Internal and external factors modulate food-calling in domestic hens

Two series of experiments investigated factors affecting utterance of food calls in the domestic hen, Gallus domesticus. The first series of experiments tested the effect of food preference and the hen’s internal state on the utterance of food calls. Different food types were presented first singly and then in a choice test to 20 hens, first when hens were laying, and then when they were maternal. The second series of experiments tested the effect of hunger level on the utterance of food calls in laying hens, and maternal hens with or without chicks. These two series of experiments showed that laying hens and maternal hens showed a similar marked preference for certain types of food, but laying hens very rarely emitted food calls, in contrast to maternal hens. This shows the effect of the bird’s psychophysiological state on her tendency to emit food calls. The more a maternal hen preferred a food type, the more food calls she emitted. This was observed from the beginning of a test in single-food tests as well as in choice tests. Hunger level positively affected food-call production under certain feeding conditions in maternal hens, but not in laying hens. When maternal hens were tested in the absence of their chicks, utterance of food calls was more sustained than in the presence of chicks. Received: 14 May 1998 / Accepted after revision: 11 October 1998     

Sensory modality and stimulus control in the pigeon: Cross-species generality of single-incentive selective-association effects

In earlier studies with rats, the effectiveness of the auditory element of a tone–light discriminative stimulus was enhanced when the conditioned incentive value of the compound was negative rather than positive. The present experiment systematically replicated these results in pigeons trained to press a treadle in the presence of a tone–light compound under food-reinforcement or shock-avoidance schedules. Positive incentive value was conditioned to the compound by associating it with either food or relative safety from shock. The compound was made negative in other groups by associating it with shock or the absence of food. When tone and light were presented separately following this training, control by the auditory element was significantly enhanced in the conditions designed to make the compound negative rather than positive. The similarity of this constraint on learning in rats and pigeons suggests that it involves a fundamental attentional and incentive-motivational process with widespread species generality.     

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.     

The role of familiarity in dietary development

The rise in inadequate and unhealthily diets in children has led investigations to examine the development of food preferences. This review outlines the ways in which children choose between foods made available to them and the subsequent shaping of their own habitual diet. Children are liable to form preferences to certain hedonic foods, and to exhibit neophobic reactions to the unfamiliar. Unfamiliar foods can elicit anxiety and suspicion. Trust and liking of a once novel food can be gained through exposure, increasing familiarity towards that food. This review examines: visual familiarity (awareness of foods within their environment); taste familiarity (knowledge and experience of the taste of foods); contextual familiarity (knowledge of how foods should be presented); and categorical familiarity (which family foods belong to). The influence of familiarity is also explained with regards to both positive and negative associative learning. These associations are influenced by the specific presentation and the social environment of a novel food. The potential benefits of understanding the nature of children’s learning and preference development for the promotion of healthy nutrition to both parent and child are discussed.     

Chimpanzees really know what others can see in a competitive situation

Chimpanzee’s perspective-taking abilities are currently disputed. Here we show that in some food competition contexts, subordinate chimpanzees do take the visual perspective of dominant individuals, preferentially targeting a hidden piece of the food that the dominant cannot see over a piece that is visible to both individuals. However, the space where the animals compete is critical in determining whether subjects demonstrate this skill. We suggest that competition intensity, as mediated by these spatial factors, may play an important role in determining the strategy chimpanzees utilize in competitive contexts. Since some strategies may not require visual perspective taking in order to be successful, chimpanzees may not always demonstrate this skill. Differences in spatial arrangement may therefore account for the conflicting results of past studies.     

