Note on aversion learning to the shape of food by monkeys

Vervet and grivet monkeys were repeatedly tested eating bar- and circle-shaped cookies. One subject was always injected with lithium immediately after eating cookies with the circle shape and learned to avoid the circular cookies while continuing to eat the bar-shaped cookies. Another subject received similar treatment except that lithium injections were always delayed 30 minutes after access to the circle-shaped cookies. She also acquired a discriminative aversion. Aversion learning was not observed with 60-minute delayed toxicosis or with lithium injections administered unpaired with access to the cookies. The two types of cookies differed only in shape, and conditioning and test sessions were conducted in total darkness to preclude the use of visual cues. Therefore, the avoidance observed in subjects conditioned with immediate and 30-minute delayed toxicosis represents a conditioned aversion to the shape of the cookies as revealed by tactile cues. These findings illustrate that monkeys can learn to select food on the basis of tactile stimuli when such stimuli are conditioned with delayed aversive stimulation.     

Flavor aversions produced by contingent drug injection: Relative effectiveness of apomorphine, emetine, and lithium

Shortly after rats began drinking saccharin solution, different groups of them were injected with different doses of apomorphine, emetine, or lithium. A control group was not injected at all. Six days later, the rats were given free access to saccharin solution and to water. Aversions to saccharin solution were obtained in all injected groups and tended to become more pronounced as the dose level increased. At similar dose levels, lithium produced the most pronounced aversions, apomorphine produced the weakest aversions, and emetine was intermediate. A follow-up study with squirrel monkeys confirmed that lithium produces more pronounced aversions than either emetine or apomorphine. From these results, it seems worthwhile to try lithium in the chemical aversion treatment of alcoholism.     

Development of co-feeding behavior in young wild Japanese macaques (Macaca fuscata)

This study describes the developmental course of the social context of feeding behavior in infants and yearlings of Japanese macaques in a provisioned free-ranging troop. Results of this longitudinal study revealed that infants and yearlings exhibited synchronous feeding behavior in the majority of cases in which they had feeding neighbors within 1 m. They consistently showed feeding behavior more often when their closest neighbor fed than when they did not. In feeding situations, infants tended mainly to be in close proximity with their mothers in the early stages of life and, later, also with peers. The results imply that potential opportunities for the social transmission of food selection habits are available for young Japanese macaques in the wild.     

When and where to practice: social influences on the development of nut-cracking in bearded capuchins (<Emphasis Type="Italic">Sapajus libidinosus</Emphasis>)

The habitual use of tools by wild capuchin monkeys presents a unique opportunity to study the maintenance and transmission of traditions. Young capuchins spend several years interacting with nuts before cracking them efficiently with stone tools. Using a two-observer method, we quantified the magnitude of the social influences that sustain this long period of practice. During five collection periods (over 26 months), one observer recorded the behavior of 16 immature monkeys, and another observer concurrently recorded behavior of group members in the focal monkey’s vicinity. The two-observer method provides a means to quantify distinct social influences. Data show that immatures match the behavior of the adults in time and especially in space. The rate of manipulation of nuts by the immatures quadrupled when others in the group cracked and ate nuts, and immatures were ten times more likely to handle nuts and 40 times more likely to strike a nut with a stone when they themselves were near the anvils. Moreover, immature monkeys were three times more likely to be near an anvil when others were cracking. We suggest a model for social influence on nut-cracking development, based on two related processes: (1) social facilitation from observing group members engaged in nut-cracking, and (2) opportunity for practice provided by the anvils, hammer stones and nut shells available on and around the anvils. Nut-cracking activities by others support learning by drawing immatures to the anvils, where extended practice can take place, and by providing materials for practice at these places.     

