Ben R. Newell

Empirical tests of a fast-and-frugal heuristic: Not everyone "takes-the-best"

Abstract The fast-and-frugal heuristics approach to decision making under uncertainty advocated by Gigerenzer and colleagues (e.g., Gigerenzer & Goldstein, 1996 ) has achieved great popularity despite a relative lack of empirical validation. We report two experiments that examine the use of one particular heuristic—“take-the-best” (TTB). In both experiments the majority of participants adopted frugal strategies, but only one-third (33%) behaved in a manner completely consistent with TTB’s search, stopping and decision rules. Furthermore, a significant proportion of participants in both experiments adopted a non-frugal strategy in which they accumulated more information than was predicted by TTB’s stopping rule. The results provide an insight into the conditions under which different heuristics are used, and question the predictive power of the fast-and-frugal approach.

Universal aesthetic of fractals

Abstract Since their discovery by Mandelbrot (The Fractal Geometry of Nature, Freeman, New York, 1977), fractals have experienced considerable success in quantifying the complex structure exhibited by many natural patterns and have captured the imaginations of scientists and artists alike. With ever-widening appeal, they have been referred to both as “fingerprints of nature” (Nature 399 (1999) 422) and “the new aesthetics” (J. Hum. Psychol. 41 (2001) 59). Here, we show that humans display a consistent aesthetic preference across fractal images, regardless of whether these images are generated by natures processes, by mathematics, or by the human hand.

Think, blink or sleep on it? The impact of modes of thought on complex decision making

This paper examines controversial claims about the merit of “unconscious thought” for making complex decisions. In four experiments, participants were presented with complex decisions and were asked to choose the best option immediately, after a period of conscious deliberation, or after a period of distraction (said to encourage “unconscious thought processes”). In all experiments the majority of participants chose the option predicted by their own subjective attribute weighting scores, regardless of the mode of thought employed. There was little evidence for the superiority of choices made “unconsciously”, but some evidence that conscious deliberation can lead to better choices. The final experiment suggested that the task is best conceptualized as one involving “online judgement” rather than one in which decisions are made after periods of deliberation or distraction. The results suggest that we should be cautious in accepting the advice to “stop thinking” about complex decisions.

On the role of recognition in decision making

In 2 experiments, the authors sought to distinguish between the claim that recognition of an object is treated simply as a cue among others for the purposes of decision making in a cue-learning task from the claim that recognition is attributed a special status with fundamental, noncompensatory properties. Results of both experiments supported the former interpretation. When recognition had a high predictive validity, it was relied on (solely) by the majority of participants; however, when other cues in the environment had higher validity, recognition was ignored, and these other cues were used. The results provide insight into when, where, and why recognition is used in decision making and also question the elevated status assigned to recognition in some frameworks (e.g., D. G. Goldstein & G. Gigerenzer, 2002).

Challenging the role of implicit processes in probabilistic category learning

Considerable interest in the hypothesis that different cognitive tasks recruit qualitatively distinct processing systems has led to the proposal of separate explicit (declarative) and implicit (procedural) systems. A popular probabilistic category learning task known as the weather prediction task is said to be ideally suited to examine this distinction because its two versions, “observation” and “feedback,” are claimed to recruit the declarative and procedural systems, respectively. In two experiments, we found results that were inconsistent with this interpretation. In Experiment 1, a concurrent memory task had a detrimental effect on the implicit (feedback) version of the task. In Experiment 2, participants displayed comparable and accurate insight into the task and their judgment processes in the feedback and observation versions. These findings have important implications for the study of probabilistic category learning in both normal and patient populations.

