Social Learning Of Food Preferences Research Articles

Social learning in bonobos: Learning of individual food preferences and copying despite better knowledge

Over the past few decades there has been a growing interest into social learning in animals. The importance of social influence on food choice has been demonstrated across a number of species including humans. Many more recent studies into social learning and conformity have looked into the influence of group social norms on the behaviour of individuals and it’s relevance in cultural evolution. The present study’s primary aim was to investigate bonobos’ capacity for social learning of food preferences from one or two demonstrators. We first wished to test whether bonobos in a captive social group could learn a food colour preference through mere observation of two conspecific demonstrators and the time-scale required for such learning. Secondly, we wished to investigate how these same individuals would perform in a reverse social learning task with one of the same demonstrators. In order to manipulate the demonstrators’ food preferences we used pink and blue artificial colouring and sweetening or bittering agents. In experiment 1, the ‘simple social learning’ task, two demonstrators consistently made a biased food colour choice (pink) in front of the subjects who were subsequently presented with the two, coloured, but palatable food items to choose from. In experiment 2, the ‘reverse social learning’ task, we used just one of the two demonstrators who consistently made the opposite colour choice (blue) with a different food type. Having observed the demonstrator, the subjects were tested once again. Overall, in the ‘simple social learning’ task, subjects preferentially chose the colour most consumed by the demonstrators (pink). In the ‘reverse social learning’ task, subjects preferentially chose the colour most consumed by the demonstrator (blue), but only after the additional 4 days of exposure. The results from experiment 1 followed our predictions and are in accordance with the literature on social learning and social facilitation of acceptance of novel foods. The results from experiment 2 showed that longer exposure was necessary in order to achieve a similar result, indicating that the ‘reverse social learning’ task was more difficult for the bonobos to manage. This corresponds nicely with previous studies of bonobos in which experimental paradigms were reversed. Furthermore, and perhaps of more interest is the fact that despite gaining knowledge that both colours were palatable during testing, subjects chose to eat more of the food consumed by the demonstrator. We discuss these findings in light of previous studies and considering influential factors such as the social status of the demonstrator.

Differential Effects of Dopamine Receptor D1-Type and D2-Type Antagonists and Phase of the Estrous Cycle on Social Learning of Food Preferences, Feeding, and Social Interactions in Mice

The neurobiological bases of social learning, by which an animal can 'exploit the expertise of others' and avoid the disadvantages of individual learning, are only partially understood. We examined the involvement of the dopaminergic system in social learning by administering a dopamine D1-type receptor antagonist, SCH23390 (0.01, 0.05, and 0.1 mg/kg), or a D2-type receptor antagonist, raclopride (0.1, 0.3, and 0.6 mg/kg), to adult female mice prior to socially learning a food preference. We found that while SCH23390 dose-dependently inhibited social learning without affecting feeding behavior or the ability of mice to discriminate between differently flavored diets, raclopride had the opposite effects, inhibiting feeding but leaving social learning unaffected. We showed that food odor, alone or in a social context, was insufficient to induce a food preference, proving the specifically social nature of this paradigm. The estrous cycle also affected social learning, with mice in proestrus expressing the socially acquired food preference longer than estrous and diestrous mice. This suggests gonadal hormone involvement, which is consistent with known estrogenic regulation of female social behavior and estrogen receptor involvement in social learning. Furthermore, a detailed ethological analysis of the social interactions during which social learning occurs showed raclopride- and estrous phase-induced changes in agonistic behavior, which were not directly related to effects on social learning. Overall, these results suggest a differential involvement of the D1-type and D2-type receptors in the regulation of social learning, feeding, and agonistic behaviors that are likely mediated by different underlying states.

Differential Effects of Estrogen Receptor Alpha and Beta Specific Agonists on Social Learning of Food Preferences in Female Mice

There is an evolutionary advantage to learning food preferences from conspecifics, as social learning allows an individual to bypass the risks associated with trial and error individual learning. The social transmission of food preferences (STFP) paradigm examines this advantage. Females in the proestrus and diestrus phases of the estrous cycle show a prolonged preference for the demonstrated food relative to estrus and ovariectomized females. Additionally, both estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta) knockout mice show impaired social recognition, which suggests that both receptors may be involved in other types of socially dependent learning, including the STFP. The present study investigated the effect of the ERalpha selective agonist PPT (1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole) and the ERbeta selective agonist WAY-200070 (7-Bromo-2-(4-hydroxyphenyl)-1,3-benzoxazol-5-ol) on the STFP. Results showed that ovariectomized (ovx) mice treated with PPT failed to learn the socially acquired preference, while WAY-200070-treated ovx mice showed a two-fold prolonged preference for the food eaten by their demonstrator. The effects of PPT on the socially acquired food preference cannot be explained by effects on the total food intake of the groups or on the type of interaction with the demonstrator mouse. The effects of WAY-200070 may be partially due to effects on Submissive Behavior. The higher WAY-200070 doses produced prolonged preferences similar to those seen previously in intact female mice during the proestrus and diestrus phases. This suggests that the estrous cycle's effects on social learning may be due to the action of ERbeta on Submissive Behavior, or to ERbeta countering that of ERalpha.

