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.     

Negations and natural sampling in data selection: Ecological versus heuristic explanations of matching bias

Matching bias occurs when people ignore negations when testing a hypothesis--for example, if A, then not 2--and select possible data types that are named in the hypothesis (i.e., A and 2; Evans & Lynch, 1973). There are two explanations of this bias: the heuristic account and the contrast class account. The latter is part of Oaksford and Chater's (1994) ecological approach to data selection. On this account, a contrast set (i.e., birds that are not ravens) has a higher probability than the original set (i.e., birds that are ravens). This article reports two experiments in which these accounts make divergent predictions. The same materials were used as those in Yama (2001), who found more support for the heuristic approach. Experiment 1 replicated Yama with Western participants. Experiment 2 used a procedure introduced by Oaksford and Wakefield (2003). Rather than present participants with one of each of the four possible data types all at once, 50 were presented one at a time. The proportions of each data type reflected the relevant probabilities. The results supported the ecological approach, showing that people constructed contrast sets that strongly influenced their data selection behavior. The results were not consistent with the heuristic approach.     

Child Impulsiveness—Inattention, Early Peer Experiences, and the Development of Early Onset Conduct Problems

The conjoint influence of child impulsiveness-inattention (I/I) and peer relationships on growth trajectories of conduct problems was assessed in a community sample of 267 boys and girls. I/I reliably predicted teacher- and parent-reported conduct problems at kindergarten entry and growth in those problems over the next 2 years for boys and girls. The relation of boys' I/I to conduct problems was mediated, in part, by peer rejection and involvement in coercive exchanges with peers. The relation of girls' I/I to conduct problems was less clearly mediated by peer processes, but peer difficulties had additive effects. The impact of peer relationships on trajectories of conduct problems was apparent to parents as well as to teachers. Although I/I increments risk for early and persisting conduct problems in concert with poor peer relationships, it does so in complex and gender-specific ways.     

Rigidity in Parent—Child Interactions and the Development of Externalizing and Internalizing Behavior in Early Childhood

Behavioral rigidity is a common feature of many psychopathologies, yet the association between rigidity and the development of childhood psychopathology has not been studied. State space grids (a dynamic systems [DS] method) were used to examine the relation between rigidity in parent-child interactions and childhood externalizing and internalizing problems. High-risk kindergarten children (n = 240) and their parents were observed for 2 hr engaging in a variety of tasks that were expected to elicit a range of affect. State space grid analysis of the observational data revealed an association between rigidity in parent-child interactions and child externalizing behavior problems in the fall and spring of kindergarten and 1st grade, and with growth in those problems over time. Rigidity was associated with concurrent levels and with chronic high-level internalizing problems. Strengths and limitations of the new DS methodology in relation to understanding child psychopathology are discussed.     

Childhood problem behaviours as precursors of drinking to intoxication trajectories – from age 1.5 to 19

Objective: We examined behaviour problem precursors (i.e. internalising and externalising) in childhood (ages 1.5 to 8.5) and early adolescence (age 12.5) and consequences (i.e. harmful alcohol use) in emerging adulthood (age 19), of developmental trajectories of drinking to intoxication across adolescence (ages 14.5–19).

Design and outcome measures: Data from 921 children and their parents followed for 18 years from the population-based Tracking Opportunities and Problems (TOPP) Study were used to examine adolescent trajectories of drinking to intoxication. Logistic regression was used to examine predictors of trajectory group membership.

Results: We identified 3 trajectory classes: low / abstainer (41%), late onset high (31%) and early onset high (28%) using latent class analyses. Logistic regression analyses showed that childhood high externalising characterised early onset of intoxication vs. other classes, while early adolescence externalising discriminated both early and late onset of intoxication. High early childhood internalising characterised those consistently low or abstinent on alcohol intoxication, while early adolescent internalising characterised those having an early onset of intoxication. However, after additional adjustment for co-occurring externalising, there were no evidence for a link between early adolescent internalising and intoxication.

Conclusions: The findings suggest that both child and early adolescent-focused prevention efforts may be warranted.     

The relationship between sleep problems and working memory in children born very preterm

In two studies, the relationship between sleep and working memory performance was investigated in children born very preterm (i.e., gestation less than 32 weeks) and the possible mechanisms underlying this relationship. In Study 1, parent-reported measures of snoring, night-time sleep quality, and daytime sleepiness were collected on 89 children born very preterm aged 6 to 7 years. The children completed a verbal working memory task, as well as measures of processing speed and verbal storage capacity. Night-time sleep quality was found to be associated with verbal working memory performance over and above the variance associated with individual differences in processing speed and storage capacity, suggesting that poor sleep may have an impact on the executive component of working memory. Snoring and daytime sleepiness were not found to be associated with working memory performance. Study 2 introduced a direct measure of executive functioning and examined whether sleep problems would differentially impact the executive functioning of children born very preterm relative to children born to term. Parent-reported sleep problems were collected on 43 children born very preterm and 48 children born to term (aged 6 to 9 years). Problematic sleep was found to adversely impact executive functioning in the very preterm group, while no effect of sleep was found in the control group. These findings implicate executive dysfunction as a possible mechanism by which problematic sleep adversely impacts upon cognition in children born very preterm, and suggest that sleep problems can increase the cognitive vulnerability already experienced by many of these children.