Expectations about numerical events in four lemur species (Eulemur fulvus, Eulemur mongoz, Lemur catta and Varecia rubra)

Although much is known about how some primates—in particular, monkeys and apes—represent and enumerate different numbers of objects, very little is known about the numerical abilities of prosimian primates. Here, we explore how four lemur species (Eulemur fulvus, E. mongoz, Lemur catta, and Varecia rubra) represent small numbers of objects. Specifically, we presented lemurs with three expectancy violation looking time experiments aimed at exploring their expectations about a simple 1+1 addition event. In these experiments, we presented subjects with displays in which two lemons were sequentially added behind an occluder and then measured subjects duration of looking to expected and unexpected outcomes. In experiment 1, subjects looked reliably longer at an unexpected outcome of only one object than at an expected outcome of two objects. Similarly, subjects in experiment 2 looked reliably longer at an unexpected outcome of three objects than at an expected outcome of two objects. In experiment 3, subjects looked reliably longer at an unexpected outcome of one object twice the size of the original than at an expected outcome of two objects of the original size. These results suggest that some prosimian primates understand the outcome of simple arithmetic operations. These results are discussed in light of similar findings in human infants and other adult primates.This revised version was published online in March 2005 with corrections to Fig. 6.     

Means-means-end tool choice in cotton-top tamarins (Saguinus oedipus): finding the limits on primates’ knowledge of tools

Most studies of animal tool use require subjects to use one object to gain access to a food reward. In many real world situations, however, animals perform more than one action in sequence to achieve their goals. Of theoretical interest is whether animals have the cognitive capacity to recognize the relationship between consecutive action sequences in which there may be one overall goal and several subgoals. Here we ask if cotton-top tamarins, a species that in captivity uses tools to solve means-end problems, can go one step further and use a sequence of tools (means) to obtain food (end). We first trained subjects to use a pulling tool to obtain a food reward. After this initial training, subjects were presented with problems in which one tool had to be used in combination with a second in order to obtain food. Subjects showed great difficulty when two tools were required to obtain the food reward. Although subjects attended to the connection between the tool and food reward, they ignored the physical connection between the two tools. After training on a two-tool problem, we presented subjects with a series of transfer tests to explore if they would generalize to new types of connections between the tools. Subjects readily transferred to new connections. Our results therefore provide the first evidence to date that tamarins can learn to solve problems involving two tools, but that they do so only with sufficient training.     

‘Core Knowledges’: a dissociation between spatiotemporal knowledge and contact‐mechanics in a non‐human primate?

Human toddlers demonstrate striking failures when searching for hidden objects that interact with other objects, yet successfully locate hidden objects that do not undergo mechanical interactions. This pattern hints at a developmental dissociation between contact-mechanical and spatiotemporal knowledge. Recent studies suggest that adult non-human primates may exhibit a similar dissociation. Here, I provide the first direct test of this dissociation using a search paradigm with adult rhesus monkeys. Subjects watched as a plum rolled behind one of two opaque barriers. In Experiment 1, subjects had to locate the plum based on the position of a wall that blocked the plum's trajectory. Subjects searched incorrectly, apparently neglecting information about the location of the wall. However, subjects searched correctly in Experiments 2-4 when they were given spatiotemporal information about the plum's movement. Results indicate that adult monkeys use spatiotemporal information, but not contact-mechanical information, to locate hidden objects. This dissociation between contact-mechanical and spatiotemporal knowledge is discussed in light of developmental theories of core knowledge and the literature on object-based attention in human adults.     

Temporal variation in Irish suicide rates

Using Irish suicide data for the period 1990-1998, the independent effects of month and day adjusting for age, gender, and calendar year effects and distinguishing between holiday and working Mondays were assessed. The male suicide rate was significantly higher on working Mondays (+31%) and Saturdays (+14%), and during April, June, and August (+17%), after adjustment for the other variables. In contrast, female suicide rates were higher only in August (+35%) and exhibited no day effect. Teenage men had a greater elevation of risk on Saturdays, Sundays, and both working and holiday Mondays than any other group. The study findings should be taken into account in the planning of specialized health care services and helplines for suicidal people. Furthermore, the findings provide support for Gabennesch's (1988) broken promise theory and the relationship between dysfunctions of the serotonergic system and suicidal behavior.     

