A Sentence Production Test for Aphasia

Abstract

Aphasia is an acquired language impairment affecting the production and/or comprehension of spoken and written language. Cognitive investigations into aphasia have focused extensively upon the production and comprehension of single words. However, people suffering from aphasia can present with intact single word production, but can experience difficulties when required to produce whole sentences. At present most tests of aphasic sentence production are qualitative only. For example, they involve examining the spontaneous speech of the individual and describing the main presenting factors. The present study set out to construct a quantitative test aimed at providing an objective measure of aphasic sentence production ability. Pictures depicting sentences were constructed and those pictures with an 80% agreement in the 'normal' population (age groups: under 30, 30-49, 50 and above) were included in the final set of pictures. Useful sentence measures obtained in the pilot studies were a score for the total sentences produced correct and a score for correct syntax despite incorrect content. Both of these scores were able to be broken down into syntactic type: transitives, single object, double object, passives and embedded. Measures of specific items included a Noun Score, a Root Verb Score Content Word Score, Function Word Score, as well as omission scores and substitution scores for each of these measures. Morphological omissions and substitutions were also included. After a pilot run with six aphasic individuals, a separate test depicting all the nouns utilised in the SPT in isolation was added as a measure for comparison for noun production in a sentence context. The final set of pictures was administered to 7 fluent and 5 non-fluent individuals with aphasia (as determined by BDAE classification; Boston Diagnostic Aphasia Examination: Goodglass & Kaplan, 1983). Results indicated that all individuals had a difficulty with sentence production. In particular, the production of double object, passive and embedded sentence structures were impaired. The results from the more specific measures indicated that most individuals appeared affected by contextual differences; Noun Scores from the SPT were lower than SNT scores. There appeared to be a relationship between the measures of the SPT and BDAE scores. For example, the ratio of nouns produced correctly against root verbs produced correctly appeared to be related to fluency as determined by the BDAE. Further, content versus function word ratio, and function word production appeared to be related to some of the more specific measures of the BDAE. In addition, we were able to obtain measures from people who were unable to do the QPA (Saffran, Berndt & Schwartz, 1989). The results are discussed in relation to other measures of sentence production, the impact of task type on sentence production and potential for future research. In conclusion, preliminary results indicated that SPT proved to be a sentence production test that is quick, easy to administer, and able to be used in a wide range of aphasic syndromes.