Michiel van Lambalgen

Von Mises' Definition of Random Sequences Reconsidered

We review briefly the attempts to define random sequences (?0). These attempts suggest two theorems: one concerning the number of subsequence selection procedures that transform a random sequence into a random sequence (??1-3 and 5); the other concerning the relationship between definitions of randomness based on subsequence selection and those based on statistical tests (?4). Acknowledgement. We thank Johan van Benthem for his deconstruction of an earlier version of this manuscript, and also Roger Cooke and Mike Keane for helpful conversations.

Coercion and compositionality

Research in psycholinguistics and in the cognitive neuroscience of language has suggested that semantic and syntactic processing are associated with different neurophysiologic correlates, such as the N400 and the P600 in the ERPs. However, only a handful of studies have investigated the neural basis of the syntax–semantics interface, and even fewer experiments have dealt with the cases in which semantic composition can proceed independently of the syntax. Here we looked into one such case—complement coercion—using ERPs. We compared sentences such as, “The journalist wrote the article” with “The journalist began the article.” The second sentence seems to involve a silent semantic element, which is expressed in the first sentence by the head of the verb phrase (VP) “wrote the article.” The second type of construction may therefore require the reader to infer or recover from memory a richer event sense of the VP “began the article,” such as began writing the article, and to integrate that into a semantic representation of the sentence. This operation is referred to as “complement coercion.” Consistently with earlier reading time, eye tracking, and MEG studies, we found traces of such additional computations in the ERPs: Coercion gives rise to a long-lasting negative shift, which differs at least in duration from a standard N400 effect. Issues regarding the nature of the computation involved are discussed in the light of a neurocognitive model of language processing and a formal semantic analysis of coercion.

Defeasible reasoning in high-functioning adults with autism: evidence for impaired exception-handling.

While autism is one of the most intensively researched psychiatric disorders, little is known about reasoning skills of people with autism. The focus of this study was on defeasible inferences, that is inferences that can be revised in the light of new information. We used a behavioral task to investigate (a) conditional reasoning and (b) the suppression of conditional inferences in high-functioning adults with autism. In the suppression task a possible exception was made salient which could prevent a conclusion from being drawn. We predicted that the autism group would have difficulties dealing with such exceptions because they require mental flexibility to adjust to the context, which is often impaired in autism. The findings confirm our hypothesis that high-functioning adults with autism have a specific difficulty with exception-handling during reasoning. It is suggested that defeasible reasoning is also involved in other cognitive domains. Implications for neural underpinnings of reasoning and autism are discussed.

Exceptions and anomalies: An ERP study on context sensitivity in autism

Several studies have demonstrated that people with ASD and intact language skills still have problems processing linguistic information in context. Given this evidence for reduced sensitivity to linguistic context, the question arises how contextual information is actually processed by people with ASD. In this study, we used event-related brain potentials (ERPs) to examine context sensitivity in high-functioning adults with autistic disorder (HFA) and Asperger syndrome at two levels: at the level of sentence processing and at the level of solving reasoning problems. We found that sentence context as well as reasoning context had an immediate ERP effect in adults with Asperger syndrome, as in matched controls. Both groups showed a typical N400 effect and a late positive component for the sentence conditions, and a sustained negativity for the reasoning conditions. In contrast, the HFA group demonstrated neither an N400 effect nor a sustained negativity. However, the HFA group showed a late positive component which was larger for semantically anomalous sentences than congruent sentences. Because sentence context had a modulating effect in a later phase, semantic integration is perhaps less automatic in HFA, and presumably more elaborate processes are needed to arrive at a sentence interpretation.

Algorithmic information theory

We present a critical discussion of the claim (most forcefully propounded by Chaitin) that algorithmic information theory sheds new light on Godels first incompleteness theorem.

There is no Opposition between Formal and Cognitive Semantics

Abstract 1. Introduction The history of modern semantics is characterised by two research traditions which are based on radically different views concerning both conceptual motivation and the purpose of semantic research. Realistic semantics conceives of semantics as characterising the relationsship between linguistic expressions and reality. In most cases this relationship is explicated by means of modeltheoretic concepts. The following quote from one of the founding fathers of realistic semantics clearly rejects a mentalist stance.

Reasoning with exceptions: An event-related brain potentials study

Defeasible inferences are inferences that can be revised in the light of new information. Although defeasible inferences are pervasive in everyday communication, little is known about how and when they are processed by the brain. This study examined the electrophysiological signature of defeasible reasoning using a modified version of the suppression task. Participants were presented with conditional inferences (of the type “if p, then q; p, therefore q”) that were preceded by a congruent or a disabling context. The disabling context contained a possible exception or precondition that prevented people from drawing the conclusion. Acceptability of the conclusion was indeed lower in the disabling condition compared to the congruent condition. Further, we found a large sustained negativity at the conclusion of the disabling condition relative to the congruent condition, which started around 250 msec and was persistent throughout the entire epoch. Possible accounts for the observed effect are discussed.

