Geometrical gaze following in common marmosets (Callithrix jacchus).

A series of experiments investigating the degree of gaze understanding in common marmosets (Callithrix jacchus) is reported. Results show that marmosets follow the gaze of a human experimenter readily and also use the gaze to locate food in a modified version of the object choice task if influences of chance probabilities and prepotent response tendencies are controlled for. In addition, this new version of the task allows the assessment of the accuracy of gaze following. Marmosets precisely extrapolate gaze direction, past distracting objects and from considerable distances, thereby meeting the criteria of so-called geometrical gaze following. The presence of this ability in common marmosets suggests that higher forms of gaze following might be more widely distributed among nonhuman primates than previously thought. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in social and vocal behavior between left- and right-handed common marmosets (Callithrix jacchus).

Common marmosets (Callithrix jacchus) show either a left- or right-hand preference for reaching to pick up food and they retain the same preference throughout adult life. We compared the behavior of 10 right-handed and 10 left-handed marmosets, matched for age and sex. They were presented with live crickets both when alone and when in their social group. The marmosets captured more crickets and the latency to capture the first cricket was shorter when they were in a group than when they were alone. This effect of social facilitation was significantly greater for right- than left-handed individuals. The number of vocalizations (tsik, crackle, very brief whistle, cough, and phee) produced by the left- and right-handed marmosets differed significantly: right-handed marmosets produced an increased number of all of these calls when the crickets were presented, whereas left-handed marmosets did not show a change from pretesting levels. The right-handed marmosets also produced more tsik (mobbing) calls than left-handed marmosets when they were presented with a fear-inducing stimulus and performed more head cocking and parallax movements than the left-handed marmosets. Hence, hand preference is associated with differences in exploratory and social behavior, the latter including vocal communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object permanence tests on gibbons (Hylobatidae).

Ten gibbons of various species (Symphalangus syndactylus, Hylobates lar, Nomascus gabriellae, and Nomascus leucogenys) were tested on object permanence tasks. Three identical wooden boxes, presented in a linear line, were used to hide pieces of food. The authors conducted single visible, single invisible, double invisible, and control displacements, in both random and nonrandom order. During invisible displacements, the experimenter hid the object in her hand before putting it into a box. The performance of gibbons was better than expected by chance in all the tests, except for the randomly ordered double displacement. However, individual analysis of performance showed great variability across subjects, and only 1 gibbon is assumed to have solved single visible and single invisible displacements without recourse to a strategy that the control test eliminated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visuospatial reaching preferences of common marmosets (Callithrix jacchus): An assessment of individual biases across a variety of tasks.

Using multiple measures of hand preference, the authors investigated lateralization at an individual level in 21 common marmosets. Despite showing group biases for sensory and communication functions, these same marmosets did not show a group bias in direction of lateralized hand use. Hand preferences were recorded on four novel reaching tasks requiring different levels of visual guidance and postural control. As found for simple food holding (with the same subjects), they displayed strong individual hand preferences but no group bias indicative of handedness. The strength of hand preference was influenced by task demands: stronger preferences were expressed when subjects adopted a suspended posture, and when "successful" versus "unsuccessful" foraging strategies were compared. Comparisons between visuospatial reaching and simple food holding preferences also revealed that half of the subjects displayed a division of function between the hands/hemispheres; subjects displayed opposing preferences in simple and visuospatial reaching, which would be beneficial for the performance of coordinated bimanual tasks. Given the apparent absence of a selective advantage for handedness, the authors suggest that hand preferences may reflect hemispheric dominance of other cognitive domains (i.e., temperament). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prolactin and paternal care: Comparison of three species of monogamous new world monkeys (Callicebus cupreus, Callithrix jacchus, and Callimico goeldii).

The authors explored whether prolactin is associated with paternal care in 3 monkey species: titi monkey (Callicebus cupreus), common marmoset (Callithrix jacchus), and Goeldi's monkey (Callimico goeldii). They compared prolactin levels in fathers before and after infant birth as well as between fathers and nonfathers. C. cupreus fathers carry infants almost exclusively, have higher prolactin levels than nonfathers, but show no prolactin increase after infant birth. C. goeldii fathers carry infants only after 3 weeks, show an increase in prolactin levels during the precarrying period, but do not have higher levels than nonfathers. C. jacchus fathers are the primary carriers, have higher prolactin levels than nonfathers, and show a trend for a prolactin increase after the birth of infants. In conclusion, species differences in the patterns of prolactin secretion were evident and reflect the different paternal roles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do Chimpanzees (Pan troglodytes) and 2-Year-Old Children (Homo sapiens) Understand Double Invisible Displacement?

