Do chimpanzees anticipate an object’s weight? A field experiment on the kinematics of hammer-lifting movements in the nut-cracking Taï chimpanzees

When humans are about to manipulate an object, our brains use visual cues to recall an internal representation to predict its weight and scale the lifting force accordingly. Such a long-term force profile, formed through repeated experiences with similar objects, has been proposed to improve manipulative performance. Skillful object manipulation is crucial for many animals, particularly those that rely on tools for foraging. However, despite enduring interest in tool use in non-human animals, there has been very little investigation of their ability to form an expectation about an object’s weight. In this study, we tested whether wild chimpanzees use long-term force profiles to anticipate the weight of a nut-cracking hammer from its size. To this end, we conducted a field experiment presenting chimpanzees with natural wooden hammers and artificially hollowed, lighter hammers of the same size and external appearance. We used calibrated videos from camera traps to extract kinematic parameters of lifting movements. We found that, when lacking previous experience, chimpanzees lifted hollowed hammers with a higher acceleration than natural hammers (overshoot effect). After using a hammer to crack open one nut, chimpanzees tuned down the lifting acceleration for the hollowed hammers, but continued lifting natural hammers with the same acceleration. Our results show that chimpanzees anticipate the weight of an object using long-term force profiles and suggest that, similarly to humans, they use internal representations of weight to plan their lifting movements.     

Aging and the visual, haptic, and cross-modal perception of natural object shape

One hundred observers participated in two experiments designed to investigate aging and the perception of natural object shape. In the experiments, younger and older observers performed either a same/different shape discrimination task (experiment 1) or a cross-modal matching task (experiment 2). Quantitative effects of age were found in both experiments. The effect of age in experiment 1 was limited to cross-modal shape discrimination: there was no effect of age upon unimodal (ie within a single perceptual modality) shape discrimination. The effect of age in experiment 2 was eliminated when the older observers were either given an unlimited amount of time to perform the task or when the number of response alternatives was decreased. Overall, the results of the experiments reveal that older observers can effectively perceive 3-D shape from both vision and haptics.     

Serotonin transporter (5-HTTLPR) genotype, childhood abuse, and suicide attempts in adult psychiatric inpatients

There is growing evidence that a functional polymorphism in the serotonin transporter gene (5-HTTLPR) moderates the impact of negative life events (e.g., childhood abuse) on the development of depression. However, it is unclear whether the gene x environment interaction predicts suicide attempts specifically. In addition, previous studies have not examined different forms of childhood abuse separately. In the current study, we found that 5-HTTLPR genotype moderated the link between childhood physical and sexual, but not emotional, abuse and adult psychiatric inpatients' histories of suicide attempts.     

The L-Type voltage-gated calcium channel Cav1.3 mediates consolidation, but not extinction, of contextually conditioned fear in mice

Using pharmacological techniques, it has been demonstrated that both consolidation and extinction of Pavlovian fear conditioning are dependent to some extent upon L-type voltage-gated calcium channels (LVGCCs). Although these studies have successfully implicated LVGCCs in Pavlovian fear conditioning, they do not provide information about the specific LVGCC isoform involved. Both of the major LVGCC subtypes found in the brain (Cav1.2 and Cav1.3) are targets of the pharmacological manipulations used in earlier work. In this study, we used mice in which the gene for the pore-forming subunit (alpha1D) Cav1.3 was deleted (Cav1.3 knockout mice) to elucidate its contribution to consolidation and extinction of conditioned fear. We find that Cav1.3 knockout mice exhibit significant impairments in consolidation of contextual fear conditioning. However, once sufficiently overtrained, the Cav1.3 knockout mice exhibit rates of extinction that are identical to that observed in wild-type mice. We also find that Cav1.3 knockout mice perform as well as wild-type mice on the hidden platform version of the Morris water maze, suggesting that the consolidation deficit in conditioned fear observed in the Cav1.3 knockout mice is not likely the result of an inability to encode the context, but may reflect an inability to make the association between the context and the unconditioned stimulus.     

The Self-Report Psychopathy Scale and passive avoidance learning: a validation study of race and gender effects

The reliability and validity of the Self-Report Psychopathy Scale (SRPS) was examined in a noninstitutionalized offender sample of mixed gender and race. Adequate alpha coefficients were obtained for the total sample and across gender and race. The SRPS was compared to measures of trait anxiety and passive avoidance errors. SRPS total, primary, and secondary scores were positively and significantly correlated with trait anxiety and passive avoidance (commission) errors, but not omission errors. Employing hierarchical regression models, no anxiety, gender, or ethnic effects were found. Intelligence confounded the relationship between psychopathic traits and passive avoidance errors. Findings provide tentative support of the SRPS as a valid measure of psychopathy.     

The science of public messages for suicide prevention: a workshop summary

There is minimal guidance for efforts to create effective public messages that increase awareness that suicide is preventable. To address this need, several agencies in the U.S. Department of Health and Human Services and the Annenberg Foundation convened a workshop consisting of suicide prevention advocates and persons with expertise in public health evaluation, suicide contagion, decision-making, and marketing. "Logic models" were used to define intended messages and audiences, assumed mechanisms of change, and outcomes. This summary describes some of the challenges and opportunities identified by workshop participants in evaluating public awareness campaigns in suicide prevention, technical assistance needs, and a proposed research agenda.     

Spatial and relational frameworks for free recall in young and older adults

Previous studies have demonstrated that older adults can use visually distinctive cues to enhance their spatial memory performance and their recall of the identities of items located in space. Other research has shown that older adults can also use relational information to enhance recall. The relationship between relational and visuospatial support for memory across the adult lifespan is complex and has been little explored. In the present study, this relationship was examined in tasks that measured free recall for item sets possessing different degrees of visuospatial and relational support for recall. It was predicted that both types of support would enhance older adult recall relative to that of the young, and that the two types of support would synergize. The results were generally consistent with these predictions. These findings show that older adults can use relatively simple relational or visuospatial support systems to enhance free recall significantly. This research was supported by Grant AGI 1605, National Institute on Aging.     

Replication of a high-probability request sequence with varied interprompt times in a preschool setting

An intervention for noncompliance consisting of a series of requests promoting a high probability of compliance followed either 5 s or 20 s later by a request with a low probability of compliance was implemented with a preschool child with autism. Results indicated that applications of the request sequence with a shorter interprompt time resulted in higher rates of compliance, and longer interprompt times resulted in near-baseline rates of compliance.