Resistance to extinction of human evaluative conditioning using a between‐subjects design

Surprise has been described in various contexts as a neutral, a positive, or a negative emotion. Six experiments are reported in which surprise ratings of unexpected positive and negative outcomes, with identical prior probabilities, were compared. For unexpected occurrences of events that are beyond the control of the protagonist, successes were consistently perceived as more surprising than failures. For unexpected action controlled outcomes for which the protagonist was partly responsible, failures were rated as more surprising than successes. The findings are interpreted as being due to an implicit contrast between out-of-control situations and success, in the first case, and between goal-directed efforts and failure, in the second.     

Looking back versus looking ahead: framing of time and work at different stages of a project

Progress on a well‐defined project can be described along a task dimension in terms of amount done, or as amount of work still to be completed. Time‐limited projects can also be described on a temporal dimension in terms of time spent versus time left. Five experiments are reported showing that such frames have predictable implications for speakers as well as for listeners: Statements by a team leader about time spent and work left are perceived as suggestions to “hurry up,” whereas complementary statements about work done and time left indicate that the team can take it more easy. The first set of statements further implies that the team is behind schedule, whereas the last two statements suggest that the team is ahead of the plan. In line with this, speakers preferred work done and time left statements when they were ahead of schedule, but not when they were behind. “Hurry up” and “behind schedule” interpretations were also shown to be dependent upon stage, being more prominent in the final stages than during the initial stages of a project. Copyright © 2005 John Wiley & Sons, Ltd.     

Framing experts' (dis)agreements about uncertain environmental events

Agreements and disagreements between expert statements influence lay people's beliefs. But few studies have examined what is perceived as a disagreement. We report six experiments where people rated agreement between pairs of probabilistic statements about environmental events, attributed to two different experts or to the same expert at two different points in time. The statements differed in frame, by focusing on complementary outcomes (45% probability that smog will have negative health effects vs. 55% probability that it will not have such effects), in probability level (45% vs. 55% probability of negative effects), or in both respects. Opposite frames strengthened disagreement when combined with different probability levels. Approximate probabilities can be “framed” in yet another way by indicating reference values they are “over” or “under”. Statements that use different directional verbal terms (over vs. under 50%) indicated greater disagreement than statements with the same directional term but different probability levels (over 50% vs. over 70%). Framing and directional terms similarly affected consistency judgments when both statements were issued by the same expert at different occasions. The effect of framing on perceived agreement was significant for medium (10 and 20 percentage points) differences between probabilities, whereas the effect of directional term was stable for numerical differences up to 40 percentage points. To emphasize agreement between different estimates, they should be framed in the same way. To accentuate disagreements or changes of opinion, opposite framings should be used.     

Verbal probabilities: a question of frame?

Verbal expressions of probability and uncertainty are of two kinds: positive (‘probable’, ‘possible’) and negative (‘not certain’, ‘doubtful’). Choice of term has implications for predictions and decisions. The present studies show that positive phrases are rated to be more optimistic (when the target outcome is positive), and more correct, when the target outcome actually occurs, even in cases where positive and negative phrases are perceived to convey the same probabilities (Experiments 1 and 2). Selection of phrase can be determined by linguistic frame. Positive quantifiers (‘some’, ‘several’) support positive probability phrases, whereas negative quantifiers (‘not all’) suggest negative phrases (Experiment 3). Positive frames induced by numeric frequencies (e.g. the number of students to be admitted) imply positive probability phrases, whereas negative frames (e.g. the number of students to be rejected) call for negative probability phrases (Experiment 4). It is concluded that choice of verbal phrase is based not only on level of probability, but also on situational and linguistic cues. Copyright © 2002 John Wiley & Sons, Ltd.     

How fast can you (possibly) do it,or how long will it (certainly) take? Communicating uncertain estimates of performance time

Recent research on verbal probability statements has revealed that some expressions (e.g., possible) are especially appropriate for describing outcomes in the high end of a distribution, whereas other expressions (e.g., certain) are more appropriate for describing low-end values. However, some dimensions appear to be reversible, with higher achievements sometimes associated with high and sometimes with low values, depending on frame. We report three experiments where this “reframing effect” is studied in communications of estimated performance time, both from a speaker's and from a listener's perspective. We hypothesize that statements describing tasks as “taking time” suggest a duration frame, and find accordingly that statements about how many hours that possibly will be spent on a task, or the time a task possibly takes, lead to high time estimates. Statements focusing on the actor's role suggest, in contrast, a speed frame, thus statements about what the actor can possibly do lead to low time estimates. Estimates of the time a task certainly takes or when it is certainly done follow the opposite pattern. The results are in line with approaches that see production and comprehension of language as a dynamical and context-driven process.     

Additivity neglect in probability estimates: Effects of numeracy and response format

When people are asked to estimate the probabilities for an exhaustive set of more than two events, they often produce probabilities that add up to more than 100%. Potential determinants for such additivity neglect are explored in four experiments. Additive responses vary between experimental conditions, mainly as a result of response format, with a scale format leading to fewer additive responses than a list format with self-generated, written probabilities. Participants with high numeracy scores produced more additive responses, especially after being primed with a numeracy scale. Additivity neglect for 100% sums appears to be unrelated to other subadditive judgments, like non-additive disjunctions. We conclude that additivity neglect is caused by a case-based approach, which comes natural in real-life situations where the full set of outcomes is not available.     

Is guilt ‘likely’ or ‘not certain’?: Contrast with previous probabilities determines choice of verbal terms

This research focuses on what determines speakers' choice of positive and negative probability phrases (e.g., “a chance” vs. “not certain”) in a legal context. We argue that choice of phrase to describe an event's probability of occurrence can be determined by the contrast between its current p value and an earlier p value, and not by that current value alone. Three experiments were conducted describing scenarios where profilers communicated a suspect's probability of guilt to the police. In the first study, a probability estimate is revised upwards or downwards. In the second one, the probability estimate of a speaker is higher or lower than that given by a previous speaker. In both cases, participants expected upward trends to lead to positive phrases, whereas downward trends were associated with negative phrases. In a third study, participants had to select probability phrases to characterize two different suspects. No contrast effects were found. We conclude that verbal probability directionality has primarily an argumentative function, where positive phrases are selected when probabilities are contrasted with smaller p values, and negative when contrasted with higher p values.     

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.