THE EFFECT OF HANDEDNESS IN TACTILE SPEECH-PERCEPTION

This study examined differential performance of normally hearing subje cts using a tactile device on the dominant versus non-dominant hand. T he study evaluated whether tactual sensitivity for non-speech stimuli was greater for the dominant hand as compared with the non-dominant ha nd, and secondly, whether there was an advantage for speech presented tactually to the dominant hand, resulting from a preferential pathway to the language processing area in the left cerebral hemisphere. Evalu ations of threshold pulse width, dynamic ranges, paired electrode iden tification, and a closed-set tactual pattern discrimination test batte ry showed no difference in tactual sensitivity measures between the tw o hands. Speech perception was assessed with closed sets of vowels and consonants and with open-set Harvey Gardner (HG) words and Arthur Boo throyd (AB) words. Group mean scores were higher in each of the tactua lly aided conditions as compared with the unaided conditions for speec h tests, with the exception of AB words in the tactile plus lip-readin g plus audition/lip-reading plus audition condition on the right hand. Overall mean scores on the closed-set vowel test and on open-set HG a nd AB words were significantly higher for the tactually aided conditio n as compared with the unaided condition. Comparison of performance be tween the dominant and non-dominant hand showed a significant advantag e for the dominant hand on the closed-set vowel test only. No signific ant differences between hands in either tactually aided or unaided con ditions were evident for any of the other speech perception tests. Fac tors influencing this result could have been variations in degree of d ifficulty of the tests, the amount of training subjects received, or t he training strategy employed. Although an advantage to presenting spe ech through the dominant hand may exist, it is unlikely to be great en ough to outweigh possible restrictions on everyday use.