Flexibility in problem solving and tool use of kea and New Caledonian crows in a multi access box paradigm

Does invasion success reflect superior cognitive ability? A case study of two congeneric lizard species (Lampropholis, Scincidae)

A species' intelligence may reliably predict its invasive potential. If this is true, then we might expect invasive species to be better at learning novel tasks than non-invasive congeners. To test this hypothesis, we exposed two sympatric species of Australian scincid lizards, Lampropholis delicata (invasive) and L. guichenoti (non-invasive) to standardized maze-learning tasks. Both species rapidly decreased the time they needed to find a food reward, but latencies were always higher for L. delicata than L. guichenoti. More detailed analysis showed that neither species actually learned the position of the food reward; they were as likely to turn the wrong way at the end of the study as at the beginning. Instead, their times decreased because they spent less time immobile in later trials; and L. guichenoti arrived at the reward sooner because they exhibited "freezing" (immobility) less than L. delicata. Hence, our data confirm that the species differ in their performance in this standardized test, but neither the decreasing time to find the reward, nor the interspecific disparity in those times, are reflective of cognitive abilities. Behavioural differences may well explain why one species is invasive and one is not, but those differences do not necessarily involve cognitive ability.

If at first you don't succeed... Studies of ontogeny shed light on the cognitive demands of habitual tool use

Many species use tools, but the mechanisms underpinning the behaviour differ between species and even among individuals within species, depending on the variants performed. When considering tool use 'as adaptation', an important first step is to understand the contribution made by fixed phenotypes as compared to flexible mechanisms, for instance learning. Social learning of tool use is sometimes inferred based on variation between populations of the same species but this approach is questionable. Specifically, alternative explanations cannot be ruled out because population differences are also driven by genetic and/or environmental factors. To better understand the mechanisms underlying routine but non-universal (i.e. habitual) tool use, we suggest focusing on the ontogeny of tool use and individual variation within populations. For example, if tool-using competence emerges late during ontogeny and improves with practice or varies with exposure to social cues, then a role for learning can be inferred. Experimental studies help identify the cognitive and developmental mechanisms used when tools are used to solve problems. The mechanisms underlying the route to tool-use acquisition have important consequences for our understanding of the accumulation in technological skill complexity over the life course of an individual, across generations and over evolutionary time.

Bird brains and tool use: beyond instrumental conditioning

Few displays of complex cognition are as intriguing as nonhuman tool use. Long thought to be unique to humans, evidence for tool use and manufacture has now been gathered in chimpanzees, dolphins, and elephants. Outside of mammals, tool use is most common in birds, especially in corvids and parrots. The present paper reviews the evidence for avian tool use, both in the wild and in laboratory settings. It also places this behavioral evidence in the context of longstanding debates about the kinds of mental processes nonhumans can perform. Descartes argued that animals are unable to think because they are soulless machines, incapable of flexible behavior. Later, as human machines became more sophisticated and psychologists discovered classical and instrumental conditioning, skepticism about animal thinking decreased. However, behaviors that involve more than simple conditioning continued to elicit skepticism, especially among behaviorists. Nonetheless, as reviewed here, strong behavioral data now indicate that tool use in some birds cannot be explained as resulting entirely from instrumental conditioning. The neural substrates of tool use in birds remain unclear, but the available data point mainly to the caudolateral nidopallium, which shares both functional and structural features with the mammalian prefrontal cortex. As more data on the neural mechanisms of complex cognition in birds accrue, skepticism about those mental capacities should continue to wane.

Explorative learning and functional inferences on a five-step means-means-end problem in Goffin's cockatoos (Cacatuagoffini)

To investigate cognitive operations underlying sequential problem solving, we confronted ten Goffin's cockatoos with a baited box locked by five different inter-locking devices. Subjects were either naïve or had watched a conspecific demonstration, and either faced all devices at once or incrementally. One naïve subject solved the problem without demonstration and with all locks present within the first five sessions (each consisting of one trial of up to 20 minutes), while five others did so after social demonstrations or incremental experience. Performance was aided by species-specific traits including neophilia, a haptic modality and persistence. Most birds showed a ratchet-like progress, rarely failing to solve a stage once they had done it once. In most transfer tests subjects reacted flexibly and sensitively to alterations of the locks' sequencing and functionality, as expected from the presence of predictive inferences about mechanical interactions between the locks.

