Habitual prospective memory in preschool children

Habitual prospective memory (PM) refers to situations in which individuals have to remember to perform a future task on a regular and frequent basis. Habitual PM tasks are ubiquitous and the ability to successfully complete these tasks (e.g., remembering to bring your lunch to school every day) is necessary for children as they begin to establish their own independence. The current investigation is the first to explore preschool children's ability to complete this kind of task. At the end of a regular testing session during which children engaged in a variety of unrelated cognitive tasks, participants were instructed to ask for a stamp on their card, which was sitting in a box on the table. Over the course of the first experiment, participants did this 13 times, spanning a time period of several months. The results demonstrated that children initially needed prompting from the experimenter to remember, but with experience, participants were able to retrieve this intention without assistance. Experiment 2 demonstrated that removing the box from participants' line of sight after numerous opportunities to perform the task did not negatively impact performance, although it did make a difference at the outset of this requirement to remember to ask for stamps. Together, these results indicate that with somewhat consistent and repeated practice, preschool children can fairly quickly demonstrate the ability to successfully perform future intentions that are likely to be repeated on numerous occasions.

The evolution of quantitative sensitivity

The ability to represent approximate quantities appears to be phylogenetically widespread, but the selective pressures and proximate mechanisms favouring this ability remain unknown. We analysed quantity discrimination data from 672 subjects across 33 bird and mammal species, using a novel Bayesian model that combined phylogenetic regression with a model of number psychophysics and random effect components. This allowed us to combine data from 49 studies and calculate the Weber fraction (a measure of quantity representation precision) for each species. We then examined which cognitive, socioecological and biological factors were related to variance in Weber fraction. We found contributions of phylogeny to quantity discrimination performance across taxa. Of the neural, socioecological and general cognitive factors we tested, cortical neuron density and domain-general cognition were the strongest predictors of Weber fraction, controlling for phylogeny. Our study is a new demonstration of evolutionary constraints on cognition, as well as of a relation between species-specific neuron density and a particular cognitive ability.

This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.

Does Exposure to Animal Cognition Research Influence the Zoo Visitor Experience?

Zoos average about 183 million visitors per year, which makes them a major source for educating the public due to the diverse and wide-ranging demographic that visit. Zoos are increasingly a source of scientific research in a variety of subfields, including animal cognition, although much of this research takes place behind the scenes. Bringing this research to the public perspective has the potential to increase engagement of zoo visitors. However, it is not always possible to show live research, but videos have been found to be an effective educational approach in other domains. Here, we presented a brief video illustrating cognitive research involving sun bears at Zoo Atlanta to determine the potential effect on visitors. We measured several aspects of visitor behavior (stay time and actual behaviors in the exhibit), attitudes (towards both animal research and educational technology), and knowledge gained at the exhibit. We also presented a control video that focused on sun bear enrichment to tease out whether potential effects on visitors were related to the research focus of the video, or merely an effect of a video playing in the exhibit space. Visitor behavior, attitudes, and knowledge were determined by observing a randomly selected visitor’s behavior throughout their time in the exhibit space, and then requesting completion of a survey when they exited the exhibit (N = 148). We compared various aspects of behavior, attitudes, and knowledge across the Scientific Video, Enrichment Video, and No Video conditions. There were no differences between the Scientific Video and the Enrichment Video conditions; however, some differences were found between visitors who experienced a video during their visit (scientific or enrichment video) versus those who did not. Attitudes towards technology in the exhibit space were generally positive. There was also a significant correlation between visitor stay time (overall time spent in the exhibit space) and knowledge gained. Visitors learning about research in zoos remains important, but it is unclear if a video is a sufficient means to share that information.

Focality and prospective memory in preschool children

We examined the influence of prospective memory (PM) cue focality in a sample of preschool children. Prior investigations in older populations indicated that focal targets were associated with enhanced PM performance, perhaps through more automatic retrieval processes. Importantly, this influential variable has not been thoroughly explored in younger samples. Over three test sessions, preschool children completed a memory task where they were shown a series of animals. During retrieval, participants were shown all of the animals except for one, and they had to name the missing animal. While engaged in this task, participants in the focal PM condition were instructed to remove particular animals (e.g., spider) from the game if they saw them. In the nonfocal condition, participants were told to remove any animal that was entirely one color (e.g., black) if they saw them during the game. The results demonstrated no difference in PM remembering between focal and nonfocal conditions. These results suggest that the effects of focality may not be present at the beginning stages of PM development. The implications for PM retrieval processes also are discussed.

