No abstract

A computer-controlled touchscreen apparatus (hereafter referred to as "touchscreen") in the orangutan exhibit at Zoo Atlanta provides enrichment to the animals and allows cognitive research to take place on exhibit. This study investigated the impact of the touchscreen on orangutan behavior and visibility, as well as its impact on zoo visitors. Despite previous research suggesting that providing a single computer system may negatively affect orangutan behavior, there was not a significant increase in aggression, stereotypic, or distress-related behaviors following the activation of the on-exhibit touchscreen. We also investigated the possibility that zoo visitors may be negatively affected by technology because it deviates from naturalism. However, we did not find a change in stay time or overall experience rating when the computer was turned on. This research was the first to assess visitor attitudes toward technology at the zoo, and we found that visitors report highly positive attitudes about technology for both animals and visitors. If subjects visited the exhibit when the computer was turned on, they more strongly agreed that orangutans benefit from interacting with computerized enrichment. This study is the first investigation of an on-exhibit touchscreen in group-housed apes; our findings of no negative effects on the animals or zoo visitors and positive attitudes toward technology suggest a significant value of this practice.

The ability to discriminate between quantities has been observed in many species. Typically, when an animal is given a choice between two sets of food, accurate performance (i.e., choosing the larger amount) decreases as the ratio between two quantities increases. A recent study reported that elephants did not exhibit ratio effects, suggesting that elephants may process quantitative information in a qualitatively different way from all other nonhuman species that have been tested (Irie-Sugimoto et al. in Anim Cogn 12:193-199, 2009). However, the results of this study were confounded by several methodological issues. We tested two African elephants (Loxodonta africana) to more thoroughly investigate relative quantity judgment in this species. In contrast to the previous study, we found evidence of ratio effects for visible and nonvisible sequentially presented sets of food. Thus, elephants appear to represent and compare quantities in much the same way as other species, including humans when they are prevented from counting. Performance supports an accumulator model in which quantities are represented as analog magnitudes. Furthermore, we found no effect of absolute magnitude on performance, providing support against an object-file model explanation of quantity judgment.

Self-control is defined as foregoing an immediate reward to gain a larger delayed reward. Methods used to test self-control comparatively include intertemporal choice tasks, delay of gratification tasks, and accumulation tasks. To date, capuchin monkeys have shown different levels of self-control across tasks. This study introduced a new task that could be used comparatively to measure self-control in an intuitive context that involved responses that required no explicit training. Capuchin monkeys (Cebus apella) were given a choice between two food items that were presented on a mechanized, revolving tray that moved those foods sequentially towards the monkeys. A monkey could grab the first item or wait for the second, but was only allowed one item. Most monkeys in the study waited for a more highly preferred food item or a larger amount of the same food item when those came later, and they inhibited the prepotent response to grab food by not reaching out to take less preferred foods or smaller amounts of food that passed directly in front of them first. These data confirm that the mechanisms necessary for self-control are present in capuchin monkeys, and indicate that the methodology can be useful for broader comparative assessments of self-control.

Metacognition can be defined as knowing what one knows, and the question of whether nonhuman animals are metacognitive has driven an intense debate. We tested three language-trained chimpanzees in an information-seeking task in which the identity of a food item was the critical piece of information needed to obtain the food. In two experiments, the chimpanzees were significantly more likely to visit a container first on trials in which they could not know its contents but were more likely to just name the item without looking into the container on trials in which they had earlier seen the contents of that container. Thus, chimpanzees showed efficient information-seeking behavior that suggested they knew what they had or had not already seen when it was time to name a hidden item.

Technology can be used in a zoological setting to improve visitor experience, increase research opportunities, and enhance animal welfare. Evaluating the quality of these technological innovations and their use by nonhuman and human counterparts is a critical part of extending the uses of technology to enhance animal welfare and visitor experience at zoological parks. Survey data from a small sample of institutions housing primates suggest that computers, television, radio, and sprinklers are the most prevalent types of technological enrichment currently used. Survey respondents were positive about the technology implemented, stating a desire to increase its use.

Sex differences in spatial cognition have been reported for many species ranging from voles to humans. The range size hypothesis predicts that sex differences in spatial ability will only occur in species in which the mating system selects for differential range size. Consistent with this prediction, we observed sex differences in spatial ability in giant pandas, a promiscuous species in which males inhabit larger ranges than females, but did not observe sex differences in Asian small-clawed otters, a related monogamous species in which males and females share home ranges. These results provide the first evidence of sex differences in spatial ability in the order Carnivora, and are consistent with the range size hypothesis.

Life history is influenced by factors both intrinsic (e.g., body and relative brain size) and extrinsic (e.g., diet, environmental instability) to organisms. In this study, we examine the prediction that energetic risk influences the life history of gorillas. Recent comparisons suggest that the more frugivorous western lowland gorilla shows increased infant dependence, and thus a slower life history, than the primarily folivorous mountain gorilla to buffer against the risk of starvation during periods of food unpredictability. We further tested this hypothesis by incorporating additional life history data from wild western lowland gorillas and captive western lowland gorillas with the assumption that the latter live under ecological conditions of energetic risk that more closely resemble those of mountain gorillas and thus should show faster life histories than wild members of the species. Overall, we found captive western lowland and wild mountain gorillas to have faster developmental life histories than wild western lowland gorillas, weaning their infants approximately a year earlier and thus reducing interbirth intervals by a year. These results provide support that energetic risk plays an important role in determining gorilla life history. Unlike previous assertions, gorillas do not have substantially faster life histories, at least at the genus level, than other great apes. This calls for a re-evaluation of theories concerning comparative ape life history and evolution and highlights the need for data from additional populations that vary in energetic risk.