Chimpanzees (Pan troglodytes) and young children (Homo sapiens) have difficulty with double invisible displacements in which an object is hidden in two nonadjacent boxes in a linear array. Experiment 1 eliminated the possibility that chimpanzees' previous poor performance was due to the hiding direction of the displacement device. As in Call (2001), subjects failed double nonadjacent displacements, showing a tendency to select adjacent boxes. In Experiments 2 and 3, chimpanzees and 24-month-old children were tested on a new adaptation of the task in which four hiding boxes were presented in a diamond-shaped array on a vertical plane. Both species performed above chance on double invisible displacements using this format, suggesting that previous poor performance was due to a response bias or inhibition problem rather than a fundamental limitation in representational capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object permanence in orangutans (Pongo pygmaeus), chimpanzees (Pan troglodytes), and children (Homo sapiens).

Juvenile and adult orangutans (n?=?5; Pongo pygmaeus), chimpanzees (n?=?7; Pan troglodytes), and 19- and 26-month-old children (n?=?24; Homo sapiens) received visible and invisible displacements. Three containers were presented forming a straight line, and a small box was used to displace a reward under them. Subjects received 3 types of displacement: single (the box visited 1 container), double adjacent (the box visited 2 contiguous containers), and double nonadjacent (the box visited 2 noncontiguous containers). All species performed at comparable levels, solving all problems except the invisible nonadjacent displacements. Visible displacements were easier than invisible, and single were easier than double displacements. In a 2nd experiment, subjects saw the baiting of either 2 adjacent or 2 nonadjacent containers with no displacements. All species selected the empty container more often when the baited containers were nonadjacent than when they were adjacent. It is hypothesized that a response bias and inhibition problem were responsible for the poor performance in nonadjacent displacements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hand preference predicts reactions to novel foods and predators in marmosets (Callithrix geoffroyi).

In chimpanzees (Pan troglodytes) and common marmosets (Callithrix jacchus), left-handed individuals are less likely than right-handed individuals to explore new objects and situations, suggesting a relationship between the hemispheric specialization of emotional states and motor function. To further explore this relationship and to test the hypothesis that fearfulness is related to hand preference, we assessed willingness to approach, sniff, and taste novel foods, and the duration of freeze reactions in response to hawk calls, in 18 Geoffroy's marmosets (Callithrix geoffroyi). In accordance with these hypotheses, left-handed marmosets were slower to explore novel foods and slower to emerge from a freeze response than right-handed marmosets. Hand preference and at least some features of temperament seem to be related in this and other species of primates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Activity of common marmosets (Callithrix jacchus) in limited spaces: Hand movement characteristics.

The increasing popularity of marmoset monkeys (Callithrix jacchus) in anatomical, behavioral, and electrophysiological studies has called for a detailed analysis of their natural behavior within limited spaces. In the present study, the authors analyzed hand movements during horizontal and vertical progressions in a cylinder. The trajectory of each hand covered the entire cylinder floor during horizontal progressions and the entire cylinder wall during vertical progressions. Different marmosets have different patterns of hand movement. The average maximum angle of hand movements for all marmosets during horizontal and vertical progressions oscillates, although the average over time is constant and similar for both hands, whereas head movements during horizontal progressions become smaller with successive progressions. Another observed difference between rats and monkeys was in the size of head and hand movements at the beginning of each experimental session. During the 1st horizontal progression, all marmosets moved their heads to a greater extent than their hands. This sequential head and hand movement is referred as bistable behavior. The bistable pattern of motor behavior, which was also observed in successive progressions, may be derived from an inherent fear of predators or exploratory interest of a novel environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of hand preferences in marmosets (Callithrix jacchus) and effects of aging.