Social transmission of food preferences in Japanese monkeys (Macaca fuscata) after mere exposure or aversion training

In Experiment 1, 3 mother-child pairs of Japanese monkeys (Macaca fuscata) were given simultaneous choice tests between raisins and popcorn. The mothers and offspring showed different choice patterns. Cofeeding opportunities were then alternated with individual choice tests. In Experiment 2,2 other pairs were added. Each animal was again offered simultaneous choice tests between marshmallows and almonds. Food aversion conditioning was used to create different choice patterns for mothers and offspring. After cofeeding and choice tests, the differences in choice patterns disappeared in both experiments. The changes after contact with the other's eating pattern during cofeeding was as follows: foods consumed by either came to be eaten by both; foods consumed by both continued to be eaten by both; and foods consumed by neither continued to be ignored. The results provide evidence for social transmission of food preferences in this species.     

Enhancement of food aversion by exposure to a poisoned conspecific in Norway rats (Rattus norvegicus)

Two experiments were conducted to determine whether exposure to a poisoned conspecific enhances prior food aversion in rats. In Experiment 1, subjects were serially exposed to two foods, cocoa‐flavored and cinnamon‐flavored ones, and were then poisoned 1 h later. On the next day, they were exposed to a poisoned conspecific that had eaten a cocoa‐flavored food. On the subsequent choice test, subjects had an enhanced aversion to cocoa‐flavored food. The result was replicated in Experiment 2, in which a cinnamon‐flavored food was assigned as a target. The results are discussed in relation to previous findings.     

Case study of a one‐sided attack by multiple troop members on a nontroop adolescent male and the death of Japanese macaques (Macaca fuscata)

An adolescent wild male Japanese macaque (Macaca fuscata), following Kinkazan A troop, was attacked one‐sidedly by multiple members of the troop. The victim was identified as PI, and was estimated to be seven±one year old. The aggressive interaction was recorded by video camera until the end. Although at least 16 troop members approached PI more than once, only three males (one adult, two adolescents) of A troop attacked him. PI kept crouching throughout the attack, then escaped to the shore and dived into the sea. The interaction continued for more than one hour. PI was found dead a few hours after the end of interaction. The damage caused by the assailants was not the direct cause of PI's death; it was due to hypothermia caused by drifting in the sea. PI's life history was reconstructed from past records. PI was a normal adolescent male who migrated from an all‐male group around B₁ troop and started ranging around A troop. The aggressive interaction is believed to be a typical example of conflict between troop males and a nontroop male. The interaction period was very long compared with previous reports on such conflicts among Japanese macaques. PI kept crouching in open areas, exposing himself as a potential competitor for the resources of the troop, and did not show any submissive or reconciliatory behavior toward the troop males. This may be why the troop males did not stop the attack. Aggr. Behav. 35:334–341, 2009. © 2009 Wiley‐Liss, Inc.     

Changes in values cognition after rating values-associated feelings

This study investigated values change as an outcome of assessing feelings elicited by contemplating the actualization of the same values. The subjects were divided into an experimental and a control group. They completed three tests in a single session. In the pretest, all subjects were asked to rate the importance of 20 values items on a 4-point scale. Subjects in the experimental group were then asked to rate the degree of pleasure they would feel in actualizing each of the values, while those in the control group rated the degree of inequality they considered women suffer in the actualization of each of the values. The post-test consisted of the same items as the pretest. The subjects in the experimental group completed a second post-test 3 months later. It was found that the experimental procedure produced significant change in the ratings of 15 values at the post-test, whereas the control procedure produced change in only five. The results suggest that rating one's emotional response to a value-related situation can change one's cognition of that value. At the post-test 3 months later, only 3-value ratings remained changed.     

Persistence of conditioned flavor preferences is not due to inadvertent food reinforcement

Almond preferences were produced by giving rats a mixture of almond and sucrose (Experiments 1-4) or saccharin (Experiment 4). A subsequent extinction procedure consisted of either repeated 2-bottle almond versus water tests (Experiment 1) or repeated exposure to almond alone (Experiments 2-4). The main independent variable was whether access to food following a session was given immediately, 30 min later, or 120 min later. No effect of extinction was found in any experiment. An important finding was that varying the delay until food access had no detectable effect. It was concluded that inadvertent flavor-food associations do not maintain preference for the flavor under extinction conditions.     

