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ABSTRACTA second case of a novel rabies variant described once in a capuchin monkey from Mato Grosso, Brazil, was discovered in a rabid wild kinkajou from the same region, indicating a public health risk following exposure to either of the two animals.

The production of action sequences is a fundamental aspect of motor skills. To examine whether primary motor cortex (M1) is involved in maintenance of sequential movements, we trained two monkeys (Cebus apella) to perform two sequential reaching tasks. In one task, sequential movements were instructed by visual cues, whereas in the other task, movements were generated from memory after extended practice. After the monkey became proficient with performing the tasks, we injected an inhibitor of protein synthesis, anisomycin, into M1 to disrupt information storage in this area. Injection of anisomycin in M1 had a marked effect on the performance of sequential movements that were guided by memory. In contrast, the anisomycin injection did not have a significant effect on the performance of movements guided by vision. These results suggest that M1 of non-human primates is involved in the maintenance of skilled sequential movements.

The present study compares the biologic behavior of BioGran and Calcitite as fillers for surgical cavities in the mandibles of 4 adult monkeys (Cebus apella). The surgical cavities were prepared through both mandibular cortices, with a diameter of 5 mm, in the angle region. Two cavities were prepared on the right side and 1 on the left and divided into 3 groups: R1 sites were filled with bioglass (BioGran), R2 sites were not filled, and L sites were filled with hydroxyapatite (Calcitite). After 180 days the animals were sacrificed and the specimens were removed for histologic processing. Results showed no bone formation in group R2 (empty cavities). BioGran-treated sites showed bone formation and total repair of the bone defect, and the bioglass particles were almost totally resorbed and substituted by bone. The few remaining crystals were in intimate contact with newly formed bone. Calcitite did not allow bone formation, and granules inside the cavities were involved by connective tissue. Based upon those results, the authors concluded that bioglass resulted in total obliteration of the surgical cavity with bone and hydroxyapatite was present in a large amount and involved by connective tissue, without bone formation. [ABSTRACT FROM AUTHOR]

When competitors are able to assess the asymmetry in the resource holding potential before interacting, individuals or groups should avoid interacting with stronger opponents, thereby avoiding the energy costs and risk of injury associated with aggressive intergroup encounters. Thus, escalated aggression is expected only between closely matched competitors. Among Argentine tufted capuchin monkeys (Sapajus nigritus), intergroup dominance is decided by the asymmetry in male group size. Using playback experiments, I simulated intergroup encounters with neighboring groups, manipulating both the apparent numerical asymmetry and the resource context. During experimental trials, I recorded the approach behavior of the focal individual, as well as changes in neighbor density and individual travel speed following the presentation of the playback stimulus, to assess whether individual willingness to participate in resource defense was affected by the probability of winning the encounter. In spite of the competitive disadvantage, neither males nor females showed a decreased probability of approach when the numerical odds strongly favored the opposing group. Instead decisions regarding whether to participate appear to be driven primarily by the resource context. Nevertheless, changes in individual behavior during approaches suggest that tufted capuchin monkeys are sensitive to the relative odds. Individuals accelerated less when approaching a larger group, although no changes in neighbor density were apparent. The absence of an effect of the numerical asymmetry on willingness to approach the playback speaker suggests that subordinate groups benefit from engaging in intergroup aggression with larger neighbors, despite the high probability of losing. These encounters may serve to assess the current subjective resource valuation of the neighboring group or limit territorial expansion by large groups by decreasing the marginal value of home range exclusivity. Because these encounters are riskier, however, individuals appear to alter their approaches, becoming more tentative as the numerical odds increasingly favor the opposing group. RESEARCH HIGHLIGHTS: Tufted capuchin monkeys will approach neighboring groups in defense of high‐quality food rewards even when the probability of winning is low due to unfavorable numerical odds. Individuals approach more slowly when the group is greatly outnumbered, suggesting they are sensitive to the competitive asymmetry and not simply making an assessment error. [ABSTRACT FROM AUTHOR]

Money is a cultural artefact with a central role in human society. Here, we investigated whether some features of money may be traced back to the exchange habits of nonhuman animals, capitalizing on their ability to flexibly use tokens in different domains. In Experiment 1, we evaluated whether capuchins can recognize token validity. Six subjects were required to exchange with the experimenter valid/familiar tokens, valid/unfamiliar tokens, invalid tokens, and no-value items. They first exchanged a similar number of valid/familiar and valid/unfamiliar tokens, followed by exchanges of invalid tokens and no-value items. Thus, as humans, capuchins readily recognized token validity, regardless of familiarity. In Experiment 2, we further evaluated the flexibility of the token-food association by assessing whether capuchins could engage in reverse food-token exchanges. Subjects spontaneously performed chains of exchanges, in which a food item was exchanged for a token, and then the token was exchanged for another food. However, performance was better as the advantage gained from the exchange increased. Overall, capuchins recognized token validity and successfully engaged in chains of reverse and direct exchanges. This suggests that—although nonhuman animals are far from having fully-fledged monetary systems—for capuchins tokens share at least some features with human money. [ABSTRACT FROM AUTHOR]

Introduction: the phylogenetic similarities between non-human primate and human being stimulate studies of its stomatognathic system, aiming its use on researches. Objective: an anatomic study of the external features of the permanent teeth of the Cebus apella was accomplished, comparing with the human features, in order to normalize as experimental model. Material and Method: two adult animals were used. After the removal of the organic tissue, the teeth were removed and photographed, being analyzed with the loupe. Result: the results showed that the teeth presented similar features to the human being, but with some peculiarities, such as: the presence of the third premolar; the roots present smaller length and volume; the apical third of the central, lateral superiors and inferior incisors are mesiodistally flat; the superior premolars have two individualized roots; the 1st and 2nd superior molars have two roots and the 3rd superior and inferior molars have just one root. Conclusion: the authors conclude that the Cebus apella can be used as experimental model in substitution to the humans in dental researches. [ABSTRACT FROM AUTHOR]

