Following and joining the informed individual in semifree-ranging tonkean macaques (Macaca tonkeana)

The authors investigated whether Tonkean macaques (Macaca tonkeana) can distinguish between 2 group mates with different knowledge and improve their foraging performance. The subjects were 8 young individuals belonging to a group raised in a 2-acre park. The authors carried out 192 tests in which subgroups of 3 individuals were released in a food search situation. Two leaders could be informed about 2 different food sites. A naive follower could choose to follow 1 leader or another. The follower could find the correct site when 1 leader was informed about food location. There was no evidence that the follower identified the best leader, however. The less well-informed leader generally joined the other leader, prompting the follower to follow them. The followers' pathways were mainly determined by the interactions of leaders.     

Withholding information in semifree-ranging Tonkean macaques (Macaca tonkeana)

The ability of Tonkean macaques (Macaca tonkeana) to deceive partner about the location of hidden food was investigated in 4 males belonging to a group raised in a 2-acre park. Before releasing subjects in the search task, the experimenter prompted 1 of the subjects to observe where the bait was hidden. The authors found that when informed, higher ranking subjects did not significantly alter their search patterns whether tested alone or in pairs. The same held for subordinates belonging to pairs with weak dominance asymmetry. To the contrary, strongly dominated subordinates modified the number of pauses when searching in pairs. They used behavioral tactics such as avoiding being followed, stopping when being watched, or taking a wrong direction. Information withholding might be acommon event in macaques.     

Monkeys fail to reciprocate in an exchange task

Exchanges form the basis of human economies. Animals too can engage in reciprocal interactions but they do not barter goods like humans, which raises the question of the abilities necessary for trading to occur. Previous studies have shown that non-human primates can exchange food with human partners. Here, we tested the ability of brown capuchin monkeys and Tonkean macaques to reciprocate in a task requiring two conspecifics to exchange tokens in order to obtain rewards from an experimenter. We recorded 56 transfers between subjects in capuchin monkeys and 10 in Tonkean macaques. All transfers were passive in both species. Capuchins preferentially picked up tokens valuable for them in the partner’s compartment. They tended to manipulate the partner-valued tokens more often than the no-value ones, leading to more opportunities for these tokens to end up within reach of the partner. Despite optimal conditions where values of goods were defined and known by partners, however, none of the pairs tested engaged in short-term reciprocal interactions. These results indicate that calculated reciprocity was difficult if not impossible in the animals tested.     

Cross-modal recognition of human individuals in domestic horses (Equus caballus)

This study has shown that domestic horses are capable of cross-modal recognition of familiar humans. It was demonstrated that horses are able to discriminate between the voices of a familiar and an unfamiliar human without seeing or smelling them at the same moment. Conversely, they were able to discriminate the same persons when only exposed to their visual and olfactory cues, without being stimulated by their voices. A cross-modal expectancy violation setup was employed; subjects were exposed both to trials with incongruent auditory and visual/olfactory identity cues and trials with congruent cues. It was found that subjects responded more quickly, longer and more often in incongruent trials, exhibiting heightened interest in unmatched cues of identity. This suggests that the equine brain is able to integrate multisensory identity cues from a familiar human into a person representation that allows the brain, when deprived of one or two senses, to maintain recognition of this person.     

Food Avoidance Learning in Squirrel Monkeys and Common Marmosets

Using a conditioned food avoidance learning paradigm, six squirrel monkeys (Saimiri sciureus) and six common marmosets (Callithrix jacchus) were tested for their ability to (1) reliably form associations between visual or olfactory cues of a potential food and its palatability and (2) remember such associations over prolonged periods of time. We found (1) that at the group level both species showed one-trial learning with the visual cues color and shape, whereas only the marmosets were able to do so with the olfactory cue, (2) that all individuals from both species learned to reliably avoid the unpalatable food items within 10 trials, (3) a tendency in both species for quicker acquisition of the association with the visual cues compared with the olfactory cue, (4) a tendency for quicker acquisition and higher reliability of the aversion by the marmosets compared with the squirrel monkeys, and (5) that all individuals from both species were able to reliably remember the significance of the visual cues, color and shape, even after 4 months, whereas only the marmosets showed retention of the significance of the olfactory cues for up to 4 weeks. Furthermore, the results suggest that in both species tested, illness is not a necessary prerequisite for food avoidance learning but that the presumably innate rejection responses toward highly concentrated but nontoxic bitter and sour tastants are sufficient to induce robust learning and retention.     

