Tufted titmouse (Baeolophus bicolor) calling and risk-sensitive foraging in the face of threat

Individuals often produce alarm or mobbing calls when they detect a threat such as a predator. Little is known about whether such calling is affected by the facial orientation of a potential threat, however. We tested for an effect of facial orientation of a potential threat on tufted titmice, Baeolophus bicolor, a songbird that uses chick-a-dee calls in a variety of social contexts. In two studies, a human observer wore an animal mask that either faced or faced away from the focal bird(s). In Study 1, focal birds were individual titmice captured in a walk-in trap, and the observer stood near the trapped bird. In Study 2, focal birds were titmouse flocks utilizing a feeding station and the observer stood near the station. In both studies, calling behavior was affected by mask orientation. In Study 2, foraging and agonistic behavior were also affected. Titmice can therefore perceive the facial orientation of a potential threat, and this perception affects different behavioral systems, including calling. Our results indicate sensitivity of titmice to the facial orientation of a potential predator in two quite different motivational contexts. This work suggests the possibility of strategic signaling by prey species depending upon the perceptual space of a detected predator.     

Audience effects on alarm calling in chickens (Gallus gallus)

The male domestic chicken (Gallus gallus) has been found to modulate the production of vocal signals in response to the presence or absence of a suitable audience. We investigated effects on alarm calling by presenting overhead predator models to cockerels in the presence of a variety of social companions. The production of aerial predator calls in response to hawk silhouettes varied with the presence or absence of a member of the same species. The kinds of audience investigated included the mate, unfamiliar females, other females and males with which subjects had had prior visual and auditory contact, and broody hens with and without young. Domestic chicks, unrelated to the subjects, were almost as effective an audience as conspecific adults. A member of another species, however, failed to potentiate alarm-call production. The subjects gave more alarm calls when they were in the presence of either a male or a female audience than when they were alone. By manipulating the visibility of overhead predator models to the subjects and to the audience, we showed that the subjects were not cued by alarm and escape behaviors of the audience. Comparisons with food calling indicate that, in deciding whether to emit a signal in response to the appropriate referent (e.g., food or predators), chickens respond to subtle differences in the nature of the audience with behaviors that vary from one communicative context to another.     

Assessment of distance to potential mates by female barking treefrogs (Hyla gratiosa)

This study investigated the cues used by female barking treefrogs, Hyla gratiosa, to assess distances to potential mates. Eight-speaker playback experiments were used to demonstrate that distance affects female choice in complex acoustic environments and to test 3 possible cues that females might use to assess distance: (a) degradation in spectral and temporal cues of calls, (b) relative call amplitude at the female's location, and (c) the rate at which the amplitude of calls increases as a female approaches a calling male. All 3 hypotheses were refuted, suggesting that females use a more complex mechanism, such as triangulation, to assess distance. Females preferred speakers with greater source amplitudes even when they had to travel further to reach those speakers. Determination of source amplitude is possible only if females can assess independently both the distance to sound sources and the amplitude of calls at the females' location. Hence, anuran amphibians may possess greater cognitive abilities than are generally attributed to them.     

Call usage learning in gray seals (Halichoerus grypus)

Call usage learning can be demonstrated on 4 different levels: signaling on command, signaling and refraining from signaling on command, responding to a trained stimulus with a signal from a specific signal class, and responding to the playback of any untrained stimulus with one from the same signal class. Two young gray seals (Halichoerus grypus) were trained successfully to demonstrate the first 2 levels. They also learned to respond to 9 moan stimuli and 9 growl stimuli with vocalizations of the same class (Level 3). However, novel moan and growl stimuli tended to elicit growls. This casts doubt on the possibility that gray seals can reach the 4th level, but it demonstrates that they are capable of the first 3 levels of usage learning.     

An integration of shifts toward risk and caution in gambling situations

Findings have been reported and replicated indicating group-induced caution at the racetrack and group-induced risk in blackjack gambling. The present research examined the effects of two consistent differences between the blackjack and racetrack situations: (a) the amount of money available to groups versus individuals; and (b) the number of bets made in the postbaseline session. It was found that group-induced caution can occur in the blackjack setting if groups have larger stakes than individuals, as was the case in the racetrack studies, and that this effect disappears over trials, due to group versus individual differences established in the previous blackjack studies. Since current explanations of choice shifts cannot account for the observed trial effects, it was suggested that traditional choice-dilemma material, on which these explanations are largely based, be examined for such effects. Implications of the possible outcomes of such an examination for current group polarization theory were discussed.     

