A Framework for Psychological Causal Induction: Integrating the Power and Covariation Views

We propose a theoretical framework for interpreting the roles of covariation and the idea of in psychological causal induction. According to this framework, the computation of inference is purely covariation-based, but covariation is computed only on a set of selected dimensions in a set of selected events. Whether or not a dimension has power or efficacy exerts an influence on whether or not that dimension is selected. W e present an experiment testing two predictions based on this framework. Our experiment showed a strong bias towards inferring a movement by a human agent (compared to a state) to be the cause of an event. In support of our hypothesis, this bias was found only when the state was not salient and the inference was made within a relatively short time, suggesting that the bias occurred at the selection stage

Alternative Approaches to Causal Induction: The Probabilistic Contrast Versus the Rescorla-Wagner Model

Rescorla and Wagner's (1972) model of associative learning (RWM ) and Cheng and Novick's (1990, 1991, 1992) Probabilistic Contrast Model (PCM) represent competing approaches to modeling the covariation component of human causal induction. Given certain patterns of environmental inputs to the learner, these models sometimes make contradictory predictions about what will be learned. Some of these situations have been tested in Pavlovian conditioning experiments using animal subjects. W e interpret these results according to PCM, and find that they are consistent with the predictions of the model. The current experiment implements similar experimental designs as a causal inference task involving humans as subjects. Tw o experimental conditions were compared to examine each model's predictions regarding when the extinction of conditioned inhibition will occur. In one condition, the RW M predicts that a previously perceived inhibitory stimulus will be judged as less inhibitory, whereas the PC M predicts that subjects will not change their causal judgments; in the second condition, the two models make the reverse claims. The data provide strong evidence favoring the PC

Pragmatic reasoning schemas

We propose that people typically reason about realistic situations using neither content-free syntactic inference rules nor representations of specific experiences. Rather, people reason using knowledge structures that we term pragmatic reasoning schemas, which are generalized sets of rules defined in relation to classes of goals. Three experiments examined the impact of a "permission schema" on deductive reasoning. Experiment 1 demonstrated that by evoking the permission schema it is possible to facilitate performance in Wason's selection paradigm for subjects who have had no experience with the specific content of the problems. Experiment 2 showed that a selection problem worded in terms of an abstract permission elicited better performance than one worded in terms of a concrete but arbitrary situation, providing evidence for an abstract permission schema that is free of domain-specific content. Experiment 3 provided evidence that evocation of a permission schema affects not only tasks requiring procedural knowledge, but also a linguistic rephrasing task requiring declarative knowledge. In particular, statements in the form if p then q were rephrased into the form p only if q with greater frequency for permission than for arbitrary statements, and rephrasings of permission statements produced a pattern of introduction of modals (must, can) totally unlike that observed for arbitrary conditional statements. Other pragmatic schemas, such as "causal" and "evidence" schemas can account for both linguistic and reasoning phenomena that alternative hypotheses fail to explain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25556/1/0000098.pd

Pragmatic versus syntactic approaches to training deductive reasoning

Two views have dominated theories of deductive reasoning. One is the view that people reason using syntactic, domain-independent rules of logic, and the other is the view that people use domain-specific knowledge. In contrast with both of these views, we present evidence that people often reason using a type of knowledge structure termed pragmatic reasoning schemas. In two experiments, syntactically equivalent forms of conditional rules produced different patterns of performance in Wason's selection task, depending on the type of pragmatic schema evoked. The differences could not be explained by either dominant view. We further tested the syntactic view by manipulating the type of logic training subjects received. If people typically do not use abstract rules analogous to those of standard logic, then training on abstract principles of standard logic alone would have little effect on selection performance, because the subjects would not know how to map such rules onto concrete instances. Training results obtained in both a laboratory and a classroom setting confirmed our hypothesis: Training was effective only when abstract principles were coupled with examples of selection problems, which served to elucidate the mapping between abstract principles and concrete instances. In contrast, a third experiment demonstrated that brief abstract training on a pragmatic reasoning schema had a substantial impact on subjects' reasoning about problems that were interpretable in terms of the schema. The dominance of pragmatic schemas over purely syntactic rules was discussed with respect to the relative utility of both types of rules for solving real-world problems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26121/1/0000197.pd

An MLL-Dependent Network Sustains Hematopoiesis

The histone methyltransferase Mixed Lineage Leukemia (MLL) is essential to maintain hematopoietic stem cells and is a leukemia protooncogene. Although clustered homeobox genes are well-characterized targets of MLL and MLL fusion oncoproteins, the range of Mll-regulated genes in normal hematopoietic cells remains unknown. Here, we identify and characterize part of the Mll-dependent transcriptional network in hematopoietic stem cells with an integrated approach by using conditional loss-of-function models, genomewide expression analyses, chromatin immunoprecipitation, and functional rescue assays. The Mll-dependent transcriptional network extends well beyond the previously appreciated Hox targets, is comprised of many characterized regulators of self-renewal, and contains target genes that are both dependent and independent of the MLL cofactor, Menin. Interestingly, PR-domain containing 16 emerged as a target gene that is uniquely effective at partially rescuing Mll-deficient hematopoietic stem and progenitor cells. This work highlights the tissue-specific nature of regulatory networks under the control of MLL/Trithorax family members and provides insight into the distinctions between the participation of MLL in normal hematopoiesis and in leukemia

Bˉ0→π+X\bar B^0 \to \pi^+ X in the Standard Model

In this paper we investigate the possibility of studying $B\to \pi$ form factor using the semi-inclusive decays $\bar B^0 \to \pi^+ + X_q$. In general $B\to PX$ semi-inclusive decays involve several hadronic parameters. But for $\bar B^0 \to \pi^+ X_q$ decays we find that in the factorization approximation, the only unknown hadronic parameters are the form factors $F^{B\to \pi}_{0,1}$. Therefore these form factors can be studied in $\bar B^0 \to \pi^+ X_q$ decays. Using theoretical model calculations for the form factors the branching ratios for $\bar B^0 \to \pi^+ X_d(\Delta S = 0)$ and $\bar B^0 \to \pi^+ X_s (\Delta S = -1)$, with the cut $E_{\pi} > 2.1$ GeV, are estimated to be in the ranges of $(3.1\sim 4.9) \times 10^{-5}(F^{B\to \pi}_1(0)/0.33)^2$ and $(2.5\sim 4.2)\times 10^{-5}(F_1^{B\to \pi}(0)/0.33)^2$, respectively, depending on the value of $\gamma$. The combined branching ratio for $\bar B^0 \to \pi^+ (X_d+ X_s)$ is about $7.4\times 10^{-5} (F^{B\to \pi}_1(0)/0.33)^2$ and is insensitive to $\gamma$. We also discuss CP asymmetries in these decay modes.Comment: RevTex 8 pages and two figure