Performance of Asian elephants (Elephas maximus) on a quantity discrimination task is similar to that of African savanna elephants (Loxodonta africana)

Using an object-choice task, we measured the relative quantity discrimination ability of Asian elephants. Two zoo-housed elephants were given auditory cues of food being dropped into two containers (Nonvisible condition), and in one condition they could also see the food on top of the containers (Visible condition). Elephants received sets of varying ratios and magnitudes. We found that the elephants chose the greater quantity of food significantly above chance in both the Visible and Nonvisible conditions. Additionally, we found the elephants' ability to discriminate between quantities decreased as the ratio, and not the absolute difference, between the quantities increased, which is predicted by the accumulator model. We also compare our findings to those from a study using the same methods with African savanna elephants and found that the two species performed at similar levels, but given our small sample size it is difficult to make strong species-level conclusions. In discussing our results, we consider differences between the two species' wild environments as well as the types of sensory cues provided in human care, and we provide recommendations for extensions of this work.

Divide and Conquer

We assessed the ability of preschool children to assign the most difficult tasks to a symbolic helper. First, children were taught that a toy "helper" could aid them in remembering the location of a hidden item. Children preferentially assigned the helper to the objectively most difficult locations to remember. Each child then completed eight more tests, assessing a range of different skills such as counting, object identification, and word reading. Children again could assign some stimuli in each task to the helper, leaving the remaining stimuli for themselves to respond to in the given tasks. They were not explicitly told to assign the hardest stimulus to the helper. However, children consistently still did so in most tasks, although some tasks showed an effect of age where older children were more proficient in assigning the objectively more difficult stimuli to the helper. These results highlight a potential form of metacognition in young children in which they can monitor difficulty across varied kinds of assessments and use a generalized tool for asking for help that does not require verbal responding.

An Investigation of Prospective Memory with Output Monitoring in Preschool Children

The ability to perform an intended behavior in some future circumstance, known as prospective memory (PM), is an important cognitive ability for young children to develop. In this study, we examined PM in preschool children, with the addition of an output monitoring component, which is the ability to remember whether a previously intended action was completed. Participants were engaged in an ongoing task of sorting cards with a variety of images such as animals, tools, and foods by the size of pictures on the card. They were also instructed to sort any cards with animals into cardboard boxes marked as zoos. The first time any given animal was seen, it was to be placed in “Zoo 1,” and if the same animal was noticed again, it was to be placed in “Zoo 2.” Participants completed the task 3 times (each with different targets) on 3 separate days. Participants’ PM accuracy improved with practice. There was a relationship between age and PM performance on the first trial, with older children detecting more PM targets. This relationship was not present on the second and third trials, and a significant relationship between ongoing task errors and PM performance emerged, such that making fewer errors on the sorting task was associated with better PM performance. Regarding output monitoring errors, children most frequently placed both occurrences of the same PM target in the first zoo.

Working memory in children assessed with serial chaining and Simon tasks

In the serial chaining task, participants are required to produce a sequence of responses to stimuli in the correct order, and sometimes must determine the sequence at trial outset if stimuli are masked after the first response is made. Similarly, the Simon memory span task presents a participant with a sequence of colors, and the participant must recreate the sequence after the full series is shown. In efforts to directly link the comparative literature on sequential planning behavior and working memory span with the developmental literature, we presented preschool children with the serial chaining task using masked Arabic numerals (N = 44) and the Simon memory span task (N = 65). Older children outperformed younger children in each task, sequencing a longer string of numbers in the serial chaining task and remembering a greater number of items in the Simon task. Controlling for the role of age, there was a significant positive relationship between task scores. These results highlight the emergence of working memory skills that might underlie planning capacities in children using a task developed for nonhuman animals, and the results indicate that improvement in general executive functions could be measured using either or both of these tasks among human children and nonhuman species.

Chimpanzees show some evidence of selectively acquiring information by using tools, making inferences, and evaluating possible outcomes

Metacognition refers to thinking about one's thinking or knowing what one knows. Research suggests that this ability is not unique to humans and may be shared with nonhuman animals. In particular, great apes have shown behaviors on a variety of tasks that are suggestive of metacognitive ability. Here we combine a metacognitive task, the information-seeking task, with tool use and variable forms of initial information provided to chimpanzees to explore how informational states impact behavioral responses in these apes. Three chimpanzees were presented with an apparatus that contained five locations where food could be hidden. If they pointed to the correct location, they received the reward, but otherwise they did not. We first replicated several existing findings using this method, and then tested novel hypotheses. The chimpanzees were given different types of information across the experiments. Sometimes, they were shown the location of the food reward. Other times, they were shown only one empty location, which was not useful information. The chimpanzees also could use a tool to search any of those locations before making a selection. Chimpanzees typically used the tool to search out the location of the reward when they could not already know where it was, but they did not use the tool when they already had been given that information. One chimpanzee made inferences about the location of hidden food, even when that food was never shown in that location. The final experiment involved hiding foods of differing preference values, and then presenting the chimpanzees with different initial knowledge states (i.e., where the best food was located, where the less-preferred food was located, or where no food was located). All chimpanzees used the tool when they needed to use it to find the best possible item on that trial, but responded by choosing a location immediately when they did not need the tool. This finding highlights that their behavior was not the result of a simple rule following such as pointing to where any food had been seen.

