The role of preparation and cue-modality in crossmodal task switching

The present study examined the effects of cue-based preparation and cue-target modality mapping in crossmodal task switching. In two experiments, we randomly presented lateralized visual and auditory stimuli simultaneously. Subjects were asked to make a left/right judgment for a stimulus in only one of the modalities. Prior to each trial, the relevant stimulus modality was indicated by a visual or auditory cue. The cueing interval was manipulated to examine preparation. In Experiment 1, we used a corresponding mapping of cue-modality and stimulus modality, whereas in Experiment 2 the mapping of cue and stimulus modalities was reversed. We found reduced modality-switch costs with a long cueing interval, showing that attention shifts to stimulus modalities can be prepared, irrespective of cue-target modality mapping. We conclude that perceptual processing in crossmodal switching can be biased in a preparatory way towards task-relevant stimulus modalities.     

Leaf swallowing behavior in chimpanzees (Pan troglodytes): biased learning and the emergence of group level cultural differences

Demonstrating the ability to ‘copy’ the behavior of others is an important aspect in determining whether social learning occurs and whether group level differences in a given behavior represent cultural differences or not. Understanding the occurrence of this process in its natural context is essential, but can be a daunting task in the wild. In order to test the social learning hypothesis for the acquisition of leaf swallowing (LS), a self-medicative behavior associated with the expulsion of parasites, we conducted semi-naturalistic experiments on two captive groups of parasite-free, naïve chimpanzees (Pan troglodytes). Individuals in the group were systematically provided appropriate stimuli (rough hispid leaves) identical to those used by chimpanzees in the wild. Individuals initially responded in a variety of ways, ranging from total aversion to normal chewing and swallowing. Over time, however, the two groups adopted different variants for inserting and folding the leaves in the mouth prior to swallowing them (complete and partial LS), following the specific method spontaneously displayed by the first and primary LS models in their respective groups. These variants were similar to LS displayed by chimpanzees in the wild. Using the option-bias method, we found evidence for social learning leading to group-level biased transmission and group-level stabilization of these two variants. This is the first report on two distinct cultural variants innovated in response to the introduction of natural stimuli that emerged and spread spontaneously and concurrently within two adjacent groups of socially housed primates. These observations support the assertion that LS may reflect a generalized propensity for ingesting rough hispid leaves, which can be socially induced and transmitted within a group. Ingesting an adequate number of these leaves induces increased gut motility, which is responsible for the subsequent expulsion of particular parasite species in the wild. Cultural transmission and maintenance of LS within a group and associative learning by the individual of the positive consequences of this otherwise non-nutritive mode of ingestion is proposed to be the pivotal link between this feeding propensity and its maintenance as a self-medicative behavior by great apes in the wild.     

Instructions to authors

Instructions for Authors

Instructions to authors     

Electrophysiological response during source memory decisions in older and younger adults

We recorded event-related potentials (ERPs) as individuals made source monitoring decisions in a paradigm in which the influence of item familiarity and goal relevance could be separately evaluated. Younger and older adults read a list of words and subsequently distinguished these words from foils in a running recognition test in which some foils were repeated after a lag of 6 items, creating familiar lures. Behaviorally, older and younger adults performed equally well in the recognition of study words and the rejection of singly presented foils. However, older adults were more likely to respond to the familiar lures as though they had come from the study list, thus producing the expected group difference in source-monitoring error. For younger adults the ERPs elicited by the targeted study words were maximal at posterior sites and significantly greater than those elicited by either familiar lures or foils. Older adults generated far less differentiated ERP waveforms but with a markedly greater amplitude at frontal sites. We interpret this frontal maximum in the context of poorer source monitoring as suggesting that older adults are more dependent on controlled processes to make discriminations that seem to occur much earlier and more automatically for younger adults.     

Psychometric properties of an adolescent version of the Barratt Impulsiveness Scale-11 for a sample of Italian high school students

The purpose of this study was to extend the development of the Italian version of the Barratt Impulsiveness Scale for use with adolescents. The analyses which led to the development of this version were based on data from 563 high school students. The internal consistency was good (Cronbach alpha=.78). A confirmatory factor analysis identified six first-order factors which converged into two second-order factors, a General Impulsiveness factor and a Nonplanning Impulsiveness factor. The General Impulsiveness factor included motor and attention or cognition items. The second-order factors differed from those obtained with the adult Italian version as well as the American version. Possible reasons for these differences are discussed. The new version correlated significantly with self-report measures of aggression and Attention-Deficit/Hyperactivity Disorder as well as with frequency of alcohol use and cigarette smoking.     

Children’s behavioral patterns, the Five-Factor model of personality, and risk behaviors

Although relations between children’s personality and health behaviors have been identified, previous research has relied primarily on survey assessments. The present study used behavioral observations to examine children’s (n = 94, mean age = 10.07 years) behavioral patterns in relation to their participation in risk behaviors 1 year later. Results contribute to previous reports linking specific personality traits to children’s likelihood of participation in risky behaviors. Specifically, girls’ participation in risky behavior was related to the expression of behavioral patterns associated with neuroticism, introversion, and disagreeableness, while boys participation in risk behaviors was related to behavioral patterns associated with extraversion and disagreeableness. Findings are discussed in terms of their potential for contributing to health promotion efforts aimed at identifying children most at risk for adopting unhealthy behaviors.     

See what you’ve done! Active touch affects the number of perceived visual objects

Previous research has shown that visual perception is affected by sensory information from other modalities. For example, sound can alter the visual intensity or the number of visual objects perceived. However, when touch and vision are combined, vision normally dominates—a phenomenon known asvisual capture. Here we report a cross-modal interaction between active touch and vision: The perceived number of brief visual events (flashes) is affected by the number of concurrently performed finger movements (keypresses). This sensorimotor illusion occurred despite little ambiguity in the visual stimuli themselves and depended on a close temporal proximity between movement execution and vision.     

Adolescent alcohol use in context: the role of parents and peers among African American and European American youth

African American youth are less likely to use alcohol than their European American counterparts; however, the greater consequences of use for African American youth highlight the need for greater research attention to this group. Two social contexts that have been linked with adolescent alcohol use are parents and peers, yet these studies have rarely included African American youth or failed to examine potential racial differences. This study examined the main and interactive effects of parents and peers, as well as the moderating role of race on alcohol use, in African American and European American rural adolescents (n=71) identified as at high-risk for alcohol use. Contrary to study hypotheses, however, parents were not a more robust moderator for African American than European American youth. Clinical implications for prevention and intervention programming for both African American and European American youth are discussed.     

The relationship between the shape of the mental number line and familiarity with numbers in 5- to 9-year old children: evidence for a segmented linear model

This experiment aimed to expand previous findings on the development of mental number representation. We tested the hypothesis that children's familiarity with numbers is directly reflected by the shape of their mental number line. This mental number line was expected to be linear as long as numbers lay within the range of numbers children were familiar with. Five- to 9-year-olds (N=78) estimated the positions of numbers on an external number line and additionally completed a counting assessment mirroring their familiarity with numbers. A segmented regression model consisting of two linear segments described number line estimations significantly better than a logarithmic or a simple linear model. Moreover, the change point between the two linear segments, indicating a change of discriminability between numbers, was significantly correlated with children's familiar number range. Findings are discussed in terms of the accumulator model, assuming a linear mental representation with scalar variability.