The authors investigated the development of unimanual hand use and hand preferences during feeding in 15 marmosets (Callithrix jacchus), ages birth to 51–70 months. Bimanual hand use was common at 1–2 months, but by 5–8 months unimanual holding had developed and so had significant hand preferences. Half of the marmosets preferred to pick up and take food to the mouth with the left hand, and half preferred the right hand. Individuals maintained the same hand preference at all ages examined. Significant relationships were also found between the postures adopted during feeding and the direction of hand preferences displayed by juvenile marmosets. There was a positive correlation between increased suspension and increased left-hand preference, and a negative correlation between increased feeding in a tripedal posture and increased left-hand preference. These results are discussed in terms, of motor development and hemispheric specialization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do Dogs (Canis familiaris) Understand Invisible Displacement?

Domestic dogs (Canis familiaris) perform above chance on invisible displacement tasks despite showing few other signs of possessing the necessary representational abilities. Four experiments investigated how dogs find an object that has been hidden in 1 of 3 opaque boxes. Dogs passed the task under a variety of control conditions, but only if the device used to displace the object ended up adjacent to the target box after the displacement. These results suggest that the search behavior of dogs was guided by simple associative rules rather than mental representation of the object's past trajectory. In contrast, Experiment 5 found that on the same task, 18- and 24-month-old children showed no disparity between trials in which the displacement device was adjacent or nonadjacent to the target box. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marmoset (Callithrix jacchus jacchus) spatial memory in a foraging task: Win-stay versus win-shift strategies.

The spatial memory of common marmosets (Callithrix jacchus jacchus) was explored in 3 experiments with a simulated foraging task. In Experiment 1, individual monkeys foraged among 8 baited food sites. They appeared to use spatial memory to accurately avoid revisiting previously depleted sites. There was no difference in accuracy between the adult monkeys and a juvenile monkey tested on the same task. In Experiment 2, a win–stay paradigm was used. The adult monkey subject very accurately remembered locations that had previously contained food. The monkey tended to visit adjacent correct sites when retrieving food and thus minimized the total distance travelled. In Experiment 3, a win–shift paradigm was used with 2 adult monkeys. Although both monkeys performed at above-chance levels of accuracy on the win–shift task, they made many errors. These results suggest that marmosets may prefer tasks that require a win–stay strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tracking the displacement of objects: A series of tasks with great apes (Pan troglodytes, Pan paniscus, Gorilla gorilla, and Pongo pygmaeus) and young children (Homo sapiens).

The authors administered a series of object displacement tasks to 24 great apes and 24 30-month-old children (Homo sapiens). Objects were placed under 1 or 2 of 3 cups by visible or invisible displacements. The series included 6 tasks: delayed response, inhibition test, A not B, rotations, transpositions, and object permanence. Apes and children solved most tasks performing at comparable levels except in the transposition task, in which apes performed better than children. Ape species performed at comparable levels in all tasks except in single transpositions, in which chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) performed better than gorillas (Gorilla gorilla) and orangutans (Pongo pygmeaus). All species found nonadjacent trials and rotations especially difficult. The number of elements that changed locations, the type of displacement, and having to inhibit predominant reaching responses were factors that negatively affected the subjects' performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parental care in marmosets (Callithrix jacchus jacchus): Development and effect of anogenital licking on exploration.

Anogenital licking of 15 infant marmosets (Callithrix jacchus jacchus) was scored from 1 to 60 days of age over four 30-min intervals per day. Mothers performed threefold the anogenital licking that fathers or siblings did. The frequency of anogenital licking was low in the first 15 days after birth, high from Days 16 to 45, and low again from Days 46 to 60. There were no significant effects of parents or sex on the amount or pattern of anogenital licking received by the offspring. The potential role of developmental changes in levels of sex hormones is discussed. Later in life, the responses of the marmosets to a fear-inducing stimulus were compared. There was a significant positive correlation between the amount of anogenital licking received and exploration of the novel stimulus. Age differences at the time of testing had no effect on exploration, nor did sex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple environmental contexts and communication in pygmy marmosets (Cebuella pygmaea).

There are multiple components to the concept of Umwelt experienced by an organism that may constrain the type and structure of communication signals as well as the usefulness of these signals. To illustrate the impact of these multiple environmental components, the authors used signals of the pygmy marmoset (Cebuella pygmaea), a small primate from the western Amazon. The authors summarize studies to show how the physical effects of the habitat; effects of other species, both predators and nonpredators; anthropogenic effects on the communication environment; within-group and between-groups influences other pygmy marmosets exert; and ontogeny influence the structure and usage of vocal signals. Communication within a species can be understood only in consideration of each of these contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hand preference of the common marmoset (Callithrix jacchus): Problem solving and responses in a novel setting.