Assessing Distinctiveness Effects and “False Memories” in Chimpanzees (Pan troglodytes)

There are many parallels between human and nonhuman animal cognitive abilities, suggesting an evolutionary basis for many forms of cognition, including memory. For instance, past research found that two chimpanzees exhibited an isolation effect, or improved memory for semantically distinctive items on a list (Beran, 2011). These results support the notion that chimpanzees are capable of semantic, relational processing in memory, and introduce the possibility that other effects observed in humans, such as distinctiveness effects or false memories, may be present in nonhuman species. The Deese-Roediger-McDermott (DRM) paradigm is a commonly used task to explore these phenomena, and it was adapted for use with chimpanzees. We tested four chimpanzees for isolation effects during encoding, distinctiveness effects during recognition, and potential “false memories” generated by the DRM paradigm by presenting a serial recognition memory task. The isolation effect previously reported (Beran, 2011) was not replicated in this experiment. Two of four chimpanzees showed improved recognition performance when information about distinctiveness could be used to exclude incorrect responses. None of the chimpanzees were significantly impaired in the “false memory” condition. However, limitations to this approach are discussed that require caution about assuming identical memory processes in these chimpanzees and in humans.

Duane Rumbaugh’s Influence on the Science and Practice of Animal Welfare

Duane Rumbaugh’s influence on the field of comparative psychology will be long lasting and far reaching. He is best known for his continuing influence on the field of primate cognition, but his work and that of his mentees has branched out into other domains as well. Here we will focus specifically on his influence on the field of animal welfare and how place or location has shaped those influences. In our narrative, we will describe how different people with different perspectives interfaced over the decades by virtue of sharing space. We will reflect on a range of physical spaces: field versus wild, different cities or geographical locations, laboratory versus zoo, and actual versus virtual. Geographic location, indirectly and/or directly, will shape the interactions among scientists and their perspectives and values. In particular we will focus on how developments in the 20th Century in San Diego and Atlanta shaped the primate research community in both laboratories and zoos. We will provide the historical context and development of perspectives that have forever altered how we think of and co-exist with great apes. These interactions have yielded positive and strong connections between people that ultimately influence our understanding of and treatment of animal welfare.

Primate cognition: attention, episodic memory, prospective memory, self-control, and metacognition as examples of cognitive control in nonhuman primates

Primate Cognition is the study of cognitive processes, which represent internal mental processes involved in discriminations, decisions, and behaviors of humans and other primate species. Cognitive control involves executive and regulatory processes that allocate attention, manipulate and evaluate available information (and, when necessary, seek additional information), remember past experiences to plan future behaviors, and deal with distraction and impulsivity when they are threats to goal achievement. Areas of research that relate to cognitive control as it is assessed across species include executive attention, episodic memory, prospective memory, metacognition, and self-control. Executive attention refers to the ability to control what sensory stimuli one attends to and how one regulates responses to those stimuli, especially in cases of conflict. Episodic memory refers to memory for personally experienced, autobiographical events. Prospective memory refers to the formation and implementation of future-intended actions, such as remembering what needs to be done later. Metacognition consists of control and monitoring processes that allow individuals to assess what information they have and what information they still need, and then if necessary to seek information. Self-control is a regulatory process whereby individuals forego more immediate or easier to obtain rewards for more delayed or harder to obtain rewards that are objectively more valuable. The behavioral complexity shown by nonhuman primates when given tests to assess these capacities indicates psychological continuities with human cognitive control capacities. However, more research is needed to clarify the proper interpretation of these behaviors with regard to possible cognitive constructs that may underlie such behaviors. WIREs Cogn Sci 2016, 7:294-316. doi: 10.1002/wcs.1397 For further resources related to this article, please visit the WIREs website.

Self-control assessments of capuchin monkeys with the rotating tray task and the accumulation task

Recent studies of delay of gratification in capuchin monkeys using a rotating tray (RT) task have shown improved self-control performance in these animals in comparison to the accumulation (AC) task. In this study, we investigated whether this improvement resulted from the difference in methods between the rotating tray task and previous tests, or whether it was the result of greater overall experience with delay of gratification tasks. Experiment 1 produced similar performance levels by capuchins monkeys in the RT and AC tasks when identical reward and temporal parameters were used. Experiment 2 demonstrated a similar result using reward amounts that were more similar to previous AC experiments with these monkeys. In Experiment 3, monkeys performed multiple versions of the AC task with varied reward and temporal parameters. Their self-control behavior was found to be dependent on the overall delay to reward consumption, rather than the overall reward amount ultimately consumed. These findings indicate that these capuchin monkeys' self-control capacities were more likely to have improved across studies because of the greater experience they had with delay of gratification tasks. Experiment 4 and Experiment 5 tested new, task-naïve monkeys on both tasks, finding more limited evidence of self-control, and no evidence that one task was more beneficial than the other in promoting self-control. The results of this study suggest that future testing of this kind should focus on temporal parameters and reward magnitude parameters to establish accurate measures of delay of gratification capacity and development in this species and perhaps others.