Learning to cope with two different food distributions: the performance of house mice (Mus musculus domesticus)

Search abilities of mice (Mus musculus domesticus) were evaluated using an arena closed by a ceiling in which 9 food sources (which mice could reach standing on their hind legs) could be arranged according to 2 configurations: a 3 x 3 square matrix and 3 clusters each containing 3 food sources. Testing conditions prevented olfactory and visual cues from being left after visits to food sources, and mice were able to choose alternative routes between food sources. Results showed that mice were more efficient with the matrix than with the cluster configuration. Sex differences were observed: Females improved their performance with both configurations, whereas males improved only with the matrix one. Mice did not develop evident search strategies that would minimize task complexity. Comparison with data published on capuchin monkeys revealed differences, with monkeys performing better with the cluster configuration than with the matrix and applying searching strategies.     

Capuchin monkeys (Cebus apella) use positive, but not negative, auditory cues to infer food location

Nonhuman primates appear to capitalize more effectively on visual cues than corresponding auditory versions. For example, studies of inferential reasoning have shown that monkeys and apes readily respond to seeing that food is present (“positive” cuing) or absent (“negative” cuing). Performance is markedly less effective with auditory cues, with many subjects failing to use this input. Extending recent work, we tested eight captive tufted capuchins (Cebus apella) in locating food using positive and negative cues in visual and auditory domains. The monkeys chose between two opaque cups to receive food contained in one of them. Cup contents were either shown or shaken, providing location cues from both cups, positive cues only from the baited cup, or negative cues from the empty cup. As in previous work, subjects readily used both positive and negative visual cues to secure reward. However, auditory outcomes were both similar to and different from those of earlier studies. Specifically, all subjects came to exploit positive auditory cues, but none responded to negative versions. The animals were also clearly different in visual versus auditory performance. Results indicate that a significant proportion of capuchins may be able to use positive auditory cues, with experience and learning likely playing a critical role. These findings raise the possibility that experience may be significant in visually based performance in this task as well, and highlight that coming to grips with evident differences between visual versus auditory processing may be important for understanding primate cognition more generally.     

Are monkeys able to plan for future exchange?

Whether or not non-human animals can plan for the future is a hotly debated issue. We investigate this question further and use a planning-to-exchange task to study future planning in the cooperative domain in two species of monkeys: the brown capuchin (Cebus apella) and the Tonkean macaque (Macaca tonkeana). The rationale required subjects to plan for a future opportunity to exchange tokens for food by collecting tokens several minutes in advance. Subjects who successfully planned for the exchange task were expected to select suitable tokens during a collection period (5/10?min), save them for a fixed period of time (20/30?min), then take them into an adjacent compartment and exchange them for food with an experimenter. Monkeys mostly failed to transport tokens when entering the testing compartment; hence, they do not seem able to plan for a future exchange with a human partner. Three subjects did however manage to solve the task several times, albeit at very low rates. They brought the correct version of three possible token types, but rarely transported more than one suitable token at a time. Given that the frequency of token manipulation predicted transport, success might have occurred by chance. This was not the case, however, since in most cases subjects were not already holding the token in their hands before they entered the testing compartment. Instead, these results may reflect subjects' strengths and weaknesses in their time-related comprehension of the task.     

