Lexical Sign Comprehension Test

Research in hearing subjects has shown that the auditory comprehension deficit often found in patients with unilateral temporal lobe damage (typically Wernicke’s aphasics) does not result primarily from deficits in phonemic-level processing (Hickok & Poeppel, 2000, 2004). More specifically, on sign-to-picture matching tasks with phonological, semantic, and unrelated foils, Wernicke’s patients perform well above chance overall in the 70-80% correct range, indicating that even destruction of the left posterior temporal lobe does not obliterate the ability to process speech at the phonological level. We examine the severity and source of single sign comprehension deficits in sign language aphasia using a similar comprehension test. The test includes a 50-item 4AFC sign-to-picture matching task, in which subjects are presented with an isolated ASL sign and asked to point to the matching picture on a card. The card contains a picture of (i) the target, (ii) a phonological distractor, which differs from the target by only one sign feature and is semantically unrelated to the target, (iii) a semantic distractor that is phonologically unrelated to the target, and (iv) an unrelated distractor. We have developed two additional variations on the task. In one, the distractor items are all phonologically related to the target, and in the other the distractor items are all semantically related to the target. Each subtest has 40 trials.

 


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