Comparing Computational Power

It is common practice to compare the computational power ofdifferent models of computation. For example, the recursivefunctions are strictly more powerful than the primitive recursivefunctions, because the latter are a proper subset of the former(which includes Ackermann's function). Side-by-side with this"containment" method of measuring power, it is also standardto base comparisons on "simulation". For example, one says thatthe (untyped) lambda calculus is as powerful—computationallyspeaking—as the partial recursive functions, because thelambda calculus can simulate all partial recursive functionsby encoding the natural numbers as Church numerals. The problem is that unbridled use of these two distinct waysof comparing power allows one to show that some computationalmodels (sets of partial functions) are strictly stronger thanthemselves! We argue that a better definition is that modelA is strictly stronger than B if A can simulate B via some encoding,whereas B cannot simulate A under any encoding. We show thatwith this definition, too, the recursive functions are strictlystronger than the primitive recursive. We also prove that therecursive functions, partial recursive functions, and Turingmachines are "complete", in the sense that no injective encodingcan make them equivalent to any "hypercomputational" model.¹     

A model of plausibility

Plausibility has been implicated as playing a critical role in many cognitive phenomena from comprehension to problem solving. Yet, across cognitive science, plausibility is usually treated as an operationalized variable or metric rather than being explained or studied in itself. This article describes a new cognitive model of plausibility, the Plausibility Analysis Model (PAM), which is aimed at modeling human plausibility judgment. This model uses commonsense knowledge of concept-coherence to determine the degree of plausibility of a target scenario. In essence, a highly plausible scenario is one that fits prior knowledge well: with many different sources of corroboration, without complexity of explanation, and with minimal conjecture. A detailed simulation of empirical plausibility findings is reported, which shows a close correspondence between the model and human judgments. In addition, a sensitivity analysis demonstrates that PAM is robust in its operations.     

Uncertainty about the rest of the sentence

A word-by-word human sentence processing complexity metric is presented. This metric formalizes the intuition that comprehenders have more trouble on words contributing larger amounts of information about the syntactic structure of the sentence as a whole. The formalization is in terms of the conditional entropy of grammatical continuations, given the words that have been heard so far. To calculate the predictions of this metric, Wilson and Carroll's (1954) original entropy reduction idea is extended to infinite languages. This is demonstrated with a mildly context-sensitive language that includes relative clauses formed on a variety of grammatical relations across the Accessibility Hierarchy of Keenan and Comrie (1977). Predictions are derived that correlate significantly with repetition accuracy results obtained in a sentence-memory experiment (Keenan & Hawkins, 1987).     

TEACHING SELF-ADMINSTRATION OF NASOGASTRIC TUBE INSERTION TO AN ADOLESCENT WITH CROHN DISEASE

We examined the effectiveness of simulation training to teach an adolescent male with Crohn disease to self-administer nasogastric tube insertion. Nasogastric tube insertion was taught using simulation training, after which self-insertion skills were assessed. Results across skill components indicated that this subject was able to self-administer insertion of the nasogastric tube.     

Blind ethics: Closing one's eyes polarizes moral judgments and discourages dishonest behavior

Four experiments demonstrate that closing one’s eyes affects ethical judgment and behavior because it induces people to mentally simulate events more extensively. People who considered situations with their eyes closed rather than open judged immoral behaviors as more unethical and moral behaviors as more ethical. In addition, considering potential decisions with closed eyes decreased stated intentions to behave ethically and actual self-interested behavior. This relationship was mediated by the more extensive mental simulation that occurred with eyes closed rather than open, which, in turn, intensified emotional reactions to the ethical situation. We discuss the implications of these findings for moral psychology and ethical decision making.     

Linkage Analysis as Evidence in Court: A Thematic Analysis of Mock Juror Deliberations

Linkage analysis has, albeit occasionally, been presented in courts across the world as evidence that a series of offences possess behavioural similarities and distinctiveness from other offences, meaning they have probably been committed by the same individual. It is therefore imperative to ascertain how linkage analysis is regarded by juries within the context of deliberations. Three groups of participants (N = 22) eligible for jury duty in England and Wales viewed a simulated rape and murder trial derived from an actual South African case. Linkage analysis formed the sole evidence against the defendant in the two later offences, although DNA matches and eyewitness identifications of the defendant were present in the two earlier offences. Participant deliberations were recorded and subjected to thematic analysis. Five themes were discovered: behavioural consistencies and inconsistencies, physical versus case linkage evidence, barriers to admissibility, potential uses of linkage analysis, and dependence of lay knowledge. Jurors' over‐reliance on erroneous lay knowledge contributed to their conclusion that linkage analysis is, at present, unrepresentative evidence that cannot independently indicate a defendant's culpability. However, participants believed that linkage analysis could be a useful tool within investigations and, with further research evidence, in court in England and Wales. Copyright © 2014 John Wiley & Sons, Ltd.     

汉语句子理解中物体隐含颜色心理模拟的ERPs研究

当前研究采用事件相关电位(ERPs)技术,同时沿用经典的句图匹配范式,考察句子理解中物体典型颜色与非典型颜色的心理加工过程在脑电活动上的反映。实验中被试先阅读句子再判断句子后呈现的图片物体是否在句子中出现过,句子中隐含的物体颜色或是关键物体的典型颜色或是非典型颜色。实验结果发现,典型颜色句子版本下句图不匹配条件比句图匹配条件引发了更大的N400效应;而非典型颜色句子版本下两者N400差异不显著。研究结果表明,人们在汉语句子理解过程中会实时对隐含的物体颜色信息进行心理模拟。并且,句子隐含物体颜色的典型性是造成匹配易化或不匹配易化的关键因素之一。     

Dominance Measuring Method Performance under Incomplete Information about Weights

In multi‐attribute utility theory, it is often not easy to elicit precise values for the scaling weights representing the relative importance of criteria. A very widespread approach is to gather incomplete information. A recent approach for dealing with such situations is to use information about each alternative's intensity of dominance, known as dominance measuring methods. Different dominance measuring methods have been proposed, and simulation studies have been carried out to compare these methods with each other and with other approaches but only when ordinal information about weights is available. In this paper, we use Monte Carlo simulation techniques to analyse the performance of and adapt such methods to deal with weight intervals, weights fitting independent normal probability distributions or weights represented by fuzzy numbers. Moreover, dominance measuring method performance is also compared with a widely used methodology dealing with incomplete information on weights, the stochastic multicriteria acceptability analysis (SMAA). SMAA is based on exploring the weight space to describe the evaluations that would make each alternative the preferred one. Copyright © 2012 John Wiley & Sons, Ltd.     

A closer look at decisions to quit

Aspects of March and Simon’s (1958) subjective expected utility model and a prediction of Lee and Mitchell’s (1994) unfolding model of voluntary employee turnover were tested. A policy capturing simulation that varied high, moderate, and low levels of five job characteristics was used to model voluntary turnover decision processes for 532 nurses. Survey measures of these job characteristics obtained over the next 2 years were multiplied by weights derived from nurse simulations to yield turnover likelihood estimates. These estimates exhibited 80%, 127%, and 190% more predictive power (depending on turnover operationalization) than post-employment survey estimates of turnover intention, job satisfaction, and job availability. Groups of nurses with homogeneous voluntary turnover decision models were also identified, though no groups with homogeneous job perceptions were observed. Evidence suggested nurses responded to “shocks” as predicted. March and Simon’s model of voluntary turnover was supported and implications drawn for managing voluntary nursing turnover.