Semantic clustering as a neuropsychological predictor for amnestic-MCI

ABSTRACT

Recent research has demonstrated that patients with Alzheimer's disease (AD) show deficits in semantic processing when compared to cognitively healthy individuals. This difference is thought to be attributed to losses in higher cortical systems that are predominantly associated with executive functioning. The first aim of the study will be to determine if differences in semantic clustering can accurately differentiate patients with amnestic mild cognitive impairment (aMCI) from cognitively normal (CN) individuals. The second aim will be to determine the extent to which semantic processing might be associated with executive functions. Data from 202 (134 CN, 68 aMCI) participants were analyzed to quantify differences in semantic clustering ratios on the HVLT-R. Study participants ages ranged from 51 to 87 with education ranging from 6 to 20 years. ANCOVA revealed statistically significant differences on semantic clustering ratios (p < .001). Moderate correlations between semantic clustering Category Fluency Test (r = .45) were also found. Statistically significant group differences were also present on Trails-B and WAIS-R Digit Symbol performance (p < .001). Overall, these data indicate that deficits in semantic clustering are present in aMCI patients.     

CoTO: A novel approach for fuzzy aggregation of semantic similarity measures

Semantic similarity measurement aims to determine the likeness between two text expressions that use different lexicographies for representing the same real object or idea. There are a lot of semantic similarity measures for addressing this problem. However, the best results have been achieved when aggregating a number of simple similarity measures. This means that after the various similarity values have been calculated, the overall similarity for a pair of text expressions is computed using an aggregation function of these individual semantic similarity values. This aggregation is often computed by means of statistical functions. In this work, we present CoTO (Consensus or Trade-Off) a solution based on fuzzy logic that is able to outperform these traditional approaches.     

The effect of verb semantic class and verb frequency (entrenchment) on children's and adults' graded judgements of argument-structure overgeneralization errors

Participants (aged 5-6 yrs, 9-10 yrs and adults) rated (using a five-point scale) grammatical (intransitive) and overgeneralized (transitive causative)(1) uses of a high frequency, low frequency and novel intransitive verb from each of three semantic classes [Pinker, S. (1989a). Learnability and cognition: The acquisition of argument structure. Cambridge, MA: MIT Press]: "directed motion" (fall, tumble), "going out of existence" (disappear, vanish) and "semivoluntary expression of emotion" (laugh, giggle). In support of Pinker's semantic verb class hypothesis, participants' preference for grammatical over overgeneralized uses of novel (and English) verbs increased between 5-6 yrs and 9-10 yrs, and was greatest for the latter class, which is associated with the lowest degree of direct external causation (the prototypical meaning of the transitive causative construction). In support of Braine and Brooks's [Braine, M.D.S., & Brooks, P.J. (1995). Verb argument strucure and the problem of avoiding an overgeneral grammar. In M. Tomasello & W. E. Merriman (Eds.), Beyond names for things: Young children's acquisition of verbs (pp. 352-376). Hillsdale, NJ: Erlbaum] entrenchment hypothesis, all participants showed the greatest preference for grammatical over ungrammatical uses of high frequency verbs, with this preference smaller for low frequency verbs, and smaller again for novel verbs. We conclude that both the formation of semantic verb classes and entrenchment play a role in children's retreat from argument-structure overgeneralization errors.     

Evidence for serial coercion: a time course analysis using the visual-world paradigm

Metonymic verbs like start or enjoy often occur with artifact-denoting complements (e.g., The artist started the picture) although semantically they require event-denoting complements (e.g., The artist started painting the picture). In case of artifact-denoting objects, the complement is assumed to be type shifted (or coerced) into an event to conform to the verb's semantic restrictions. Psycholinguistic research has provided evidence for this kind of enriched composition: readers experience processing difficulty when faced with metonymic constructions compared to non-metonymic controls. However, slower reading times for metonymic constructions could also be due to competition between multiple interpretations that are being entertained in parallel whenever a metonymic verb is encountered. Using the visual-world paradigm, we devised an experiment which enabled us to determine the time course of metonymic interpretation in relation to non-metonymic controls. The experiment provided evidence in favor of a non-competitive, serial coercion process.     

