A diffusion model decomposition of the practice effect

When people repeatedly perform the same cognitive task, their mean response times (RTs) invariably decrease. The mathematical function that best describes this decrease has been the subject of intense debate. Here, we seek a deeper understanding of the practice effect by simultaneously taking into account the changes in accuracy and in RT distributions with practice, both for correct and error responses. To this end, we used the Ratcliff diffusion model, a successful model of two-choice RTs that decomposes the effect of practice into its constituent psychological processes. Analyses of data from a 10,000-trial lexical decision task demonstrate that practice not only affects the speed of information processing, but also response caution, response bias, and peripheral processing time. We conclude that the practice effect consists of multiple subcomponents, and that it may be hazardous to abstract the interactive combination of these subcomponents in terms of a single output measure such as mean RT for correct responses. Supplemental materials may be downloaded from http://pbr .psychonomic-journals.org/content/supplemental.     

THE MODAL ARGUMENT FOR A PRIORI JUSTIFICATION

Kant famously argued that, from experience, we can only learn how something actually is, but not that it must be so. In this paper, I defend an improved version of Kant's argument for the existence of a priori knowledge, the Modal Argument , against recent objections by Casullo and Kitcher. For the sake of the argument, I concede Casullo's claim that we may know certain counterfactuals in an empirical way and thereby gain epistemic access to some nearby, nomologically possible worlds. But I maintain that our beliefs about metaphysical necessities still cannot be justified empirically. Furthermore, I reject Casullo's deflationary thesis about the significance of such justification. Kitcher's most troublesome objection is that we can gain any modal justification whatsoever through testimony , i.e. in an experiential way. This can be countered by distinguishing between productive sources of justification, like perception, and merely reproductive sources, like testimony. Thus, some productive a priori source will always be needed somewhere. ¹     

A Hierarchical Ornstein–Uhlenbeck Model for Continuous Repeated Measurement Data

In this paper, we present a diffusion model for the analysis of continuous-time change in multivariate longitudinal data. The central idea is to model the data from a single person with an Ornstein–Uhlenbeck diffusion process. We extend it hierarchically by allowing the parameters of the diffusion process to vary randomly over different persons. With this approach, both intra and interindividual differences are analyzed simultaneously. Furthermore, the individual difference parameters can be regressed on covariates, thereby providing an explanation of between-person differences. Unstructured and unbalanced data pose no problem for the model to be applied. We demonstrate the method on data from an experience sampling study to investigate changes in the core affect. It can be concluded that different factors from the five factor model of personality are related to features of the trajectories in the core affect space, such as the cross-correlation and variability of the changes.     

International Union of History and Philosophy of Science Division of Logic,Methodology and Philosophy of Science (IUHPS/DLMPS)

International Union of History and Philosophy of Science Division of Logic, Methodology and Philosophy of Science (IUHPS/DLMPS)Bulletin no. 16     

A comparison of the common-sense and ‘scientific’ conceptions of extroversion—introversion

From research on the organization of implicit personality theory, and on the fakability of psychometrically sophisticated scales a general argument about the conceptual overlap between implicit personality theory and ‘scientific’ theories of personality is developed. This is tested in the case of the common-sense conception of extroversion—introversion, and that of Eysenck. The convergent validity of these two conceptions are found to be high enough to support the argument. The implications of the argument are discussed in relation to the correspondences between implicit personality theory and personality theory, and the functions of personality theory in psychology and implicit personality theory in everyday life.     

Children's voluntary exploration and preference for tactually presented nonsense shapes differing in complexity

This study represents an extension of research on children's response to nonsense shapes varying in complexity to the tactual modality. Wooden cut-out shapes varying in number of turns from 3 to 40 were presented to children at Grades I, III, and VI, both for voluntary haptic exploration, and for preference choices. Both of these measures yielded monotonically increasing functions in the oldest group, while the youngest showed a similar but much flatter gradient for exploration times, and an inverted-U shaped preference function; data for the Third Grade subjects were in both cases intermediate. Supplementary data based on an analysis of preference choice latencies for stimulus pairs of adjacent levels of complexity, as well as on ratings of subject's mode of exploration of the stimuli under both response sets showed a marked shift from a predominantly passive to an increasingly active mode of exploration. These results are related to the age differences for the exploration-time and preference data, and discussed in relation to Schachtel's differentiation between allocentric and autocentric modes of perception.     

Carnap's inductive probabilities as a contribution to decision theory

Common probability theories only allow the deduction of probabilities by using previously known or presupposed probabilities. They do not, however, allow the derivation of probabilities from observed data alone. The question thus arises as to how probabilities in the empirical sciences, especially in medicine, may be arrived at. Carnap hoped to be able to answer this question byhis theory of inductive probabilities. In the first four sections of the present paper the above mentioned problem is discussed in general. After a short presentation of Carnap's theory it is then shown that this theory cannot claim validity for arbitrary random processes. It is suggested that the theory be only applied to binomial and multinomial experiments. By application of de Finetti's theorem Carnap's inductive probabilities are interpreted as consecutive probabilities of the Bayesian kind. Through the introduction of a new axiom the decision parameter λ can be determined even if no a priori knowledge is given. Finally, it is demonstrated that the fundamental problem of Wald's decision theory, i.e., the determination of a plausible criterion where no a priori knowledge is available, can be solved for the cases of binomial and multinomial experiments.     

Implicit and self-attributed motives to achieve: two separate but interacting needs

This research examined how implicit and self-attributed needs to achieve (labeled as n Ach and san Ach, respectively) combine with self-referenced and norm-referenced feedback to predict effort-related (task performance) and choice-related (task continuation) indexes of students' engagement in a mental concentration task. In Experiment 1 the authors found that in a task-focused setting, task performance was predicted by the joint effect of self-referenced feedback and n Ach, whereas task continuation was predicted by the joint effect of norm-referenced feedback and san Ach. In Experiment 2 the authors found that in an ego-focused setting, n Ach and san Ach interacted in the prediction of task performance but not of task continuation. In Experiment 3 the authors found that the effects of n Ach and san Ach on students' performance were mediated by the anticipated affective value of achievement outcomes. These findings are discussed in relation to a 2-system approach to achievement motivation.