Knowledge that Transforms

A series of four studies explored how the ability to comprehend and transform probability numbers relates to performance on judgment and decision tasks. On the surface, the tasks in the four studies appear to be widely different; at a conceptual level, however, they all involve processing numbers and the potential to show an influence of affect. Findings were consistent with highly numerate individuals being more likely to retrieve and use appropriate numerical principles, thus making themselves less susceptible to framing effects, compared with less numerate individuals. In addition, the highly numerate tended to draw different (generally stronger or more precise) affective meaning from numbers and numerical comparisons, and their affective responses were more precise. Although generally helpful, this tendency may sometimes lead to worse decisions. The less numerate were influenced more by competing, irrelevant affective considerations. Analyses showed that the effect of numeracy was not due to general intelligence. Numerical ability appears to matter to judgments and decisions in important ways.

Few studies have investigated how physical and social facial cues are integrated in the formation of face preferences. Here we show that expression differentially qualifies the strength of attractiveness preferences for faces with direct and averted gaze. For judgments of faces with direct gaze, attractiveness preferences were stronger for smiling faces than for faces with neutral expressions. By contrast, for judgments of faces with averted gaze, attractiveness preferences were stronger for faces with neutral expressions than for smiling faces. Because expressions can differ in meaning depending on whether they are directed toward or away from oneself, it is only by integrating gaze direction, facial expression, and physical attractiveness that one can unambiguously identify the most attractive individuals who are likely to reciprocate one's own social interest.

People often draw trait inferences from the facial appearance of other people. We investigated the minimal conditions under which people make such inferences. In five experiments, each focusing on a specific trait judgment, we manipulated the exposure time of unfamiliar faces. Judgments made after a 100-ms exposure correlated highly with judgments made in the absence of time constraints, suggesting that this exposure time was sufficient for participants to form an impression. In fact, for all judgments—attractiveness, likeability, trustworthiness, competence, and aggressiveness—increased exposure time did not significantly increase the correlations. When exposure time increased from 100 to 500 ms, participants' judgments became more negative, response times for judgments decreased, and confidence in judgments increased. When exposure time increased from 500 to 1,000 ms, trait judgments and response times did not change significantly (with one exception), but confidence increased for some of the judgments; this result suggests that additional time may simply boost confidence in judgments. However, increased exposure time led to more differentiated person impressions.

We tested whether interacting with a gun increased testosterone levels and later aggressive behavior. Thirty male college students provided a saliva sample (for testosterone assay), interacted with either a gun or a children's toy for 15 min, and then provided another saliva sample. Next, subjects added as much hot sauce as they wanted to a cup of water they believed another subject would have to drink. Males who interacted with the gun showed significantly greater increases in testosterone and added more hot sauce to the water than did those who interacted with the children's toy. Moreover, increases in testosterone partially mediated the effects of interacting with the gun on this aggressive behavior.

This study examined how an erroneous rumor circulated among preschoolers can influence their memory. One fourth of the children overheard a rumor from an adult conversation in which it was alleged that an event the children had not experienced themselves had occurred. A second fourth were the classmates of those who overheard the rumor. A third group had no exposure to the rumor. The remaining children actually experienced the event suggested by the rumor. One week later, the children were interviewed in either a neutral or a suggestive manner. Results from a second interview after a 2-week delay revealed that under both interview conditions, children who overheard the rumor, either from the adult conversation or during naturally occurring interactions with classmates, were as likely to report experiencing the rumored but nonexperienced event as were those who actually experienced it. Most reports of the rumored but nonexperienced event were in children's free recall and were accompanied by high levels of fictitious elaboration.

Research on adult reactions to potentially traumatic events has focused almost exclusively on post-traumatic stress disorder (PTSD). Although there has been relatively little research on the absence of trauma symptoms, the available evidence suggests that resilience following such events may be more prevalent than previously believed. This study examined the prevalence of resilience, defined as having either no PTSD symptoms or one symptom, among a large (n = 2,752) probability sample of New York area residents during the 6 months following the September 11th terrorist attack. Although many respondents met criteria for PTSD, particularly when exposure was high, resilience was observed in 65.1% of the sample. Resilience was less prevalent among more highly exposed individuals, but the frequency of resilience never fell below one third even among the exposure groups with the most dramatic elevations in PTSD.

Human perception and memory are often explained as optimal statistical inferences that are informed by accurate prior probabilities. In contrast, cognitive judgments are usually viewed as following error-prone heuristics that are insensitive to priors. We examined the optimality of human cognition in a more realistic context than typical laboratory studies, asking people to make predictions about the duration or extent of everyday phenomena such as human life spans and the box-office take of movies. Our results suggest that everyday cognitive judgments follow the same optimal statistical principles as perception and memory, and reveal a close correspondence between people's implicit probabilistic models and the statistics of the world.

Does emotion affect how people see? We investigated the effects of emotion and attention, as well as their conjoint effect, on contrast sensitivity, a dimension of early vision. We manipulated the emotional valence and the attentional distribution of cues preceding a target stimulus and asked observers to judge the orientation of the target as contrast varied. This study provides the first behavioral evidence that (a) emotion enhances contrast sensitivity irrespective of attention and (b) emotion potentiates the effect of attention on contrast sensitivity.

People seem to think that a unit of some entity (with certain constraints) is the appropriate and optimal amount. We refer to this heuristic as unit bias. We illustrate unit bias by demonstrating large effects of unit segmentation, a form of portion control, on food intake. Thus, people choose, and presumably eat, much greater weights of Tootsie Rolls and pretzels when offered a large as opposed to a small unit size (and given the option of taking as many units as they choose at no monetary cost). Additionally, they consume substantially more M&M's when the candies are offered with a large as opposed to a small spoon (again with no limits as to the number of spoonfuls to be taken). We propose that unit bias explains why small portion sizes are effective in controlling consumption; in some cases, people served small portions would simply eat additional portions if it were not for unit bias. We argue that unit bias is a general feature in human choice and discuss possible origins of this bias, including consumption norms.

Accumulating evidence suggests that executive functions (EFs) are related to intelligence, despite neuropsychological results initially considered evidence of no such relation. However, findings that EFs are not unitary raise the issue of how intelligence relates to different EFs. This study examined the relations of fluid and crystallized intelligence and Wechsler Adult Intelligence Scale IQ to three separable EFs—inhibiting prepotent responses (inhibiting), shifting mental sets (shifting), and updating working memory (updating)—in young adults. Updating was highly correlated with the intelligence measures, but inhibiting and shifting were not. Furthermore, in structural equation models controlling for the inter-EF correlations, updating remained strongly related to intelligence, but the relations of inhibiting and shifting to intelligence were small and not significant. The results indicate that intelligence measures differentially relate to these three EFs, suggesting that current intelligence measures do not equally assess a wide range of executive control abilities likely required for many “intelligent” behaviors.