Communicative Informativeness in Aphasia: Investigating the Relationship Between Linguistic and Perceptual Measures.

Purpose Informativeness refers to how successfully a person is able to convey their intended message. This study explores the relationship between perceptual ratings of informativeness and selected linguistic measures of lexical and structural content. It considers which linguistic measures have ecological validity in terms of what listeners view as important. Method Two complex picture description samples from 20 people with aphasia were analyzed. Linguistic measures included number of correct information units (NCIU), percentage of correct information units, number of propositions (NP), propositional idea density (PID), and mean length of utterance in words (MLU-w). Eleven naïve listeners produced direct magnitude estimation (DME) ratings of informativeness. A correlational design was used to investigate the relationship between mean DME informativeness ratings and each of the linguistic measures. Results The 2 picture description samples elicited similar informativeness ratings. Positive significant correlations were identified between mean DME informativeness ratings and NCIU, percentage of correct information units, NP, and MLU-w; the strength of correlation differed across variables. No significant correlation was found between mean DME informativeness ratings and PID. Significant correlations were also seen between the linguistic variables, particularly between NP and PID as well as NP and MLU-w. Conclusions Overall, the linguistic measures corresponded to rated informativeness, highlighting their ecological validity. The strongest relationship was between NCIU and rated informativeness, emphasizing the importance of complete and accurate production of lexical information, particularly nouns. Less strong, but still significant, relationships were seen with variables looking at the efficiency of information giving and the connection of ideas within sentences. The importance of different types of informative measures is considered in relation to the elicitation stimuli.