Introduction: the phylogenetic similarities between non-human primates and humans stimulate studies of their stomatognathic system, aiming their use in research. Objective: the objective of this study was to describe the anatomical structures of the maxilla and mandible of Cebus apella comparing to human characteristics. Material and Method: two adult animals were used. After removing the organic tissue, the skulls and jaws were x-rayed and photographed, being analyzed with the magnifying glass. Results: the results showed that the anatomical structures of the maxilla and the mandible had similar characteristics to the human being, but with some peculiarities, such as: the presence of the third premolar; prominent canine prominences in both arches; the mental setting of the majestic; width of ascending branch of maxilla; the presence of the mandibular foramen; V shape of the jaw; incisor foramen size; presence of the incisive suture. With respect to the radiographic interpretation of the pulp chamber and root canal of this species, the maxillary and mandibular maxillary teeth, maxillary and mandibular maxillary teeth are teeth with single, wide, easily accessible ideal for endodontic experiments. Conclusion: thus, the authors conclude that Cebus apella can be used as a study model in endodontic treatment. [ABSTRACT FROM AUTHOR]

Quantifying cortisol concentration in hair is a non‐invasive biomarker of long‐term hypothalamic‐pituitary‐adrenal (HPA) activation, and thus can provide important information on laboratory animal health. Marmosets (Callithrix jacchus) and capuchins (Cebus apella) are New World primates increasingly used in biomedical and neuroscience research, yet published hair cortisol concentrations for these species are limited. Review of the existing published hair cortisol values from marmosets reveals highly discrepant values and the use of variable techniques for hair collection, processing, and cortisol extraction. In this investigation we utilized a well‐established, standardized protocol to extract and quantify cortisol from marmoset (n = 12) and capuchin (n = 4) hair. Shaved hair samples were collected from the upper thigh during scheduled exams and analyzed via methanol extraction and enzyme immunoassay. In marmosets, hair cortisol concentration ranged from 2,710 to 6,267 pg/mg and averaged 4,070 ± 304 pg/mg. In capuchins, hair cortisol concentration ranged from 621 to 2,089 pg/mg and averaged 1,092 ± 338 pg/mg. Hair cortisol concentration was significantly different between marmosets and capuchins, with marmosets having higher concentrations than capuchins. The incorporation of hair cortisol analysis into research protocols provides a non‐invasive measure of HPA axis activity over time, which offers insight into animal health. Utilization of standard protocols across laboratories is essential to obtaining valid measurements and allowing for valuable future cross‐species comparisons. [ABSTRACT FROM AUTHOR]

O objetivo desse trabalho foi contribuir com o estudo anatômico, morfométrico, ultraestrutural e propriedades físicas dos dentes permanentes do primata Sapajus apella. Para tal, foram utilizados 10 animais adultos e machos. Os dentes foram avaliados quanto ao seu comprimento e quanto à anatomia radicular externa e interna considerando número de raízes e canais, forma e direção radicular e forma do canal, assim como análise da densidade e diâmetro tubular do canal radicular, composição e microdureza dentinária. A anatomia radicular desse primata apresentou especificidades, como o número de raízes do segundo pré-molar superior e a presença do terceiro pré-molar. Quanto à densidade e o diâmetro dos túbulos dentinários, observou-se uma diminuição do número e diâmetro de túbulos ao longo do canal radicular, havendo diferença estatisticamente significante ao se comparar o terço apical com as regiões cervical e média, padrão de densidade e tamanho semelhantes a dentes humanos. Semelhanças também foram encontradas com dentes humanos quando comparados os valores de microdureza e proporção de elementos químicos encontrados na dentina radicular.

Cytogenetic studies in Cebus spp. have highlighted a peculiar genomic feature: the presence of conspicuous regions of extracentromeric heterochromatin distributed throughout the karyotype. This study investigates the distribution, variability and composition of heterochromatin and their possible implications for genome dynamics. We performed a molecular cytogenetic analysis in 253 individuals from seven of the 12 currently recognized species. The proportion of heterochromatin was related to genome size and ranked, from smallest to largest, from C. xanthosternos to C. albifrons. Interspecies comparative genome hybridization analyses suggested that the differences among species are not related to heterochromatin content but to changes in the Y chromosome. The pattern revealed by DAPI/ CMA3 staining showed that Cebus heterochromatic DNA has a GC-rich composition. The distribution frequencies of heteromorphisms and polymorphisms were not randomly distributed, because a distinguishable pattern could be recognized for each group. Cebus cay and C. nigritus had a higher level of heterochromatin variability than previously reported. In conclusion, the wide variability among species of the genus Cebus is mostly due to the repetitive DNA fraction of its genome. [ABSTRACT FROM AUTHOR]

The adaptive significance of human brain evolution has been frequently studied through comparisons with other primates. However, the evolution of increased brain size is not restricted to the human lineage but is a general characteristic of primate evolution. Whether or not these independent episodes of increased brain size share a common genetic basis is unclear. We sequenced and de novo assembled the transcriptome from the neocortical tissue of the most highly encephalized nonhuman primate, the tufted capuchin monkey (Cebus apella). Using this novel data set, we conducted a genome-wide analysis of orthologous brain-expressed protein coding genes to identify evidence of conserved gene-phenotype associations and species-specific adaptations during three independent episodes of brain size increase. We identify a greater number of genes associated with either total brain mass or relative brain size across these six species than show species-specific accelerated rates of evolution in individual large-brained lineages. We test the robustness of these associations in an expanded data set of 13 species, through permutation tests and by analyzing how genome-wide patterns of substitution co-vary with brain size. Many of the genes targeted by selection during brain expansion have glutamatergic functions or roles in cell cycle dynamics. We also identify accelerated evolution in a number of individual capuchin genes whose human orthologs are associated with human neuropsychiatric disorders. These findings demonstrate the value of phenotypically informed genome analyses, and suggest at least some aspects of human brain evolution have occurred through conserved gene-phenotype associations. Understanding these commonalities is essential for distinguishing human-specific selection events from general trends in brain evolution. [ABSTRACT FROM AUTHOR]

The capuchin monkey is widespread both north and south of the Legal Amazon and in the Brazilian cerrado. Ten clinically healthy capuchin monkeys were submitted to an anatomical and radiographic study of their thoracic cavities. The radiographic evaluation allowed the description of biometric values associated with the cardiac silhouette and thoracic structures. Application of the VHS (vertebral heart size) method showed positive correlation (PO macaco-prego é muito comum tanto no norte, quanto no sul da Amazônia Legal e no cerrado brasileiro. Dez macacos-prego clinicamente saudáveis foram submetidos a um estudo anatômico e radiográfico de suas cavidades torácicas. A avaliação radiográfica permitiu a descrição de valores biométricos associados à silhueta cardíaca e estruturas torácicas. A aplicação do método de VHS (vertebral heart size) demonstrou correlação positiva (P