Social learning of food preferences by white-tailed ptarmigan chicks

The social-learning function of a food call is to share information about resources with conspecifics. Field studies on the social learning of food and parent–offspring interactions regarding food in a natural environment are rare. Our aims in a 2-year study in the Rocky Mountain National Park, U.S.A., were to monitor white-tailed ptarmigan, Lagopus leucurus , hens' food calls, a vocalizing and tidbitting display, to determine whether the hens selected foraging areas based on food availability and whether chicks learned about important food resources from hen food calls. Our findings indicate that the white-tailed ptarmigan hen's food call is a form of cultural transmission in which information regarding available food is disseminated from hens to chicks. Hens chose foraging patches where certain plant species were abundant and called their chicks to these foods, which dominated their diet. Chick consumption mirrored the calling rates of hens and as a result chicks ate high-protein foods, which are critical for chick growth and development. The results suggest that white-tailed ptarmigan hens' food calls may function to enhance survival of juvenile ptarmigan.

Roosts as information centres: social learning of food preferences in bats

The short-tailed fruit bat, Carollia perspicillata, lives in groups in tree hollows and caves. To investigate whether these roosts might serve as information centres, we tested whether individuals' preferences for novel foods could be enhanced through social learning at the roost. We also determined whether socially learned preferences for novel foods were reversed through interaction with other roost mates by simulating changes in available food resources such as those associated with variations in timing of fruit production in different plant species. Bats exhibited socially induced preferences that were readily reversible. We suggest that for frugivorous bats, roosts can serve as centres for information exchange about novel and familiar, ephemeral foods without requiring conspecific recruitment to these resources.

Effects of environmental stability and demonstrator age on social learning of food preferences by young Norway rats

We used socially learned food preferences of Norway rats, Rattus norvegicus, to examine two common predictions of formal models of social learning in animals: (1) that animals living in relatively stable environments should be more attentive to socially acquired information than animals living in highly variable environments, and (2) that older demonstrators should have greater influence than younger demonstrators on the behaviour of young observers. Old and young demonstrators were equally effective in modifying the food preferences of juveniles that interacted with them. However, food choices of rats that were moved daily from one cage to another and fed at unpredictable times for unpredictable periods were less affected by demonstrators than were rats maintained in stable environments. Our results thus provided experimental support for the first, but not the second, prediction from theory.

Ultrasonic vocalizations and social learning of food preferences by female Norway rats

We examined whether ultrasonic vocalizations facilitate social learning of food preferences in female Norway rats, Rattus norvegicus. Females produced ultrasonic vocalizations at higher rates when they were reunited with a familiar conspecific if one member of the reunited pair had eaten an unfamiliar food while the pair members were separated. However, the influence of demonstrator rats on food choices of their observers was as great in pairs of rats that had been devocalized surgically as it was in sham-operated controls. The latter result is not consistent with the hypothesis that ultrasonic vocalizations facilitate social learning of food preferences in Norway rats.

Social Learning of Food Preferences in Rodents: Rapid Appetitive Learning

A procedure is described for quantitating the transfer of information about inducing increased intake of distinctively-flavored foods or fluids among common laboratory rodents. The method provides a simple, efficient, non-invasive way to produce robust, long-lasting changes in appetitive behaviors of laboratory rodents that can be used in studies of the neuroanatomical, neurochemical or genetic substrates of learning and memory.

Establishing good dietary habits -- capturing the minds of children.

To review the psycho-social research with respect to relevance for the development of nutritional education strategies. The eating behaviour of the newborn baby is controlled by innate preferences and dislikes, and by biological self-regulation. These innate control-systems are modified by learning processes, most importantly by the mere exposure to unknown food, by social influences, and by associating the physiological consequences of food intake with taste cues. The last decades have witnessed a change of the social meaning of food and eating, and the social context of eating is subject to dramatic changes. While on the one hand, prevalence of overweight and obesity is increasing, even young children deliberately practise weight control measures ranging from selective food choice to self-induced vomiting thus including behaviours which are clearly symptomatic of eating disorders. Such behaviour is motivated by unrealistic conceptions of a healthy body weight and shape. Children are interested in a range of nutrition topics. However, these topics have to be related to direct perceivable benefits from nutrition. Educational strategies should: firstly, focus on providing a variety of foods, including a range of nutrient-dense 'healthy' food and encouraging children to taste it; secondly, provide a stable and predictive pattern of social eating occasions to promote the social meaning and importance of eating and to enable social learning of food preferences; and finally, encourage a positive body image by providing advice and reassurance regarding the range of healthy and acceptable body weights and shapes.

Explaining social learning of food preferences without aversions: an evolutionary simulation model of Norway rats.