Giant Panda Maternal Care: A Test of the Experience Constraint Hypothesis

The body condition constraint and the experience condition constraint hypotheses have both been proposed to account for differences in reproductive success between multiparous (experienced) and primiparous (first-time) mothers. However, because primiparous mothers are typically characterized by both inferior body condition and lack of experience when compared to multiparous mothers, interpreting experience related differences in maternal care as support for either the body condition constraint hypothesis or the experience constraint hypothesis is extremely difficult. Here, we examined maternal behaviour in captive giant pandas, allowing us to simultaneously control for body condition and provide a rigorous test of the experience constraint hypothesis in this endangered animal. We found that multiparous mothers spent more time engaged in key maternal behaviours (nursing, grooming, and holding cubs) and had significantly less vocal cubs than primiparous mothers. This study provides the first evidence supporting the experience constraint hypothesis in the order Carnivora, and may have utility for captive breeding programs in which it is important to monitor the welfare of this species' highly altricial cubs, whose survival is almost entirely dependent on receiving adequate maternal care during the first few weeks of life.

Capuchin monkeys (Cebus apella) modulate their use of an uncertainty response depending on risk

Metacognition refers to thinking about thinking, and there has been a great deal of interest in how this ability manifests across primates. Based on much of the work to date, a tentative division has been drawn with New World monkeys on 1 side and Old World monkeys and apes on the other. Specifically, Old World monkeys, apes, and humans often show patterns reflecting metacognition, but New World monkeys typically do not, or show less convincing behavioral patterns. However, recent data suggest that this difference may relate to other aspects of some experimental tasks. For example, 1 possibility is that risk tolerance affects how capuchin monkeys, a New World primate species, tend to perform. Specifically, it has recently been argued that on tasks in which there are 2 or 3 options, the "risk" of guessing is tolerable for capuchins because there is a high probability of being correct even if they "know they do not know" or feel something akin to uncertainty. The current study investigated this possibility by manipulating the degree of risk (2-choices vs. 6-choices) and found that capuchin monkeys used the uncertainty response more on 6-choice trials than on 2-choice trials. We also found that rate of reward does not appear to underlie these patterns of performance, and propose that the degree of risk is modulating capuchin monkeys' use of the uncertainty response. Thus, the apparent differences between New and Old World monkeys in metacognition may reflect differences in risk tolerance rather than access to metacognitive states.

The elusive illusion: Do children (Homo sapiens) and capuchin monkeys (Cebus apella) see the Solitaire illusion?

One approach to gaining a better understanding of how we perceive the world is to assess the errors that human and nonhuman animals make in perceptual processing. Developmental and comparative perspectives can contribute to identifying the mechanisms that underlie systematic perceptual errors often referred to as perceptual illusions. In the visual domain, some illusions appear to remain constant across the lifespan, whereas others change with age. From a comparative perspective, many of the illusions observed in humans appear to be shared with nonhuman primates. Numerosity illusions are a subset of visual illusions and occur when the spatial arrangement of stimuli within a set influences the perception of quantity. Previous research has found one such illusion that readily occurs in human adults, the Solitaire illusion. This illusion appears to be less robust in two monkey species, rhesus macaques and capuchin monkeys. We attempted to clarify the ontogeny of this illusion from a developmental and comparative perspective by testing human children and task-naïve capuchin monkeys in a computerized quantity judgment task. The overall performance of the monkeys suggested that they perceived the numerosity illusion, although there were large differences among individuals. Younger children performed similarly to the monkeys, whereas older children more consistently perceived the illusion. These findings suggest that human-unique perceptual experiences with the world might play an important role in the emergence of the Solitaire illusion in human adults, although other factors also may contribute.

Go when you know: Chimpanzees' confidence movements reflect their responses in a computerized memory task

Three chimpanzees performed a computerized memory task in which auditory feedback about the accuracy of each response was delayed. The delivery of food rewards for correct responses also was delayed and occurred in a separate location from the response. Crucially, if the chimpanzees did not move to the reward-delivery site before food was dispensed, the reward was lost and could not be recovered. Chimpanzees were significantly more likely to move to the dispenser on trials they had completed correctly than on those they had completed incorrectly, and these movements occurred before any external feedback about the outcome of their responses. Thus, chimpanzees moved (or not) on the basis of their confidence in their responses, and these confidence movements aligned closely with objective task performance. These untrained, spontaneous confidence judgments demonstrated that chimpanzees monitored their own states of knowing and not knowing and adjusted their behavior accordingly.