The phylogenetic relationships of primates have been extensively investigated, but key issues remain unresolved. Complete mitochondrial genome (mitogenome) data have many advantages in phylogenetic analyses, but such data are available for only 46 primate species. In this work, we determined the complete mitogenome sequence of the black-capped capuchin (Cebus apella). The genome was 16,538 bp in size and consisted of 13 protein-coding genes, 22 tRNAs, two rRNAs and a control region. The genome organization, nucleotide composition and codon usage did not differ significantly from those of other primates. The control region contained several distinct repeat motifs, including a putative termination-associated sequence (TAS) and several conserved sequence blocks (CSB-F, E, D, C, B and 1). Among the protein-coding genes, the COII gene had lower nonsynonymous and synonymous substitutions rates while the ATP8 and ND4 genes had higher rates. A phylogenetic analysis using Maximum likelihood and Bayesian methods and the complete mitogenome data for platyrrhine species confirmed the basal position of the Callicebinae and the sister relationship between Atelinae and Cebidae, as well as the sister relationship between Aotinae (Aotus) and Cebinae (Cebus/Saimiri) in Cebidae. These conclusions agreed with the most recent molecular phylogenetic investigations on primates. This work provides a framework for the use of complete mitogenome information in phylogenetic analyses of the Platyrrhini and primates in general.

Los primates son uno de los grupos de mamíferos más decomisados por la autoridades ambientales (SDA) en Bogotá, Colombia. Un total de 133 primates fueron confiscados en Bogotá durante el año 2008 y mantenidos en las instalaciones de la SDA. De ellos, 115 fueron secuenciados para el gen mitocondrial citocromo oxidasa II (mtCOII) y en 112 ejemplares, las secuencias obtenidas fueron de alta calidad. Esas secuencias se compararon con las obtenidas para ejemplares muestreados directamente en campo por nuestro grupo de investigación y con origen geográfico conocido. De ese modo, se pudo determinar las áreas geográficas, en el territorio colombiano, donde pueden liberarse esos ejemplares después del tratamiento de rehabilitación oportuno. Los resultados principales para las cinco especies de primates fueron como siguen: 1- Para Saguinus leucopus, los animales analizados pueden ser liberados en cualquier área geográfica dentro del rango de distribución de la especie, ya que solo se detectó un acervo genético sin estructura espacial. 2- Para los 14 Aotus sp. secuenciados procedentes de la SDA, se determinó que: uno de ellos pertenecía a A. vociferans, propio de la Amazonía; siete ejemplares pertenecieron a A. griseimembra, propio del valle del Magdalena hasta la costa Caribe colombiana; cuatro ejemplares representaron a A. brumbacki, de los Llanos Orientales de Colombia; y dos ejemplares se asociaron con A. azarae azarae del norte de Argentina y Paraguay, con lo cual se muestra que en Colombia se está recibiendo fauna ilegal procedente de otros países. 3- De los 14 Cebus albifrons secuenciados, dos pertenecieron al área geográfica de distribución de C. a. versicolor; uno al de C. a. pleei, 10 al de C. a. leucocephalus, y uno no pudo ser asignado ya que su secuencia mostraba gran divergencia respecto a los otros ejemplares secuenciados de esta especie. 4- Los dos Cebus capucinus secuenciados mostraron estar asociados a un acervo genético encontrado en el norte del Chocó, Sucre y Córdoba. 5- De 11 Cebus apella secuenciados, 10 mostraron pertenecer al acervo genético que se encuentra en los Llanos Orientales de Colombia y altamente relacionado a Cebus apella apella de la Guyana Francesa, aunque podrían representar un acervo propio de Colombia, C. a. fatuellus sensu Groves (2001). Un individuo no pudo ser relacionado con ningún grupo de los otros C. apella estudiados, ni con los taxones relacionados a la especie mencionada, pero, probablemente, con su propio estatus taxonómico (C. a. paraguayanus = C. cay, C. xanthosternos, C. nigritus).

This study aimed to identify, describe and analyze the behavioral patterns of capuchin monkeys in captivity. Were observed seven individuals of the species Cebus apella, six males (four adults, one sub-adult and one juvenile) and one adult female. Initially, observations were performed by using the ad libitum for preparing the ethogram; after, were used the scan sampling method to establish the behavioral patterns during four days over a period of 8 hours and 50 minutes consecutively, in the period from 7:00 a.m. to 16:00 p.m. Among the observed behaviors, Rest, Picking, Drinking Water, Foraging, Scratching, Displacement, Observation, Play and Use and/or handling of tools showed significant differences in the statistical analysis were the behaviors (P

O objetivo do estudo foi avaliar a água de coco em pó (ACP) na conservação do sêmen e liquefação do coágulo seminal de Cebus apella. O sêmen de seis machos adultos foi coletado por eletroejaculação (EEJ), diluído em solução à base de ACP-118® e submetido à incubação em banho-maria a 33, 35 e 37°C, por 24 horas. Avaliou-se a integridade espermática por meio da coloração eosina-nigrosina a cada uma hora durante as seis horas iniciais e após 24 horas de incubação. Os volumes médios e as concentrações espermáticas das frações coagulada e líquida foram de 0,20±0,02 e 0,20±0,10mL; 1,1±0,3x10(8) e 1,3±0,9x10(7) espermatozoides mL-1, respectivamente. Somente em uma amostra da fração líquida foram verificados espermatozoides com motilidade (20%) e vigor (4), perdurando por 40 minutos. A maior parte do coágulo liquefez em ACP-118® após 12 horas de incubação. O melhor tratamento observado foi sob 33°C, por manter até 47±12,8% de espermatozoides vivos após 24 horas. Conclui-se que o diluente à base de ACP é eficiente na liquefação do coágulo seminal e na manutenção da integridade espermática até 24 horas após a EEJ, nas temperaturas de 33, 35 e 37°C.The aim of this study was to evaluate the powdered coconut water (PCW) in the semen conservation and seminal clot liquefaction. The semen of six adult male Cebus apella was collected by electroejaculation (EEJ), diluted in ACP-118® extender and stayed in water bath at 33, 35 and 37°C for 24 hours. The sperm integrity was evaluated by eosin-nigrosine staining every one hour during the six initial hours and after 24 hours of incubation. The average volumes and sperm concentrations of clotted and liquid fractions were 0.20±0.02 and 0.20±0.10mL, 1.1±0.3x108 and 1.3±0.9x107 sperm mL-1, respectively. Immediately after collection, only in a sample of liquid fraction was observed 20% motility and vigor 4, which stopped after 40 minutes. Most of the clot was liquefied in ACP-118® after 12 hours of incubation. The best observed treatment was 33°C, because it kept 47±12.8% of sperm integrity after 24 hours. It was concluded that the PCW extender is effective in the liquefaction of seminal clot and maintenance of sperm viability 24 hours after the EEJ at 33, 35 and 37°C.