Degree of illiteracy and phonological and metaphonological skills in unschooled adults

Phonological and metaphonological skills are explored in 97 Brazilian illiterate and semiliterate adults. A simple letter- and word-reading task was used to define the degree of illiteracy. Phonemic awareness was strongly dependent on the level of letter and word reading ability. Phonological memory was very low in illiterates and unrelated to letter knowledge. Rhyme identification was relatively preserved in illiterates and semiliterates, and unrelated to letter and word reading level. Phonetic discrimination (minimal pairs) was fairly good and marginally related to reading ability. These results suggest that phonological sensitivity, phonological memory, rhyme identification, and phonemic awareness are distinctive cognitive processes, and that only phonemic awareness is clearly and strongly dependent on the alphabetical acquisition.     

Measuring "negative body image": validation of the Body Image Disturbance Questionnaire in a nonclinical population

Despite numerous measures of facets of the body image construct, no single assessment broadly measures a continuum of body image disturbance. Accordingly, this study developed the Body Image Disturbance Questionnaire (BIDQ), derived from the Body Dysmorphic Disorder Questionnaire. Participants were 220 college women and 75 college men who completed an online survey containing this new assessment and established measures of body image and psychosocial functioning. Results confirmed that the Body Image Disturbance Questionnaire was internally consistent and free of impression-management response bias. For both sexes, the measure converged appropriately with other body image indices (evaluation, affect, investment, and impact), was positively correlated with depression, social anxiety, and eating disturbance. Scores on this assessment also predicted psychosocial functioning above and beyond body dissatisfaction as a predictor. Greater body image disturbance was observed among women than men, among heavier than lighter women, and among White than African American women. Limitations and future research implications are discussed.     

Treating boys with low school achievement and behavior problems: comparison of two kinds of intervention

Children with low school achievement frequently have behavior problems and interpersonal difficulties that pose a risk for psychosocial maladjustment. 39 boys were assessed and randomly assigned to one of two group treatment conditions: (a) interpersonal cognitive problem-solving for whom training was provided through oral and written language activities that met children's social and academic needs and (b) a language workshop, during which only academic difficulties were treated. Parents of children in both groups received group attention. Posttreatment assessments indicated that boys in both conditions showed significant improvements on school achievement and behavior problems, as they were measured by behavior scales reported by mothers and by an academic achievement test. Children in the problem-solving group improved significantly more than the other group on most measures. These results suggest that work with interpersonal cognitive problem-solving skills combined with reading and writing activities is a useful means to produce improvements in child behavior and school achievement.     

Gravity biases in a non-human primate?

Pre-school children expect falling objects to travel in a straight line even when there are clear physical mechanisms that deviate the object's path (Hood, 1995). The current study set out to determine whether this expectancy is limited to humans. Cotton-top tamarins (Saguinus oedipus oedipus), a New World monkey species, were tested on Hood's (1995) experimental task where objects are dropped down a chimney connected by an opaque tube to one of three containers. Like human children, there was a significant tendency to search in the container underneath the chimney where the food was dropped on the first trial, even though aligned chimneys and containers were never connected. These search errors suggest that there may be a gravity bias that operates when both primate species fail to understand the constraints operating on object trajectories. Unlike human children however, tamarins were generally more likely to perseverate in making errors even though repeated testing and cost incentives were used.     

The Structure of Idealization in Biological Theories: The Case of the Wright-Fisher Model

In this paper we present a new framework of idealization in biology. We characterize idealizations as a network of counterfactual and hypothetical conditionals that can exhibit different ??degrees of contingency??. We use this idea to say that, in departing more or less from the actual world, idealizations can serve numerous epistemic, methodological or heuristic purposes within scientific research. We defend that, in part, this structure explains why idealizations, despite being deformations of reality, are so successful in scientific practice. For illustrative purposes, we provide an example from population genetics, the Wright-Fisher Model.     

Inhibition of mTOR by rapamycin in the amygdala or hippocampus impairs formation and reconsolidation of inhibitory avoidance memory

Mammalian target of rapamycin (mTOR), a central regulator of protein synthesis in neurons, has been implicated in synaptic plasticity and memory. Here we show that mTOR inhibition by rapamycin in the basolateral amygdala (BLA) or dorsal hippocampus (DH) impairs both formation and reconsolidation of memory for inhibitory avoidance (IA) in rats. Male Wistar rats received bilateral infusions of vehicle or rapamycin into the BLA or DH before or after IA training or retrieval. Memory retention was tested at different time points after drug infusion. Rapamycin impaired long-term IA retention when given before or immediately after training or retrieval into the BLA. When infused into the DH, rapamycin produced memory impairment when given before training or immediately after retrieval. The impairing effects of post-retrieval rapamycin required memory retrieval and were not reversed by a reminder shock. The results provide the first evidence that mTOR in the BLA and DH might play a role in IA memory reconsolidation.