To Beg,or Not to Beg? That Is the Question: Mangabeys Modify Their Production of Requesting Gestures in Response to Human’s Attentional States

Background

Although gestural communication is widespread in primates, few studies focused on the cognitive processes underlying gestures produced by monkeys.

Methodology/Principal Findings

The present study asked whether red-capped mangabeys (Cercocebus torquatus) trained to produce visually based requesting gestures modify their gestural behavior in response to human’s attentional states. The experimenter held a food item and displayed five different attentional states that differed on the basis of body, head and gaze orientation; mangabeys had to request food by extending an arm toward the food item (begging gesture). Mangabeys were sensitive, at least to some extent, to the human’s attentional state. They reacted to some postural cues of a human recipient: they gestured more and faster when both the body and the head of the experimenter were oriented toward them than when they were oriented away. However, they did not seem to use gaze cues to recognize an attentive human: monkeys begged at similar levels regardless of the experimenter’s eyes state.

Conclusions/Significance

These results indicate that mangabeys lowered their production of begging gestures when these could not be perceived by the human who had to respond to it. This finding provides important evidence that acquired begging gestures of monkeys might be used intentionally.     

Domestic Dogs Use Contextual Information and Tone of Voice when following a Human Pointing Gesture

Domestic dogs are skillful at using the human pointing gesture. In this study we investigated whether dogs take contextual information into account when following pointing gestures, specifically, whether they follow human pointing gestures more readily in the context in which food has been found previously. Also varied was the human''s tone of voice as either imperative or informative. Dogs were more sustained in their searching behavior in the ‘context’ condition as opposed to the ‘no context’ condition, suggesting that they do not simply follow a pointing gesture blindly but use previously acquired contextual information to inform their interpretation of that pointing gesture.Dogs also showed more sustained searching behavior when there was pointing than when there was not, suggesting that they expect to find a referent when they see a human point. Finally, dogs searched more in high-pitched informative trials as opposed to the low-pitched imperative trials, whereas in the latter dogs seemed more inclined to respond by sitting. These findings suggest that a dog''s response to a pointing gesture is flexible and depends on the context as well as the human''s tone of voice.     

Imitation of Body Movements Facilitated by Joint Attention through Eye Contact and Pointing in Japanese Monkey

Eye contact and pointing are typical gestures in order to direct another individual''s attention toward a target. We previously investigated on Japanese monkeys whether joint attention ability encouraged by eye contact and pointing was associated with the imitation of human''s actions. The monkeys with the joint attention skills showed the imitation of human''s actions. In the current study, we investigated on a monkey whether joint attention ability also facilitated the imitation of human body-movements. Results showed that the monkey being taught eye contact and pointing showed the imitation of human body-movements. These results suggest that the monkeys have basic potential for following another individual''s motion, and that what imitation expresses depends on where the monkeys are paying attention. Thus, eye contact and pointing are suitable for directing the monkey''s attention toward the human.     

Effects of surface substances of untransformed fibroblastic cells on the adhesion and proliferation of neighboring cells: a study using fixed confluent cell sheets

To study the effects of surface materials of cells on the behavior of other neighboring cells in a crowded culture, confluent sheets of rat 3Y1 fibroblasts were fixed and then 3Y1 cells were seeded on to them. Among confluent sheets unfixed, fixed with formalin and fixed with ethanol and an empty plastic dish surface, the substrate activity to permit cell adhesion was compared. After confluent 3Y1 cells (mainly composed of cells with a G1-DNA content) were reseeded with fresh medium on to these substrates, the capacity to initiate DNA synthesis per attached cell was also compared. The substrate activity of the ethanol-fixed cell sheet to permit cell adhesion was as high as that of the empty dish surface, whereas that of the unfixed cell sheet and that of the formalin-fixed cell sheet were low. When the ethanol-fixed cell sheet and the empty dish surface were coated with the ethanol extract of the unfixed cell sheet, the substrate activity diminished, indicating that during the fixation process with ethanol an adhesion-inhibitory factor (s) was removed. The capacity to initiate DNA synthesis of each cell that had completed adhesion and spreading on the cell sheets unfixed, fixed with formalin, and fixed with ethanol was lower compared to the cell that had adhered to the empty dish surface. We conclude that factors over the 3Y1 cell surface inhibit the overlapping cell adhesion and the proliferation of cells contacting each other, resulting in the ordered cell configuration in the confluent culture.     

