= 1,495 adults), I found that paying people to engage in moralistic punishment reduces their willingness to do so. In an economic game with real stakes, providing a monetary bonus for engaging in third-party punishment of unfair offers nearly cut participants' willingness to do so in half. In judgments of hypothetical transgressions, participants viewed punishers who accepted payment as having worse character and rated the punishers' punitive actions as less morally acceptable. Willingness to engage in punishment was restored if participants were offered large enough payments or were told that punishment accompanied by payment still signals moral virtue. Data were consistent with a signal-corruption mechanism whereby payment interferes with the prosocial signal that moralistic punishment provides about a punisher's motives. These findings have implications for the cultural evolution of punishment and suggest that understanding perpetrators' sociomoral incentives is essential to implementing conflict-reduction policies.

Parents of 162 infants ages 6 to 20 months modeled subsets of four of the same set of eight behaviors, each for a maximum of 3 min, and encouraged their infants to imitate. Proportions of infants producing each behavior (a) when it was modeled and (b) during modeling of a different behavior were compared to estimate the age at which infants mimicked each kind of behavior. No reproduction of these motor acts--that is, no mimicry--was observed at 6 months. Mimicry appeared to develop slowly through most of the 2nd year, emerging at different ages for different behaviors. The findings suggest that newborns' behavioral matching may not be continuous with mimicry later in infancy. Imitation is probably not one behavioral competency with one underlying mechanism. It is more likely a category of different ways of combining and using different types of knowledge, some of which develop across the first 2 years of life.

Stroop interference refers to the finding that it takes longer to name the color of an incongruent color word (e g, the word blue shown in green) than it does to name the color of a neutral stimulus (e g, a series of number signs shown in green) Incongruent color-word stimuli can differ in the similarity between the color in which the word is printed and the color denoted by the word (e g, the word blue shown in green vs yellow) This research shows that the amount of interference obtained is related to color-word similarity, suggesting that word-reading and color-naming processes interact at a conceptual level prior to response emission

The knowledge base on neural substrates and mechanisms involved in classical eyeblink conditioning makes it an ideal paradigm for investigating fundamental issues in learning and memory. New applications for the model system presented here include its use in (a) assessment to evaluate neurocognitive development in infancy, (b) theory building in abnormal psychology to test relationships between obsessive-compulsive behavior and learning rate, (c) evaluation of hypotheses about brain memory systems, and (d) exploration of the role of brain structures such as the cerebellum in learning and timing. Human eyeblink conditioning is a prototype of the utility of a model system that has become well characterized at both the behavioral and the neurobiological levels.

On May 23, 1997, the National Institute on Drug Abuse and the American Psychological Society co-sponsored a conference titled “Cognitive Sciences Research: More Than Thinking About Drug Abuse.” The conference highlighted important lines of research, both within and outside of drug abuse, that may elucidate the relationships between substance abuse and cognitive processes. This Special Section of Psychological Science presents a compilation of articles from that conference by scientists who are working in the forefront of this exciting new research area. The research questions posed by these articles take the following forms: What are the cognitive and developmental effects (i.e., the consequences) of substance abuse? What are the antecedents or precursors of drug use that render persons vulnerable to taking drugs? How do the effects of drugs, in turn, become antecedents for changes in perception, behavior, and cognition that further enhance vulnerability to drugs?

Two experiments tested college students in a delayed matching-to-sample procedure designed to explore how multiple competitive sources of control interact in determining choice behavior The primary sources of potential control were the frequency with which each of two colors was correct (base rates) and the accuracy of a sample in predicting the correct choice (accuracy rate) In one experiment, subjects ignored the base rates, and therefore made nonoptimal choices These results mimicked the well-known base-rate error found in verbal responses to questions In a second experiment, manipulations to increase subjects' motivation did not alleviate the error significantly Together, these results suggest that the base-rate error may represent a broad behavioral pattern not restricted to verbal arenas The results are compared with previous attempts to reconcile behavioral and cognitive lines of experimentation

Family, twin, and adoption studies have produced strong evidence that genes play a major role in schizophrenic conditions. These conventional approaches, however, are not able to reveal anything about the way in which genes influence that disease except that the family prevalence of schizophrenia is too low to fit a classical Mendelian transmission mode. New molecular biological techniques offer bright possibilities for identifying the chromosomal loci of genetic diseases, but these techniques rely for their effectiveness on a Mendelian distribution of the trait under investigation. We show how psychological methods can play a decisive role in making these new biological techniques available for the study of schizophrenia by expanding the phenotype (schizophrenia) to include associated behaviors that fit a model of transmission by major loci.