Flavour aversion produced by running and attenuated by prior exposure to wheels

In two experiments hungry rats were given access to running wheels. When given the novel flavour, almond, prior to novel access to the wheels, a conditioned aversion to almond was revealed by a subsequent two-bottle test. No such aversion was found in rats with previous experience of wheel running, whether this prior running occurred in the absence of any novel flavour, as in Experiment 1, or following access to saccharin, as in Experiment 2. These results suggest that the failure of rats with prior experience of the running wheels to develop a flavour aversion (unconditioned stimulus, US, preexposure effect) is unlikely to be due to associative blocking. Instead it seems that increasing exposure to a wheel produces habituation of its nausea-inducing properties.     

Potentiation by a taste of toxicosis-based context conditioning: Effects of varying the test fluid

Rats that drank water in a distinctive environment and were then injected with lithium chloride (water-lithium condition) were compared with those given an added taste on those conditioning sessions (sucrose-lithium condition). In three experiments this taste potentiated a conditioned aversion to the context, as measured by suppression of intake of another solution: either a novel sour taste (Experiments 1 and 2) or a familiar saline solution (Experiment 3). In contrast, this potentiation effect was not detected when subjects were tested with water, whether a high or low dose of lithium was used (Experiment 2). Instead, in Experiments 1 and 2 water-lithium subjects drank less water than did the sucrose-lithium subjects on such tests i.e. an apparent overshadowing effect, which was the opposite outcome to that found previously using almost identical procedures. Intake on recovery sessions in another context suggested that, when water is used as the test fluid, potentiation can be masked by two factors: a context-dependent aversion to water in water-lithium subjects, and a conditioned inhibition effect of water in sucrose-lithium subjects. These may account for previous failures to detect potentiation of context conditioning.     

Stone-Tool Use in Wild Monkeys: Implications for the Study of the Body-Plus-Tool System

Handheld tools transform the actor's body into a body-plus-tool system such that the fit of the actor's body, the tool, and the task demand channel movement in action. In this study, we performed a biomechanical analysis of percussive actions in wild bearded capuchin monkeys, Sapajus libidinosus at Fazenda Boa Vista, Brazil, as they cracked open tucum nuts with anvil-and-hammer tools from the frame of reference of the body-plus-tool system. The ratio of hammer mass to body mass—the “body-scaled hammer mass”—influenced the monkeys' actions with a hammer and their performance in cracking nuts. Both body mass and hammer mass did not independently influence the monkeys' actions with a hammer and their performance in cracking nuts. These findings support the hypothesis that the properties of the body-plus-tool system are not simply the sum of the properties of the body and the tool.     

Aggressive behavior in the free-ranging rhesus monkeys of kathmandu,nepal

We present a composite sample of the aggressive behavior of free-ranging rhesus monkeys (Macaca mulatta), recorded at two temples in Kathmandu, Nepal. We analyze the total number and the rate per monkey of threats, chases, attacks, fights, and aggressive acts directed at other species (principally humans), in order to elucidate social dynamics of the troop as a whole. Our 1,506 hours of observation were divided among the four seasons; between a.m. and p.m.; and among a temple yard, two parklands, and a forested garden. We found seasonal patterns to be the most important correlates of aggressive behavior. Habitat was a modulating influence, and time of day was the least important factor. Rates of aggression were generally higher per male monkey than per female. In terms of total aggression recorded, however, females instigated significantly more than males, both in encounters between monkeys and in aggression against other species. This finding is consistent with the females' greater numbers in the troop and with their lifelong membership in the troop. Analysis of behavior by social groups, rather than by individual rates, points up the iomportance of adult females and their social stability in troop behavior.     

Factors influencing sexual performance in male rhesus monkeys.

A 5-yr retrospective study of the sexual behavior of eight adult male rhesus monkeys showed that sexual vigor declined over the years but testosterone levels in peripheral vein plasma did not. Two prospective experiments were then carried out on these males during the sixth year. (a) The four poorest performers were injected daily for 28 days with testosterone propionate (1 mg/kg of body weight). There was no significant increase in level of performance, and behavior was not correlated with plasma levels of testosterone either before or 24 hr after the last hormone injection. (b) All eight males were exposed to novel nonspecific sensory stimulation during tests of sexual behavior. Eight different adult male rhesus strangers-present in the room but not in the test cage-were used as stimuli, one for each experimental test. Sexual behavior during experimental and control tests did not differ.     

