A common representational system governed by Weber's law: nonverbal numerical similarity judgments in 6-year-olds and rhesus macaques

This study compared nonverbal numerical processing in 6-year-olds with that in nonhuman animals using a numerical bisection task. In the study, 16 children were trained on a delayed match-to-sample paradigm to match exemplars of two anchor numerosities. Children were then required to indicate whether a sample intermediate to the anchor values was closer to the small anchor value or the large anchor value. For two sets of anchor values with the same ratio, the probability of choosing the larger anchor value increased systematically with sample number, and the psychometric functions superimposed when plotted on a logarithmic scale. The psychometric functions produced by the children also superimposed with the psychometric functions produced by rhesus monkeys in an analogous previous experiment. These examples of superimposition demonstrate that nonverbal number representations, even in children who have acquired the verbal counting system, are modulated by Weber's law.     

Creative thinking in adolescents with attention deficit hyperactivity disorder (ADHD).

A widened attentional focus, that is typically associated with ADHD, has been postulated to be accompanied by enhanced creative ability. However, creativity has been only limitedly examined in ADHD. Performance across several creativity measures were investigated in three groups: adolescents with ADHD, those with conduct disorder, and a healthy control sample. The ADHD group exhibited selective cognitive advantages and disadvantages by demonstrating an enhanced ability in overcoming the constraining influence of examples, but a reduced capacity to generate a functional invention during an imagery task. These findings are interpreted with reference to inhibitory control mechanisms and the contextual modulation of creative cognition.     

Analysis of social interaction gestures in infants with autism.

This study analyzes the emergent use of gestures used among 9-12-month-old infants with autism and typical development using retrospective video analysis. The purpose of the present investigation was to examine the frequency, initiation, prompting, and diversity of types of gestures used for social interaction purposes. It was hypothesized that a restricted variety in type(s) of gestures as well as fewer child-initiated gestures and more prompted gestures would be associated with later diagnosis of autism. Logistic regression analysis found that decreased variety in type of gestures used was significantly associated with autism status. Neither number of total gestures nor initiation of gestures (child-initiated vs. prompted) was significantly associated with autism status.     

Are members of low status groups perceived as bad, or badly off? Egalitarian negative associations and automatic prejudice

Three studies explored the hypothesis that implicit measures of prejudice can tap negative, yet egalitarian associations. In Study 1, automatically associating African Americans with oppression predicted greater automatic prejudice. In Studies 2 and 3, classically conditioning associations between the novel group Noffians and words like oppressed, maltreated, and victimized led to greater automatic prejudice against Noffians. Results suggest that White Americans’ negative automatic associations with African Americans may partly result from associating members of low status groups with unfair circumstances. Because automatic associations predict prejudiced behaviors, the burden of proof is on those wishing to argue that egalitarian negative associations complicate the assessment of automatic attitudes rather than contribute to prejudiced responses. Discussion focuses on the implications of egalitarian negative associations for the theory and measurement of automatic prejudice.     

The psychology of engagement with indigenous identities: a cultural perspective

In a questionnaire study among 124 students at Haskell Indian Nations University, the authors investigated the hypothesis that engagement with Indigenous identity--assessed along three dimensions including degree (identification scale), content (panethnic or tribal nation), and context (reservation or nonreservation)--can serve as a psychological resource for well-being and liberation from oppression. Consistent with this hypothesis, degree of identification was positively correlated with community efficacy and perception of racism. Apparently inconsistent with this hypothesis, degree of identification among students who had resided on a reservation was negatively correlated with the Social Self-Esteem subscale of the Current Thoughts Scale. Rather than evidence against the identity-as-resource hypothesis, this pattern may reflect the cultural grounding of self-esteem and tools designed to measure it.     

A temporally distinct role for group I and group II metabotropic glutamate receptors in object recognition memory

Recognition memory, involving the ability to discriminate between a novel and familiar object, depends on the integrity of the perirhinal cortex (PRH). Glutamate, the main excitatory neurotransmitter in the cortex, is essential for many types of memory processes. Of the subtypes of glutamate receptor, metabotropic receptors (mGluRs) have received less study than NMDA receptors; thus, the reported experiments examined the role of mGluRs in familiarity discrimination in the rat PRH. Experiments 1 and 2 assessed the effects of systemic administration of MPEP, a group I mGluR (specifically mGluR5) antagonist, and/or LY341495, a group II mGluR antagonist, on a spontaneous object novelty preference task. Simultaneous antagonism of both group I and II mGluRs impaired familiarity discrimination following a 24-h but not a 15-min delay, while antagonism of either mGluR subtype alone had no effect at either delay. The impairment was in acquisition, as in Experiment 3 coadministration of MPEP and LY341495 did not affect recognition memory performance when administered either after the sample phase or prior to test. The impairment in long-term recognition memory was mediated by mGluRs in the PRH, as localized intracortical antagonism of group I and II mGluRs also produced a deficit (Experiment 4). No evidence was found for an involvement of group III mGluRs in the acquisition of long-term familiarity discrimination (Experiment 5). These findings establish that glutamatergic neurotransmission in the PRH via group I and II mGluRs is crucial for the acquisition, but not for the consolidation or retrieval of long-term object recognition memory.     

What is the role of mothers in the acquisition of termite-fishing behaviors in wild chimpanzees (Pan troglodytes schweinfurthii)?

This paper explores the role of maternal influences on the acquisition of a tool-using task in wild chimpanzees (Pan troglodytes schweinfurthii) in order to build on and complement previous work done in captivity. Young chimpanzees show a long period of offspring dependency on mothers and it is during this period that offspring learn several important skills, especially how to and on what to forage. At Gombe National Park, one skill that is acquired during dependency is termite-fishing, a complex behavior that involves inserting a tool made from the surrounding vegetation into a termite mound and extracting the termites that attack and cling to the tool. All chimpanzees observed at Gombe have acquired the termite-fishing skill by the age of 5.5 years. Since the mother is the primary source of information throughout this time period, I investigated the influence of mothers' individual termite-fishing characteristics on their offsprings' speed of acquisition and proficiency at the skill once acquired. Mother's time spent alone or with maternal family members, which is highly correlated to time spent termite-fishing, was positively correlated to offspring's acquisition of critical elements of the skill. I also investigated the specific types of social interactions that occur between mothers and offspring at the termite mound and found that mothers are highly tolerant to offspring, even when the behavior of the offspring may disrupt the termite-fishing attempt. However, no active facilitation by mothers of offsprings' attempts were observed. Electronic Supplementary Material Electronic supplementary material Supplementary material is available for this article at http://dx.doi.org/10.1007/s10071-005-0002-7 and accessible for authorised users.