Language, linguistics and cognition

Experimental research during the last few decades has provided evidence that language is embedded in a mosaic of cognitive functions. An account of how language interfaces with memory, perception, action and control is no longer beyond the scope of linguistics, and can now be seen as part of an explanation of linguistic structure itself. However, although our view of language has changed, linguistic methodology is lagging behind. This chapter is a sustained argument for a diversification of the kinds of evidence applicable to linguistic questions at di↵erent levels of theory, and a defense of the role of linguistics in experimental cognitive science. 1.1 Linguistic methodology and cognitive science At least two conceptual issues are raised by current interactions between linguistics and cognitive science. One is whether the structures and rules described by linguists are cognitively real. There exist several opinions in this regard, that occupy di↵erent positions on the mentalism/anti-mentalism spectrum. At one extreme is cognitive linguistics [ Croft and Cruse, 2004 ] , endorsing both theoretical and methodological mentalism. The former is the idea that linguistic structures are related formally and causally to other mental entities. The latter calls for a revision of traditional linguistic methodology, and emphasizes the role of cognitive data in linguistics. At the opposite side of the spectrum lies formal semantics which, partly inspired by Frege’s anti-psychologistic stance on meaning and thought [ Frege, 1980; Lewis, 1970; Burge, 2005 ] , rejects both versions of mentalism. Somewhere between the two poles is Chomsky’s [ Chomsky, 1965 ] theoretical mentalism, which sees linguistic rules as ultimately residing in the brain of speakers. However, his commitment to the cognitive reality of grammar does not imply a revision of linguistic methodology, which is maintained in its traditional form based on native speakers’ intuitions and the competence/performance distinction. The second problem, in part dependent on the first, is whether experimental data on language acquisition, comprehension and production have any bearing on linguistic theory. On this point too, there is no consensus among linguists. The division between competence and performance has often been used to secure linguistics from experimental evidence of various sorts [ Bunge, 1984 ] , while

A logic of vision

This essay attempts to develop a psychologically informed semantics of perception reports, whose predictions match with the linguistic data. As suggested by the quotation from Miller and Johnson-Laird, we take a hallmark of perception to be its fallible nature; the resulting semantics thus necessarily differs from situation semantics. On the psychological side, our main inspiration is Marrs (1982) theory of vision, which can easily accomodate fallible perception. In Marrs theory, vision is a multi-layered process. The different layers have filters of different gradation, which makes vision at each of them approximate. On the logical side, our task is therefore twofoldThis essay attempts to develop a psychologically informed semantics of perception reports, whose predictions match with the linguistic data. As suggested by the quotation from Miller and Johnson-Laird, we take a hallmark of perception to be its fallible nature; the resulting semantics thus necessarily differs from situation semantics. On the psychological side, our main inspiration is Marrs (1982) theory of vision, which can easily accomodate fallible perception. In Marrs theory, vision is a multi-layered process. The different layers have filters of different gradation, which makes vision at each of them approximate. On the logical side, our task is therefore twofold- to formalise the layers and the ways in which they may refine each other, and- to develop logical means to let description vary with such degrees of refinement.The first task is formalised by means of an inverse systems of first order models, with reality appearing as its inverse limit. The second task is formalised by means of so-called conditional quantifiers, a new form of generalised quantification which can best be described as resource bounded quantification. We show that the logic provides for a semantics and pragmatics of direct perception reports. In particular, direct perception reports have a possibly nonveridical, approximative semantics, which becomes veridical only by virtue of our pragmatic expectation that what is perceived would continue to be the case, were we to perceive more accurately.It is a general feature of resource bounded logics that the underlying logics are weak, but that stronger principles can be obtained pragmatically, by strengthening the resource. For the logic of vision this feature is clarified by showing how changes in the resource capture different notions of partiality, and by studying how the perception verb interacts with connectives and quantifiers in different visual contexts. The inference Veridicality, which is now viewed rather as a nonmonotonic inference, is also studied in depth.We end with an attempt to buttress the proposed model by comparing it with suggestions put forward in Cognitive or Conceptual Semantics, in the literature on evidentials, and in Husserls philosophy of perception.

Discourse Processing in Attention-Deficit Hyperactivity Disorder (ADHD)

ADHD is a psychiatric disorder characterised by persistent and developmentally inappropriate levels of inattention, impulsivity and hyperactivity. It is known that children with ADHD tend to produce incoherent discourses, e.g. by narrating events out of sequence. Here the aetiology of ADHD becomes of interest. One prominent theory is that ADHD is an executive function disorder, showing deficiencies of planning. Given the close link between planning, verb tense and discourse coherence postulated in van Lambalgen and Hamm (The proper treatment of events, 2004), we predicted specific deviations in the verb tenses produced by children with ADHD. Here we report on an experiment corroborating these predictions.