A behavioral view on chimpanzee personality: exploration tendency, persistence, boldness, and tool-orientation measured with group experiments

Human and nonhuman animals show personality: temporal and contextual consistency in behavior patterns that vary among individuals. In contrast to most other species, personality of chimpanzees, Pan troglodytes, has mainly been studied with non-behavioral methods. We examined boldness, exploration tendency, persistence and tool-orientation in 29 captive chimpanzees using repeated experiments conducted in an ecologically valid social setting. High temporal repeatability and contextual consistency in all these traits indicated they reflected personality. In addition, Principal Component Analysis revealed two independent syndromes, labeled exploration-persistence and boldness. We found no sex or rank differences in the trait scores, but the scores declined with age. Nonetheless, there was considerable inter-individual variation within age-classes, suggesting that behavior was not merely determined by age but also by dispositional effects. In conclusion, our study complements earlier rating studies and adds new traits to the chimpanzee personality, thereby supporting the existence of multiple personality traits among chimpanzees. We stress the importance of ecologically valid behavioral research to assess multiple personality traits and their association, as it allows inclusion of ape studies in the comparison of personality structures across species studied behaviorally, and furthers our attempts to unravel the causes and consequences of animal personality.

How to solve a mechanical problem: the relevance of visible and unobservable functionality for kea

Animals sometimes succeed quickly in solving a mechanical problem that is a modification of one they have previously learnt to solve. However, they may do so by attending to the visible features of the relevant physical dimension without knowing its causal functionality, if that is not directly perceivable. This kind of problem solving can be tested by simultaneously offering two mechanical devices with the same visual features but different inherent appropriateness for problem solving. Here, we provide data collected by following this procedure for the first time in a bird species. Captive kea, Nestor notabilis, a parrot species highly interested in the affordances of objects, were offered a mechanical problem in which they had to remove a baited tube from one of two upright poles where removal was blocked at the end of one pole but not the other. With extended but not with restricted exploration of a baseline apparatus, the kea immediately succeeded in removing the tube from an apparatus that had modified pole ends when they were able to visually observe (without touching) that one of these ends would block tube removal but the other would not. However, when the kea were allowed to explore two poles that had a removable and a fixed obstruction where the difference in function was not visible, they preferred the removable one during unbaited exploration but failed afterwards to push a tube to the end of the pole with the loose structure during subsequent baited test trials. Thus, in spite of the speed with which the kea learnt the tasks, there was no indication that they understood the underlying unobservable causal structure of the problem.

Innovative problem solving by wild spotted hyenas

Innovative animals are those able to solve novel problems or invent novel solutions to existing problems. Despite the important ecological and evolutionary consequences of innovation, we still know very little about the traits that vary among individuals within a species to make them more or less innovative. Here we examine innovative problem solving by spotted hyenas (Crocuta crocuta) in their natural habitat, and demonstrate for the first time in a non-human animal that those individuals exhibiting a greater diversity of initial exploratory behaviours are more successful problem solvers. Additionally, as in earlier work, we found that neophobia was a critical inhibitor of problem-solving success. Interestingly, although juveniles and adults were equally successful in solving the problem, juveniles were significantly more diverse in their initial exploratory behaviours, more persistent and less neophobic than were adults. We found no significant effects of social rank or sex on success, the diversity of initial exploratory behaviours, behavioural persistence or neophobia. Our results suggest that the diversity of initial exploratory behaviours, akin to some measures of human creativity, is an important, but largely overlooked, determinant of problem-solving success in non-human animals.