Female transfer between one-male groups of proboscis monkey (<Emphasis Type="Italic">Nasalis larvatus</Emphasis>)

Successful or unsuccessful female transfers were observed seven times during a 32-month field study of proboscis monkeys (Nasalis larvatus) inhabiting a riverine forest along a tributary of the Kinabatangan River, Sabah, Malaysia. In all cases, the females voluntarily left their own groups and immediately joined with another one. When adult females tried to shift to other groups, adult males called them back to their own groups, but appeared to be indifferent to subadult females. When the adult females returned, the males never attacked the females physically, but instead often emitted herding sounds to them. One subadult female was repelled by a resident adult female. When one adult female transferred into a new one-male group, she left her behind son in an all-male group. The number of females often fluctuated in most study groups, with this fluctuation being more prominent among subadult females than adult females. It is likely that female transfer in proboscis monkeys is not a rare occurrence and that it is especially common among sub-adult females.     

Dogs (Canis familiaris), but not chimpanzees (Pan troglodytes), understand imperative pointing

Chimpanzees routinely follow the gaze of humans to outside targets. However, in most studies using object choice they fail to use communicative gestures (e.g. pointing) to find hidden food. Chimpanzees' failure to do this may be due to several difficulties with this paradigm. They may, for example, misinterpret the gesture as referring to the opaque cup instead of the hidden food. Or perhaps they do not understand informative communicative intentions. In contrast, dogs seem to be skilful in using human communicative cues in the context of finding food, but as of yet there is not much data showing whether they also use pointing in the context of finding non-food objects. Here we directly compare chimpanzees' (N = 20) and dogs' (N = 32) skills in using a communicative gesture directed at a visible object out of reach of the human but within reach of the subject. Pairs of objects were placed in view of and behind the subjects. The task was to retrieve the object the experimenter wanted. To indicate which one she desired, the experimenter pointed imperatively to it and directly rewarded the subject for handing over the correct one. While dogs performed well on this task, chimpanzees failed to identify the referent. Implications for great apes' and dogs' understanding of human communicative intentions are discussed.     

Mother and peer attachment under conditions of fear in rhesus monkeys (Macaca mulatta)

Attachment behavior of six infant rhesus monkeys was examined in a fear situation under two experimental conditions. When both a familiar agemate and the infant's mother were present in separate cages, the infants spent significantly more time in proximity to their mother than to their agemate. When a caged agemate and an empty cage were present, the infants distributed their time approximately equally between the empty cage and the agemate. Five additional behavioral measures also indicated that the infants did not use their peers as mother substitutes in a fear-arousing situation. These findings supportHarlow's postulate of independence of the infant-mother and agemate affectional systems.     

Effect of others' attentional states on vocalizations in Japanese monkeys (Macaca fuscata)

We investigated the effects of other's attentional states on vocalizations in monkeys. The subjects were 14 Japanese monkeys (Macaca fuscata), which vocalized spontaneously in the feeding context. In the initial experiment, an experimenter moved towards and away from the subject monkeys. The monkeys vocalized more frequently when the experimenter moved away rather than towards them. To examine the effects of the experimenter's body orientations and moving directions separately, additional experiments were conducted. When the experimenter stood facing towards and facing away from the subject monkeys, the monkeys vocalized more frequently when the experimenter stood facing away rather than facing towards. When the experimenter moved towards and away from the subject monkeys while facing them, the monkeys vocalized more frequently when the experimenter moved away from them rather than towards them. These results suggested that the monkeys vocalized more frequently when the situation changed to that where the monkeys were not likely get food from the experimenter. It seems that monkeys recognize the attentional states of others by body orientation and modify their vocalizing behavior accordingly.     