Arbitrary conditional discriminations are difficult to obtain in non-human subjects. This study evaluates the efficacy of sample stimulus shaping procedure. Two experiments were carried out. In Experiment I two capuchin monkeys, M12 and M15, acquired quickly the discriminations, and a third subject, M09, required longer training. In Experiment II, the procedure was modified and a new training with M09 was carried out, and M09 performance improved. However, lack of stimulus control coherence was found, precluding the conclusion of the shaping process. Key procedural variables in stimulus control research and intervention with non-humans and people with developmental disabilities are discussed.

Estudou-se quatorze palatos duros de primatas neotropicais (Cebus apella, L.1766), fixados em formaldeído (10%) conservados em álcool etílico (70%) coletados dentro das normas internacionais de bioética. Os animais foram cedidos pela Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo em 1994. São provenientes do Zoológico de São Paulo e vieram a óbito por morte natural. Mediu-se em centímetros no vícero crânio (8 adultos e 6 jovens): comprimento do palato (CP), distâncias; interpremolares (DP), intermolares (DM), interorbitais (DO), altura da face média (FM). O palato apresentou cristas completas direitas (7,64 a 1,22), esquerdas (8,07 a 1,71) e incompletas direitas (1,71 a 1,43), esquerdas (1,64 a 1,3). O diastema entre os dentes incisivos laterais marcou o início das cristas cuja terminação coincidiu com os segundos molares independente da maturidade do indivíduo. O palato é peculiar: ligeiramente côncavo indo da arcada dentária em direção a rafe mediana; revestido por mucosa despigmentada, com arcabouço ósseo composto pelas lâminas horizontais dos maxilares e palatinos; submucosa aderida ao periósteo e mucosa exibindo cristas palatinas relativamente proeminentes. As cristas apresentam-se como relevos rígidos da mucosa, ocorrendo variações nos antímeros, podendo-se inferir que quantitativamente o cumprimento do palato duro está fortemente correacionado à maturidade do indivíduo, relativamente a distância interorbital, sendo que esta última guardou correlação com o comprimento do palato e a abertura da rima labial.

O macaco-prego, Cebus apella, é muito difundido no norte e sul da Amazônia Legal Brasileira e no Cerrado. Estes animais encontram-se rotineiramente submetidos à caça predatória, aumentando assim a necessidade de preservação desta espécie silvestre. Realizou-se um estudo ultra-sonográfico de 10 macacos-prego como forma de descrever a anatomia ultra-sonográfica normal de sua cavidade abdominal. A vesícula urinária apresentou parede com espessura média 0,2cm e em posição anatômica cuja topografia permitiu contato com as paredes do corpo do útero e cólon descendente. À varredura abdominal caudal foi visualizada a aorta, veia cava caudal e veia ilíaca direita. O fígado foi visto em varredura sagital e transversal, possibilitando a observação da vesícula biliar e vasos hepáticos. A varredura renal demonstrou com precisão a pelve, seio renal e relação cortico-medular. O comprimento médio de ambos os rins foi de 6,24±0,31cm, não existindo diferença estatística entre o rim direito e esquerdo (Teste t de Student e ANOVA). O volume renal foi 2,37±0,18cm³. Os coeficientes de Correlação de Pearson entre os comprimentos renais direito e esquerdo e entre volumes renais direito e esquerdo foram dispostos como r = 0,74 e 0,51. As espessuras médias para a região cortical e medular foram 0,75±0,11cm e 0,39±0,06cm, respectivamente. O coeficiente de correlação para a relação cortico-medular entre os rins direito e esquerdo foi de r = 0,19. O exame ultrasonográfico mostrou-se como uma técnica eficiente, nãoinvasiva, rápida e reprodutível, que provê dados importantes aos profissionais da área de clínica e cirurgia de animais silvestres.The Brown Capuchin, Cebus apella, has a wide distribution in the northern and southern Brazilian Amazon region and in the Cerrado (savanna). These monkeys are usually submitted to predatory chase, increasing the need for preservation of this wild animal species. An ultrasonographic examination of 10 Brown Capuchins was made in order to describe the normal ultrasonographic anatomy of their abdominal cavity. The urinary bladder revealed its wall thickness with an average of 0.2cm, the topographic situation of which allowed close relation with the wall of uterus and descendent colon. Using caudal abdominal scan, images of aorta, caudal vena cava and right iliac vein were obtained. Liver was accessible for examination by sagittal and cross-section ultrasound, allowing visualization of gallbladder and hepatic vessels. Renal scan allowed accuracy to evidence the echogenicity differences between pelvis, renal sinus, as well as the cortical-medullary relationship. The mean length of the kidneys was 6.24±0.31cm, and no significant differences were observed between left and right kidney length (Student's t-test and ANOVA). The renal volume obtained was 2.37±0.18cm³. Correlation Coefficients of Pearson between right and left renal length and between right and left renal volume were r = 0.74 and 0.51. Mean thickness for cortical and medullar regions was 0.75±0.11 and 0.39±0.06cm, respectively. Correlation Coefficient of corticomedullar relation between right and left renal was r = 0.19. Examination by ultrasound was considered an efficient, noninvasive, fast and repeatable technique which provides useful data for clinicians and surgeons engaged in wild animal medicine.

Considering the importance of the cerebellum's function in the control and maintenance of body equilibrium and muscle tonus, as well as the establishment of posture, harmony and movement coordination, this work proposes to analyze, in Cebus apella, the macro- and mesoscopic morphology of its cerebellum. The aim was to achieve a better knowledge of the macroscopic morphology of this organ in comparison to those of other non-human primates and domestic mammals. The 20 animals used for macroscopic and mesoscopy analysis (supplied by anatomy collection of Universidade Federal de Uberlândia, MG) were fixed and maintained in formaldehyde 10%. After the preparation of each part, the cerebellum hemispheres, that seemed little developed in relation to the vermis, were inspected. Three portions of cerebellum body were identified: the anterior lobe, posterior and floculonodular lobes. The primary, horizontal, secondary, posterolateral, intraculminal and post-clival fissures were well defined. The pre-central, pre-culminal and intra-biventer fissures were less obvious. The cuts for morphological internal analysis were affected according to the median and horizontal sagittal planes at a distance of 2 to 3mm, being stained by Mulligan's solution. The most evident structures are described in detail, comparing the data obtained with that of the relevant literature.