Smells like sib spirit: kin recognition in three-spined sticklebacks (<Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>) is mediated by olfactory cues

The ability to recognise kin has been demonstrated in several animal species. However, the mechanisms of kin recognition often remain unknown. The most frequently discussed sensory modalities to recognise kin are visual, olfactory and acoustical cues. Three-spined sticklebacks (Gasterosteus aculeatus) are able to differentiate between kin and non-kin when presented visual and olfactory cues combined. To elucidate, which cues they use to recognise kin female sticklebacks were given the choice between two identical computer animations of courting stickleback males. Next to one animation, water conditioned by a brother was added, while near the other, water from an unrelated male was added. In half of the experiments, the brother was familiar while in the other half he was unfamiliar to the female. Both scenarios were carried out with both outbred and inbred fish. The results showed that the females adjusted their choice behaviour according to relatedness. Furthermore, they were able to recognise both familiar as well as unfamiliar brothers. Inbreeding did not affect this ability. Hence, three-spined sticklebacks are able to recognise their relatives using olfactory cues alone. The cognitive mechanisms underlying this ability were independent from familiarity and not impaired by inbreeding.     

Use of visual, acoustic, and olfactory information during embedded invertebrate foraging in brown capuchins (Cebus apella)

Experiments were conducted to investigate which sensory cues are used by brown capuchins (Cebus apella) in embedded invertebrate foraging. The importance of visual, olfactory, and acoustic cues in such foraging was determined by presenting subjects with a stimulus log modified to block out given sensory cues. Experiment 1 was designed to investigate whether subjects could locate an invertebrate embedded in wood when only visual, acoustic, or olfactory information was available. Experiments 2 and 3 were designed to investigate extractive foraging behavior when two sensory cues were provided. It was hypothesized that the combination of visual and acoustic information would be necessary for subjects to successfully locate embedded invertebrates. Results indicated that subjects' performance was most successful when both visual and acoustic information was available.     

Tool-use learning in Tonkean macaques (Macaca tonkeana)

The transmission of tool use is a rare event in monkeys. Such an event arose in a group of semi-free-ranging Tonkean macaques (Macaca tonkeana) in which leaning a pole against the parks fence (branch leaning) appeared and spread to several males. This prompted us to test individual and social learning of this behavior in seven young males. In the first experiment, three males learned individually to obtain a food reward using a wooden pole as a climbing tool. They began using the pole to retrieve the reward only when they could alternatively experience acting on the object and reaching the target. In a second experiment, we first tested whether four other subjects could learn branch leaning after having observed a group-mate performing the task. Despite repeated opportunities to observe the demonstrator, they did not learn to use the pole as a tool. Hence we exposed the latter subjects to individual learning trials and they succeeded in the task. Tool use was not transmitted in the experimental situation, which contrasts with observations in the park. We can conclude that the subjects were not able to recognize the target as such. It is possible that they recognized it and learned the task individually when we alternated the opportunity to act upon the object and to reach the reward. This suggests that these macaques could then have associated the action they exercised upon the pole and the use of the pole as a means to reach the reward.     

Signals use by leaders in Macaca tonkeana and Macaca mulatta: group-mate recruitment and behaviour monitoring

Animals living in groups have to make consensus decisions and communicate with each other about the time, or the direction, in which to move. In some species, the process relies on the proposition of a single individual, i.e. a first individual suggests a movement and the other group members decide whether or not to join this individual. In Tonkean (Macaca tonkeana) and rhesus macaques (Macaca mulatta), it has been observed that this first individual displays specific signals at departure. In this paper, we aimed to explore the function of such behaviours, i.e. if these behaviours were recruitment signals or only cues about the motivation of the first departed individual. We carried out temporal analyses and studied the latencies of the first departed individual’s behaviours and of the joining of other group members. We also assessed whether the social style of a species in terms of dominance and kinship relationships influenced the patterns of signal emissions. We then analyzed how the first departed individual decided to make a pause or to stop it according to the identities of group members that joined the collective movement. Results showed that Tonkean macaques and rhesus macaques seemed to use back-glances to monitor the joining of other group members and pauses to recruit such individuals. This was especially the case for highly socially affiliated individuals in Tonkean macaques and kin-related individuals in rhesus macaques. Moreover, back-glances and pauses disappeared when such individuals joined the first departed individual. From these results, we suggested that such behaviour could be considered intentional. Such findings could not be highlighted without temporal analyses and accurate observations on primate groups in semi-free ranging conditions.     