Learning interspecific communicative responses in Pampas foxes (Lycalopex gymnocercus)

Domestic dogs show remarkable communicative abilities in their interaction with people. These skills maybe explained by the interaction between the domestication process and learning experiences during ontogeny. Studies carried out on other species of canids, which have not been domesticated are relevant to this topic. The purpose of this article is to study the effect of instrumental learning on captive Pampas foxes’ (Lycalopex gymnocercus) communicative responses to humans. Seven foxes were tested in a conflict situation involving food within sight but out of their reach. In these situations dogs typically gaze at the human face to ask for food. In Study 1, there was an increase in gaze duration as a consequence of reinforcement and a decrease during extinction, when animals did not receive any more food. In Study 2, all of the four foxes tested successfully followed proximal pointing gesture to find hidden food. When a distal pointing cue was given, three out of four followed it in the first session and one in the second session. These results are consistent with those previously found in dogs, and suggest that learning experiences allow the development of communicative skills, even in not domesticated canid species.     

Behavioral and neural correlates of communication via pointing

Communicative pointing is a human specific gesture which allows sharing information about a visual item with another person. It sets up a three-way relationship between a subject who points, an addressee and an object. Yet psychophysical and neuroimaging studies have focused on non-communicative pointing, which implies a two-way relationship between a subject and an object without the involvement of an addressee, and makes such gesture comparable to touching or grasping. Thus, experimental data on the communicating function of pointing remain scarce. Here, we examine whether the communicative value of pointing modifies both its behavioral and neural correlates by comparing pointing with or without communication. We found that when healthy participants pointed repeatedly at the same object, the communicative interaction with an addressee induced a spatial reshaping of both the pointing trajectories and the endpoint variability. Our finding supports the hypothesis that a change in reference frame occurs when pointing conveys a communicative intention. In addition, measurement of regional cerebral blood flow using H(2)O(15) PET-scan showed that pointing when communicating with an addressee activated the right posterior superior temporal sulcus and the right medial prefrontal cortex, in contrast to pointing without communication. Such a right hemisphere network suggests that the communicative value of pointing is related to processes involved in taking another person's perspective. This study brings to light the need for future studies on communicative pointing and its neural correlates by unraveling the three-way relationship between subject, object and an addressee.     

Social Monitoring Reflects Dominance Relationships in a Small Captive Group of Brown Capuchin Monkeys (Cebus apella)

In several studies of social monitoring in primates, subordinate animals directed more visual attention toward dominant animals than vice versa. This behavior is thought to enable subordinate animals to avoid conflict. We sought to clarify whether visual attention behavior functions in this manner in a small captive group of brown capuchin monkeys, Cebus apella. We tested the hypothesis that social monitoring is related to dominance status. Dominance status was determined based on the directionality of aggressive behavior, and visual attention was quantified by using focal animal sampling. Subordinate animals directed significantly more visual attention toward others than dominant animals. Subordinate animals also looked more frequently at the animals that attacked them and others the most. The results indicate that social monitoring behavior in this captive group was driven by conflict‐avoidance.     

The use and misuse of public information by foraging red crossbills

Group foragers may assess patch quality more efficiently bypaying attention to the sampling behavior of group members foragingin the same patch (i.e., using "public information"). To determinewhether red crossbills (Loxia curvirostra) use public informationto aid their patch departure decisions, we conducted experimentsthat compared the sampling behavior of crossbills foraging ona two-patch system (one patch was always empty, one patch containingseeds) when alone, in pairs, and in flocks of three. When foragingalone, crossbills departed from empty patches in a way thatwas qualitatively consistent with energy maximization. We foundevidence for the use of public information when crossbills werepaired with two flock mates, but not when paired with one flockmate. When foraging with two flock mates, crossbills sampledapproximately half the number of cones on the empty patch beforedeparting as compared to when solitary. Furthermore, as expected ifpublic information is used, the variance in both the numberof cones and time spent on the empty patch decreased when crossbillsforaged with two flock mates as compared to when alone. Althoughhigh frequencies of scrounging reduce the availability of publicinformation, scrounging is usually uncommon in crossbills, apparentlybecause they exploit divisible patches. Consequently, publicinformation is likely to be important to crossbills in the wild.We also show that feeding performance is greatly diminishedwhen the feeding performances of flock mates differ. This providesa mechanism that will favor assortative grouping by phenotypewhen phenotypes affect feeding performance, which may in turnpromote speciation in some groups of animals.     

