TY - JOUR
T1 - Decision-making without a brain
T2 - How an amoeboid organism solves the two-armed bandit
AU - Reid, Chris R.
AU - MacDonald, Hannelore
AU - Mann, Richard P.
AU - Marshall, James A.R.
AU - Latty, Tanya
AU - Garnier, Simon
N1 - Funding Information:
This work was funded by the Branco Weiss Society in Science Fellowship to T.L., and by the Australian Research Council (DP110102998) to T.L. and (DP140103643) to T.L. and S.G. The authors thank Amyjaelle Belot and Sima Kalam for help with performing experiments, and Warren Powell for discussion.
Publisher Copyright:
© 2016 The Authors.
PY - 2016/6/1
Y1 - 2016/6/1
N2 - Several recent studies hint at shared patterns in decision-making between taxonomically distant organisms, yet few studies demonstrate and dissect mechanisms of decision-making in simpler organisms. We examine decision-making in the unicellular slime mould Physarum polycephalum using a classical decision problem adapted from human and animal decision-making studies: the two-armed bandit problem. This problem has previously only been used to study organisms with brains, yet here we demonstrate that a brainless unicellular organism compares the relative qualities of multiple options, integrates over repeated samplings to perform well in random environments, and combines information on reward frequency and magnitude in order to make correct and adaptive decisions. We extend our inquiry by using Bayesian model selection to determine the most likely algorithm used by the cell when making decisions. We deduce that this algorithm centres around a tendency to exploit environments in proportion to their reward experienced through past sampling. The algorithm is intermediate in computational complexity between simple, reactionary heuristics and calculation-intensive optimal performance algorithms, yet it has very good relative performance. Our study provides insight into ancestral mechanisms of decision-making and suggests that fundamental principles of decision-making, information processing and even cognition are shared among diverse biological systems.
AB - Several recent studies hint at shared patterns in decision-making between taxonomically distant organisms, yet few studies demonstrate and dissect mechanisms of decision-making in simpler organisms. We examine decision-making in the unicellular slime mould Physarum polycephalum using a classical decision problem adapted from human and animal decision-making studies: the two-armed bandit problem. This problem has previously only been used to study organisms with brains, yet here we demonstrate that a brainless unicellular organism compares the relative qualities of multiple options, integrates over repeated samplings to perform well in random environments, and combines information on reward frequency and magnitude in order to make correct and adaptive decisions. We extend our inquiry by using Bayesian model selection to determine the most likely algorithm used by the cell when making decisions. We deduce that this algorithm centres around a tendency to exploit environments in proportion to their reward experienced through past sampling. The algorithm is intermediate in computational complexity between simple, reactionary heuristics and calculation-intensive optimal performance algorithms, yet it has very good relative performance. Our study provides insight into ancestral mechanisms of decision-making and suggests that fundamental principles of decision-making, information processing and even cognition are shared among diverse biological systems.
KW - Bayesian model selection
KW - Decision-making
KW - Exploration-exploitation trade-off
KW - Physarum polycephalum
KW - Slime mould
KW - Two-armed bandit
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U2 - 10.1098/rsif.2016.0030
DO - 10.1098/rsif.2016.0030
M3 - Article
C2 - 27278359
AN - SCOPUS:84983020775
SN - 1742-5689
VL - 13
JO - Journal of the Royal Society Interface
JF - Journal of the Royal Society Interface
IS - 119
M1 - 20160030
ER -