How prosimian primates represent tools: experiments with two lemur species (Eulemur fulvus and Lemur catta)

The authors examined how 2 lemur species (Eulemur fulvus and Lemur catta) reason about tools. Experiment 1 allowed subjects to use 1 of 2 canes to retrieve an inaccessible food reward. Lemurs learned to solve this problem as quickly as other primates. Experiment 2 then presented subjects with novel tools differing from the originals along one featural dimension. Subjects attended more to tools' sizes than to their colors and made no distinction between tools' shapes and textures. Experiments 3 and 4 presented problems in which some of the tools' orientations had to be modified relative to the food. Subjects performed well on these problems, sometimes modifying the position of the tool. These results are discussed in light of the performance of other primates on this task.     

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.     

Inferences about the location of food in lemurs (Eulemur macaco and Eulemur fulvus): a comparison with apes and monkeys

The ability of black and brown lemurs (Eulemur macaco and Eulemur fulvus) to make inferences about hidden food was tested using the same paradigm as in Call’s (J Comp Psycol 118:232–241, 2004) cup task experiment. When provided with either visual or auditory information about the content of two boxes (one empty, one baited), lemurs performed better in the auditory condition than in the visual one. When provided with visual or auditory information only about the empty box, one subject out of four was above chance in the auditory condition, implying inferential reasoning. No subject was successful in the visual condition. This study reveals that (1) lemurs are capable of inferential reasoning by exclusion and (2) lemurs make better use of auditory than visual information. The results are compared with the performances recorded in apes and monkeys under the same paradigm.     

Effects of neonatal treatment with 1-(2,5-dimethoxy-4-lodophenyl)-2 aminopropane HCI (DOI) and ritanserin on agonistic behavior in adult male and female rats

The role played by the neonatal 5-hydroxytryptamine (5HT) system in the organization and sexual differentiation of adult agonistic behavior was investigated in rats. Focus was on the 5HT2 receptor subtype, which has been demonstrated to be involved in agonism control in the adult. 5HT2 activity was experimentally manipulated by administration of a specific agonist [1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI)] or antagonist (ritanserin) during the second week of life, when serotonin is known to concur to anatomical and behavioral sexual differentiation. Interactions between early 5HT2 activity, genetic sex, and neonatal circulating testosterone (T) were studied by administering the ligands to males, females, and androgenized females. At adulthood, the animals were tested for both aspects of agonism, i. e., aggression and defense, in a 20-min confrontation with an unfamiliar conspecific of the same sex, age, body weight, and social experience. Neonatal administration of the 5HT2 antagonist ritanserin increased aggression independently of sex; it also increased defense, but this effect was confined to males. The agonist DOI had no effect on aggression, but enhanced defense in males and androgenized females, with an effect which depended therefore more on neonatal T than genetic sex. Females appeared in general less sensitive to neonatal 5HT2 manipulation than both androgenized females and males; this suggests that neonatal T is crucial for experimental modifications of neonatal 5HT2 activity to have any consistent effect on adult agonistic behavior. On the other hand, effects observed in males and androgenized females were dependent on the behavior considered and the drug administered. This was especially evident for defense, enhanced by ritanserin in males only, and in both males and androgenized females by DOI. Neonatal 5HT2 activity seems therefore to play a role in the modulation of adult agonistic behaviors, which depends on the behavior considered and is under multiple control of genetic sex and hormonal neonatal substrate. © 1994 Wiley-Liss, Inc.     

The dual path of the rejection (dis)identification model: A study on adolescents with a migrant background

Ethnic-based rejection, especially when prolonged over time, can result in withdrawal (e.g., resignation) and antisocial (e.g., delinquent) behaviors. Rejection (dis)identification literature suggests that identification with the minority (ethnic) group and disidentification with the majority (national) group mediate the relationship between rejection and different dimensions of well-being. Through secondary analyses of survey data from an international sample of adolescents with a migrant background (N = 1,163) we tested the predictions that, following chronic experiences of rejection, disidentification from the national (rejecting) group will increase withdrawal and feelings of resignation whereas identification with the ethic (rejected) group will have a protective role toward delinquent behaviors. Results of the path analysis were consistent with these hypotheses without significant differences between immigrant generations. The study sheds light on the multifaceted nature of identification processes following social rejection and contributes to the integration of the rejection-identification model with classical theorizations of social exclusion.     

Computerised cognitive‐behaviour therapy (cCBT) and older people: A pilot study to determine factors that influence willingness to engage with cCBT

Objective: The aim of this study was to explore whether older people with depression and/or anxiety were potentially willing to engage with computerised cognitive‐behaviour therapy (cCBT). Method: A short questionnaire was sent to 60 service users aged 65+ who were identified as having anxiety and/or depression. Results: There was a 63.3% response rate for the questionnaire. Almost half of the respondents said they would be interested in using cCBT, and would be willing to learn the necessary computer skills. Conclusions: This pilot study suggests that older people with anxiety and/or depression may be willing to engage with cCBT. However, a number of important factors are highlighted that would need to be considered in deciding whether to develop access to cCBT for older people.     

Neuropsychological Functioning in Children with Medium Chain Acyl Coenzyme A Dehydrogenase Deficiency (MCADD): The Impact of Early Diagnosis and Screening on Outcome

Children with medium chain acyl coenzyme A dehydrogenase deficiency (MCADD) have been reported to be at high risk for neurocognitive deficits. However this has not been systematically studied and little is known about the exact nature of neuropsychological sequelae or of the impact of early diagnosis and screening on outcome. We examined cognitive and adaptive outcome in children with MCADD (N?=?38, age range: 2 years, 2 months – 10 years, 3 months) diagnosed either through a newborn screening program (tandem mass spectrometry/MSMS) or upon clinical presentation. There was no evidence of overall intellectual impairment in either groups but there was some suggestion of poorer verbal and specific executive functioning (i.e., planning) abilities in the unscreened cohorts. Adaptive functioning was relatively intact with the exception of reduced Daily Living Skills in both our screened and unscreened groups. Early diagnosis and greater number of hospitalizations were related to higher verbal, communication, and socialization skills. Overall, our results highlight the importance of early diagnosis and management for children with MCADD.