A behavioral study of alpha-1b adrenergic receptor knockout mice: increased reaction to novelty and selectively reduced learning capacities

Knockout mice lacking the alpha-1b adrenergic receptor were tested in behavioral experiments. Reaction to novelty was first assessed in a simple test in which the time taken by the knockout mice and their littermate controls to enter a second compartment was compared. Then the mice were tested in an open field to which unknown objects were subsequently added. Special novelty was introduced by moving one of the familiar objects to another location in the open field. Spatial behavior and memory were further studied in a homing board test, and in the water maze. The alpha-1b knockout mice showed an enhanced reactivity to new situations. They were faster to enter the new environment, covered longer paths in the open field, and spent more time exploring the new objects. They reacted like controls to modification inducing spatial novelty. In the homing board test, both the knockout mice and the control mice seemed to use a combination of distant visual and proximal olfactory cues, showing place preference only if the two types of cues were redundant. In the water maze the alpha-1b knockout mice were unable to learn the task, which was confirmed in a probe trial without platform. They were perfectly able, however, to escape in a visible platform procedure. These results confirm previous findings showing that the noradrenergic pathway is important for the modulation of behaviors such as reaction to novelty and exploration, and suggest that this is mediated, at least partly, through the alpha-1b adrenergic receptors. The lack of alpha-1b adrenergic receptors in spatial orientation does not seem important in cue-rich tasks but may interfere with orientation in situations providing distant cues only.     

Organization of behavior in unfamiliar female rabbits

Under natural conditions, female European rabbits usually spend the whole of their life in their natal groups, establishing a network of stable relationships with their group-mates, particularly with other females. Indeed, female social interactions with groupmates are ultimately responsible for the dimension, structure, and cohesion of the group itself. Despite their importance in social organization, non-reproductive female behaviors are poorly known. This study aims to provide information on the nature and distribution of these behaviors in familiar and unfamiliar milieux. For this purpose, female rabbits unfamiliar with each other were experimentally grouped, housed in outdoor enclosures new to them, and observed as they gradually familiarized with their environment and group-mates. When females were unfamiliar with both environment and group-mates, they would often mark objects (but never conspecifics) and engage in agonistic activities, preceded by approach and olfactory investigation. Once females had become familiar with their environment and group-mates, they spent a lot of time eating and self-grooming. Marking frequency decreased, and agonistic behavior became rare and appeared no longer related to introductory behaviors, which under these conditions led to amiable interactions, such as lying side by side with group-mates or grooming them. Under both unfamiliar and familiar conditions, high-ranking females appeared more active and interactive than low-ranking ones.     

Honey bee cognition

The visual memory of honey bees is stored pictorially. Bees will accept a mirror-image reversal of a familiar pattern in the absence of the original, but prefer the original over the reversal; the matching system of bees, therefore, does not incorporate a mirror-image ambiguity. Bees will not accept a rotation of a familiar vertical pattern, but readily recognize any rotation of a horizontal pattern; the context-specific ability to make a mental transformation seems justified by natural contingencies. Bees are able to construct and use cognitive maps of their home area, though it is possible to create conditions under which they lack useful cues. Other experiments suggest that recruits, having attended a dance in the hive specifying the distance and direction of a food source, can evaluate the "plausibility" of the location without leaving the hive; this suggests a kind of imagination.     

Long-delay and selective association in food aversion learning: The role of cue location

Cue location has been an uncontrolled variable in food-aversion studies. While tastes are always attributes of the ingested object, visual, auditory and olfactory cues are often attributes of the food container or are located elsewhere in the conditioning chamber. A review of experimental studies indicates that cues which are attributes of the ingested object are almost invariably associated with both immediate and delayed illness, regardless of the sense modality of the cue and of the animal species involved. Cues which are attributes of the food container or conditioning chamber are associated with immediate but not delayed illness, again regardless of the sense modality and animal subject. Within the limits of present evidence, the same effects of cue location appear to occur when shock is the reinforcer. It is suggested that the association of attribute cues across delays is mediated by the conditioned behaviour, which is directed at the object of which they are attributes and which is biologically related to the subsequent reinforcement.     