Variations in the sensitivity of instrumental responding to reinforcer devaluation

In five experiments hungry rats were trained to make a lever press response for a sucrose reinforcer. That sucrose was subsequently devalued by conditioning a food-aversion to it, and the ability of the rats to integrate knowledge about the instrumental contingency with that gained from aversion training was assessed in an extinction test. Experiment I showed successful integration following limited but not extended instrumental training. Experiment II suggested that the crucial factor was the spacing of training; successful integration was seen after massed but not distributed training. The third experiment implicated distributed experience with the reinforcer, rather than distributed response practice, in failures of integration. Experiment IV showed that if the distribution of food-aversion learning was dissimilar to that of instrumental training then a failure of integration could result; this finding was able to account for the distribution of training effects seen in previous studies, but not the effect of extended training. Experiment V replicated the extended training effect seen in Experiment I, and provided evidence that this may reflect the degree of exposure to the reinforcer rather than the extent of response practice.     

Characterization of a dose-response curve for nicotine-induced conditioned taste aversion in rats: relationship to elevation of plasma beta-endorphin concentration

In the first experiment a conditioned taste aversion paradigm was used to characterize a dose-response curve for the aversive properties of nicotine in male Sprague-Dawley rats. Doses of nicotine ranging from 0.01 to 0.46 mg/kg, 2.0 ml of 0.47 M lithium chloride, or saline were injected, ip, 10 min after exposure to a novel saccharin solution. Amount of saccharin consumed in a two-bottle test was assessed 72 h later. Nicotine doses of 0.046 mg/kg and above produced a significant degree of conditioned taste aversion. In a second experiment, four groups of 10 rats each were injected with saline, 0.022 mg/kg nicotine, 0.46 mg/kg nicotine, or 2.0 ml 0.47 of M LiCl. Doses of 0.46 mg/kg nicotine and 0.47 M LiCl elevated plasma beta-endorphin concentrations significantly above saline control values. The 0.022 mg/kg dose, the highest dose that did not produce conditioned taste aversion in Experiment 1, did not significantly increase plasma beta-endorphin concentrations. This finding suggests that doses of nicotine that produce conditioned taste aversion also promote the release of pituitary stress hormones. Taken together these data suggest that some of the pharmacological and behavioral effects attributed to nicotine, including the release of endogenous neuromodulators, may be dose-dependent concomitants of the aversive effects of nicotine in nicotine-naive animals.     

Extinction of conditioned taste aversions: Effects of concentration and overshadowing

Extinction of conditioned taste aversions was examined as a function of taste concentration and of the presence of an additional taste. The results of Experiment 1 were consistent with previous evidence in that a conditioned aversion to high concentration saline was more persistent in extinction than an aversion to a low concentration. However, when floor effects were avoided the rate of extinction was faster for the higher (1%) concentration than for 0.2% saline (Experiment 2), a result consistent with accounts of extinction in other preparations. Three further experiments examined extinction of a conditioned sucrose aversion. The addition of 1% saline, but not of 0.2% saline, to sucrose during extinction produced overshadowing ("protection from extinction"; Experiment 3). Such overshadowing by saline was detected after two, but not after a single extinction trial (Experiment 4). This last finding suggests that under the conditions of the present experiments sweet and salty tastes function as elemental stimuli competing for loss of associative strength. No overshadowing was found when almond (an aqueous odour) was used in place of saline as the added stimulus, even when high concentrations of almond were used that produced observable neophobia (Experiments 5A and 5B).     

