Hartmut Blank

Presentation and content: The use of base rates as a continuous variable

Do subjects, in probability revision experiments, generally neglect base rates due to the use of a representativeness heuristic, or does the use of base rates depend on what we call the internal problem representation? In Experiment 1, we used Kahneman and Tversky’s (1973) engineer-lawyer problem, where random sampling of descriptions is crucial to the internal representation of the problem as one in probability revision. If random sampling was performed and observed by the subjects themselves, then their judgments conformed more to Bayesian theory than to the representativeness hypothesis. If random sampling was only verbally asserted, judgments followed the representativeness heuristic. In Experiment 2 we used the soccer problem, which has the same formal structure but which the subjects’ every day experience already represents as a probability revision problem. With this change in content, subjects’ judgments were indistinguishable from Bayesian performance. We conclude that by manipulating presentation and content, one can elicit either base rate neglect or base rate use, as well as points in between. Th is result suggests that representativeness is neither an all-purpose mental strategy nor even a tendency, but rather a function of the content and the presentation of crucial information. From its origins circa 1660 until the mid-nineteenth century, probability theory was closely identifi ed with rational thinking. In Laplace’s famous phrase, probability theory was believed to be “only common sense reduced to calculus” (Laplace, 1814/1951, p. 196). For the classical probabilists, their calculus codifi ed the intuitions of an elite of reasonable men in the face of uncertainty. And if these reasonable intuitions deviated from the laws of probability theory, it was the latter that were cast into doubt. Such discrepancies actually infl uenced the way in which probability theory developed mathematically (Daston, 1980). In the early decades of the nineteenth century, probability theory shifted from being a description of the intuitions of rational individuals to one of the behavior of the irrational masses (Porter, 1986). But in the 1960s and 1970s experimental psychology reestablished the link between probability theory and rational thinking under uncertainty. However, the new alliance diff ered from the old in two important respects. First, it was now probability theory, rather than intuitive judgments, that was the normative standard. Although probabilists have from time to time doubted whether the additivity law holds in all cases (Shafer, 1978), and although there is evidence that diff erent statistical approaches suggest diff erent answers to the same problem (Birnbaum, 1983), psychologists have generally assumed that statistics spoke with one voice—a necessary assumption for the new normative approach. Second, the link between probability theory and human thinking has become the subject of experimental research. First, by using urn-and-balls problems (e.g., Edwards, 1968; Phillips & Edwards, 1966) and then more

Changing likes and dislikes through the back door: The US-revaluation effect

US-revaluation refers to the observation that subsequent changes in the valence of an unconditioned stimulus (US) after pairing it with a neutral, conditioned stimulus (CS) also changes the valence of the associated CS. Experiment 1 found evidence for the US-revaluation effect using an unobtrusive measure of evaluation. However, US-revaluation effects were more pronounced for positive-to-negative compared to negative-to-positive revaluations. Experiment 2 replicated this finding for self-reported evaluations, further showing that US-revaluation effects are stable over time and independent of explicit memory for the revaluating information. Using a modified paradigm, Experiment 3 ruled out method-related explanations for these findings and showed that changes in CS evaluations are correlated with parallel changes in US evaluations. These findings encourage the view of evaluative conditioning as an instance of stimulus–stimulus (S–S) rather than stimulus-response (S–R) learning. Implications for basic and applied research are discussed.

How many hindsight biases are there

The answer is three: questioning a conceptual default assumption in hindsight bias research, we argue that the hindsight bias is not a unitary phenomenon but consists of three separable and partially independent subphenomena or components, namely, memory distortions, impressions of foreseeability and impressions of necessity. Following a detailed conceptual analysis including a systematic survey of hindsight characterizations in the published literature, we investigated these hindsight components in the context of political elections. We present evidence from three empirical studies that impressions of foreseeability and memory distortions (1) show hindsight effects that typically differ in magnitude and sometimes even in direction, (2) are essentially uncorrelated, and (3) are differentially influenced by extraneous variables. A fourth study found similar dissociations between memory distortions and impressions of necessity. All four studies thus provide support for a separate components view of the hindsight bias. An important consequence of such a view is that apparent contradictions in research findings as well as in theoretical explanations (e.g., cognitive vs. social-motivational) might be alleviated by taking differences between components into account. We also suggest conditions under which the components diverge or converge.

Remembering: a theoretical interface between memory and social psychology

There is increasing awareness that memory is embedded in social context and subject to social influence, with little concomitant theoretical integration of memory and social psychological thinking. Following a brief classification of social memory phenomena, I attempt such an integration through an extended conception of memory retrieval – inspired by social psychological theorizing – that describes the conversion of accessed memory information into memory beliefs (validation stage) and further into memory statements (communication stage). Both stages draw on external context, including social influence: Broadly, informational influence shapes memory beliefs, and normative influence memory statements. Apart from deepening our understanding of memory retrieval and social memory, this model propagates the further use of social psychology to analyse memory phenomena.