Brogaard and Salerno on antirealism and the conditional fallacy

Brogaard and Salerno (2005, Nous, 39, 123–139) have argued that antirealism resting on a counterfactual analysis of truth is flawed because it commits a conditional fallacy by entailing the absurdity that there is necessarily an epistemic agent. Brogaard and Salerno’s argument relies on a formal proof built upon the criticism of two parallel proofs given by Plantinga (1982, Proceedings and Addresses of the American Philosophical Association, 56, 47–70) and Rea (2000, Nous, 34, 291–301). If this argument were conclusive, antirealism resting on a counterfactual analysis of truth should probably be abandoned. I argue however that the antirealist is not committed to a controversial reading of counterfactuals presupposed in Brogaard and Salerno’s proof, and that the antirealist can in principle adopt an alternative reading that makes this proof invalid. My conclusion is that no reductio of antirealism resting on a counterfactual analysis of truth has yet been provided.

Structural realism and Davidson

Structural realism is an attempt to balance the competing demands of the No Miracles Argument and the Pessimistic Meta-Induction. In this paper I trace the development of the structuralist idea through the work of one of its leading advocates, John Worrall. I suggest that properly thought through what the structuralist is offering or should be offering is not an account of how to divide up a theory into two parts—structure and ontology—but (perhaps surprisingly) a certain kind of theory of meaning—semantic holism. I explain how a version of structural realism can be developed using Davidson’s theory of meaning and some advantages this has over the Ramsey-sentence version of structuralism.     

Elaborative processing in the Korsakoff syndrome: context versus habit

Using a procedure of Hay and Jacoby [Hay, J. F., & Jacoby, L. L. (1999). Separating habit and recollection in young and older adults: Effects of elaborative processing and distinctiveness. Psychology and Aging, 14, 122–134], Korsakoff patients’ capacity to encode and retrieve elaborative, semantic information was investigated. Habits were created during initial training, whereupon cued-recall memory performance was examined, with habit opposing as well as facilitating recollection of earlier studied words. A first group of patients was instructed and tested in the same way as healthy controls and showed poor test performance. Nevertheless, when given more processing and response time, additional explanation, and explicit encouragement, a second group of patients performed similarly to healthy controls. The results suggest that, when given adequate support, Korsakoff patients are able to encode and make use of semantic, contextual, and sequential information. Word distinctiveness, however, only influenced performance of controls.     

Looking both ways through time: the Janus model of lateralized cognition

Existing models of laterality, while often successful at describing circumscribed domains, have not been successful as explanations of the overall patterns of hemispheric asymmetries. It is therefore suggested that a new approach is needed based on shared contributions to adaptive hemispheric roles rather than functional and structural intrahemispheric similarities. This paper proposes a model of laterality, the Janus model, based on evolutionary considerations of complementary hemispheric roles. It is proposed that the left hemisphere has the role of anticipating future scenarios and choosing between them while the right hemisphere has the role of integrating ongoing information into a unitary view of the past in order to immediately detect and respond to novel and unexpected events. Evidence for these complementary roles is provided in research on motor control and semantic priming. Finally, the Janus model is contrasted with efforts to cast the frequency model as a general model of laterality.     

The social semantics of Mikhail Pokrovskij and Nikolaj Marr

Criticizing the works of “Western” specialists in semantics, Soviet academician M. M. Pokrovskij (1868–1942) comes to the conclusion that social factors are essential for semantic evolution, while psychological factors constitute an intermediate link between the “external” life of a society and the semantics of the corresponding language. This conception resembles the general explanations of semantic evolution proposed by N. Ja. Marr (1864–1934). Nevertheless, despite a number of common points in the semantic theories of these two researchers, Pokrovskij’s attitude towards Marr was negative: in particular, he disagreed with the thesis of the chronological primacy of Marr’s discoveries in the domain of semantics. The article investigates why Pokrovskij had for a long time constituted an intermediate link between Russian and “Western” “traditions” in the field of semantics.

Contexts and control operations used in accessing list-specific, generalized, and semantic memories

The human ability to focus memory retrieval operations on a particular list, episode or memory structure has not been fully appreciated or documented. In Experiment 1-3, we make it increasingly difficult for participants to switch between a less recent list (multiple study opportunities), and a more recent list (single study opportunity). Task performance was good, although there was a cost associated with switching. In Experiment 4, list-specific learning experiences were used to create a generalized memory as a step towards semantic memory. List-specific memories intruded during attempts to retrieve the generalized memory and the generalized memory enhanced list-specific performance. The generalized memory also intruded in a free-association task. We propose that a hierarchy of contexts and control operations underlie the human ability to access different memory structures and that there is no sharp discontinuity in the control operations needed to access list-specific, generalized, and semantic memories.