Recent research in adult pronunciation of foreign languages has assigned a significant role to affective variables. It has been shown that certain language functions, including many aspects of pronunciation, are handled by the right brain hemisphere. An experiment was conducted to study the extent to which the right hemisphere might be activated during the task of listening to and pronouncing tone language sounds. The strategy employed was to study the effect of the pronunciation task on reaction time to light in the right or left visual field. The subjects, 12 male and 12 female right-handed university students enrolled in an elementary French course, attended three sessions. During the first two sessions they responded to light stimuli and heard and repeated Thai phrases. Reaction times to the stimuli, while listening to or repeating phrases, were measured and recorded. During the third session subjects repeated French sentences and had their eye movements assessed. Analysis of the results shows a correlation between the measure of hemisphere efficiency and approximation of native-like pronunciation. The conclusion is drawn that it is possible to associate "affective variables" with a specific neuroanatomical structure, and that right hemispheric activity will predict the quality of pronunciation in a foreign language. (AMH)