Waiting for what comes later: capuchin monkeys show self-control even for nonvisible delayed rewards

Self-control tasks used with nonhuman animals typically involve the choice between an immediate option and a delayed, but more preferred option. However, in many self-control scenarios, not only does the more impulsive option come sooner in time, it is often more concrete than the delayed option. For example, studies have presented children with the option of eating a visible marshmallow immediately, or foregoing it for a better reward that can only be seen later. Thus, the immediately available option is visible and concrete, whereas the delayed option is not visible and more abstract. We tested eight capuchin monkeys to better understand this potential effect by manipulating the visibility of the response options and the visibility of the baiting itself. Monkeys observed two food items (20 or 5 g pieces of banana) each being placed either on top of or inside of one of the two opaque containers attached to a revolving tray apparatus, either in full view of monkeys or occluded by a barrier. Trials ended when monkeys removed a reward from the rotating tray. To demonstrate self-control, monkeys should have allowed the smaller piece of food to pass if the larger piece was forthcoming. Overall, monkeys were successful on the task, allowing a smaller, visible piece of banana to pass from reach in order to access the larger, nonvisible banana piece. This was true even when the entire baiting process took place out of sight of the monkeys. This finding suggests that capuchin monkeys succeed on self-control tasks even when the delayed option is also more abstract than the immediate one-a situation likely faced by primates in everyday life.

Looking ahead? Computerized maze task performance by chimpanzees (Pan troglodytes), rhesus monkeys (Macaca mulatta), capuchin monkeys (Cebus apella), and human children (Homo sapiens)

Human and nonhuman primates are not mentally constrained to the present. They can remember the past and-at least to an extent-anticipate the future. Anticipation of the future ranges from long-term prospection such as planning for retirement to more short-term future-oriented cognition such as planning a route through a maze. Here we tested a great ape species (chimpanzees), an Old World monkey species (rhesus macaques), a New World monkey species (capuchin monkeys), and human children on a computerized maze task. All subjects had to move a cursor through a maze to reach a goal at the bottom of the screen. For best performance on the task, subjects had to "plan ahead" to the end of the maze to move the cursor in the correct direction, avoid traps, and reverse directions if necessary. Mazes varied in difficulty. Chimpanzees were better than both monkey species, and monkeys showed a particular deficit when moving away from the goal or changing directions was required. Children showed a similar pattern to monkeys regarding the effects of reversals and moves away from the goal, but their overall performance in terms of correct maze completion was similar to the chimpanzees. The results highlight similarities as well as differences in planning across species and the role that inhibitory control may play in future-oriented cognition in primates.

Exploring Potential Mechanisms Underlying the Lack of Uncertainty Monitoring in Capuchin Monkeys

In a widely used animal-metacognition paradigm, monkeys are positively reinforced with food for correct classifications of stimuli as sparse or dense and punished with timeouts for incorrect responses, but they also have access to an "uncertainty" response that moves them to the next trial without either of these forms of feedback. Rhesus monkeys use this uncertainty response most often for trials on which they are at greatest risk for making an error, suggesting that they are monitoring their ability to make these classifications. Capuchin monkeys do not succeed to the same degree on these tasks-conceivably as a result of differential contingencies in place in all existing studies between the sparse/dense responses (food delivery or timeout) and the uncertainty response (avoidance of a timeout but also no chance for food reward). Here, we used a novel variation of this task in which the outcomes of the three response classes (sparse, dense, uncertain) were functionally equivalent. All responses simply determined the delay interval before presentation of a second task (matching-to-sample), and that task yielded potential food rewards. Overall, capuchin monkeys used the dense and sparse responses appropriately, including some animals that had no prior experience in performing this classification task. However, none used the uncertainty response appropriately even when it was placed on the same contingency plane as the dense and sparse responses. This suggests that the failure of capuchin monkeys to use an uncertainty response is not the result of that response producing a qualitatively different outcome compared to the dense and sparse responses.

Exploring Potential Mechanisms Underlying the Lack of Uncertainty Monitoring in Capuchin Monkeys

In a widely used animal-metacognition paradigm, monkeys are positively reinforced with food for correct classifications of stimuli as sparse or dense and punished with timeouts for incorrect responses, but they also have access to an “uncertainty” response that moves them to the next trial without either of these forms of feedback. Rhesus monkeys use this uncertainty response most often for trials on which they are at greatest risk for making an error, suggesting that they are monitoring their ability to make these classifications. Capuchin monkeys do not succeed to the same degree on these tasks—conceivably as a result of differential contingencies in place between the sparse/dense responses (food delivery or timeout) and the uncertainty response (avoidance of a timeout but also no chance for food reward). Here, we used a novel variation of this task in which the outcomes of the three response classes (sparse, dense, uncertain) were functionally equivalent. All responses simply determined the delay interval before presentation of a second task (matching-to-sample), and that task yielded potential food rewards. Overall, capuchin monkeys used the dense and sparse responses appropriately, including some animals that had no prior experience in performing this classification task. However, none used the uncertainty response appropriately even when it was placed on the same contingency plane as the dense and sparse responses. This suggests that the failure of capuchin monkeys to use an uncertainty response is not the result of that response producing a qualitatively different outcome compared to the dense and sparse responses.

