Adaptive Levy Processes and Area-Restricted Search in Human Foraging

This source preferred by Jan Wiener

Authors: Hills, T., Kalff, C. and Wiener, J.

http://eprints.bournemouth.ac.uk/21716/

Journal: PLoS One

Volume: 8

Issue: 4

Pages: 1-7

DOI: 10.1371/journal.pone.0060488

This data was imported from PubMed:

Authors: Hills, T.T., Kalff, C. and Wiener, J.M.

http://eprints.bournemouth.ac.uk/21716/

Journal: PLoS One

Volume: 8

Issue: 4

Pages: e60488

eISSN: 1932-6203

DOI: 10.1371/journal.pone.0060488

A considerable amount of research has claimed that animals' foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods-comparing alternative distributions using maximum likelihood methods-showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments-where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources-as both patched and dispersed conditions led to similar Lévy-like movement distributions.

This data was imported from Scopus:

Authors: Hills, T.T., Kalff, C. and Wiener, J.M.

http://eprints.bournemouth.ac.uk/21716/

Journal: PLoS ONE

Volume: 8

Issue: 4

eISSN: 1932-6203

DOI: 10.1371/journal.pone.0060488

A considerable amount of research has claimed that animals' foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods-comparing alternative distributions using maximum likelihood methods-showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments-where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources-as both patched and dispersed conditions led to similar Lévy-like movement distributions. © 2013 Hills et al.

This data was imported from Web of Science (Lite):

Authors: Hills, T.T., Kalff, C. and Wiener, J.M.

http://eprints.bournemouth.ac.uk/21716/

Journal: PLOS ONE

Volume: 8

Issue: 4

ISSN: 1932-6203

DOI: 10.1371/journal.pone.0060488

This data was imported from Europe PubMed Central:

Authors: Hills, T.T., Kalff, C. and Wiener, J.M.

http://eprints.bournemouth.ac.uk/21716/

Journal: PloS one

Volume: 8

Issue: 4

Pages: e60488

eISSN: 1932-6203

A considerable amount of research has claimed that animals' foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods-comparing alternative distributions using maximum likelihood methods-showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments-where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources-as both patched and dispersed conditions led to similar Lévy-like movement distributions.

The data on this page was last updated at 04:39 on October 23, 2017.