Correcting Too Much or Too Little? The Performance of Three Chi-Square Corrections

This simulation study investigates the performance of three test statistics, T₁, T₂, and T₃, used to evaluate structural equation model fit under non normal data conditions. T₁ is the well-known mean-adjusted statistic of Satorra and Bentler. T₂ is the mean-and-variance adjusted statistic of Sattertwaithe type where the degrees of freedom is manipulated. T₃ is a recently proposed version of T₂ that does not manipulate degrees of freedom. Discrepancies between these statistics and their nominal chi-square distribution in terms of errors of Type I and Type II are investigated. All statistics are shown to be sensitive to increasing kurtosis in the data, with Type I error rates often far off the nominal level. Under excess kurtosis true models are generally over-rejected by T₁ and under-rejected by T₂ and T₃, which have similar performance in all conditions. Under misspecification there is a loss of power with increasing kurtosis, especially for T₂ and T₃. The coefficient of variation of the nonzero eigenvalues of a certain matrix is shown to be a reliable indicator for the adequacy of these statistics.     

Do computer simulations support the Argument from Disagreement?

According to the Argument from Disagreement (AD) widespread and persistent disagreement on ethical issues indicates that our moral opinions are not influenced by moral facts, either because there are no such facts or because there are such facts but they fail to influence our moral opinions. In an innovative paper, Gustafsson and Peterson (Synthese, published online 16 October, 2010) study the argument by means of computer simulation of opinion dynamics, relying on the well-known model of Hegselmann and Krause (J Artif Soc Soc Simul 5(3):1–33, 2002; J Artif Soc Soc Simul 9(3):1–28, 2006). Their simulations indicate that if our moral opinions were influenced at least slightly by moral facts, we would quickly have reached consensus, even if our moral opinions were also affected by additional factors such as false authorities, external political shifts and random processes. Gustafsson and Peterson conclude that since no such consensus has been reached in real life, the simulation gives us increased reason to take seriously the AD. Our main claim in this paper is that these results are not as robust as Gustafsson and Peterson seem to think they are. If we run similar simulations in the alternative Laputa simulation environment developed by Angere and Olsson (Angere, Synthese, forthcoming and Olsson, Episteme 8(2):127–143, 2011) considerably less support for the AD is forthcoming.     

A DDL Approach to Pluralistic Ignorance and Collective Belief

A group is in a state of pluralistic ignorance (PI) if, roughly speaking, every member of the group thinks that his or her belief or desire is different from the beliefs or desires of the other members of the group. PI has been invoked to explain many otherwise puzzling phenomena in social psychology. The main purpose of this article is to shed light on the nature of PI states – their structure, internal consistency and opacity – using the formal apparatus of Dynamic Doxastic Logic, and also to study the sense in which such states are “fragile”, i.e. to identify plausible conditions under which a PI state cascades into a state of shared belief as the result of announcement.     

The testing effect as a function of explicit testing instructions and judgments of learning

During study, people monitor their learning; the output of this monitoring is captured in so-called judgments of learning (JOLs). JOLs predict later recall better if they are made after a slight delay, instead of immediately after study (the delayed JOL effect). According to the self-fulfilling prophecy (SFP) hypothesis delayed JOLs are based on covert retrieval attempts from long-term memory, and successful retrieval attempts in themselves enhance learning (the testing effect). We compared memory for 40 Swahili-Swedish paired associates after a week as a function of three different learning conditions, namely study plus (i) explicitly instructed self-testing, (ii) delayed JOLs, or (iii) less self-testing. We showed that repeated delayed JOLs lead to a memory improvement that does not differ significantly from a comparable condition where the participants are explicitly testing memory, and both the latter groups performed reliably better than a group that self-tested less. The results suggest that delayed JOLs improve long-term retention as efficiently as explicit memory testing and lend support to the SFP hypothesis.     

Opening the cuebox: The information children and young adults generate and rely on when making inferences from memory

We used a cue‐generation and a cue‐selection paradigm to investigate the cues children (9‐ to 12‐year‐olds) and young adults (17‐year‐olds) generate and select for a range of inferences from memory. We found that children generated more cues than young adults, who, when asked why they did not generate some particular cues, responded that they did not consider them relevant for the task at hand. On average, the cues generated by children were more perceptual but as informative as the cues generated by young adults. When asked to select the most informative of two cues, both children and young adults tended to choose a hidden (i.e., not perceptual) cue. Our results suggest a developmental change in the cuebox (i.e., the set of cues used to make inferences from memory): New cues are added to the cuebox as more cues are learned, and some old, perceptual cues, although informative, are replaced with hidden cues, which, by both children and young adults, are generally assumed to be more informative than perceptual cues.     

Does adolescent heavier alcohol use predict young adult aggression and delinquency? Parallel analyses from four Australasian cohort studies

While the association between heavy alcohol consumption and aggression has been well documented, the causal direction of this association, particularly at a population level, is disputed. A number of causal sequences have been proposed. First, that aggression leads to heavy alcohol use. Second, that heavy alcohol use leads to aggression. Third, that the association between alcohol use and aggression is due to confounding by (a) sociodemographic variables or (b) delinquency. We report here data from four Australasian prospective longitudinal studies of adolescents, to assess the temporal sequence of heavy drinking and aggression over the period from adolescence to young adulthood. The four cohort studies provide a total sample of 6,706 persons (Australian Temperament Project, n = 1701; Christchurch Health and Development Study, n = 931; Mater-University of Queensland Study of Pregnancy, n = 2437; Victorian Adolescent Health Cohort Study, n = 1637). We use multinomial logistic regression to determine whether early adolescent aggression predicts subsequent age of onset of heavy episodic drinking (HED), after adjustment for concurrent sociodemographic factors and delinquency. We then consider whether HED predicts subsequent aggression, after adjusting for past aggression, concurrent delinquency, and a range of confounders. There are broadly consistent findings across the four cohort studies. Early aggression strongly predicts subsequent HED. HED predicts later aggression after adjustment for prior aggression and other confounders. Policies that alter population levels of alcohol consumption are likely to impact on levels of aggression in societies where HED linked to aggression is more common.