In conflict with ourselves? An investigation of heuristic and analytic processes in decision making

Many theorists propose two types of processing: heuristic and analytic. In conflict tasks, in which these processing types lead to opposing responses, giving the analytic response may require bothdetection andresolution of the conflict. The ratio bias task, in which people tend to treat larger numbered ratios (e.g., 20/100) as indicating a higher likelihood of winning than do equivalent smaller numbered ratios (e.g., 2/10), is considered to induce such a conflict. Experiment 1 showed response time differences associated with conflict detection, resolution, and the amount of conflict induced. The conflict detection and resolution effects were replicated in Experiment 2 and were not affected by decreasing the influence of the heuristic response or decreasing the capacity to make the analytic response. The results are consistent with dual-process accounts, but a single-process account in which quantitative, rather than qualitative, differences in processing are assumed fares equally well in explaining the data.

The role of experience in decisions from description

We extend research on the distinction between decisions from experienceor description to situations in which people are given perfect information about outcome probabilitiesand have experience in an environment which matches the described information. Participants read a description of a die with more sides of one color than another (e.g., 4 black and 2 white sides) and were then asked either to predict the outcomes of rolls of the die or to select the best strategy for betting on the most likely outcome for each roll in a hypothetical game. Experience in the environment (trials), contingency (probability of the more likely alternative), and outcome feedback all had significant effects on the adoption of the optimal strategy (always predicting the most likely outcome), despite their normative irrelevance. Comparisons of experience with description-only conditions suggested that experience exerted an influence on performance if it was active—making predictions—but not if it was passive—observing outcomes. Experience had anegative initial impact on optimal responding: participants in description-only conditions selected the optimal strategy more often than those with 60 trials of prediction experience, a finding that reflects the seduction of “representative” responding.

When and why rare events are underweighted: A direct comparison of the sampling, partial feedback, full feedback and description choice paradigms

Two paradigms are commonly used to examine risky choice based on experiential sampling. The feedback paradigm involves a large number of repeated, consequential choices with feedback about the chosen (partial feedback) or chosen and foregone (full feedback) payoffs. The sampling paradigm invites cost-free samples before a single consequential choice. Despite procedural differences, choices in both experience-based paradigms suggest underweighting of rare events relative to their objective probability. This contrasts with overweighting when choice options are described, thereby leading to a ‘gap’ between experience and description-based choice. Behavioural data and model-based analysis from an experiment comparing choices from description, sampling, and partial- and full-feedback paradigms replicated the ‘gap’, but also indicated significant differences between feedback and sampling paradigms. Our results suggest that mere sequential experience of outcomes is insufficient to produce reliable underweighting. We discuss when and why underweighting occurs, and implicate repeated, consequential choice as the critical factor.

The Dimensionality of Perceptual Category Learning: A State-Trace Analysis

State-trace analysis was used to investigate the effect of concurrent working memory load on perceptual category learning. Initial reanalysis of Zeithamova and Maddox (2006, Experiment 1) revealed an apparently two-dimensional state-trace plot consistent with a dual-system interpretation of category learning. However, three modified replications of the original experiment found evidence of a single resource underlying the learning of both rule-based and information integration category structures. Follow-up analyses of the Zeithamova and Maddox data, restricted to only those participants who had learned the category task and performed the concurrent working memory task adequately, revealed a one-dimensional plot consistent with a single-resource interpretation and the results of the three new experiments. The results highlight the potential of state-trace analysis in furthering our understanding of the mechanisms underlying category learning.

Evaluating Three Criteria for Establishing Cue-Search Hierarchies in Inferential Judgment

The authors identify and provide an integration of 3 criteria for establishing cue-search hierarchies in inferential judgment. Cues can be ranked by information value according to expected information gain (Bayesian criterion), cue-outcome correlation (correlational criterion), or ecological validity (accuracy criterion). All criteria significantly predicted information acquisition behavior; however, in 3 experiments, the most successful predictor was the correlational criterion (followed by the Bayesian). Although participants showed sensitivity to task constraints, searching for less information when it was more expensive (Experiment 1) and when under time constraints (Experiment 2), concomitant changes in the relative frequency of acquisition of cues with different information values were not observed. A rational analysis illustrates why such changes in the frequency of acquisition would be beneficial, and reasons for the failure to observe such behavior are discussed.