Cashing out: The decisional flexibility of uncertainty responses in rhesus macaques (Macaca mulatta) and humans (Homo sapiens)

Researchers are exploring whether animals share with humans something like a metacognitive capacity. Though some results point to human-animal continuities in this domain, they face the dominant criticism that animals' performances might be associative. A persistent problem is that animal-metacognition paradigms present static environments of risk and reward that may foster inflexible and conditioned responding. Those environments do not challenge animals to show the flexibility in their decision strategies that could indicate an antecedent capacity to metacognition. Accordingly, we tested macaques and humans on an uncertainty-monitoring paradigm in which risk changed dynamically. Participants classified stimuli of different difficulties while also choosing when to use a cashout response to collect the accumulated rewards that would be forfeit on a discrimination error. Macaques (Macaca mulatta) and humans flexibly adjusted their decision criteria to achieve appropriate protection against the cost of error that could differ depending on trial difficulty and the number of rewards at risk. In particular, monkeys widened their cashout-response region as their accumulated rewards increased, providing more protection against a more costly error. These findings demonstrate a new continuity between humans' and animals' uncertainty systems. They reveal a calibration by macaques of present risk to trial difficulty tolerated. They show that animals' uncertainty-monitoring and risk-management systems have substantial trial-by-trial flexibility.

Double invisible displacement understanding in orangutans: testing in non-locomotor and locomotor space

The nonadjacent double invisible displacement task has been used to test for the ability of different species to mentally represent the unperceived trajectory of an object. The task typically requires three occluders/boxes in a linear array and involves hiding an object in one of two nonadjacent boxes visited in succession. Previous research indicates that 19-, 26-, and 30-month-old children and various nonhuman species cannot solve these displacements. It has been hypothesized that this is because individuals are unable to inhibit searching in the unbaited center box that was never visited by the experimenter. It has been suggested that presenting the task in a large-scale locomotor space might allow individuals to overcome this inhibition problem. In the present study, we tested orangutans on adjacent and nonadjacent double invisible displacements with the traditional setup (experiment 1) and in locomotor space with boxes placed 1.22 m apart (experiment 2). In both experiments, subjects were able to solve adjacent, but not nonadjacent, trials. The failure on nonadjacent trials appeared to be because of an inability to inhibit sequential search on the second choice as well as because of a large number of first-choice errors (directly choosing an incorrect box). The current results support previous findings that orangutans exhibit some constraints when representing the invisible trajectory of objects.

What are my chances? Closing the gap in uncertainty monitoring between rhesus monkeys (Macaca mulatta) and capuchin monkeys (Cebus apella)

Previous studies have indicated that rhesus monkeys (Macaca mulatta) but not capuchin monkeys (Cebus apella) respond to difficult or ambiguous situations by choosing not to respond or by seeking more information. Here we assessed whether a task with very low chance accuracy could diminish this species difference, presumably indicating that capuchins—compared to macaques—are less risk averse as opposed to less sensitive to signals of uncertainty. Monkeys searched for the largest of 6 stimuli on a computer screen. Trial difficulty was varied, and monkeys could choose to opt out of any trial. All rhesus monkeys, including some with no prior use of the uncertainty response, selectively avoided the most difficult trials. The majority of capuchins sometimes made uncertainty responses, but at lower rates than rhesus monkeys. Nonetheless, the presence of some adaptive uncertainty responding suggests that capuchins also experience uncertainty and can respond to it, though with less proficiency than macaque monkeys.

Working and waiting for better rewards: self-control in two monkey species (Cebus apella and Macaca mulatta)

Self-control is typically defined as choosing a greater, delayed reward over a lesser, more immediate reward. However, in nature, there are other costs besides delay associated with obtaining the greatest outcome including increased effort, potential punishment, and low probability of reward. Effort is an interesting case because it sometimes impairs self-control, by acting as an additional cost, and at other times facilitates self-control, by distracting one from impulsive options. Additionally, different species may perform differently in effortful self-control tasks, based on their natural ecology. To gain insight into these aspects of self-control behavior, we examined capuchin monkeys' and rhesus monkeys' self-control in separate working and waiting choice tasks. We hypothesized that capuchins would show greater self-control in the working task, given their naturally higher activity level, whereas rhesus would perform similarly in both tasks. Rhesus performed as predicted, whereas contrary to our hypothesis, capuchins exhibited lesser performance in the working task. Nonetheless, these results may still stem from inherent species differences interacting with details of the methodology. Capuchins, being highly energetic and social monkeys, may have divided their energy and attention between the working task and other elements of the test environment such as visible group mates or manipulanda.