A new approach to comparing problem solving, flexibility and innovation

Comparative cognition aims at unfolding the cognitive processes underlying animal behavior and their evolution, and is concerned with testing hypotheses about the evolution of the brain and intelligence in general. It is a developing field still challenged by conceptual and methodological issues. Systematic cross-species comparisons of cognitive abilities, taking both phylogeny and ecology into account are still scarce. One major reason for this is that it is very hard to find universally applicable paradigms that can be used to investigate the same cognitive ability or 'general intelligence' in several species. Many comparative paradigms have not paid sufficient attention to interspecific differences in anatomical, behavioral and perceptual features, besides psychological variables such as motivation, attentiveness or neophobia, thus potentially producing misrepresentative results. A new stance for future comparative research may be to establish behavioral and psychological profiles prior or alongside to comparing specific cognitive skills across species. Potentially revealing profiles could be obtained from examining species differences in how novel experimental (extractive foraging) tasks are explored and approached, how solutions are discovered and which ones are preferred, how flexibly multiple solutions are used and how much individual variation occurs, before proceeding to more detailed tests. Such new comparative approach is the Multi-Access-Box. It presents the animal with a novel problem that can be solved in several ways thus offering the possibility to examine species differences in all the above, and extract behavioral and perceptual determinants of their performance. Simultaneously, it is a suitable paradigm to collect comparative data about flexibility, innovativeness and problem solving ability, i.e., theoretical covariates of 'general intelligence', in a standardized manner.

Navigating a tool end in a specific direction: stick-tool use in kea (Nestor notabilis)

This study depicts how captive kea, New Zealand parrots, which are not known to use tools in the wild, employ a stick-tool to retrieve a food reward after receiving demonstration trials. Four out of six animals succeeded in doing so despite physical (beak curvature) and ecological (no stick-like materials used during nest construction) constraints when handling elongated objects. We further demonstrate that the same animals can thereafter direct the functional end of a stick-tool into a desired direction, aiming at a positive option while avoiding a negative one.

Donepezil treatment of severe Alzheimer's disease in nursing home settings. A responder analysis

BACKGROUND/AIMS

Our objective was to define clinically meaningful outcomes in donepezil versus placebo treatment in severe Alzheimer's disease (AD) and to describe characteristics of responders.

METHODS

Analyses were performed on data from a 6-month, double-blind, parallel-group, placebo-controlled study on the efficacy of donepezil in 248 nursing home residents. Various individual responses were defined as stabilisation or improvement on the Severe Impairment Battery (SIB), Alzheimer's Disease Cooperative Study-activities of daily living scale (ADCS-ADL), Mini-Mental State Examination, Neuropsychiatric Inventory (NPI) or Clinical Global Impression of Improvement. Three composite measures were defined by combining the individual response criteria on these outcomes. The impact of baseline disease severity and of concomitant use of psychotropic drugs was also analysed.

RESULTS

At 6 months, greater proportions of patients defined as responders to donepezil on individual efficacy measures showed significant stabilisation or improvement compared with placebo on the SIB (>or=0, >or=4 or >or=7 points) and Mini-Mental State Examination (>or=0 or >or=3 points), and positive trends on the ADCS-ADL-severe (>or=3 points) and the NPI cluster based on mood items. All 3 composite measures of efficacy showed a significantly higher proportion of responders in the donepezil group. The responders had a similar distribution between the 2 subgroups of cognitive and functional disease severity at baseline. The donepezil-treated patients taking psychotropic drugs showed significantly greater improvement on the SIB, less deterioration on the ADCS-ADL, and had higher Clinical Global Impression of Improvement scores and a trend towards lower NPI scores. The baseline demographic and clinical profile did not differ between the non-responders and responders on the composite outcome measures.

CONCLUSION

The results demonstrate that donepezil treatment of patients with severe AD consistently shows stabilisation or improvement across multiple outcome measures in individual patients, including cognitive, functional and behavioural symptoms.