Biomedical subjects

Karl Halvor Teigen

Publications and source records attributed to Karl Halvor Teigen.

6 recordsLinked to original sources

PubMed2006

Waiting for the bus: when base-rates refuse to be neglected.

The paper reports the results from 16 versions of a simple probability estimation task, where probability estimates derived from base-rate information have to be modified by case knowledge. In the bus problem [adapted from Falk, R., Lipson, A., & Konold, C. (1994). The ups and downs of the hope function in a fruitless search. In G. Wright & P. Ayton (Eds.), Subjective probability (pp. 353-377). Chichester, UK: Wiley], a passenger waits for a bus that departs before schedule in 10% of the cases, and is more than 10 min delayed in another 10%. What are Fred's chances of catching the bus on a day when he arrives on time and waits for 10 min? Most respondents think his probability is 10%, or 90%, instead of 50%, which is the correct answer. The experiments demonstrate the difficulties people have in replacing the original three-category 1/8/1 partitioning with a normalized, binary partitioning, where the middle category is discarded. In contrast with typical studies of "base-rate neglect", or under-weighing of base-rates, this task demonstrates a reversed base-rate fallacy, where frequentistic information is overextended and case information ignored. Possible explanations for this robust phenomenon are briefly discussed.

Humans↗

PubMed2005

The proximity heuristic in judgments of accident probabilities.

In daily life, probabilities are often assessed informally through the perceived distance to a target event. Accident probabilities are believed to be high when a disastrous outcome appears to be close. This proximity heuristic can lead to exaggerated p(death) estimates in risky situations (Experiment 2), and sometimes higher probabilities for death after near-accidents than after actual accidents (Experiment 3 and 4). Near-accidents are also believed to be equally good, or better, predictors of future disasters than actual accidents, despite being less serious and more frequent (Experiment 5). The proximity heuristic influences the way people talk about their own and other people's chances (Experiment 1), and how they prepare to avoid (or, if necessary, to produce) a disastrous outcome (Experiment 6).

Accidents, Traffic↗

PubMed2005

Giver-receiver asymmetries in gift preferences.

When people are asked to choose between gift items, givers and receivers sometimes show different patterns of preferences. The article reports four experimental studies exploring these giver-receiver asymmetries. Whereas givers tend to prefer exclusive, but smaller gift items, receivers appear to prefer less luxurious, and more useful gifts (Experiment 1). Givers prefer gift vouchers to cash, and are concerned about timing, whereas more receivers accept cash gifts, and claim that it does not matter if the gift arrives late (Experiment 2). One interpretation of the results could be that givers conform more strongly to gift conventions (cultural norms for gift exchange). It is further argued that these differences are not due to a perceived difference between self and others (Experiment 3), but rather because of situational differences. When receivers perform separate evaluations of gifts rather than joint evaluations (pairwise comparisons), they tend to change their preference pattern towards a higher rating of exclusive gift items (Experiment 4).

Adult↗

PubMed2003

Surprises: low probabilities or high contrasts?

Outcome expectations can be expressed prospectively in terms of probability estimates, and retrospectively in terms of surprise. Surprise ratings and probability estimates differ, however, in some important ways. Surprises are generally created by low-probability outcomes, yet, as shown by several experiments, not all low-probability outcomes are equally surprising. To account for surprise, we propose a contrast hypothesis according to which the level of surprise associated with an outcome is mainly determined by the extent to which it contrasts with the default, expected alternative. Three ways by which contrasts can be established are explored: contrasts due to relative probabilities, where the obtained outcome is less likely than a default alternative; contrasts formed by novelty and change, where a contrast exists between the obtained outcome and the individual's previous experience; and contrasts due to the perceptual or conceptual distance between the expected and the obtained. In all these cases, greater contrast was accompanied by higher ratings of surprise.

Affect↗

PubMed2002

One hundred years of laws in psychology.

Mainstream psychology in the 20th century has been conceived as a nomothetic science, but few psychological "laws" have been proposed. A PsycLit search of journal abstracts from 1900 to 1999 yielded a total of 3,093 "law" citations, or 22 per 10,000 entries, with two psychophysical laws (Weber's law and Stevens's power law) and two learning laws (Herrnstein's matching law and Thorndike's law of effect) as the most frequently cited. The number of law citations has been decreasing throughout the century, to 10 per 10,000 entries in the last decade, with few references to laws of recent origin. This could be the result of increasing doubts about the lawfulness of psychological processes coupled with a general preference for less ambitious terms (such as effects, principles, models, or functions).

History, 19th Century↗

PubMed2001

When Equal Chances = Good Chances: Verbal Probabilities and the Equiprobability Effect.

When six equally qualified candidates compete for the same position, p = 1/6 for each. People seem to accept this principle more readily for numerical than for verbal probabilities. Equal chances with three to six alternatives are often verbally described in a positive vein as "entirely possible" or "a good chance" and rarely negatively as "doubtful" or "improbable." This equiprobability effect of verbal probabilities is demonstrated in five studies describing job applicants, lottery players, competing athletes, and examination candidates. The equiprobability effect is consistent with a causal (propensity) view of probabilities, where chances are believed to reflect the relative strength of facilitating and preventive causes. If important conditions in support of the target outcome are present (the candidate is qualified for the position), and there is little to prevent it from occurring (no stronger candidates), chances appear to be good. In the presence of obstacles (one stronger candidate), or in the absence of facilitating conditions (the candidate is poorly qualified), chances appear to be poor, even when numerical p values remain constant. The findings indicate that verbal and numerical probability estimates can reflect different intuitions. Copyright 2001 Academic Press.

Journal Article↗