Comparative Cognition: Past, Present, and Future

Comparative cognition is the field of inquiry concerned with understanding the cognitive abilities and mechanisms that are evident in nonhuman species. Assessments of animal cognition have a long history, but in recent years there has been an explosion of new research topics, and a general broadening of the phylogenetic map of animal cognition. To review the past of comparative cognition, we describe the historical trends. In regards to the present state, we examine current "hot topics" in comparative cognition. Finally, we offer our unique and combined thoughts on the future of the field.

Comparative Cognition: Past, Present, and Future

Comparative cognition is the field of inquiry concerned with understanding the cognitive abilities and mechanisms that are evident in nonhuman species. Assessments of animal cognition have a long history, but in recent years there has been an explosion of new research topics, and a general broadening of the phylogenetic map of animal cognition. To review the past of comparative cognition, we describe the historical trends. In regards to the present state, we examine current “hot topics” in comparative cognition. Finally, we offer our unique and combined thoughts on the future of the field.

Language-trained chimpanzees (Pan troglodytes) name what they have seen but look first at what they have not seen

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 3 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. The chimpanzees could either report the identity of the food immediately or first check a container in which the food had been hidden. In two experiments, the chimpanzees were significantly more likely to visit the container first on trials in which they could not know its contents but were more likely to just name the food item without looking into the container on trials in which they had seen its contents. 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.

Chimpanzees (Pan troglodytes) transfer tokens repeatedly with a partner to accumulate rewards in a self-control task

There has been extensive research investigating self-control in humans and nonhuman animals, yet we know surprisingly little about how one's social environment influences self-control. The present study examined the self-control of chimpanzees in a task that required active engagement with conspecifics. The task consisted of transferring a token back and forth with a partner animal in order to accumulate food rewards, one item per token transfer. Self-control was required because at any point in the trial, either chimpanzee could obtain their accumulated rewards, but doing so discontinued the food accumulation and ended the trial for both individuals. Chimpanzees readily engaged the task and accumulated the majority of available rewards before ending each trial, and they did so across a number of conditions that varied the identity of the partner, the presence/absence of the experimenter, and the means by which they could obtain rewards. A second experiment examined chimpanzees' self-control when given the choice between immediately available food items and a potentially larger amount of rewards that could be obtained by engaging the token transfer task with a partner. Chimpanzees were flexible in their decision-making in this test, typically choosing the option representing the largest amount of food, even if it involved delayed accumulation of the rewards via the token transfer task. These results demonstrate that chimpanzees can exhibit self-control in situations involving social interactions, and they encourage further research into this important aspect of the self-control scenario.

Can black-and-white ruffed lemurs (Varecia variegata) solve object permanence tasks?

We examined object permanence in black-and-white-ruffed lemurs (Varecia variegata) at Zoo Atlanta. A series of visible and invisible displacement tasks with suitable controls were presented to five adult subjects. Subjects performed significantly above chance on all regular tasks, except for the double invisible displacements. Subjects failed visible and invisible controls. Failure on the control trials did not appear to be because subjects used the "last box touched" strategy (subjects did not choose the last box touched significantly more than expected by chance). However, a substantial percentage of choices was made to the last box touched by the experimenter. There was no significant difference between this percentage, and the percentage of choices made to the baited box (on both visible and invisible controls), which indicates that subjects were drawn to both boxes which the experimenter visited/touched, and thus failed the controls. Based on the results from the present study, we believe that there is no evidence that black-and-white ruffed lemurs understand visible and invisible tasks in the traditional object permanence battery.

Cognitive Research in Asian Small-Clawed Otters

Little research has been conducted on cognitive abilities in Asian small-clawed otters (Aonyx cinereus) despite behavioral and social characteristics which suggest that this species would perform well on cognitive tasks and are likely to provide relevant data for comparison to other taxa. Asian small-clawed otters are relatively long-lived and have complex social systems that t involve cooperative breeding, paternal care and reproductive suppression. These life-history characteristics have been associated with highly intelligent behavior, yet little is known about the cognitive abilities of this species. The current study explored spatial memory in Asian small-clawed otters using a modification of the radial arm maze. Performance on all measures improved significantly across sessions. These results provide evidence that Asian small-clawed otters have spatial memory for food locations and illustrate the potential for cognitive testing with this species.

Do Social Conditions Affect Capuchin Monkeys' (Cebus apella) Choices in a Quantity Judgment Task?

