Quantity judgments of sequentially presented food items by capuchin monkeys (Cebus apella)

Recent assessments have shown that capuchin monkeys, like chimpanzees and other Old World primate species, are sensitive to quantitative differences between sets of visible stimuli. In the present study, we examined capuchins’ performance in a more sophisticated quantity judgment task that required the ability to form representations of food quantities while viewing the quantities only one piece at a time. In three experiments, we presented monkeys with the choice between two sets of discrete homogeneous food items and allowed the monkeys to consume the set of their choice. In Experiments 1 and 2, monkeys compared an entirely visible food set to a second set, presented item-by-item into an opaque container. All monkeys exhibited high accuracy in choosing the larger set, even when the entirely visible set was presented last, preventing the use of one-to-one item correspondence to compare quantities. In Experiment 3, monkeys compared two sets that were each presented item-by-item into opaque containers, but at different rates to control for temporal cues. Some monkeys performed well in this experiment, though others exhibited near-chance performance, suggesting that this species’ ability to form representations of food quantities may be limited compared to previously tested species such as chimpanzees. Overall, these findings support the analog magnitude model of quantity representation as an explanation for capuchin monkeys’ quantification of sequentially presented food items.

Seeking an ethical and legal way of procuring transplantable organs from the dying without further attempts to redefine human death

Because complex organs taken from unequivocally dead people are not suitable for transplantation, human death has been redefined so that it can be certified at some earlier stage in the dying process and thereby make viable organs available without legal problems. Redefinitions based on concepts of "brain death" have underpinned transplant practice for many years although those concepts have never found universal philosophical acceptance. Neither is there consensus about the clinical tests which have been held sufficient to diagnose the irreversible cessation of all brain function – or as much of it as is deemed relevant – while the body remains alive.     

Caffeine deprivation state modulates expression of acquired liking for caffeine-paired flavours

Previous studies found that caffeine consumers acquired a liking for the flavour of novel caffeinated drinks when these drinks were consumed repeatedly in a caffeine-deprived, but not nondeprived, state. Expression of this acquired liking appeared acutely sensitive to current caffeine deprivation state, but the use of between-subjects designs confounded interpretation of those studies. The present study evaluated these findings further using a within-subject design, with one flavour paired with caffeine (CS + ) and the second with the absence of caffeine (CS-). During four CS + and four CS- training days, 32 moderate caffeine consumers alternatively consumed a novel flavoured drink a CS + paired with caffeine and a CS- flavour paired with placebo. Participants evaluated both drinks before and after training in two motivational states: caffeine deprived and nondeprived. As predicted, pleasantness ratings for the caffeine-paired flavour increased overall. However, this acquired liking was only significant when tested in a caffeine-deprived state. These data are consistent with a conditioned-flavour preference model and imply that expression of acquired liking for a novel caffeinated flavour depends on the need for the effects of caffeine at the time when the drink is evaluated.     

Iffy beliefs: Conditional thinking and belief change

The ability to entertain possibilities and draw inferences about them is essential to human intelligence. We examine the hypothesis that conditional if-then statements trigger a mental simulation process in which people suppose the antecedent (if statement) to be true and evaluate the consequent (then statement) in that context. On the assumption that supposing an event to be true increases belief that the event has occurred or will occur, this hypothesis is consistent with the claim that evaluating a conditional will heighten belief in its antecedent more than in its consequent. Two experiments, employing conditionals of the form If animal A has property X, then animal B will have property X, in which X was a property that people could not readily relate to the animals, supported this claim. The effect was stronger following the evaluation of conditionals with dissimilar animal categories.     

Parents as moderators of psychological and physiological correlates of inner-city children's exposure to violence

This paper discusses the psychological and physiological correlates of inner-city violence on children, and the potential mediating and moderating roles of parents. Data are based on interviews regarding exposure to community violence (ECV), parenting practices, child distress, posttraumatic symptomology, and competence. Cardiovascular activation was also measured. Community violence exposure related to distress, posttraumatic symptomology, and incompetence. Harsh parenting related to aggression, distress, incompetence, and higher heart rates. Parenting moderated but did not mediate the effects of violence on measures of competence. High violence plus harsh parenting predicted lower levels of systolic (SBP) and diastolic blood pressure (DBP). Results are discussed within an ecological framework of parent–child relations and as they relate to the conclusion that children undergoing dual levels of stress may experience a dissociative response.     

Necessity, possibility and belief: A study of syllogistic reasoning

The present study extended the investigation of the belief bias effect in syllogistic reasoning in two ways: (1) The effect was studied under instructions to decide whether conclusions were possible, as well as necessary, given the premises; and (2) the effect was studied for types of syllogism where people rarely endorse the conclusions as well as those (valid and fallacious) where endorsements are common. Three experiments are reported, which show first that there is a marked tendency to reject unbelievable conclusions relative to abstract or neutral controls on all kinds of syllogism and under both types of instruction. There was also significant evidence of positive belief bias (increased acceptance of believable conclusions) and of interactions between belief bias effects and logical form. The results are discussed with particular respect to accounts of belief bias offered by theorists in the mental-model tradition.