A Computational Evaluation of Two Models of Retrieval Processes in Sentence Processing in Aphasia

Can sentence comprehension impairments in aphasia be explained by difficulties arising from dependency completion processes in parsing? Two distinct models of dependency completion difficulty are investigated, the Lewis and Vasishth (2005) activation-based model and the direct-access model (DA; McElree, 2000). These models' predictive performance is compared using data from individuals with aphasia (IWAs) and control participants. The data are from a self-paced listening task involving subject and object relative clauses. The relative predictive performance of the models is evaluated using k-fold cross-validation. For both IWAs and controls, the activation-based model furnishes a somewhat better quantitative fit to the data than the DA. Model comparisons using Bayes factors show that, assuming an activation-based model, intermittent deficiencies may be the best explanation for the cause of impairments in IWAs, although slowed syntax and lexical delayed access may also play a role. This is the first computational evaluation of different models of dependency completion using data from impaired and unimpaired individuals. This evaluation develops a systematic approach that can be used to quantitatively compare the predictions of competing models of language processing.     

Cortical Acetylcholine, Reality Distortion, Schizophrenia, and Lewy Body Dementia: Too Much or Too Little Cortical Acetylcholine?

Aberrations in cortical cholinergic transmission have been hypothesized to mediate the development and manifestation of psychotic cognition. Based primarily on hypotheses about mesolimbic dopaminergic hyperactivity in schizophrenia, the actions of antipsychotic drugs, the trans-synaptic regulation of the excitability of basal forebrain corticopetal cholinergic neurons, and the role of cortical cholinergic inputs in attentional functions, we hypothesized that persistent disinhibition of cortical cholinergic inputs mediates the fundamental cognitive dysfunctions which form the basis for the development of positive symptoms in schizophrenia. In contrast to this hypothesis, Perry and Perry (1995), based on evidence from hallucinating patients with Lewy Body Dementia (LBD), concluded that the extensivelossof cortical acetylcholine allows irrelevant information to enter “conscious awareness” and thus hallucinations to emerge. The discussion of these contrasting hypotheses highlights the need for more dynamic and precise theories describing the cognitive variables and neuronal processes which contribute to the development and manifestation of psychotic cognition. While the hypothesis that a disinhibited cholinergic system mediates the evolution of psychotic symptoms corresponds more convincingly with current theories about the cognitive functions of cortical cholinergic inputs, both hypotheses stress the critical role of cortical acetylcholine in the highest levels of cognitive functioning.     

Conversation and Behavior Games in the Pragmatics of Dialogue

In this article we present the bases for a computational theory of the cognitive processes underlying human communication. The core of the article is devoted to the analysis of the phases in which the process of comprehension of a communicative act can be logically divided: (1) literal meaning, where the reconstruction of the mental states literally expressed by the actor takes place: (2) speaker's meaning, where the partner reconstructs the communicative intentions of the actor; (3) communicative effect, where the partner possibly modifies his own beliefs and intentions; (4) reaction, where the intentions for the generation of the response are produced; and (5) response, where an overt response is constructed. The model appears to be compatible with relevant facts about human behavior. Our hypothesis is that, through communication, an actor tries to exploit the motivational structures of a partner so that the desired goal is generated. A second point is that social behavior requires that cooperation be maintained at some level. In the case of communication, cooperation is, in general, pursued even when the partner does not adhere to the actor's goals, and therefore no cooperation occurs at the behavioral level. This important distinction is reflected in the two kinds of game we introduce to account for communication. The main concept implied in communication is that two agents overtly reach a situation of shared mental states. Our model deals with sharedness through two primitives: shared beliefs and communicative intentions.     

Context-dependent and seasonal fluctuation in bottlenose dolphin (Tursiops truncatus) vocalizations

Animal Cognition - A fundamental question in animal behaviour is the role of vocal communication in the regulation of social interactions in species that organise themselves into social groups....     

Apocalyptic Specularity in Dante's Eschatology: Narcissus and the Imagination of Salvation

Dante's Commedia provides a performative eschatology or “apocalyptic specularity” that shows well how to keep concerns for apophasis, imagination, and salvation in balance. His literary appreciation for mirroring enables him to re‐present and imitate revelation. Displaying a metaphysically robust imagination, Dante's eschatology is akin to the biblical genre of apocalypse. Dantean analogy—personal and historical while theological and apocalyptical—resists tendencies to account for theology in reducibly negativist terms. The Divine Comedy hopes for the salvation of Narcissus, whose figure reflects the “everyman,” who would furthermore reflect even the triune God.     

Repair Avoidance: When Faithful Informational Exchanges Don't Matter That Much

Common-sense intuition suggests that, when people are engaged in informational exchanges, they communicate so as to be reasonably sure that they perform the exchanges faithfully. Over the years, we have found evidence suggesting that this intuition, which is woven into several influential theories of human communication, may be misleading. We first summarize this evidence and discuss its potential limitations. Then, we present a new study that addresses the potential limitations. A confederate instructed participants to “pick up the skask” from a tray containing six objects and move it to a specific location. Since skask is a non-word invented by us, participants had to ask for clarification to perform the instruction faithfully. In contradiction with the intuition that people pursue faithfulness when engaged in informational exchanges, 29 of the 48 participants we tested performed the instruction without asking for clarification. We identified a possible cause for this behavior, which occurred more frequently when avoiding the clarification was unlikely to result in an overt consequence (an error in the execution of the instruction that could be noticed by the confederate or the experimenter). Other factors such as individual differences and the specific interpersonal dynamics of the experimental settings, if they played a role at all, did it to an extent that is unlikely to be comparable to that of the role played by overt consequences. Considered together, our various assessments of the extent to which people engage in faithful informational exchanges converge on a simple conclusion: Communicating faithfully is a substantially demanding task, and people often fail at it. We discuss the implications of this conclusion and speculate on its relevance for understanding the evolutionary past of human communication.     

Orienting to guilty knowledge

The Guilty Knowledge Test (GKT; Lykken, 1959) assesses whether suspects conceal information about a crime ( “guilty knowledge”). Previous studies have demonstrated larger physiological reactions to guilty knowledge compared to unknown information. In three experiments, we investigated whether guilty knowledge also demands attention. During an alleged polygraph examination, participants were presented with to‐be‐detected pictures ( “guilty knowledge”), nonsignificant, familiar pictures ( “mere knowledge”), and previously unseen pictures ( “neutral information”) for 250 ms in a modified dot probe task. In all three experiments, probe responses were slower on guilty knowledge trials as compared to the neutral trials. Results are discussed in terms of an information‐processing view on orienting to guilty knowledge.