Disfluencies and human language comprehension

Spoken language contains disfluencies, which include editing terms such as uh and um as well as repeats and corrections. In less than ten years the question of how disfluencies are handled by the human sentence comprehension system has gone from virtually ignored to a topic of major interest in computational linguistics and psycholinguistics. We discuss relevant empirical findings and describe a computational model that captures how disfluencies influence parsing and comprehension. The research reviewed shows that the parser, which presumably evolved to handle conversations, deals with disfluencies in a way that is efficient and linguistically principled. The success of this research program reinforces the current trend in cognitive science to view cognitive mechanisms as adaptations to real-world constraints and challenges.     

Conceptual accessibility and sentence production in a free word order language (Odawa)

The study reported here was conducted in the Algonquian language of Odawa (a.k.a. Ottawa), with the goal of gaining new insight into the ways that conceptual accessibility affects human sentence production. The linguistic characteristics of Odawa are quite different from those found in the languages most often examined by psycholinguists. The data obtained from the sentence production experiment reported here are thus relevant to production in a heretofore unexamined language. Moreover, the data inform broader theoretical issues, such as the extent to which sentence production can be considered as an incremental process, and the interaction of the various factors affecting conceptual accessibility. In addition, the study stands as evidence that experimental psycholinguistic research can and should be carried out in typologically diverse languages.     

Role of cholinergic system on the construction of memories: taste memory encoding

There is a large body of evidence suggesting that cholinergic activity is involved in memory processes. It seems that cholinergic activity is essential to learn several tasks and recent works suggest that acetylcholine plays an important role during the early stages of memory formation. In this review, we will discuss the results related to taste memory formation, focusing particularly on the conditioned taste aversion paradigm. We will first give evidence that nucleus basalis magnocellularis is involved in taste memory formation, due to its cholinergic projections. We then show that the cholinergic activity of the insular (gustatory) cortex is related to the taste novelty, and that the cholinergic signals initiated by novelty are crucial for taste memory formation. Then we present recent data indicating that cortical activation of muscarinic receptors is necessary for taste trace encoding, and also for its consolidation under certain circumstances. Finally, interactions between the cholinergic and other neuromodulatory systems inducing intracellular mechanisms related to plastic changes will be proposed as important processes underlying gustatory memory trace storage.     

Age Preservation of the Syntactic Processor in Production

Two experiments are reported on the influence of cognitive aging on grammatical choice in language production. In both experiments, participants from two age-groups (young and old) produced sentences in a formulation task (V. Ferreira, 1996) that contrasted conditions allowing a choice between alternative sentence arrangements (i.e., double object or prepositional dative) or that permitted no choice (i.e., prepositional dative only). Experiment 1 showed that older adults were able to formulate the alternative sentence arrangements with the same speed and fluency as young adults. Experiment 2 showed that cueing attention to one of the two object nouns to be included in the sentence resulted in the earlier expression of the cued noun in choice conditions, but with little evidence of a response time or dysfluency cost in the no-choice condition. As in Experiment 1, there were no substantive age differences in latencies or dysfluencies. These results support existing models for the mechanisms that choose between grammatical alternatives and bind phrases to available argument positions and provide evidence that older adults are not impaired in their use of these mechanisms.     

Crisis phenomena among African adolescents

This study investigated inadequate parent-child relationships, problems with regard to sexuality, and substance abuse among African university students. They reported experiencing positive aspects of the parent-child relationship, such as acceptance, love, understanding, encouragement, and guidance, as well as negative aspects, including inadequate communication and parents' authoritarian attitudes. Numerous sexual issues and the abuse of alcohol and other drugs were perceived as serious problems among teenagers in general. Although an inadequate parent-child relationship appears to contribute to substance abuse and sexuality problems, it cannot be regarded as solely responsible, as a multitude of factors also play a role. The results indicate the need for life-skills training for both adolescents and parents, particularly regarding communication.     

A Note on Finiteness in the Predicative Foundations of Arithmetic

Recently, Feferman and Hellman (and Aczel) showed how to establish the existence and categoricity of a natural number system by predicative means given the primitive notion of a finite set of individuals and given also a suitable pairing function operating on individuals. This short paper shows that this existence and categoricity result does not rely (even indirectly) on finite-set induction, thereby sustaining Feferman and Hellman's point in favor of the view that natural number induction can be derived from a very weak fragment of finite-set theory, so weak that finite-set induction is not assumed. Many basic features of finiteness fail to hold in these weak fragments, conspicuously the principle that finite sets are in one-one correspondence with a proper initial segments of a (any) natural number structure. In the last part of the paper, we propose two prima facie evident principles for finite sets that, when added to these fragments, entail this principle.     

Amnesia by post-training infusion of glutamate receptor antagonists into the amygdala, hippocampus, and entorhinal cortex.

The blockers of glutamate receptors, aminophosphonovaleric acid (AP5) (5.0 micrograms) and cyano-nitroquinoxaline-dione (CNQX) (0.5 microgram), were infused bilaterally into the amygdala, dorsal hippocampus, or entorhinal cortex of rats through indwelling cannulae 0, 90, 180, or 360 min after step-down inhibitory avoidance training. Animals were tested for retention 24 h after training. In the amygdala or hippocampus, AP5 was amnestic when given 0 min after training and CNQX was amnestic when given 0, 90, or 180 min after training. In the entorhinal cortex, AP5 was amnestic when given 90 or 180 min after training and CNQX had no effect. The results suggest that a phenomenon sensitive first to AP5 and then to CNQX in the amygdala and hippocampus, probably long-term potentiation (LTP), is crucial to post-training memory processing. LTP in these two structures could underlie their role in memory consolidation and could explain the late involvement of the entorhinal cortex in post-training memory processing.     

Use of verb information in syntactic parsing: evidence from eye movements and word-by-word self-paced reading

We investigated whether readers use verb information to aid in their initial parsing of temporarily ambiguous sentences. In the first experiment, subjects' eye movements were recorded. In the second and third experiments, subjects read sentences by using a noncumulative and cumulative word-by-word self-paced paradigm, respectively. The results of the first two experiments supported Frazier and Rayner's (1982) garden-path model of sentence comprehension: Verb information did not influence the initial operation of the parser. The third experiment indicated that the cumulative version of the self-paced paradigm is not appropriate for studying on-line parsing. We conclude that verb information is not used by the parser to modify its initial parsing strategies, although it may be used to guide subsequent reanalysis.