Axel Buchner

GPOWER : A GENERAL POWER ANALYSIS PROGRAM

GPOWER is a completely interactive, menu-driven program for IBM-compatible and Apple Macintosh personal computers. It performs high-precision statistical power analyses for the most common statistical tests in behavioral research, that is,t tests,F tests, andχ2 tests. GPOWER computes (1) power values for given sample sizes, effect sizes andα levels (post hoc power analyses); (2) sample sizes for given effect sizes,α levels, and power values (a priori power analyses); and (3)α andβ values for given sample sizes, effect sizes, andβ/α ratios (compromise power analyses). The program may be used to display graphically the relation between any two of the relevant variables, and it offers the opportunity to compute the effect size measures from basic parameters defining the alternative hypothesis. This article delineates reasons for the development of GPOWER and describes the program’s capabilities and handling.

Toward unbiased measurement of conscious and unconscious memory processes within the process dissociation framework.

L.L. Jacobys (1991) process dissociation framework has been welcomed as a tool for differentiating controlled and automatic cognitive processes. Several variants of the original process dissociation measurement model are integrated in this article, and it is shown that the model ignores guessing and, hence, response bias. An extension of the original model is suggested that includes guessing parameters. The original model and the extended model are evaluated empirically. In 3 experiments using a yes-no recognition task, response bias was manipulated in various ways. The original model falsely attributes effects of response biases to either controlled or uncontrolled processes or to both. The extended model, in contrast, results in estimates of the contributions of controlled and uncontrolled memory processes that are relatively unaffected by response biases. The extended model is recommended as a measurement tool.

Implicit learning of unique and ambiguous serial transitions in the presence and absence of a distractor task

Three experiments investigated the effects of task load, time of secondary task onset, and response-stimulus time interval on direct and indirect measures of learning in the M. J. Nissen and P. Bullemer (1987) task. Experiment 1 demonstrated that both unique and ambiguous serial transitions can be learned in the absence and presence of an attentional distractor task. Experiment 2 showed that the time of secondary task onset affects the degree to which unique and ambiguous serial transitions are learned. Experiment 3 demonstrated that the learning of a sequential transition is affected by the length of the time interval between the response to a stimulus and the presentation of the next stimulus

On the reliability of implicit and explicit memory measures.

Functional dissociations between implicit and explicit memory tests often take the form of large differences between groups or experimental conditions (e.g., amnesics and controls, elderly and younger persons, or persons learning with and without a distracting secondary task) when performance is assessed using explicit memory tests, whereas no difference is observed with implicit memory tests. We argue that the interpretation of such dissociations in terms of the memory processes or systems involved in performance is problematic because the same data pattern would emerge as a result of a mere methodological artifact, that is, the situation that implicit memory tests have low reliability whereas explicit memory tests are fairly reliable measurement instruments. We present reasons for such a reliability difference, and we demonstrate it empirically in Experiments 1a, 1b, and 2. However, our analysis also shows, and Experiment 3 confirms empirically, that implicit memory tests need not necessarily be less reliable measurement instruments than explicit memory tests.

Decomposing the hindsight bias : A multinomial processing tree model for separating recollection and reconstruction in hindsight

After having received feedback about the correct answer to a question, a memory judgment about ones own past answer, the original judgment (OJ), is often biased toward the feedback. The authors present a multinomial model that explains this hindsight bias effect in terms of both memory impairments and reconstruction biases for nonrecollected OJs. The model was tested in 4 experiments. As predicted, the parameters measuring OJ recollection could be influenced selectively by contrasting items whose OJs were or were not retrieved successfully earlier (Experiment 1). Increasing the feedback-recall delay reduced reconstruction biases exclusively (Experiment 2), whereas discrediting the feedback enhanced recollection of the OJs to feedback items (Experiment 3). hi Experiment 4, the models guessing parameters, but no other parameters, varied as a function of the number of response alternatives. The authors discuss implications for hindsight bias theories.

Negative Correlations between Control Performance and Verbalizable Knowledge: Indicators for Implicit Learning in Process Control Tasks?