Interacting roles of attention and visual salience in V4

Attention increases the contrast gain of V4 neurons, causing them to respond to an attended stimulus as though its contrast had increased. When multiple stimuli appear within a neuron's receptive field (RF), the neuron responds primarily to the attended stimulus. This suggests that cortical cells may be "hard wired" to respond preferentially to the highest-contrast stimulus in their RF, and neural systems for attention capitalize on this mechanism by dynamically increasing the effective contrast of the stimulus that is task relevant. To test this, we varied the relative contrast of two stimuli within the recorded neurons' RFs, while the monkeys attended away to another location. Increasing the physical contrast of one stimulus caused V4 neurons to respond preferentially to that stimulus and reduced their responses to competing stimuli. When attention was directed to the lower-contrast stimulus, it partially overcame the influence of a competing, higher-contrast stimulus.     

Le geste et la forme dans l’expression graphique du Néolithique

The parietal painted sign keeps on the memory of gesture that produces it. It is one of the distinctive features of this particular artefact. However, it is not possible to reconstruct this gesture if we do not give the context of the sign, if we do not present the numerous physical and cultural parameters which are in charge of their production. About schematic paintings of Neolithic age, we must take the union of criterions into account such as the parietal and site topography, the cultural constraints that appoint the location of figures and the ritual practices originally of the graphical expression, etc. The painter perceives, adapts and behaves according to this spatial and social environment. We refer here to several strategies: the attention for the parietal microtopography in accordance with the signs to draw, the respect of some criterions that specify the choice of the site like the hygrophilie of places and the rubefaction of rock walls, the need to paint at the limits of the accessibility of site and wall, the use of drawing tools for increase the capacities of the body. The efficiency of the gesture consists in realizing a sign bearing a meaning because in harmony with the features of its support.     

Use of gesture sequences in chimpanzees

Gestural communication in a group of 19 captive chimpanzees (Pan troglodytes) was observed, with particular attention paid to gesture sequences (combinations). A complete inventory of gesture sequences is reported. The majority of these sequences were repetitions of the same gestures, which were often tactile gestures and often occurred in play contexts. Other sequences combined gestures within a modality (visual, auditory, or tactile) or across modalities. The emergence of gesture sequences was ascribed to a recipient's lack of responsiveness rather than a premeditated combination of gestures to increase the efficiency of particular gestures. In terms of audience effects, the chimpanzees were sensitive to the attentional state of the recipient, and therefore used visually-based gestures mostly when others were already attending, as opposed to tactile gestures, which were used regardless of whether the recipient was attending or not. However, the chimpanzees did not use gesture sequences in which the first gesture served to attract the recipient's visual attention before they produced a second gesture that was visually-based. Instead, they used other strategies, such as locomoting in front of the recipient, before they produced a visually-based gesture.     

Mated pairs of owl monkeys (Aotus nancymaae) exhibit sex differences in response to unfamiliar male and female conspecifics

In socially monogamous species, mate‐guarding could be a reproductive strategy that benefits both males and females, especially when males contribute to parental care. By actively guarding mates, males may reduce their chances of being cuckolded, whereas females that mate‐guard may reduce the likelihood that their mates will desert them or acquire additional mates, and hence limit or reduce paternal care of offspring. Owl monkeys (Aotus spp.) are socially monogamous with biparental care of young and, hence, potential beneficiaries of mate‐guarding. We presented mated pairs of captive owl monkeys (A. nancymaae) with unfamiliar male and female conspecifics, to determine if either member of the pair exhibits intraspecific aggression toward an intruder or stays close to its mate, behaviors indicative of mate‐guarding. Male mates were more responsible for the maintenance of close proximity between mates than females. Male mates also exhibited elevated levels of behavior that signify arousal when presented with a male conspecific. These responses by mated male owl monkeys are consistent with patterns that may help prevent cuckoldry. Am. J. Primatol. 72:942–950, 2010. © 2010 Wiley‐Liss, Inc.     