Damage caused by Sapajus nigritus to pine plantations is common in southern and southeastern Brazil. To assess the susceptibility to these primate attacks, the average percentage of trees with damage was calculated in continuous inventory plots of nine tropical and temperate Pinus spp. species, from four company plantations within the states of Parana and Santa Catarina. The results indicated a preference for P. taeda and P. greggii, with almost 97% of trees damaged. Regarding the least susceptible species, P. patula and P. palustris trees showed little (0.01%) or no damage. The other Pinus species ranged from 1.4 to 11.8% damage. The preference of Brown-capuchin monkeys for P. taeda is particularly worrying, as it is the most widely planted species in southern Brazil. However, other species that suffer little or no damage could be used as an alternative plantation species that enable the diversification of crops and opens new perspectives for the improvement and genetic engineering of pine, which take into account the needs of different producers. It is recommended however, that these strategies are combined with the recovery of native forests, since damage to forest plantations is related to the low quality of the remaining surrounding native forest patches. [ABSTRACT FROM AUTHOR]

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Non-human primates demonstrate food preferences much like humans. We have little insight, however, into how those preferences impact oral processing in primates. To begin describing this relationship, we conducted a preliminary analysis measuring food preference in two tufted capuchins ( Cebus apella ) and comparing ranked preference to physiological variables during chewing of these foods. Food preference was assessed for each monkey across 12 foods, including monkey biscuits and 11 foods consumed by humans (e.g., various fruits and nuts). Animals chose from randomized pairs of foods to generate a ranked scale across the 12 foods. Contemporaneous with preference testing, electromyographic (EMG) activity was measured for the jaw-closing muscles to assess oral physiology during chewing of these foods. As expected, these capuchins exhibited clear preferences among these 12 foods. Based on their preferences, we identified sets of preferred and non-preferred brittle (i.e., almond versus monkey chow) and ductile (i.e., dates and prunes versus apricots) foods for physiological comparisons that broadly control variation in food mechanical properties (FMPs). As expected, oral physiology varied with FMPs in each animal. Within brittle and ductile groupings, we observed several significant differences in chewing cycle length and relative muscle activation levels that are likely related to food preference. These differences tended to be complex and individual specific. The two capuchins chewed non-preferred apricots significantly faster than preferred dates and prunes. Effect sizes for preference were smaller than those for FMPs, supporting the previous focus on FMPs in primate dietary research. Although preliminary, these results suggest that food preference may influence oral physiology in non-human primates. The prospect that this relationship exists in monkeys raises the possibility that a link between food preference and oral processing in humans may be based on shared tendencies with non-human primates, such as aversion to bitter items or preference for sweet foods. [ABSTRACT FROM AUTHOR]

A key issue in understanding the evolutionary and developmental emergence of numerical cognition is to learn what mechanism(s) support perception and representation of quantitative information. Two such systems have been proposed, one for dealing with approximate representation of sets of items across an extended numerical range and another for highly precise representation of only small numbers of items. Evidence for the first system is abundant across species and in many tests with human adults and children, whereas the second system is primarily evident in research with children and in some tests with non-human animals. A recent paper (Choo & Franconeri, Psychonomic Bulletin & Review, 21, 93-99, 2014) with adult humans also reported 'superprecise' representation of small sets of items in comparison to large sets of items, which would provide more support for the presence of a second system in human adults. We first presented capuchin monkeys with a test similar to that of Choo and Franconeri in which small or large sets with the same ratios had to be discriminated. We then presented the same monkeys with an expanded range of comparisons in the small number range (all comparisons of 1-9 items) and the large number range (all comparisons of 10-90 items in 10-item increments). Capuchin monkeys showed no increased precision for small over large sets in making these discriminations in either experiment. These data indicate a difference in the performance of monkeys to that of adult humans, and specifically that monkeys do not show improved discrimination performance for small sets relative to large sets when the relative numerical differences are held constant. [ABSTRACT FROM AUTHOR]

Questionnaires that allow people who are familiar with individual animals to rate the welfare of these animals are an underutilised tool. We designed a 12-item welfare questionnaire and tested its reliability and associations with subjective well-being (SWB), locomotor stereotypy, and personality traits. The welfare questionnaire included questions relating to physical health, stress and coping, satisfaction with social relationships, psychological stimulation, and the display of positive and negative welfare indicators. We collected ratings of 66 brown capuchins ( Sapajus apella ) living in three facilities. Each capuchin was rated on the welfare questionnaire by an average of 2.8 raters. The interrater reliability of the welfare questionnaire items ranged from ICC(3, k ) 0.51 to 0.86. A principal components analysis indicated that the 12 welfare items loaded onto one component. We repeated this process with the welfare and four items used to measure subjective well-being and found all the items were defined by a single component (welfareSWB). We then conducted three sets of analyses, one predicting the welfare component, one predicting the SWB component, and predicting the welfareSWB component. The independent variables were frequency of locomotor stereotypy, personality, age, and sex; facility was included as a random effect. In models including stereotypy, age, and sex we found frequency of stereotypy to be significantly associated with all three predicted components (ps < 0.01). After controlling for stereotypy ( b = −0.25, p = 0.17), age ( b = −0.54, p = 0.01), and sex ( b = −0.32, p = 0.07), the personality traits of Sociability ( b = 1.02, p < 0.001), Assertiveness, ( b = 0.63, p < 0.001), and Attentiveness ( b = 0.54, p = 0.01) were associated with higher scores on the joint welfareSWB component; Neuroticism was negatively associated with welfare SWB ( b = −0.60, p = 0.01). Our results suggest that welfare questionnaires is a useful, reliable, and valid tool for primate welfare assessment. [ABSTRACT FROM AUTHOR]

