Optimal data selection: Revision,review, and reevaluation

Since it first appeared, there has been much research and critical discussion on the theory of optimal data selection as an explanation of Wason’s (1966, 1968) selection task (Oaksford & Chater, 1994). In this paper, this literature is reviewed, and the theory of optimal data selection is reevaluated in its light. The information gain model is first located in the current theoretical debate in the psychology of reasoning concerning dual processes in human reasoning. A model comparison exercise is then presented that compares a revised version of the model with its theoretical competitors. Tests of the novel predictions of the model are then reviewed. This section also reviews experiments claimed not to be consistent with optimal data selection. Finally, theoretical criticisms of optimal data selection are discussed. It is argued either that the revised model accounts for them or that they do not stand up under analysis. It is concluded that some version of the optimal data selection model still provides the best account of the selection task. Consequently, the conclusion of Oaksford and Chater’s (1994) original rational analysis (Anderson, 1990), that people’s hypothesis-testing behavior on this task is rational and well adapted to the environment, still stands.     

Adherence to antiretroviral therapy for pediatric HIV infection: review of the literature and recommendations for research

This review described and compared empirical investigations of adherence to pediatric antiretroviral therapy (ART) and predictors/correlates of adherence with regard to methodology and outcome. Thirteen empirical studies of children's adherence to ART, conducted between the years 1981 and 2002 were identified. Investigations varied by age of participant, drug therapy regimen, method of adherence assessment, and by the reporting of predictors/correlates of adherence. Conclusions from the literature are limited by the lack of common sample characteristics and adherence assessment methodologies. Nevertheless, consistent with much of the pediatric adherence literature, adherence to antiretroviral medications among children and adolescents appears to be frequently suboptimal. Few investigations identified predictors/correlates of adherence, but these appear generally similar to those found in adult samples. Recommendations for future investigations are proposed.     

English letter frequencies and their applications: part I

This article presents data regarding the relative frequencies of single letters in English, organized by word length and letter position. Derived from a parsimonious sample of English word use patterns presented by Whissell in 1998, the data accurately represent letter frequencies found in modern English. These data provide a resource for various applications, including reading research and practice.     

Who when where: An experimental test of the event-indexing model

We tested the event-indexing model proposed by Zwaan, Langston, and Graesser (1995). Participants read narratives containing target sentences that involved situational shifts. Independently of each other, continuity and shifting of the protagonist, time, and location dimensions were varied. In Experiment 1, reading times of the target sentences increased for protagonist shifts and temporal shifts, whereas the effect of spatial shifts was weak. Moreover, an interaction of protagonist shifts and spatial shifts was found. These results were replicated in Experiment 2, which also revealed strong effects of these situational shifts on coherence ratings that participants gave immediately after reading each target sentence. Experiment 3 addressed the interaction of protagonist shifts and spatial shifts, showing that it may be due to the differential involvement of unexplained protagonist motions. These experimental results support the processing load predictions of the event-indexing model and extend previous correlational results.     

Explicit and implicit processes in multicue judgment

In two experiments, a multicue probability learning task was used to train participants in relating judgments to a criterion, on the basis of several cues that could or could not be relevant. The outcome feedback had 25% added noise to simulate real-world experience-based learning. Judgmental strategies acquired were measured by individual multiple linear regression analyses of a test phase (with no feedback) and were compared with self-ratings of cue relevance. In a third experiment, participants were instructed explicitly on cue relevance, with no training phase. The pattern of results suggested that both implicit and explicit cognitive processes influenced judgments and that they may have been sensitive to different task manipulations in the learning phase. On more complex tasks, despite weak explicit learning, explicit processes continued to influence judgments, producing a decrement in performance. These findings explain why studies of expert judgment often show only moderate levels of self-insight, since people have only partial access to the processes determining their judgments.     

Data selection and natural sampling: Probabilities do matter

Probabilistic accounts of Wason's selection task (Oaksford & Chater, 1994, 1996) are controversial, with some researchers failing to replicate the predicted effects of probability manipulations. This paper reports a single experiment in which participants sampled the data naturally-that is, sequentially. The proportions of possible data types (i.e., cards in the selection task) also reflected the probability manipulation. Other than this procedural difference, the materials were the same as those in Oberauer, Wilhelm, and Rosas-Diaz's (1999) Experiment 3, which failed to show probabilistic effects. Significant probabilistic effects were observed. Moreover, in a comparative model-fitting exercise, a revised version of the information gain model (Hattori, 1999, 2002; Oaksford & Chater, in press-b) was shown to provide better fits to these data than did competing explanations.     

Testing a positional model of the Hebb effect

In two experiments, we investigated the hypothesis that a strengthening of position-item associations underlies the improvement seen in performance on an immediate serial recall task, for a list that is surreptitiously repeated every third trial. Having established a strong effect of repetition, performance was tested on transfer lists in which half the items held the same position as in the repeated list (S-items) and the remainder moved (D-items). In Experiment 1, S-items showed a small advantage in order errors over control and D-items. A second experiment tested whether a design feature in Experiment 1 underlay this advantage. When the experimental design was better controlled, no improvement was shown for either S- or D-items over controls. These data were shown to be inconsistent with the results of computer simulations of a positional model. An alternative model is outlined.     

Action priming by briefly presented objects

Three experiments investigated how visual objects prime the actions they afford. The principal concern was whether such visuomotor priming depends upon a concurrent visual input--as would be expected if it is mediated by on-line dorsal system processes. Experiment 1 showed there to be essentially identical advantages for making afforded over non-afforded responses when these were made to objects still in view and following brief (30 or 50 ms) object exposures that were backward masked. Experiment 2 showed that affordance effects were also unaffected by stimulus degradation. Finally, Experiment 3 showed there to be statistically equal effects from images of objects and their names. The results suggest that an active object representation is sufficient to generate affordance compatibility effects based on associated actions, whether or not the object is concurrently visible.