Gaze direction and request gesture in social interactions

One of the most important faculties of humans is to understand the behaviour of other conspecifics. The present study aimed at determining whether, in a social context, request gesture and gaze direction of an individual are enough to infer his/her intention to communicate, by searching for their effects on the kinematics of another individual's arm action. In four experiments participants reached, grasped and lifted a bottle filled of orange juice in presence of an empty glass. In experiment 1, the further presence of a conspecific not producing any request with a hand and gaze did not modify the kinematics of the sequence. Conversely, experiments 2 and 3 showed that the presence of a conspecific producing only a request of pouring by holding the glass with his/her right hand, or only a request of comunicating with the conspecific, by using his/her gaze, affected lifting and grasping of the sequence, respectively. Experiment 4 showed that hand gesture and eye contact simultaneously produced affected the entire sequence. The results suggest that the presence of both request gesture and direct gaze produced by an individual changes the control of a motor sequence executed by another individual. We propose that a social request activates a social affordance that interferes with the control of whatever sequence and that the gaze of the potential receiver who held the glass with her hand modulates the effectiveness of the manual gesture. This paradigm if applied to individuals affected by autism disorder can give new insight on the nature of their impairment in social interaction and communication.     

Voluntary progression order in captive rhesus macaques

The sequence in which 14 laboratory rhesus macaques left their home enclosure during a routine catching procedure was recorded on 30 occasions during 6 weeks. The animals were trained to voluntarily exit one by one and enter a transport cage for weighing and/or treatment. Mean weekly exit orders cross-correlated significantly, and individuals retained their exit positions with remarkable consistency throughout the study period. An animal's position did not depend on its sex, age, or dominance rank. The oldest female never failed to enter the transport cage as number 1. When she was prevented from taking the lead, the group was hesitant but eventually proceeded in the usual order. Food was a strong, yet not absolute, incentive for the monkeys to cooperate. If they could not expect a reward, they took more time before proceeding, but did so in the habitual order. The predictability of the exit sequence has practical managerial value because it makes it possible for a single person to quickly catch a selected group member when necessary.     

Perception of shape-from-motion in macaque monkeys and humans

Motion is one of the most efficient cues for shape perception. We conducted behavioral experiments to examine how monkeys perceive shapes defined by motion cues and whether they perceive them as humans do. We trained monkeys to perform a shape discrimination task in which shapes were defined by the motion of random dots. Effects of dot density and dot speed on the shape perception of monkeys were examined. Human subjects were also tested using the same paradigm and the test results were compared with those of monkeys. In both monkeys and humans, correct performance rates declined when density or speed of random dots was reduced. Both of them tended to confuse the same combinations of shapes frequently. These results suggest that monkeys and humans perceive shapes defined by motion cues in a similar manner and probably have common neural mechanisms to perceive them. Electronic Publication     

Effects of Context on Visuomotor Interference Depends on the Perspective of Observed Actions

Visuomotor interference occurs when the execution of an action is facilitated by the concurrent observation of the same action and hindered by the concurrent observation of a different action. There is evidence that visuomotor interference can be modulated top-down by higher cognitive functions, depending on whether own performed actions or observed actions are selectively attended. Here, we studied whether these effects of cognitive context on visuomotor interference are also dependent on the point-of-view of the observed action. We employed a delayed go/no-go task known to induce visuomotor interference. Static images of hand gestures in either egocentric or allocentric perspective were presented as “go” stimuli after participants were pre-cued to prepare either a matching (congruent) or non-matching (incongruent) action. Participants performed this task in two different cognitive contexts: In one, they focused on the visual image of the hand gesture shown as the go stimulus (image context), whereas in the other they focused on the hand gesture they performed (action context). We analyzed reaction times to initiate the prepared action upon presentation of the gesture image and found evidence of visuomotor interference in both contexts and for both perspectives. Strikingly, results show that the effect of cognitive context on visuomotor interference also depends on the perspective of observed actions. When focusing on own-actions, visuomotor interference was significantly less for gesture images in allocentric perspective than in egocentric perspective; when focusing on observed actions, visuomotor interference was present regardless of the perspective of the gesture image. Overall these data suggest that visuomotor interference may be modulated by higher cognitive processes, so that when we are specifically attending to our own actions, images depicting others’ actions (allocentric perspective) have much less interference on our own actions.