Erroneous choice and foregone gains in hoarding gray jays (Perisoreus canadensis)

Under the conventional assumption that natural selection favors choice behavior that maximizes some fitness-related currency, a forager making repeated binary choices should consistently choose the more valuable option. Under the alternative assumption that natural selection favors choice behavior that minimizes costly errors, erroneous choice is not only expected but is expected to be common when the cost of errors is low. This cost depends on the potential rate of return: the higher this rate, the smaller the cost of choosing the less valuable option. When this rate is very high, a forager may err frequently and yet forego no appreciable fitness gain. Errors should thus be more common when interruptions to foraging are shorter. Our experimental results supported this prediction: gray jays chose the less valuable option more frequently when subjected to shorter interruptions (experimentally imposed delays to access to food rewards). This tendency is consistent with the idea that an adaptive decision-making process may routinely produce errors, not because errors are in some way adaptive but because their fitness cost is minimal, particularly when delays are short. From a proximate perspective, this tendency to commit errors more frequently following shorter delays may be due to constraints on the jays’ information-processing capacity. In general, choice behavior should be viewed as the joint byproduct of adaptive decision making and cognitive constraints. Received: 8 June 2000 / Accepted after revision: 21 October 2000     

Informed consent as a prescription calling for debate between analysts and researchers(1)

This article is a review of the international scientific literature on informed consent and its use in some of the constituent organizations of the International Psychoanalytical Association (IPA). Because psychoanalysis comprises a theory based on practice, the dearth of clinical material for study, training and research purposes is a serious problem for analysts. Supervisions, presentations at scientific societies and congresses, publications and teaching material involve patients to an extent that goes beyond the work done in their sessions. Should consent be requested in these cases? This contribution addresses controversial and long‐standing issues such as informed consent and confidentiality, audio recording of treatments, knowledge production, the ambivalence of participating subjects over time and the perspective of analysts and patients respectively. The authors consider the various alternative approaches available for the handling of these ethical dilemmas without losing sight of the patient’s dignity and personal rights, while also taking account of the position of the analyst.     

Group size and social interactions are associated with calling behavior in Carolina chickadees (Poecile carolinensis)

The complexity of a social group may influence the vocal behavior of group members. Recent evidence in Carolina chickadees, Poecile carolinensis, indicated that one component of social complexity, group size, influenced the complexity of the "chick-a-dee" call, a vocalization functioning in social cohesion. Individuals in larger social groups used calls with greater information than did individuals in smaller social groups. Here, the authors review this earlier work, and describe a recent study indicating that social interactions between females and males within female-male pairs of chickadees were associated with rates of chick-a-dee call production in the males. Together, these studies suggest that the nature and complexity of social interactions among members of chickadee social groups influence chick-a-dee calling behavior.     

Human gestures trigger different attentional shifts in chimpanzees (Pan troglodytes) and humans (Homo sapiens)

Brain lateralization has been the matter of extensive research over the last centuries, but it remains an unsolved issue. While hand preferences have been extensively studied, very few studies have investigated laterality of eye use in non-human primates. We examined eye preference in 14 Campbell’s monkeys (Cercopithecus c. campbelli). We assessed eye preference to look at a seed placed inside a tube using monocular vision. Eye use was recorded for 100 independent and non-rewarded trials per individual. All of the 14 monkeys showed very strong preferences in the choice of the eye used to look inside the tube (mean preference: 97.6%). Eight subjects preferred the right eye and six subjects preferred the left eye. The results are discussed in light of previous data on eye preference in primates, and compared to data on hand preference from these subjects. Our findings would support the hypothesis for an early emergence of lateralization for perceptual processes compared to manual motor functions.     

Attention shifts and the Simon effect: a failure to replicate Stoffer (1991)

The Simon effect refers to the intrusion of an irrelevant spatial dimension in the selection of a response to a stimulus. Recently, Stoffer (1991) proposed a specific role for attention orienting in the Simon effect. According to Stoffer, attentional shifts from an initial fixation point to a stimulus location are associated with the generation of a spatial code which specifies the position of the stimulus in relation to the last attended location. This spatial code forms the basis for the Simon effect because it is used to specify the selection of the right or left response. Three experiments were performed to examine further the attention-shift hypothesis forwarded by Stoffer. Experiment 1 was an attempt to replicate Stoffer (1991), but failed to do so. Experiments 2 and 3 were designed to optimize conditions for replicating crucial aspects of Stoffer's findings, but also failed to yield support for the attention-shift account.     

Sex differences in aggressive behavior in a marsupial,the gray short-tailed opossum (Monodelphis domestica)

In male and female gray short-tailed opossums (Monodelphis domestica), same-sex interactions were characterized by high levels of threat behavior (open-mouth postures and screeching vocalizations). Actual fighting behavior (biting, locking, and tumbling) was seen almost exclusively in male-male interactions. In male-female interactions, females showed high levels of threat behavior and males showed little aggressive behavior of any kind. Clicking vocalizations, submissive behavior in marsupials, were displayed almost exclusively by males. These findings are discussed with respect to the uses of auditory and olfactory communication in marsupials.