Effects of stimulus material on the dichotic listening performance of aphasic patients

Sixteen aphasic patients were given five different verbal dichotic listening tests. The differences among results obtained on a digit test, a high-contrast word test (perception of either vocalic or consonantal information was sufficient for accurate responses), and a vowel-word test (perception of vocalic information was required for accurate responses) were not significant. However, a consonant-word test resulted in significant decreases in both left- and right-ear scores and an increase in the performance levels, and the magnitude of difference scores between ears was limited by low levels of performance for the majority of patients. Attempts to identify relations between patterns of performance on dichotic listening tests and radiographic evidence of lesion location were most profitable when they involved the right-ear (RE) scores on the digit test. The discontinuity in the distribution of these scores corresponded to the presence of absence of damage to the geniculo-temporal system. That is, when the geniculo-temporal system was spared, the RE scores exceeded 75% correct, whereas damage to the geniculo-temporal system was associated with RE scores of less than 50% correct.