Context-sensitive heuristics in statistical reasoning

Previous work has shown that people use anchor-and-adjust heuristics to forecast future data points from previous ones in the same series. We report three experiments that show that they use different versions of this heuristic for different types of series. To forecast an untrended series, our subjects always took a weighted average of the long-term mean of the series and the last data point. In contrast, the way that they forecast a trended series depended on the serial dependences in it. When these were low, people forecast by adding a proportion of the last difference in the series to the last data point. When stronger serial dependences made this difference less similar to the next one, they used a version of the averaging heuristic that they employed for untrended series. This could take serial dependences into account and included a separate component for trend. These results suggest that people use a form of the heuristic that is well adapted to the nature of the series that they are forecasting. However, we also found that the size of their adjustments tended to be suboptimal. They overestimated the degree of serial dependence in the data but underestimated trends. This biased their forecasts.     

Potentiation by a novel flavour of conditioned place aversions based on both toxicosis and shock

Three experiments examined how a flavour modified the development of aversions to the place in which it was presented and paired with a reinforcer. Experiment 1 confirmed the cue-to-consequence effect: rats made sick after exposure to a flavour in a novel place (Skinner boxes) displayed stronger aversions than shocked animals when they were presented with the flavour in a second, familiar place; rats shocked after exposure to water acquired stronger place aversions than animals made sick. Experiment 2 confirmed the potentiation effect: rats made sick after exposure to the flavour developed stronger place aversions than those made sick after ingestion of water. This experiment also revealed that rats shocked after exposure to the flavour likewise acquired stronger place aversions than the animals shocked after ingestion of water. Experiment 3 replicated this flavour potentiation of place aversions based on shock. The results are not consistent with Garcia, Lasiter, Bermudez-Rottoni, & Deems' (1985) account of how a flavour interacts with an aversive reinforcer to modify what is learned about its associates in a compound.     

Controlling lexical contributions to the reading of pseudohomophones

Reynolds and Besner (2005) presented a computational account of six effects that emerge when readers are asked to pronounce pseudohomophones (nonwords—e.g., brane—that sound like words when pronounced). In the dual route cascaded (DRC) model of reading, they varied a parameter controlling the rate of inhibition from letter units to the orthographic lexicon to mimic strategic control over the extent of specific lexical processing. In this article, we provide an account in which the effects are simulated by varying the DRC’s reading-aloud criterion—a parameter that sets the minimal level of phonemic activation required to pronounce a letter string. We show that varying this parameter provides another means of controlling lexical contributions to reading aloud.     

Focus of attention,self-esteem,and the attribution of causality

An experiment was conducted to investigate how actors' attributions of causality are affected by their expectancy about the outcome of an action and their observation of the actual outcome while in a state of high or low objective self-awareness. In the presence or absence of a camera, subjects delivered therapeutic instructions which were expected to have a positive or a negative effect and which resulted in a positive or a negative effect on a supposedly phobic patient. Principal findings were that (1) attributions to self were greater under high objective self-awareness for positive relative to negative outcomes, (2) attributions to the patient were relatively great under high objective self-awareness when a positive outcome was expected but a negative outcome actually occurred. The results are discussed in terms of the joint role of focus of attention and self-esteem processes in the attribution of causality and in terms of their relationship to Duval and Wicklund's (1973) “focus of attention” attributional analysis.