Beran et al. (2012) reported that capuchin monkeys closely matched the performance of humans in a quantity judgment test in which information was incomplete but a judgment still had to be made. In each test session, subjects first made quantity judgments between two known options. Then, they made choices where only one option was visible. Both humans and capuchin monkeys were guided by past outcomes, as they shifted from selecting a known option to selecting an unknown option at the point at which the known option went from being more than the average rate of return to less than the average rate of return from earlier choices in the test session. Here, we expanded this assessment of what guides quantity judgment choice behavior in the face of incomplete information to include manipulations to the unselected quantity. We manipulated the unchosen set in two ways: first, we showed the monkeys what they did not get (the unchosen set), anticipating that "losses" would weigh heavily on subsequent trials in which the same known quantity was presented. Second, we sometimes gave the unchosen set to another monkey, anticipating that this social manipulation might influence the risk-taking responses of the focal monkey when faced with incomplete information. However, neither manipulation caused difficulty for the monkeys who instead continued to use the rational strategy of choosing known sets when they were as large as or larger than the average rate of return in the session, and choosing the unknown (riskier) set when the known set was not sufficiently large. As in past experiments, this was true across a variety of daily ranges of quantities, indicating that monkeys were not using some absolute quantity as a threshold for selecting (or not) the known set, but instead continued to use the daily average rate of return to determine when to choose the known versus the unknown quantity.

Capuchin monkeys (Cebus apella) let lesser rewards pass them by to get better rewards

Self-control is defined as foregoing an immediate reward to gain a larger delayed reward. Methods used to test self-control comparatively include inter-temporal 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 toward 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.

Prospective Memory in a Language-Trained Chimpanzee (Pan troglodytes)

Prospective memory involves the encoding, retention, and implementation of an intended future action. Although humans show many forms of prospective memory, less is known about the future oriented processes of nonhuman animals, or their ability to use prospective memory. In this experiment, a chimpanzee named Panzee, who had learned to associate geometric forms called lexigrams with real-world referents, was given a prospective memory test. Panzee selected between two foods the one she wanted to receive more immediately. That food was scattered in an outdoor yard where she could forage for it. Also outdoors were lexigram tokens, one of which represented the food item that remained indoors throughout a 30 minute period, and that could be obtained if Panzee brought in the token that matched that food item. After foraging for the selected food item, Panzee consistently remembered to retrieve and return the correct token when food was available indoors, whereas on control trials involving no indoor food she rarely returned a token. This indicated that Panzee encoded information relevant to the future action of token retrieval after extended delays for one type of food, even when a more immediately preferred food was available.

How is chimpanzee self-control influenced by social setting?

Self-control is often required in natural situations involving interactions with other individuals, and personal self-control can be compromised if other individuals act impulsively. In this study, we tested self-control in pairs of chimpanzees in a variety of settings where at least one chimpanzee of each pair performed an established test for self-control in which candies accumulated one at time as long as the chimpanzee did not eat any of them. When tested alone, some chimpanzees exhibited greater self-control as compared to when tested alongside a chimpanzee that independently performed the same type of test. However, when the nonfocal animal freely consumed rewards while the focal chimpanzee performed the accumulation task, the self-control of some focal chimpanzees was elevated as compared to when working alone. Finally, when the focal and nonfocal animals worked jointly on the same test and the number of rewards accumulated was dependent on both animals' continued ability to inhibit eating the items, chimpanzees performed the same when housed together or in adjacent enclosures. On the whole, the effects of social setting were modest, but these results may relate to the literature on vicarious depletion of self-control, and they present interesting avenues for future research.

Behavioral and hormonal consequences of transporting giant pandas from China to the United States

Zoological institutions strive to ensure the welfare of nonhuman animals in captivity. Part of this effort involves reducing the level of distress experienced by an animal to the greatest extent possible. However, some necessary zoo management practices such as transportation induce stress responses. An extensive literature exists concerning the animal welfare implications of road transportation for farm and laboratory animals. There has, however, been little focus on the effects of air transportation on wild animals in captivity. Because many endangered species are transported by air for breeding purposes, it is especially important to study the effects of stress on these species. This study investigated the behavioral and hormonal consequences of transporting 4 giant pandas (2 male-female pairs) by air from China to the United States. An autoregressive test revealed that urinary cortisol measures were highest for 2 subjects, Lun Lun and Tian Tian, during the flight than during the remainder of the 30-day period posttransport (p < .01). No long-term behavioral changes or problems emerged as a result of the transport. The study found that more research is needed to develop a complete understanding of transportation stress and welfare in captive wildlife.

Technology at the zoo: the influence of a touchscreen computer on orangutans and zoo visitors

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.

Sex differences in spatial ability: a test of the range size hypothesis in the order Carnivora

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.

The use of technology to enhance zoological parks

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.

Factors affecting aggression in a captive flock of Chilean flamingos (Phoenicopterus chilensis)

The influence of pair bond status, age and sex on aggression rates in a flock of 84 captive Chilean flamingos at Zoo Atlanta was examined. Analysis showed no difference between aggression rates of male and female flamingos, but adult flamingos had higher rates of aggression than juveniles. There were also significant differences in aggression depending on pair bond status (single, same-sex pair, male-female pair or group). Bonded birds were significantly more aggressive than single birds, which is consistent with the concept that unpaired birds are not breeding and do not need to protect pair bonds or eggs. Birds in typical pair bonds (male-female) and atypical pair bonds (same-sex pairs or groups) exhibited similar rates of aggression. These results contribute to the existing body of research on aggression in captive flamingos.