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Identifying social learning in animal populations: a new 'option-bias' method.

Kendal RL, Kendal JR, Hoppitt W, Laland KN - PLoS ONE (2009)

Bottom Line: We illustrate the method on data from groups of monkeys provided with novel two-option extractive foraging tasks, demonstrating that social learning can indeed be distinguished from unlearned processes and a social learning, and revealing that the monkeys only employed social learning for the more difficult tasks.The method is further validated against published datasets and through simulation, and exhibits higher statistical power than conventional inferential statistics.It will also be of value in enabling investigation of the social learning strategies deployed in captive and natural animal populations.

View Article: PubMed Central - PubMed

Affiliation: Centre for Social Learning and Cognitive Evolution, School of Psychology, University of St Andrews, St Andrews, Fife, United Kingdom.

ABSTRACT

Background: Studies of natural animal populations reveal widespread evidence for the diffusion of novel behaviour patterns, and for intra- and inter-population variation in behaviour. However, claims that these are manifestations of animal 'culture' remain controversial because alternative explanations to social learning remain difficult to refute. This inability to identify social learning in social settings has also contributed to the failure to test evolutionary hypotheses concerning the social learning strategies that animals deploy.

Methodology/principal findings: We present a solution to this problem, in the form of a new means of identifying social learning in animal populations. The method is based on the well-established premise of social learning research, that--when ecological and genetic differences are accounted for--social learning will generate greater homogeneity in behaviour between animals than expected in its absence. Our procedure compares the observed level of homogeneity to a sampling distribution generated utilizing randomization and other procedures, allowing claims of social learning to be evaluated according to consensual standards. We illustrate the method on data from groups of monkeys provided with novel two-option extractive foraging tasks, demonstrating that social learning can indeed be distinguished from unlearned processes and a social learning, and revealing that the monkeys only employed social learning for the more difficult tasks. The method is further validated against published datasets and through simulation, and exhibits higher statistical power than conventional inferential statistics.

Conclusions/significance: The method is potentially a significant technological development, which could prove of considerable value in assessing the validity of claims for culturally transmitted behaviour in animal groups. It will also be of value in enabling investigation of the social learning strategies deployed in captive and natural animal populations.

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Related in: MedlinePlus

Diagrams and photos of (a) the flip-top task used by a golden headed lion tamarin, (b) the round-box task used by emperor tamarins, and (c) the cylinder task used by golden headed lion tamarins.Arrows indicate the movement of the devices that prevent simultaneous use of the task options.
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pone-0006541-g001: Diagrams and photos of (a) the flip-top task used by a golden headed lion tamarin, (b) the round-box task used by emperor tamarins, and (c) the cylinder task used by golden headed lion tamarins.Arrows indicate the movement of the devices that prevent simultaneous use of the task options.

Mentions: Each group was exposed to three different extractive foraging tasks (each a puzzle box containing a desired food) over separate trials (i.e. one task per group per trial) in a randomised order (see Fig. 1). Pilot studies established that the tasks, labelled ‘round-box’, ‘flip-top’ and ‘cylinder’, were of increasing difficulty for the monkeys to solve. All three were opaque white plastic boxes, of varying shapes, containing raisins [see 27 for more information]. When the boxes were closed, subjects had limited visual and olfactory access to the food and had two spatially separated doors, or options, from which to extract the raisins. The options, which could not be used simultaneously, were distinguished by colour combinations (blue versus either green, red or yellow) visible to both di- and trichromatic individuals, and the order of task presentation to each group was pseudo-randomised. There was no effect of colour preference across all groups for any task (Mann-Whitney: flip-top: U94,95 = 4303, p = 0.534; cylinder: U94,95 = 4379, p = 0.681; round-box: U94,95 = 4403, p = 0.844) and no instances of scrounging were observed. Although the large size of the tasks relative to the monkeys should have eliminated any effects of handedness, any side-biases were controlled for as the orientation of the tasks was randomised across trials. The tasks were designed to be solved using foraging actions, natural to all genera, such as employed when turning over bark, exploring crevices and rummaging in leaf litter.


