Abstract: Food-storing birds, black-capped chickadees (Poecile atricapilla), and nonstoring birds, dark-eyed juncos (Junco hyemalis), matched color or location on a touch screen. Both species showed a divided attention effect for color but not for location (Experiment 1). Chickadees performed better on location than on color with retention intervals up to 40 s, but juncos did not (Experiment 2). Increasing sample-distractor distance improved performance similarly in both species. Multidimensional scaling revealed that both use a Euclidean metric of spatial similarity (Experiment 3). When choosing between the location and color of a remembered item, food storers choose location more than do nonstorers. These results explain this effect by differences in memory for location relative to color, not division of attention or spatial discrimination ability.

Abstract: The way in which cognitive functioning is affected by stressors is an important area of research for applied ethologists because stress caused by captive conditions may disrupt cognitive processes and lead to welfare and husbandry problems. Such problems may be minimised through an understanding of the links between stress and cognition. The effects of stress on cognitive function have been studied in disciplines ranging from human perceptual psychology to animal neuroscience. The aim of this paper is to provide an introduction to this research, focusing on the effects of stressors on attention, memory formation and memory recall. Findings from such a diverse literature with little apparent inter-disciplinary communication are inevitably complex and often contradictory. Nevertheless, some generalities do emerge. The idea that an inverted U-shaped relationship exists between an individual's state of stress or arousal and its ability to perform a cognitive task effectively, the so-called Yerkes-Dodson law, is commonly encountered. The law has limited explanatory value because it is unlikely that different stressors act on cognitive function via the same intervening, non-specific state. Furthermore, the law only provides a very general description of the relationship between stress and cognitive function. Empirical research on attention and memory processes reveals more specific findings. Stressors appear to cause shifts, lapses and narrowing of attention, and can also influence decision speed. These processes may be viewed as serving an adaptive role helping the animal to search for and scrutinise a source of danger. There is conflicting evidence as to whether hormones involved in the hypothalamic-pituitary-adrenal stress response play a part in these processes. These hormones and those involved in the sympathetic-adrenomedullary stress response do appear to play an important role in memory formation. Low or moderate concentrations of circulating glucocorticoids and catecholamines can enhance memory formation, while excessively high or prolonged elevations of these hormones can lead to memory disruption. The effects of stressors on memory recall are less clear. There is evidence for disruptive effects, and for facilitatory effects indicating state-dependent memory recall; events experienced under conditions of high arousal may be best recalled under similar conditions. Applied ethologists have the opportunity to extend work in this area, which often involves studies of single stressors/stress hormones acting in isolation and limited measures of cognitive function, by focusing on real-life husbandry stressors encountered by captive animals. This will yield fundamental information which also has direct relevance to animal welfare and management issues.

Abstract: A. Whiten, D. M. Custance, J.-C. Gomez, P. Teixidor, and K. A. Bard (1996) tested chimpanzees' (Pan troglodytes) and human children's (Homo sapiens) skills at imitation with a 2-action test on an “artificial fruit.” Chimpanzees imitated to a restricted degree; children were more thoroughly imitative. Such results prompted some to assert that the difference in imitation indicates a difference in the subjects' understanding of the intentions of the demonstrator (M. Tomasello, 1996). In this experiment, 37 adult human subjects were tested with the artificial fruit. Far from being perfect imitators, the adults were less imitative than the children. These results cast doubt on the inference from imitative performance to an ability to understand others' intentions. The results also demonstrate how any test of imitation requires a control group and attention to the level of behavioral analysis.

Abstract: Patterned string tasks are a test of perceptual capacity and the understanding of means-end connections. Primates can solve complex forms of this task in laboratories. However, this may not indicate the level of such cognition that is commonly employed in the wild, where decision-making time is often short and distractions such as predator avoidance and competition between conspecifics are often prevalent. The current study tests whether wild common marmosets (Callithrix jacchus) can successfully complete the simplest form of the patterned string task, parallel strings, while in their natural environment. Although 12 out of 13 marmosets could successfully complete the task, in previous laboratory-based studies on primates, the errors at this task by all primate species tested were consistently lower than in the present study. This is probably explained by the added difficulties imposed by the natural setting of the task in the present study, exemplified by a significant increase in observed vigilance behaviour by subject animals prior to attempts at the task that were unsuccessful. The undertaking of such tasks by common marmosets in situ probably provides a more reasonable representation of the levels of cognitive capacity expressed by this species in the wild than do laboratory-based studies of the task.

Abstract: The ability of animals to use behavioral/facial cues in detection of human attention has been widely investigated. In this test series we studied the ability of dogs to recognize human attention in different experimental situations (ball-fetching game, fetching objects on command, begging from humans). The attentional state of the humans was varied along two variables: (1) facing versus not facing the dog; (2) visible versus non-visible eyes. In the first set of experiments (fetching) the owners were told to take up different body positions (facing or not facing the dog) and to either cover or not cover their eyes with a blindfold. In the second set of experiments (begging) dogs had to choose between two eating humans based on either the visibility of the eyes or direction of the face. Our results show that the efficiency of dogs to discriminate between “attentive” and “inattentive” humans depended on the context of the test, but they could rely on the orientation of the body, the orientation of the head and the visibility of the eyes. With the exception of the fetching-game situation, they brought the object to the front of the human (even if he/she turned his/her back towards the dog), and preferentially begged from the facing (or seeing) human. There were also indications that dogs were sensitive to the visibility of the eyes because they showed increased hesitative behavior when approaching a blindfolded owner, and they also preferred to beg from the person with visible eyes. We conclude that dogs are able to rely on the same set of human facial cues for detection of attention, which form the behavioral basis of understanding attention in humans. Showing the ability of recognizing human attention across different situations dogs proved to be more flexible than chimpanzees investigated in similar circumstances.