Negative correlations between task performance in dynamic control tasks and verbalizable knowledge, as assessed by a post-task questionnaire, have been interpreted as dissociations that indicate two antagonistic modes of learning, one being “explicit”, the other “implicit”. This paper views the control tasks as finite-state automata and offers an alternative interpretation of these negative correlations. It is argued that “good controllers” observe fewer different state transitions and, consequently, can answer fewer post-task questions about system transitions than can “bad controllers”. Two experiments demonstrate the validity of the argument by showing the predicted negative relationship between control performance and the number of explored state transitions, and the predicted positive relationship between the number of explored state transitions and questionnaire scores. However, the experiments also elucidate important boundary conditions for the critical effects. We discuss the implications of these findings, and of other problems arising from the process control paradigm, for conclusions about implicit versus explicit learning processes.

The nature of memory processes underlying recognition judgments in the process dissociation procedure

The hypothesis is tested that the memory processes involved in recognition judgments in the process dissociation procedure are the same as those involved in standard source-monitoring tasks. It is shown how source-monitoring response categories can be mapped onto process dissociation response categories. On the basis of this observation, an experiment was conducted in which it was possible to compare, using a multinomial modeling approach, the parameters representing memory processes in the process dissociation procedure with those involved in source monitoring. For the two different encoding conditions realized, the results are compatible with the hypothesis that the same processes are involved in source monitoring and in recognition judgments in the process dissociation procedure. Implications for the interpretation of the model’s parameters are discussed.

A latent state-trait anxiety model and its application to determine consistency and specificity coefficients

Abstract In the present study the consistency model (Steyer, 1987) was applied to data gathered with the German version of the State-Trait Anxiety Inventory (Laux, Glanzmann, Schaffner, and Spielberger, 1981). The questionnaire was presented twice to 64 university students with an interval of two months between first and second testing. The consistency and specificity coefficients, estimated by LISREL (Joreskog and Sorbom, 1984), support the state-trait distinction. The state variables have high specificity and consistency coefficients; the trait variables, in contrast, have high consistency coefficients but low or even negligible specificity coefficients. The discussion points out the advantages of the consistency model over the stability model; the most important advantage is that the theoretical structure of the consistency model is more appropriate for the type of application considered. It contains a state factor for each occasion of measurement and a trait factor common to all occasions of measureme...

Finite-state automata: Dynamic task environments in problem-solving research.

This paper presents a new research paradigm for analysing human learning in dynamic task environments based on the theory of finite-state automata. Some of the advantages of the approach are outlined. (1) It is possible to design classes of formally well-described dynamic task environments instead of idiosyncratic microworlds that are difficult if not impossible to compare. (2) The approach suggests assumptions about the mental representation of a discrete dynamic system. (3) The finite-state automata formalism suggests systematic and appropriate diagnostic procedures. (4) Using finite-state automata to design dynamic task environments, one does not have to give up the “ecological validity” appeal of computer-simulated scenarios. An experiment on the utility of an external memory support system with system complexity and type of memory support as independent variables is reported to illustrate the application of the formal framework. Systematically derived dependent variables reflect both system knowledge and control performance. The results suggest that the benefits due to the availability of the external aid vary as a function of the complexity of the task. Also, using reaction time measurements, priming phenomena have been found that point to the importance of sequentiality in the representation of discrete systems. It is concluded that the approach, although not entirely new in experimental psychology, awaits further exploration in research on human learning in dynamic task environments and promises to be a stimulating paradigm for both basic and applied research.

Further evidence on the similarity of memory processes in the process dissociation procedure and in source monitoring

Buchner, Erdfelder, Steffens, and Martensen (1997) proposed that the memory processes involved in recognition judgments in the process dissociation procedure are the same as those involved in standard source monitoring tasks. Two extensions of that research are presented here. First, following a line of reasoning recently brought forward by Jacoby (1998), the instructions in the earlier study could have triggered different processes from those triggered by his instructions. However, with instructions conforming as closely as possible to those reported by Jacoby (1991), Experiment 1 replicated the earlier recognition judgment finding almost perfectly. Second, the memory processes underlying fame judgments in the process dissociation procedure could also resemble those involved in source monitoring tasks. Indeed, the results of Experiment 2 are compatible with the hypothesis that the same processes are involved in fame judgments given a source monitoring or a process dissociation procedure.