Identifying social learning in animal populations: a new 'option-bias' method.

Kendal RL, Kendal JR, Hoppitt W, Laland KN - PLoS ONE (2009)

Diagrams and photos of (a) the flip-top task used by a golden headed lion tamarin, (b) the round-box task used by emperor tamarins, and (c) the cylinder task used by golden headed lion tamarins.Arrows indicate the movement of the devices that prevent simultaneous use of the task options.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2717327&req=5

pone-0006541-g001: Diagrams and photos of (a) the flip-top task used by a golden headed lion tamarin, (b) the round-box task used by emperor tamarins, and (c) the cylinder task used by golden headed lion tamarins.Arrows indicate the movement of the devices that prevent simultaneous use of the task options.
Mentions: Each group was exposed to three different extractive foraging tasks (each a puzzle box containing a desired food) over separate trials (i.e. one task per group per trial) in a randomised order (see Fig. 1). Pilot studies established that the tasks, labelled ‘round-box’, ‘flip-top’ and ‘cylinder’, were of increasing difficulty for the monkeys to solve. All three were opaque white plastic boxes, of varying shapes, containing raisins [see 27 for more information]. When the boxes were closed, subjects had limited visual and olfactory access to the food and had two spatially separated doors, or options, from which to extract the raisins. The options, which could not be used simultaneously, were distinguished by colour combinations (blue versus either green, red or yellow) visible to both di- and trichromatic individuals, and the order of task presentation to each group was pseudo-randomised. There was no effect of colour preference across all groups for any task (Mann-Whitney: flip-top: U94,95 = 4303, p = 0.534; cylinder: U94,95 = 4379, p = 0.681; round-box: U94,95 = 4403, p = 0.844) and no instances of scrounging were observed. Although the large size of the tasks relative to the monkeys should have eliminated any effects of handedness, any side-biases were controlled for as the orientation of the tasks was randomised across trials. The tasks were designed to be solved using foraging actions, natural to all genera, such as employed when turning over bark, exploring crevices and rummaging in leaf litter.

Bottom Line: We illustrate the method on data from groups of monkeys provided with novel two-option extractive foraging tasks, demonstrating that social learning can indeed be distinguished from unlearned processes and a social learning, and revealing that the monkeys only employed social learning for the more difficult tasks.The method is further validated against published datasets and through simulation, and exhibits higher statistical power than conventional inferential statistics.It will also be of value in enabling investigation of the social learning strategies deployed in captive and natural animal populations.

View Article: PubMed Central - PubMed

Affiliation: Centre for Social Learning and Cognitive Evolution, School of Psychology, University of St Andrews, St Andrews, Fife, United Kingdom.

ABSTRACT

Background: Studies of natural animal populations reveal widespread evidence for the diffusion of novel behaviour patterns, and for intra- and inter-population variation in behaviour. However, claims that these are manifestations of animal 'culture' remain controversial because alternative explanations to social learning remain difficult to refute. This inability to identify social learning in social settings has also contributed to the failure to test evolutionary hypotheses concerning the social learning strategies that animals deploy.

Methodology/principal findings: We present a solution to this problem, in the form of a new means of identifying social learning in animal populations. The method is based on the well-established premise of social learning research, that--when ecological and genetic differences are accounted for--social learning will generate greater homogeneity in behaviour between animals than expected in its absence. Our procedure compares the observed level of homogeneity to a sampling distribution generated utilizing randomization and other procedures, allowing claims of social learning to be evaluated according to consensual standards. We illustrate the method on data from groups of monkeys provided with novel two-option extractive foraging tasks, demonstrating that social learning can indeed be distinguished from unlearned processes and a social learning, and revealing that the monkeys only employed social learning for the more difficult tasks. The method is further validated against published datasets and through simulation, and exhibits higher statistical power than conventional inferential statistics.

Conclusions/significance: The method is potentially a significant technological development, which could prove of considerable value in assessing the validity of claims for culturally transmitted behaviour in animal groups. It will also be of value in enabling investigation of the social learning strategies deployed in captive and natural animal populations.

Show MeSH
Related in: MedlinePlus