Assessing cognitive alignment in different types of dialog by means of a network model.

We present a network model of dialog lexica, called TiTAN (Two-layer Time-Aligned Network) series. TiTAN series capture the formation and structure of dialog lexica in terms of serialized graph representations. The dynamic update of TiTAN series is driven by the dialog-inherent timing of turn-taking. The model provides a link between neural, connectionist underpinnings of dialog lexica on the one hand and observable symbolic behavior on the other. On the neural side, priming and spreading activation are modeled in terms of TiTAN networking. On the symbolic side, TiTAN series account for cognitive alignment in terms of the structural coupling of the linguistic representations of dialog partners. This structural stance allows us to apply TiTAN in machine learning of data of dialogical alignment. In previous studies, it has been shown that aligned dialogs can be distinguished from non-aligned ones by means of TiTAN -based modeling. Now, we simultaneously apply this model to two types of dialog: task-oriented, experimentally controlled dialogs on the one hand and more spontaneous, direction giving dialogs on the other. We ask whether it is possible to separate aligned dialogs from non-aligned ones in a type-crossing way. Starting from a recent experiment (Mehler, Lücking, & Menke, 2011a), we show that such a type-crossing classification is indeed possible. This hints at a structural fingerprint left by alignment in networks of linguistic items that are routinely co-activated during conversation.

Reliability and validity of cervical auscultation.

We conducted a two-part study that contributes to the discussion about cervical auscultation (CA) as a scientifically justifiable and medically useful tool to identify patients with a high risk of aspiration/penetration. We sought to determine (1) acoustic features that mark a deglutition act as dysphagic; (2) acoustic changes in healthy older deglutition profiles compared with those of younger adults; (3) the correctness and concordance of rater judgments based on CA; and (4) if education in CA improves individual reliability. The first part of the study focused on a comparison of the "swallow morphology" of dysphagic as opposed to healthy subjects' deglutition in terms of structure properties of the pharyngeal phase of deglutition. We obtained the following results. The duration of deglutition apnea is significantly higher in the older group than in the younger one. Comparing the younger group and the dysphagic group we found significant differences in duration of deglutition apnea, onset time, and number of gulps. Just one parameter, number of gulps, distinguishes significantly between the older and the dysphagic groups. The second part of the study aimed at evaluating the reliability of CA in detecting dysphagia measured as the concordance and the correctness of CA experts in classifying swallowing sounds. The interrater reliability coefficient AC1 resulted in a value of 0.46, which is to be interpreted as fair agreement. Furthermore, we found that comparison with radiologically defined aspiration/penetration for the group of experts (speech and language therapists) yielded 70% specificity and 94% sensitivity. We conclude that the swallowing sounds contain audible cues that should, in principle, permit reliable classification and view CA as an early warning system for identifying patients with a high risk of aspiration/penetration; however, it is not appropriate as a stand-alone tool.