Probabilistic inference in human semantic memory

The idea of viewing human cognition as a rational solution to computational problems posed by the environment has influenced several recent theories of human memory. The first rational models of memory demonstrated that human memory seems to be remarkably well adapted to environmental statistics but made only minimal assumptions about the form of the environmental information represented in memory. Recently, several probabilistic methods for representing the latent semantic structure of language have been developed, drawing on research in computer science, statistics and computational linguistics. These methods provide a means of extending rational models of memory retrieval to linguistic stimuli, and a way to explore the influence of the statistics of language on human memory.     

Empathy-motivated helping: the moderating role of group membership

In this article, the authors present two laboratory experiments testing a group-level perspective on the role of empathy in helping. Experiment 1 tested the authors' predictions in an intercultural context of helping. Confirming their specific Empathy x Group Membership moderation hypothesis, empathy had a stronger effect on helping intentions when the helper and the target belonged to the same cultural group than when they belonged to different groups. Experiment 2 replicated these findings in a modified minimal group paradigm using laboratory-created groups. Moreover, this second experiment also provides evidence for the hypothesized psychological mechanisms underlying the empathy-(ingroup) helping relationship. Specifically, analyses in the ingroup condition confirmed that the strength of the empathy-(ingroup) helping relationship systematically varied as a function of perceived similarities among ingroup members. The general implications of these findings for empathy-motivated helping are discussed.     

Suicide rate and national scores on the Big Five personality factors

Across 46 nations around the world, suicide rates were negatively correlated with national scores on the Big Five personality factors of Agreeableness and Conscientiousness (two facets indicating low Psychoticism), thus not replicating previous findings of Lester (1993, 2005).     

The structure and function of explanations

Generating and evaluating explanations is spontaneous, ubiquitous and fundamental to our sense of understanding. Recent evidence suggests that in the course of an individual's reasoning, engaging in explanation can have profound effects on the probability assigned to causal claims, on how properties are generalized and on learning. These effects follow from two properties of the structure of explanations: explanations accommodate novel information in the context of prior beliefs, and do so in a way that fosters generalization. The study of explanation thus promises to shed light on core cognitive issues, such as learning, induction and conceptual representation. Moreover, the influence of explanation on learning and inference presents a challenge to theories that neglect the roles of prior knowledge and explanation-based reasoning.     

Post-traumatic stress disorder symptoms of children following the occurrence of Tehran City Park disaster

The authors investigated the post-traumatic stress disorder (PTSD) symptoms of young adolescents who had been directly involved in a disaster in Tehran. The participants were 19 chlidren who had survived a boat sinking in Tehran's city park in 2002. By using the Post-Traumatic Stress Disorder Symptom Scale (PSS; E. B. Foa, D. S. Riggs, C. V. Dancu, & B. O. Rothbaum, 1993) as well as a clinical interview based on the definition cited in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994, p. 424), 16 participants (84.2%) were diagnosed with PTSD using the PSS and 17 (89.5%) were diagnosed with PTSD using the psychiatric interview.     

Adults' ability to detect children's lying

Adults are poor deception detectors when examining lies told by adults, on average. However, there are some adults who are better at detecting lies than others. Children learn to lie at a very young age, a behavior that is socialized by parents. Yet, less is known about the ability to detect children's lies, particularly with regard to individual differences in the ability to detect this deception. The current study explored adult raters' ability to discern honesty in children who lied or told the truth about committing a misdeed. Results showed that adults are no better at detecting children's lies than they are with adult lies. In particular, adults were very poor at identifying children's honest statements. However, individual differences did emerge, suggesting that the ability to detect lying in children might be facilitated by relevant experience working with children. Implications for legal and mental health contexts are discussed.     

A novel view of between-categories contrast and within-category assimilation

This research manipulated the portion of a category distribution that is misclassified by the optimal classifier and investigated the impact on assessments of category attributes. Three separate studies manipulated the direction of overlap, the extent of overlap, and the relative base rate of the comparison category. All 3 studies produced large between-categories contrast and within-category assimilation. As expected, these effects were enhanced in conditions in which the optimal classifier misclassified a larger portion of the target category. Study 4 demonstrated that intercategory overlap in the absence of overt classification does not produce contrast and assimilation. Ironically, optimizing categorization accuracy can produce highly inaccurate beliefs about category attributes.     

Contingent muscular tension during a choice reaction task

This study examined the effects of contingent muscular tension on a choice reaction task, and especially, the effects various amounts of muscular tension have on the information processing of choice reaction time. The reactive movement task included a choice reaction task. Ten right-handed healthy men (ages 18 to 19 years) underwent trials with stimulus presentation probabilities of 50% and 20% on the muscular tension task and choice reaction tasks. The conditions for the muscular tension tasks were divided into seven different conditions: 0%, 10%, 20%, 30%, 40%, 50%, and 60% of maximum voluntary contraction. On these tasks, subjects performed isometric contraction of the biceps brachii. The choice reaction task was a rapid extension of the left or right knee as a choice reaction. Measures were choice reaction time, movement time, and total reaction time. Analysis indicated that shortening choice reaction time of the left and right feet was observed under 10% muscular tension of maximum strength. Muscular tension appreciably influenced information processing, including choice reaction time. Muscular tension did not affect movement time. Results are discussed with respect to previous research and the optimal muscular tension for best performance.     

Event plausibility does not determine children's false memories

In this paper we ask how the plausibility of an event affects the likelihood that children will develop a false memory for it. Over three interviews 6-year-olds and 10-year-olds were shown two true photos and two false photos-a plausible and less plausible event-and reported what they could remember about those events. Children also rated their confidence that the events happened, and how much they could remember about the events. By the final interview, within each age group, there were no differences in children's confidence ratings for the two false events. In addition, within each age group, the rate of false memories was the same for each event; across age groups, younger children developed more false memories than older children.     

The prepared mind: neural activity prior to problem presentation predicts subsequent solution by sudden insight

Insight occurs when problem solutions arise suddenly and seem obviously correct, and is associated with an "Aha!" experience. Prior theorizing concerning preparation that facilitates insight focused on solvers' problem-specific knowledge. We hypothesized that a distinct type of mental preparation, manifested in a distinct brain state, would facilitate insight problem solving independently of problem-specific knowledge. Consistent with this hypothesis, neural activity during a preparatory interval before subjects saw verbal problems predicted which problems they would subsequently solve with, versus without, self-reported insight. Specifically, electroencephalographic topography and frequency (Experiment 1) and functional magnetic resonance imaging signal (Experiment 2) both suggest that mental preparation leading to insight involves heightened activity in medial frontal areas associated with cognitive control and in temporal areas associated with semantic processing. The results for electroencephalographic topography suggest that noninsight preparation, in contrast, involves increased occipital activity consistent with an increase in externally directed visual attention. Thus, general preparatory mechanisms modulate problem-solving strategy.