Experimental evidence for route integration and strategic planning in wild capuchin monkeys

Both in captivity and the wild, primates are found to travel mostly to the nearest available resource, but they may skip over the closest resource and travel to more distant resources, which are often found to be more productive. This study examines the tradeoff between distance and reward in the foraging choices of one group of wild capuchin monkeys (Cebus apella nigritus) using feeding platforms in large-scale foraging experiments conducted over four years. Three feeding sites were arrayed in an oblique triangle, such that once the monkey group had chosen one site to feed, they had a choice between two remaining sites, a close one with less food and the other up to 2.3 times as far away but with more food. Sites were provisioned once per day. The capuchins generally chose the closer feeding site, even when the more distant site offered up to 12 times as much food. The distances to, rewards of, or various profitability measures applied to each alternative site individually did not explain the group’s choices in ways consistent with foraging theory or principles of operant psychology. The group’s site choices were predicted only by comparing efficiency measures of entire foraging pathways: (1) direct travel to the more rewarding distant site, versus (2) the longer ‘detour’ through the closer site on the way to the more distant one. The group chose the detour more often when the reward was larger and the added detour distance shorter. They appeared to be more sensitive to the absolute increase in detour distance than to the relative increase compared to the straight route. The qualitative and quantitative results agree with a simple rule: do not use the detour unless the energy gain from extra food outweighs the energy cost of extra travel. These results suggest that members of this group integrate information on spatial location, reward, and perhaps potential food competition in their choice of multi-site foraging routes, with important implications for social foraging. This contribution is part of the special issue “ A Socioecological Perspective on Primate Cognition” (Cunningham and Janson 2007b).     

Tufted capuchins (<Emphasis Type="Italic">Cebus apella</Emphasis>) attribute value to foods and tools during voluntary exchanges with humans

This research examined exchange and value attribution in tufted capuchin monkeys (Cebus apella). We presented subjects with opportunities to obtain various foods and a tool from an experimenter in exchange for the foods or tool in the subjects' possession. The times elapsed before the first chow biscuits were expelled and/or an exchange took place were recorded as the dependent measures. Laboratory chow biscuits, grapes, apples, and a metal bolt (a tool used to probe for syrup) were used as experimental stimuli. The subjects demonstrated the ability to recognize that exchanges could occur when an experimenter was present with a desirable food. Results indicate that subjects exhibited significant variation in their willingness to barter based upon the types of foods that were both in their possession and presented by the experimenter. Subjects more readily traded chow biscuits for fruit, and more readily traded apples for grapes than grapes for apples. During the exchange of tools and food, the subjects preferred the following in descending order when the probing apparatus was baited with sweet syrup: grapes, metal bolts, and chow biscuits. However when the apparatus was not baited, the values changed to the following in descending order: grapes, chow, and metal bolts. These results indicate that tufted capuchins recognize opportunities to exchange and engage in a simple barter system whereby low-valued foods are readily traded for more highly valued food. Furthermore, these capuchins demonstrate that their value for a tool changes depending upon its utility.     

Patterns of Aberrant Eating Among Pre-adolescent Children in Foster Care

The paper reports epidemiological and phenomenological investigations of aberrant eating among 347 pre-adolescent children in court-ordered foster and kinship care, in New South Wales, Australia. A quarter of children displayed clinically significant aberrant eating problems, with no evidence of gender or age effects. Two distinct patterns were identified. The first is a pattern of excessive eating and food acquisition and maintenance behaviors without concurrent obesity (termed Food maintenance syndrome), resembling the behavioral correlates of Hyperphagic Short Stature (Psychosocial Dwarfism). Various data suggest this pattern is primarily triggered by acute stress, including maltreatment in care, against a background of complex psychopathology and developmental disabilities. The second is a cluster of pica-type eating behaviors that correlates with self-injurious behavior, and is closely associated with developmental disabilities. The paper includes recommendations for clinicians working with pre-adolescent children in care.     

The Light = Healthy Intuition

This research documents a “light = healthy” intuition, such that consumers perceive foods that weigh less are healthier than their heavier counterparts with the same serving size. Subsequently, consumers consume a larger quantity of lighter-weight foods. The intuition is based on a coactivation of two meanings of the word “light”: light in physical weight and light in calorie content. An implicit attitude test finds support for this association between physical weight and food healthiness. ​Subsequently, physically lighter foods are perceived to be healthier because they are assumed to contain fewer calories. In line with the proposed coactivation mechanism, the intuition is bidirectional, where consumers also expect healthier foods to weigh less. Consequently, they discredit health claims issued for heavier foods. Finally, it was found that activating a competing intuition is effective at debiasing the “light = healthy” intuition.