In comparative psychology, both similarities and differences among species are studied to better understand the evolution of their behavior. To do so, we first test species in tasks using similar procedures, but if differences are found, it is important to determine their underlying cause(s) (e.g., are they due to ecology, cognitive ability, an artifact of the study, and/or some other factor?). In our previous work, primates performed unexpectedly poorly on an apparently simple two-choice discrimination task based on the natural behavior of cleaner fish, while the fish did quite well. In this task, if the subjects first chose one of the options (ephemeral) they received both food items, but if they chose the other (permanent) option first, the ephemeral option disappeared. Here, we test several proposed explanations for primates' relatively poorer performance. In Study 1, we used a computerized paradigm that differed from the previous test by removing interaction with human experimenters, which may be distracting, and providing a more standardized testing environment. In Study 2, we adapted the computerized paradigm from Study 1 to be more relevant to primate ecology. Monkeys' overall performance in these adapted tasks matched the performance of the fish in the original study, showing that with the appropriate modifications they can solve the task. We discuss these results in light of comparative research, which requires balancing procedural similarity with considerations of how the details of the task or the context may influence how different species perceive and solve tasks differently. [ABSTRACT FROM AUTHOR]

The present study aimed to obtain quanti-qualitative data about the follicular ovarian population in Cebus apella females. Seven ovaries were obtained from 4 C. apella adult females. The ovaries were subjected to light microscopy. The number of preantral and antral follicles for each ovary was estimated using the Fractionator method. The preantral follicles were classified into primordial, transitional, primary and secondary follicles. Antral follicles were those that presented an antral cavity. All counted follicles were classified as normal or degenerated. The diameter of the follicles, oocytes and their nuclei were determined to accompany the follicular development. All results were represented as mean ± SE. The number of preantral follicles was 56,938 ± 21,888 and 49,133 ± 26,896 for the right and left ovaries, respectively. The percentage of normal follicles was 80 ± 4.95%. The follicular diameter ranged from 22 ± 0.5 µm to 61.2 ± 4.0 µm. Regarding the antral follicles, the number of normal and degenerate follicles per ovary were 60.0 ± 19.0 and 3 ± 1.8 follicles, respectively. The antral follicular diameter was 514.4 + 56.6 µm. In conclusion, the information obtained in this study can be used as a parameter for subsequent in vivo or in vitro studies about folliculogenesis in non-human neotropical primates of the C. apella species.O objetivo do presente trabalho foi obter dados quantitativos e qualitativos da população folicular ovariana de fêmeas de Cebus apella. Foram obtidos 7 ovários de 4 fêmeas adultas de C. apella através de ovariectomia. Os ovários foram submetidos à preparação para histologia ótica de rotina. O número de folículos pré-antrais e antrais por ovário foi estimado utilizando o Método Fracionador. Os folículos pré-antrais foram classificados em primordial, transição, primário e secundário. Foram considerados folículos antrais todos aqueles que apresentavam uma cavidade antral. Todos os folículos contados foram classificados em normais ou degenerados. Com o intuito de acompanhar o desenvolvimento folicular, os diâmetros médios folicular, oocitário e do núcleo do oócito foram determinados. Todos os resultados foram apresentados em Média ± Erro Padrão. A população média de folículos pré-antrais foi de 56.938 ± 21.888 e 49.133 ± 26.896 para os ovários direito e esquerdo, respectivamente. A percentagem de folículos pré-antrais estimados normais foi de 80,00 ± 4,95 %. O diâmetro médio folicular variou de 22,0 ± 0,5 µm a 61,2 ± 4,0 µm. No tocante aos folículos antrais, a população média de folículos normais e degenerados por ovário foi de 60,0 ± 19,0 e 3 ± 1,8 folículos, respectivamente. O diâmetro médio folicular foi de 514,4 ± 56,6 µm. Para concluir, as informações obtidas neste trabalho poderão servir como parâmetro para posteriores estudos in vivo ou in vitro da foliculogênese de primatas não-humanos neotropicais da espécie C. apella.

The aim of this study was to adapt a mechanical procedure for the isolation of intact preantral follicles from Cebus apella ovaries. The interval effect of serial sections of the tissue chopper was tested on a number of preantral follicles isolated from ovaries (n=6) of three C. apella females, two prepubertal and one adult. Ovaries were divided into four equal parts and fragmented with a tissue chopper, adjusted for serial sections at intervals of 250, 500, 750 and 1,000µm, respectively. Isolated follicles were counted in a Neubauer's chamber and classified as primordial, primary or secondary. The number (mean±SE) of preantral follicles isolated from 1/4 ovary varied from 68,330+17,590 (at the 1,000µm cut interval) to 300,830+111,460 (at the 500µm cut interval. The mean diameter of the isolated preantral follicles varied from 11.6µm to 27.8µm.

Fusobacterium nucleatum is a strict anaerobe and is indigenous of the human oral cavity. This organism is commonly recovered from different monomicrobial and mixed infections in humans and animals. In this study, the plasmid profile, the plasmid stability and the penicillin-resistance association in oral F. nucleatum isolated from periodontal patients, healthy subjects and Cebus apella monkeys were evaluated. Forty-five F. nucleatum strains from patients, 38 from healthy subjects and seven from C. apella were identified and analyzed. Plasmid extraction was performed in all the isolated strains. These elements were found in 26.7% strains from patients and one strain from C. apella. Strains from healthy subjects did not show any plasmid. Most of strains showed two plasmid bands ranging from 4 to 16 Kb, but digestions with endonucleases showed that they belonged to a single plasmid. The plasmid profile was similar and stable in human and monkey strains. Also, plasmids were classified into three groups according to size. Two strains were positive to beta-lactamase production and no plasmid DNA-hybridization with a beta-lactamase gene probe was observed, suggesting a chromosomal resistance.

Recent work in judgment and decision-making has shown that a good’s price can have irrational effects on people’s preferences. People tend to prefer goods that cost more money and assume that such expensive goods will be more effective, even in cases where the price of the good is itself arbitrary. Although much work has documented the existence of these pricing effects, unfortunately little work has addressed where these price effects come from in the first place. Here we use a comparative approach to distinguish between different accounts of this bias and to explore the origins of these effects. Specifically, we test whether brown capuchin monkeys (Cebus apella) are also susceptible to pricing effects within the context of an experimentally trained token economy. Using a capuchin population previously trained in a token market, we explored whether monkeys used price as an indicator of value across four experiments. Although monkeys demonstrated an understanding of which goods had which prices (consistently shifting preferences to cheaper goods when prices were increased), we observed no evidence that such price information affected their valuation of different kinds of goods. These results suggest that human price effects may involve more sophisticated human-unique cognitive capacities, such as an understanding of market forces and signaling.