Common marmosets (Callithrix jacchus) with a right-hand preference displayed shorter latencies to enter a novel room containing novel structures and objects, touched more objects, and performed more touches and more parallax movements than marmosets with a left-hand preference. These results are consistent with specialization of the right hemisphere (left hand) for fear and negative emotional states and specialization of the left hemisphere (right hand) for approach and positive emotional states. There were no effects of age or sex on any of these behaviors. This relationship between exploration and hand preference did not occur when the marmosets were tested in the home cage with a novel problem, although significant effects of both age and dominance were found in solving the problem. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object permanence in adult cats (Felis catus).

Human analog tests of object permanence were administered to 14 adult cats to assess as accurately as possible their developmental level in this particular cognitive capacity and to analyze their search behavior in situations in which an object has disappeared. Exp I compared 2 groups, one that received the tests in their usual order of presentation and another that received first the invisible displacement tests and then the visible displacement tests. Results conflict with previous research conducted by E. Triana and R. Pasnak (see record 1982-00510-001): The Ss in the present experiment were able to solve problems with visible displacements but failed with invisible displacement. Exp II compared 2 modalities of object disappearance. The object was hidden under a cover through either its front or its rear panel. This experiment confirmed, in a 5-choice hiding task, that cats are unable to understand invisible displacements. Ss searched for the object in the last location they had seen it disappear or under the nearest cover from this location. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object permanence in ring doves (Streptopelia risoria).

Object permanence tests were administered to ring doves (Streptopelia risoria). In Experiment 1 (N?=?4), doves received tests in which a food cup was moved behind a screen as the subject watched. The birds successfully retrieved the food when a single screen was used but failed to do so when food was displaced behind 1 of 2 simultaneously present screens. In Experiment 2 (N?=?4), doves were allowed to initiate search movement before the object disappeared behind 1 of 2 screens. This procedural change improved performance. In Experiment 3 (N?=?2), a screen was lowered over a stationary object as the subject approached the object. Lowering the screen interrupted search behavior temporarily without impairing performance. It is argued that interruption of search behavior requires some cognitive flexibility that the typical Stage 4a capacity described in Piaget's theory does not include. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object permanence in rhesus monkeys (Macaca mulatta).

We evaluated the performance of 6 adult rhesus monkeys (Macaca mulatta) on object permanence tasks. In Experiment 1, monkeys received search tasks that correspond to Stages 4, 5, and 6 of object permanence. Subjects were successful on tasks of visible displacements (Stages 4 and 5) but failed to find the object in invisible displacements (Stage 6). The monkeys adopted a search strategy of investigating a specific hiding location. In Experiment 2, monkeys were given a second opportunity to find the object if they investigated a location that was part of the displacement on their first search. Subjects relied on the same search strategy identified in Experiment 1. In Experiment 3, the experimenter hid the object in her hand rather than a container. The monkeys failed to recover the object, and individual differences were found in the strategies used. These results suggest that the upper limit of object permanence in rhesus monkeys is Stage 5. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing of contour closure by baboons (Papio papio).

This study investigated the Gestalt law of closure in baboons. Using a computer-controlled self-testing procedure, we trained baboons (Papio papio) to discriminate open versus closed shapes presented on a touch screen with a two-alternative forced choice procedure. Ten baboons (OPEN + group) were trained with the open shapes serving as the positive stimulus (S+), and nine others (CLOSE + group) were trained with the closed shape serving as S+. The OPEN + group obtained higher discrimination performance than the CLOSE + group (Exp 1), but its scores declined when new line segments were added to the stimuli (Exp 2) and after smoothing the end points of the open shapes (Exp 3). The CLOSE + group was less affected by the above manipulations of local stimulus dimension, but its performance was disrupted when the collinearity end points was reduced (Exp 3). Use of a visual search task revealed that the search for an open shape among closed distractors was less attention demanding in baboons than the search for a closed shape among open ones (Exp 4). It is concluded that (1) end lines rather than closeness per se are perceptual primitives for the open versus closed discrimination in baboons, and (2) the relative emphasis on local or configural cues when processing contour closure depends on experiential factors in baboons and is thus subject to interindividual variations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)