Temporal contiguity in electric aversion therapy for cigarette smoking

Seventy dependent heavy smokers (32 cigarettes per day) were randomly assigned to one of five treatment and control procedures: (1) electric aversion therapy, involving ten 20-trial sessions of shocks contiguous with the smoking act. (2) simulated electric aversion. with non-contiguous shocks, (3) non-shock smoking sessions, to control for stimulus satiation and negative practice effects. (4) simple support and attention from therapist, (5) no-treatment. Before treatment, simple ‘self-monitoring’ and ‘self-control’ reduced cigarette consumption by an average of 12% (p < 0.001) and 26% (p < 0.001) respectively. Thirty-four of the 56 treated subjects (61%) were able to stop smoking compared with two out of fourteen (14%) of the no-treatment controls (p < 0.005). Treatment was highly effective at reducing and stopping smoking during the 4-week course and for 2 weeks afterwards (p < 0.005). Its effect was rapid, but not immediate. Outcome was virtually decided after 1 week (five sessions); subjects who had not stopped or almost stopped at this stage were most unlikely to respond later on (p < 0.001). All four treatments were equally effective, regular attendance for 15 min of simple support being as effective as the treatments involving additional 45-min sessions with a second therapist. The effects of contiguous vs non-contiguous shocks did not differ. A motor response was conditioned in 19 of the 28 subjects who received shocks but this was therapeutically irrelevant. The clinical outcome depended on the kind of subject rather than the kind of treatment. Those who were depressed, with poor psychiatric adjustment and a high Eysenck-Scale P score tended to do badly, while those who initially expressed high confidence in the outcome were more likely to succeed (p < 0.001). It is concluded that traditional conditioning processes do not contribute significantly to the clinical response of human subjects to electric aversion therapy for cigarette smoking.     

Odor-aversion learning and retention span in neonatal mouse pups

One hundred and sixty-four litters of Swiss CD-1 random-bred mice were used to assess learning and retention capacities during the first postnatal week. In Experiment 1, whole 7-day litters were exposed for 65 min to commercial extracts of either mint or lemon sprinkled over wood shavings. Five minutes after the beginning of the exposure, half of the litters were injected ip with the illness-inducing agent lithium chloride (LiCl; 0.20 M, 2% of body weight); the other half was treated with saline solution (8% NaCl). On Postnatal Day 10, the animals were singly introduced in a warmed arena for a 180-s preference test, and the time spent in the mint- and lemon-scented areas of the apparatus was recorded. When compared with saline-injected pups, mice that experienced lemon-LiCl pairings showed a significant aversion for the lemon-scented area, while the mint aversion in the mint-LiCl group just missed statistical significance. Three additional control groups (unhandled on Day 7, or only LiCl- or saline-injected) did not show significant preferences for either the mint or the lemon odor. In Experiment 2, litters of 3, 5, or 7 days were similarly exposed to lemon-scented shavings for either 5 or 20 min, injected with LiCl or saline, and then exposed for an additional 60 min to the shavings. On Postnatal Day 10, tests like those of Experiment 1 showed a significant odor-aversion in animals conditioned on Day 7, but not in those conditioned on Day 3 or 5. In Experiment 3, 3- and 5-day old pups were exposed to lemon odor-LiCl or -NaCl pairings, and tested for aversion after 3 or 7 days (CS duration 5 min before injection and either 30 or 60 min after injection). Only when the conditioning-testing interval was limited to 3 days did LiCl-injected groups show a significant aversion, which did not depend on duration of CS exposure.     

Transport of tools to food sites in tufted capuchin monkeys (<Emphasis Type="Italic">Cebus apella</Emphasis>)

Tool use and transport represent cognitively important aspects of early hominid evolution, and nonhuman primates are often used as models to examine the cognitive, ecological, morphological and social correlates of these behaviors in order to gain insights into the behavior of our early human ancestors. In 2001, Jalles-Filho et al. found that free-ranging capuchin monkeys failed to transport tools (stones) to food sites (nuts), but transported the foods to the tool sites. This result cast doubt on the usefulness of Cebus to model early human tool-using behavior. In this study, we examined the performance of six captive tufted capuchin monkeys (Cebus apella) in a tool transport task. Subjects were provided with the opportunity to transport two different tools to fixed food reward sites when the food reward was visible from the tool site and when the food reward was not visible from the tool site. We found that the subjects quickly and readily transported probing tools to an apparatus baited with syrup, but rarely transported stones to a nut-cracking apparatus. We suggest that the performance of the capuchins here reflects an efficient foraging strategy, in terms of energy return, among wild Cebus monkeys.