Recent research suggests that many primate species understand others' actions not only in terms of their physical movements, but also in terms of the actor's underlying goals and intentions. Impressively, apes also have the capacity to incorporate previously acquired contextual information into their goal representations. To date, little work has tested whether other primates demonstrate this level of flexibility when inferring others' goals. To help address this question, we tested capuchin monkeys using a procedure similar to one that Buttelmann, Schiitte, Carpenter, Call, and Tomasello (2012) used to test apes. Capuchin subjects were repeatedly shown an experimenter manipulating locking mechanisms on a series of boxes. In an experimental condition, the experimenter gave subjects food retrieved from inside the boxes, whereas in a control condition subjects never received food from inside the boxes. We then explored how capuchin subjects would interpret the experimenter's ambiguous manipulation of a novel box. In contrast to apes, subjects in our experiment showed little evidence of being able to flexibly use temporally dissociated contextual cues to make inferences regarding others' goals. This result may point to a crucial difference in the sophistication with which ape and nonape primates understand others' actions. [ABSTRACT FROM AUTHOR]

Objectives: Capuchin monkeys are well known to have a high degree of manual dexterity. In this study, we assessed the variability of capuchin grasping actions involving power grips, i.e., manual actions in which the object is grasped between the palm and one or several parts of the fingers and that do not necessarily involve individually controlled finger movements. Planning abilities in executing actions were also evaluated. Methods: Twenty tufted capuchins (Sapajus spp.) were tested in a task requiring individuals to grasp a dowel inserted into a vertical tube. We examined their grasping techniques, focusing on the following aspects: (i) the different hand postures made during grasping, (ii) the frequency of thumb use in opposition to the other fingers, (iii) the asymmetric use of the hands, and (iv) the configuration of the grasping action for the purpose of comfortably bringing the food to the mouth. Results: Eight power-grip variants were identified, with individual capuchins performing an average of more than five different grips. The use of the thumb in opposition to the other areas of the hand, as reported in studies of precision grips, also appears to be a common feature in power grips. No evidence of group-level manual asymmetries was found. Adult capuchins were better than immature individuals in planning grasping actions in relation to following task demands. Discussion: Overall, these findings clarify the extent to which manual dexterity and cognitive abilities can be expressed in the grasping tasks of highly manually skilled primate species. [ABSTRACT FROM AUTHOR]

The renal lesions are of special importance in the captive primates. The most commonly pathologies are: pyelonephritis, nephrocalcinosis, glomerulonephritis, congenital malformations, hydronephrosis and functional diseases. We report the histopathological study of renal lesions of five cases of deaths in Cebus apella (Primates) of the Argentinean Primate Center. The ages of the monkeys were from 4 months to 15 years old. Microscopically, we have observed principally acute diffuse proliferative glomerulonephritis, hilar mesangio proliferative glomerulonephritis, extracapilar glomerulonephritis with crescents, chronic interstitial nephritis and chronic pyelophritis.

Asymmetries in resource-holding potential between opposing groups frequently determine outcomes of intergroup contests. Since both numerical superiority and high intergroup dominance rank may confer competitive advantages, group members should benefit from assessing the relative strength of rivals prior to engaging in defensive displays. However, differences in individual assessment may emerge when cost-benefit trade-offs differ among group members. We examine the influence of numerical superiority and intergroup dominance relationships on individual participation in intergroup encounters in black howler monkeys (Alouatta pigra) and tufted capuchin monkeys (Sapajus nigritus). Black howlers responded with longer vocal displays during encounters with neighbours with an equal number of resident males, while tufted capuchins increased their participation with increasing relative male group size. Within each species, males and females responded similarly to varying numerical odds, suggesting that despite pay-off asymmetries between males and females, both sexes were similarly influenced by numerical asymmetries in deciding to participate in collective group defence. Whereas the outcome of contests among tufted capuchins was determined by relative male group size, reflected in a pronounced intergroup dominance hierarchy, the absence of dominance relationships among black howler groups may have provoked prolonged vocal displays in order to assess rival groups with matching competitive abilities. [ABSTRACT FROM AUTHOR]

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When faced with choices between smaller sooner options and larger later options (i.e. intertemporal choices), both humans and non-human animals discount future rewards. Apparently, only humans consistently show the magnitude effect, according to which larger options are discounted over time at a lower rate than smaller options. Most of the studies carried out in non-human animals led instead to negative results. Here, we tested ten tufted capuchin monkeys ( Sapajus spp.) in a delay choice task to evaluate whether they show a magnitude effect when choosing between different quantities of the same food or when the options are represented by high- and low-preferred foods in different conditions. Whereas food quality did not play a role, we provided the first evidence of an effect of the reward amount on temporal preferences in a non-human primate species, a result with potential implications for the validity of comparative studies on the evolution of delay tolerance. In contrast with human results, but as shown in other animal species, capuchins' choice of the larger later option decreased as the amount of the smaller sooner option increased. Capuchins based their temporal preferences on the quantity of the smaller sooner option, rather than on that of the larger later option, probably because in the wild they virtually never have to choose between the above two options at the same time, but they more often encounter them consecutively. Thus, paying attention to the sooner option and deciding on the basis of its features may be an adaptive strategy rather than an irrational response. [ABSTRACT FROM AUTHOR]

Social relationships vary in content, quality and patterning. Most researchers focus on whether and how nondispositional factors, including age, sex, kinship and rank, predict variance in the content, quality and patterning of relationships. However, within a species, these factors do not always predict partner choice. We examined whether similarity in any of five personality traits, Assertiveness, Openness, Neuroticism, Sociability and Attentiveness, independently contributed to variation in the affiliative and agonistic relationships of pairs of brown capuchin monkeys, Sapajus sp. Capuchins that were more similar in Neuroticism had higher affiliative relationship scores, while capuchins that were more similar in Sociability shared overall higher-quality relationships (i.e. the difference between the dyad's affiliative and agonistic scores). These effects were independent of age, sex, kinship and rank, suggesting that certain aspects of the psychology of these animals may contribute uniquely to the quality of their social relationships. [ABSTRACT FROM AUTHOR]