Norway rats (Rattus norvegicus) transmit preferences for novel foods socially by smelling each other's breath. However, rats fail to learn aversions, acquiring a preference even if the rat whose breath they smell has been poisoned. Rats can distinguish between sick and healthy conspecifics and social learning of both preferences and aversions is present in other species - hence it is unclear why rats cannot learn aversions socially. We constructed an evolutionary simulation in which a population of rats foraged from a central location, exploiting food sites that could contain edible or toxic foodstuffs. We examined the relationship between toxin lethality and selection for individual versus social learning and discrimination between sick and healthy conspecifics in order to allow learning of both preferences and aversions. At low lethality levels individual learning was selected for and at intermediate levels we found social learning of both preferences and aversions. Finally, given high lethality levels the simulated rats would employ social learning but failed to learn aversions, matching the behaviour of real rats. We argue that Norway rats do not learn aversions socially because their environment may contain only highly lethal toxins which make interaction with a sick conspecific an extremely rare event.

Outline for social learning of food selection in rats

This paper reviews studies that investigated social learning of food preferences and aversions in rats. Many studies have found that rats can learn about food preferences by social processes. Rats exposed to a conspecific that had eaten a certain food increase their preferences for that food. On the other hand, the findings about social learning of food aversions are equivocal. Although poisoned conspecifics may function as unconditioned stimuli in food aversion learning, a few studies suggested that rats can socially transmit learned food aversions only under limited conditions. Finally, it is argued that researches of communication in ethology can complement those of social learning in psychology.

The Effects of Social Learning On the Food Choice of the House Sparrow (Passer Domesticus)

The effects of social feeding on the selection of novel coloured food and food intake by house sparrows (Passer domesticus) were studied in three experiments. In the first experiment, birds were given the choice of feeding on two novel types of coloured food after observations of an experienced bird feeding on them. These observers consumed more food of the colour that they had observed being eaten and also had an elevated total consumption compared to birds that had observed coloured food alone. In the second experiment, birds were given a choice between red and yellow food while adjacent to an experienced bird that was feeding on either red food or quinine-treated red food. The group observing consumption of treated red food consumed less red food than the other group. There was a significant correlation between consumption by the experienced bird and the consumption of red food by the observer which suggested that this effect was not due to a learned aversion. The third experiment was carried out to investigate the effect of previous experience on the behaviour of observers feeding in the presence of demonstrators eating red food or quinine-treated red food. The observers had either 'good' (untreated red food) or 'bad' (quinine-treated red food) experience before observation trials. It was found that only the previous good or bad experience of the observers affected consumption and there was no difference based on the feeding experiences of the demonstrators. These results are discussed in relation to the opportunities for, and types of, social learning of food preferences that may occur in house sparrow flocks.

Social transmission of food preferences among norway rats by marking of food sites and by gustatory contact

Three experiments were conducted to investigate the social learning and transmission of food preferences by excretory marking among adult male Norway rats. The experiments extend our earlier findings that rats prefer to eat from a food bowl marked by the excretory deposits of conspecifics and that this mechanism can result in the communication and social learning of food preferences (Laland & Plotkin, 1991). Here we investigate whether a tradition of food and food site preferences can become established by these means. Experiment 1 established that the residual cues deposited by rats lose their powers of communication as “markers” of food sites over a 72-h period. Experiment 2 showed that while a socially enhanced preference for one flavored diet could be transmitted from one animal to the next along a chain, it was unstable for an alternative diet. This suggests that social transmission may be more stable when it reinforces a prior preference than when it conflicts with one. In Experiment 3, the stability of socially transmitted food preferences was bolstered by the addition of a second process for the communication of diet preferences-namely, gustatory cues on the demonstrator’s breath. This finding suggests that when a socially transmitted trait is mediated by more than one process, the processes may interact, and the diffusion is likely to be more stable.

Excretory deposits surrounding food sites facilitate social learning of food preferences in Norway rats

Experiments were conducted to investigate the communication and social learning of food preferences via excretory marking amoungst adult male Norway rats, Rattus norvegicus. In experiment 1 animals were placed in a large enclosure with a choice of two food sites each containing a different novel food. For rats in the experimental conditions the enclosure had previosly house four “demonstrator” conspecifics that had eaten one of the foods at one of the sites, whilst controls were placed in a clean enclosure. Experimental animals consistently ate more of the diet eaten by their demonstrators than controls, and consumed more food in total. The experiment also investigated whether this marking of food sites could result in social learning. Animals were replaced in a clean enclosure with a choice between the two foods at unmarked sites, 24 h after their first experience in the soiled enclosure, and again exhibited a preference for the demonstrators’ diet. The remaining experiments investigated the communication process underlying these results. From these it is concluded that what renders food sites attractive to ras is a stimulus complex that includes local urine marking of the sites and peripheral urinal and faecal deposits, neither of which on their own is sufficient to mediate the transmission of information about food preference, but which together is an effective means of transmitting information between rats.