A cognitive approach to lie detection: A meta-analysis

Introduction This article provides a meta-analysis of a new, cognitive approach to (non-)verbal lie detection. This cognitive lie detection approach consists of three techniques: (1) imposing cognitive load, (2) encouraging interviewees to say more, and (3) asking unexpected questions. Method A meta-analysis was carried out on studies using the cognitive approach, 14 of which directly compared the cognitive approach to a standard approach. Results The cognitive lie detection approach produced superior accuracy results in truth detection (67%), lie detection (67%), and total detection (truth and lie detection combined, 71%) compared to a traditional standard approach (truth detection: 57%; lie detection: 47%; total detection: 56%). Conclusions Practitioners may find it useful to use a cognitive lie detection approach in their daily practice.

Hindsight bias in political elections

Two studies on political hindsight bias were conducted on the occasions of the German parliament election in 1998 and the Nordrhein-Westfalen state parliament election in 2000. In both studies, participants predicted the percentage of votes for several political parties and recalled these predictions after the election. The observed hindsight effects were stronger than those found in any prior study on political elections (using percentage of votes as the dependent variable). We argue that the length of the retention interval between original judgement and recollection is mainly responsible for this difference. In our second study, we investigated possible artifacts in political hindsight biases using a control-group design where half of the participants recalled their predictions shortly before or after the election. Hindsight bias was preserved, reinforcing the results of earlier studies with non-control-group designs. Finally, we discuss the possibility that the hindsight experience (in political judgement and in general) actually consists of three different, partly independent components.

Hindsight bias doesn't always come easy: causal models, cognitive effort, and creeping determinism.

Creeping determinism, a form of hindsight bias, refers to peoples hindsight perceptions of events as being determined or inevitable. This article proposes, on the basis of a causal-model theory of creeping determinism, that the underlying processes are effortful, and hence creeping determinism should disappear when individuals lack the cognitive resources to make sense of an outcome. In Experiments 1 and 2, participants were asked to read a scenario while they were under either low or high processing load. Participants who had the cognitive resources to make sense of the outcome perceived it as more probable and necessary than did participants under high processing load or participants who did not receive outcome information. Experiment 3 was designed to separate 2 postulated subprocesses and showed that the attenuating effect of processing load on hindsight bias is not due to a disruption of the retrieval of potential causal antecedents but to a disruption of their evaluation. Together the 3 experiments show that the processes underlying creeping determinism are effortful, and they highlight the crucial role of causal reasoning in the perception of past events.

Perceiving events as both inevitable and unforeseeable in hindsight: The Leipzig candidacy for the Olympics

We present a new conceptualization of hindsight bias in terms of three separate hindsight components (foreseeability impressions, perceptions of necessity and memory distortions) and report three kinds of supporting evidence from an internet study (N = 101) of the unsuccessful application of the City of Leipzig to host the Olympic Games: (1) strongly diverging hindsight effects, (2) low intercorrelations between the components, and (3) dissociative effects of third variables on them. Specifically, experiencing the failure of the application as personally negative (due to a pro-application attitude and previous commitment), led to perceiving it as inevitable but also as unforeseeable. This surprising result helps to resolve seeming contradictions between previous findings (Louie, 1999; Mark et al., 2003; Tykocinski, 2001) by relating the opposite hindsight effects to differences in the nature and functions (dissonance reduction vs. coping with disappointment) of the foreseeability and necessity components.

Prejudiced Behavior Toward Lesbians and Gay Men A Field Experiment on Everyday Helping

Investigations of prejudice toward lesbians and gay men mostly rely on self-report questionnaires and rarely make use of indirect, behavioral measures. This field experiment investigated helping in an everyday face-to-face situation as an indicator of discrimination. Members of the public (N = 240) were approached by a person asking for 10 pence for a parking meter. The requestor wore either a neutral or a pro-gay T-shirt. Additional independent variables were the requestor’s and the target person’s gender. Results showed that a person perceived as being a lesbian or a gay man received much less help, especially from men, than the same person perceived as being heterosexual. Findings are discussed in comparison with earlier studies involving either behavioral or self-report measures.Investigations of prejudice toward lesbians and gay men mostly rely on self-report questionnaires and rarely make use of indirect, behavioral measures. This field experiment investigated helping in an everyday face-to-face situation as an indicator of discrim- ination. Members of the public (N = 240) were approached by a person asking for 10 pence for a parking meter. The requestor wore either a neutral or a pro-gay T-shirt. Additional independent variables were the requestors and the target persons gender. Results showed that a person perceived as being a lesbian or a gay man received much less help, especially from men, than the same person perceived as being heterosexual. Findings are discussed in comparison with earlier studies involving either behavioral or self-report measures.

Another look at retroactive and proactive interference: a quantitative analysis of conversion processes.

Traditionally, the causes of interference phenomena were sought in “real” or “hard” memory processes such as unlearning, response competition, or inhibition, which serve to reduce the accessibility of target items. I propose an alternative approach which does not deny the influence of such processes but highlights a second, equally important, source of interference—the conversion (Tulving, 1983) of accessible memory information into memory performance. Conversion is conceived as a problem-solving-like activity in which the rememberer tries to find solutions to a memory task. Conversion-based interference effects are traced to different conversion processes in the experimental and control conditions of interference designs. I present a simple theoretical model that quantitatively predicts the resulting amount of interference. In two paired-associate learning experiments using two different types of memory tests, these predictions were corroborated. Relations of the present approach to traditional accounts of interference phenomena and implications for eyewitness testimony are discussed.