On Interpreting Chaitin's Incompleteness Theorem

The aim of this paper is to comprehensively question the validity of the standard way of interpreting Chaitin's famous incompleteness theorem, which says that for every formalized theory of arithmetic there is a finite constant c such that the theory in question cannot prove any particular number to have Kolmogorov complexity larger than c. The received interpretation of theorem claims that the limiting constant is determined by the complexity of the theory itself, which is assumed to be good measure of the strength of the theory.I exhibit certain strong counterexamples and establish conclusively that the received view is false. Moreover, I show that the limiting constants provided by the theorem do not in any way reflect the power of formalized theories, but that the values of these constants are actually determined by the chosen coding of Turing machines, and are thus quite accidental.     

Assessment of information content in visual signal: analysis of optical flow fractal complexity

We make a first attempt at distinguishing an information-carrying visual signal by comparing visual characteristics of American Sign Language to everyday human motion, to identify what clues might be available in one but not in the other. The comparison indicated significantly higher fractal complexity in sign language across tested frequency bands (0.01–15?Hz), as compared to everyday motion. A comparison of our results with other work showing high fractal complexity in the speech signal allows us to suggest the underlying properties of linguistic signals which allow babies to “tune into” a specific channel, or modality, during language acquisition.     

When and why hierarchy steepness is related to team performance

This study develops and tests a contingency theory on the functions of status hierarchy steepness in teams. Findings from a field study among 438 employees working in 72 work teams across diverse business settings demonstrate that task complexity moderates the relationships between status hierarchy steepness, different types of team conflict, and team performance. Steeper status hierarchies were negatively related to both process and task conflict, and hence increased team performance in teams working on tasks with lower complexity but did not yield such clear conflict and performance effects in teams working on more complex tasks. By showing that various levels of task complexity determine whether status hierarchy steepness has a conflict-regulating function that drives team performance, this research generates valuable insights about the context dependency of team responses to status hierarchy steepness.     

The potential effects of protected nests and cage complexity on maternal aggression in house mice

I studied the behavior of nursing house mice (Mus musculus) in captivity and used a two-by-two factorial design to test the hypothesis that the combination of a protected nest along with a chance for the intruders to retreat would improve the ability of resident females to defend their litters from infanticidal males. A chance for the intruder to retreat was manipulated by testing the resident females in either a single- or a two-compartment cage. The effect of a protected nest was examined by providing females with a nest box having a narrow entrance. During each test, an infanticidal adult male was introduced into the cage of a resident female and her pups. I observed that neither the presence of a protected nest nor the chance for the intruders to retreat to a different compartment, or a combination of the two, increased the ability of a female to defend her litter against an intruder male. Moreover, neither of these two factors influenced the overall behavior of the resident females. I obtained similar results after using data from previous studies to examine the influence of both of these factors on the efficiency of maternal aggression. Overall, these two approaches showed that females are often unable to prevent intruders from committing infanticide. I discuss the validity of the hypothesis that maternal aggression evolved as a mechanism to protect offspring from infanticide. Aggr. Behav. 24:385–396, 1998. © 1998 Wiley-Liss, Inc.     

Context and Complexity in Incremental Sentence Interpretation: An ERP Study on Temporal Quantification

The present event-related potential (ERP) study used picture–sentence verification to investigate the neurolinguistic correlates of the online processing of compositional-semantic information. To this end, we examined context effects on sentences involving temporal adverbial quantification likeJana war jeden Morgen schwimmen an den Arbeitstagen (“Jana went for a swim every morning during the working week”). We tested whether the conceptual complexity associated with quantifying over time intervals leads to delayed predictions regarding the upcoming words in a sentence. The present study replicated previous results relating to quantification over individuals, which are conceptually less complex than time intervals. Analogous to previous studies, false vs. true sentences elicited an N400 whenever contextual cues did not permit a potential revision of a locally assigned truth value. The present results are compatible with an approach under which contextual cues are immediately considered for predicting how a sentence continues. The fact that the contextual complexity did not lead to processing delays indicates that the processing system quickly abstracts away from the conceptual complexity associated with the linguistic input if such an abstraction is possible.     

Issues in Assessing Psychological Characteristics at a Distance: An Introduction to the Symposium

This article provides an overview of the issues, methods, and constructs presented in the papers for the symposium Issues in Assessing Psychological Characteristics at a Distance. These papers share a substantive focus on the psychological characteristics of U.S. presidents and a common commitment to the use of 'at-a-distance' assessment techniques. In this context, at-a distance measures raise several substantive and methodological issues, including the connections between leaders and advisors, the value of public versus private rhetoric, and differences between spontaneous and prepared source material. The authors of the papers use two psychological constructs, the operational code and conceptual complexity, to investigate these issues and to illustrate the utility of at-a-distance methods for assessing psychological characteristics.     

ThePrepared and Spontaneous Remarks of Presidents Reagan and Bush: A Validity Comparison for At-a-Distance Measurements

This paper examines the spontaneous and prepared remarks of Presidents Reagan and Bush in the domain of U.S.-Soviet relations at the end of the Cold War. The findings suggest thatm researchers should be cautious when drawing their sample frames, because scores gleaned from prepared remarks may contain systematic differences large enough to affect the workings of models using at-a-distance measurements. However, if the leader is involved in the preparation of speeches he or she delivers, then these prepared speeches typically are as valid an indicator of the leader's psychological variables as are spontaneous remarks from interviews. Context effects may be present for both cognitive and personal variables in remarks from spontaneous and prepared statements. Impression management, therefore, may be a bigger problem than authorship in assessing leaders at a distance.     

An O(n log n)-Space Decision Procedure for the Relevance Logic B+

In previous work we gave a new proof-theoretical method for establishing upper-bounds on the space complexity of the provability problem of modal and other propositional non-classical logics. Here we extend and refine these results to give an O(n log n)-space decision procedure for the basic positive relevance logic B⁺. We compute this upper-bound by first giving a sound and complete, cut-free, labelled sequent system for B⁺, and then establishing bounds on the application of the rules of this system.     

Does Agrammatic Speech Constitute a Regression to Child Language? A Three-Way Comparison between Agrammatic, Child, and Normal Ellipsis

When children are in the process of learning their mother tongue, they show frequent use of nonfinite clauses, even though they produce finite clauses at the same time, thereby demonstrating the availability of the functional domain associated with finiteness. In this study the hypothesis was tested that this behavior results from an overuse of the normal elliptical repertoire that has also been observed in agrammatic aphasia. The purpose of this overuse is prevention of computational overload. In support of the hypothesis it was found that children behaved very similar to aphasics and normal adults with respect to the following parameters: (a) distribution of types of ellipsis, (b) elaboration of ellipses, (c) word order, (d) subject omission, (e) frequency of weak subject pronouns, and (f) verb type (eventivity). The results also support the Jackson/Jakobson regression hypothesis, at least at the grammatical level.