Experimental disorientation and conceptual confusion

Thirty-two subjects were examined on a visual matching task. They were tested for their ability to maintain an orientation with respect to a particular direction in the horizontal plane, while being kept in circumstances designed to minimize their input of information and create thereby some conceptual confusion.

The results suggest that subjects tend to make corrections as if they were in the same position in space throughout, even though they have no necessary reason for supposing this to be true and some reasons for supposing the opposite. It seemed that non-verbal information had to be presented to the subjects in order to suppress this tendency.

Voluntary rotation of the subject from one setting to the next produced no more than chance errors, while arbitrary rotations only produced errors when cues were inconsistent, or possibly where no cues were available at all. In the cases where no cues—or minimal cues-were available, assumptions were made by the subjects about the nature of the environment. This caused both errors and correct responses for reasons that were not justified by the evidence in the hands of the subject.

Introspective reports revealed some interesting results as to the cues utilized and concepts consciously formulated by the subjects for their use.     

Comprehension of human pointing gestures in horses (Equus caballus)

Twenty domestic horses (Equus caballus) were tested for their ability to rely on different human gesticular cues in a two-way object choice task. An experimenter hid food under one of two bowls and after baiting, indicated the location of the food to the subjects by using one of four different cues. Horses could locate the hidden reward on the basis of the distal dynamic-sustained, proximal momentary and proximal dynamic-sustained pointing gestures but failed to perform above chance level when the experimenter performed a distal momentary pointing gesture. The results revealed that horses could rely spontaneously on those cues that could have a stimulus or local enhancement effect, but the possible comprehension of the distal momentary pointing remained unclear. The results are discussed with reference to the involvement of various factors such as predisposition to read human visual cues, the effect of domestication and extensive social experience and the nature of the gesture used by the experimenter in comparative investigations.     

Redundant food searches by capuchin monkeys (Cebus apella): a failure of metacognition?

This study investigated capuchin monkeys' understanding of their own visual search behavior as a means to gather information. Five monkeys were presented with three tubes that could be visually searched to determine the location of a bait. The bait's visibility was experimentally manipulated, and the monkeys' spontaneous visual searches before tube selection were analyzed. In Experiment 1, three monkeys selected the baited tube significantly above chance; however, the monkeys also searched transparent tubes. In Experiment 2, a bent tube in which food was never visible was introduced. When the bent tube was baited, the monkeys failed to deduce the bait location and responded randomly. They also continued to look into the bent tube despite not gaining any pertinent information from it. The capuchin monkeys' behavior contrasts with the efficient employment of visual search behavior reported in humans, apes and macaques. This difference is consistent with species-related variations in metacognitive abilities, although other explanations are also possible.     

Modality-specific imagery reduces cravings for food: an application of the elaborated intrusion theory of desire to food craving

Based on converging evidence that visual and olfactory images are key components of food cravings, the authors tested a central prediction of the elaborated intrusion theory of desire, that mutual competition between modality-specific tasks and desire-related imagery can suppress such cravings. In each of Experiments 1 and 2, 90 undergraduate women underwent an imaginal food craving induction protocol and then completed either a visual, auditory, or olfactory imagery task. As predicted, the visual and olfactory imagery tasks were superior to the auditory imagery task in reducing participants' craving for food in general (Experiment 1) and for chocolate in particular (Experiment 2). Experiment 3 replicated these findings in a sample of 96 women using a nonimagery craving induction procedure involving a combination of chocolate deprivation and exposure to chocolate cues. Thus, imagery techniques in the visual or olfactory domain hold promise for treating problematic cravings in disordered eating populations.