded that individuals with specific language impairment may have a cognitive deficit related to attention in addition to a language processing deficit related to left hemisphere function.