Recent evidence indicates that oxytocin plays an important role in promoting prosocial behaviour amongst humans and other species. We tested whether oxytocin affected cooperation and food sharing in capuchin monkeys, a highly cooperative New World primate. Subjects received either 2IU oxytocin or an inert adjuvent intranasally prior to each session. Oxytocin influenced food sharing in capuchins in ways we did not anticipate. Recipients were less likely to passively acquire food from possessors when either individual had received OT than in the control, and also spent less time in proximity to their partner. Passive food sharing requires proximity, and oxytocin decreased the capuchins' typical congregating behaviour, apparently resulting in decreased sharing. We propose that the likely mechanism for increased social distance is the known anxiolytic effect of oxytocin. Our results indicate a need to consider how oxytocin affects the context of interactions and interacts with modes of sociality unique to each species. [ABSTRACT FROM AUTHOR]

Previous research has suggested that the presence of zoo visitors may be stressful for various primate species, and visual contact with visitors may be the sensory stimuli that mediate visitor effects. We studied a group of black-capped capuchins, Cebus apella , in a controlled experiment, randomly imposing two treatments: customised one-way vision screens on the exhibit viewing windows to reduce visual contact with visitors; and unmodified viewing windows that allow full visual contact with visitors. We sampled capuchin behaviour including intra-group aggression and other social interactions, vigilance and abnormal behaviours. To provide a measure of physiological stress, we also analysed capuchin faecal samples for glucocorticoid metabolite (FGM) concentration. When the view of visitors was obscured, we found marked reductions in capuchin aggression (from 14.5 bouts to 4.6 bouts per weekend, P = 0.004) and FGM concentration (from 620 to 410 ng/g, P = 0.008) among all adults, as well as reductions in abnormal behaviour ( P = 0.01) in two individuals. The capuchins also avoided the visitor viewing area ( P = 0.003) in the unmodified viewing window treatment. These results suggest that reducing the capuchins’ ability to view visitors improved their welfare. However we also found a reduction in the number of visitors when visual contact was reduced (from an average of 23 visitors per scan to 15, P = 0.008), suggesting that the visitor experience may have been compromised by the lack of interaction with the capuchins. These results highlight a possible dilemma for the zoo industry between enhancing animal welfare in primates and providing for visitor experience. [ABSTRACT FROM AUTHOR]

Motor planning is a relatively complex cognitive skill in which an actor modifies a behavior to anticipate the future consequences of the action. Studying motor planning in nonhuman primates may provide a better understanding of the roots of human planning abilities. In this study we presented capuchin monkeys (Sapajus apella) with a horizontal dowel baited on either the left or right end. A radial grasp on the dowel with the thumb facing toward the baited end would be the most efficient grip selection when bringing the dowel to one's mouth and indicate motor planning. Ten of the 12 monkeys tested spontaneously used a radial grasp significantly more often than expected by chance. Results demonstrate a more ubiquitous expression of motor planning abilities than previously seen in capuchin monkeys. Adaptation of this method of testing may be useful in evaluating motor planning capacity in other primates. [ABSTRACT FROM AUTHOR]

Human adults and children respond negatively to inequity, even sacrificing personal gain to avoid both disadvantageous (more for you, less for me) and advantageous (more for me, less for you) resource allocations. Recent work has argued that some nonhuman animals share this response, but findings for inequity aversion outside of humans are controversial. Unfortunately, animals' negative responses to inequity are difficult to interpret because animal inequity aversion tasks differ in critical ways from the tasks used to test human inequity aversion. Here we present evidence from a novel task testing disadvantageous and advantageous inequity aversion in capuchin monkeys, Cebus apella . Our task was designed to closely mirror inequity aversion studies of human adults and children. We found no evidence for either disadvantageous or advantageous inequity aversion. Instead, capuchins' decisions were guided solely by the food resource that they were offered. Moreover, subjects' decisions and reaction times did not vary across social and nonsocial conditions. Our findings suggest that capuchin monkeys do not exhibit a human-like response to inequity on tasks in which even young children are known to demonstrate inequity aversion. We discuss these results in the context of existing theories for the evolution of fairness. [ABSTRACT FROM AUTHOR]

Animal communication has become a widely studied field of research, especially because of the associated debates on the origin of human language. Due to their phylogenetic proximity with humans, non-human primates represent a suitable model to investigate the precursors of language. This study focuses on the perception of the attentional states of others, an important prerequisite to intentional communication. We investigated whether capuchins ( Cebus apella) produce a learnt pointing gesture towards a hidden and unreachable food reward as a function of the attentional status of the human experimenter. For that purpose, we tested five subjects that we first trained to indicate by a pointing gesture towards the human partner the position of a reward hidden by an assistant. Then, capuchins were tested in two experimental conditions randomly ordered. In the first condition-motivation trial-the experimenter was attentive to the subject gestures and rewarded him immediately when it pointed towards the baited cylinder. During the second condition-test trial-the experimenter adopted one of the following attention states and the subject was rewarded after 10 s has elapsed, regardless of the subject's behaviour. Five attentional states were tested: (1) experimenter absent, (2) experimenter back to the monkey, (3) experimenter's head away, (4) experimenter watching above the monkey, and (5) experimenter watching the monkey face. Our results reveal a variation in our subjects' communicative behaviours with a discrimination of the different postural clues (body and head orientation) available in our experimental conditions. This study suggests that capuchins can flexibly use a communicative gesture to adapt to the attentional state of their partner and provides evidence that acquired communicative gestures of monkeys might be used intentionally. [ABSTRACT FROM AUTHOR]

Most experimental paradigms to study visual cognition in humans and non-human species are based on discrimination tasks involving the choice between two or more visual stimuli. To this end, different types of stimuli and procedures for stimuli presentation are used, which highlights the necessity to compare data obtained with different methods. The present study assessed whether, and to what extent, capuchin monkeys’ ability to solve a size discrimination problem is influenced by the type of procedure used to present the problem. Capuchins’ ability to generalise knowledge across different tasks was also evaluated. We trained eight adult tufted capuchin monkeys to select the larger of two stimuli of the same shape and different sizes by using pairs of food items (Experiment 1), computer images (Experiment 1) and objects (Experiment 2). Our results indicated that monkeys achieved the learning criterion faster with food stimuli compared to both images and objects. They also required consistently fewer trials with objects than with images. Moreover, female capuchins had higher levels of acquisition accuracy with food stimuli than with images. Finally, capuchins did not immediately transfer the solution of the problem acquired in one task condition to the other conditions. Overall, these findings suggest that – even in relatively simple visual discrimination problems where a single perceptual dimension (i.e., size) has to be judged – learning speed strongly depends on the mode of presentation. [ABSTRACT FROM AUTHOR]