Evaluating measures of global coherence ability in stories in adults

Abstract

Discourse coherence is a reflection of the listener's ability to interpret the overall meaning conveyed by the speaker. Measuring global coherence (maintenance of thematic unity of the discourse) is useful for quantifying communication impairments at the discourse level in clinical populations and for measuring response to discourse-level treatments. The aim was to determine feasibility of a four-point global coherence scale developed by the authors. Specifically, they were (1) to estimate measurement reliability of the four-point global coherence scale; and (2) to estimate construct validity for the four-point global coherence scale. Fifty cognitively healthy adults aged between 28 and 58 years participated in the study. Participants viewed and then told the stories depicted in two wordless picture books. Participants' stories were orthographically transcribed and segmented into communication units (C-unit). Raters scored each participant's story for global coherence using two global coherence scales (four- and five-point scales). Each C-unit received an individual score, then the mean global coherence score was computed, resulting in two mean global coherence scores for each coherence scale, one for each story, for all participants. Results indicated high reliability estimates for the scale. In addition, construct validity, specifically face validity and convergent validity, was effectively estimated for using the four-point scale as a measure of maintenance of global coherence in stories told by cognitively healthy adults. Lastly, it was found that the wordless picture books elicited stories that are comparable and can be reliably interchanged as different forms to evaluate maintenance of global coherence. The assumptions that the measure is feasible were achieved and face and convergent validity were adequately estimated. Future investigations should consider estimating predictive validity, concurrent validity and discriminant validity of the measure.