Monday, 3 November 2014

JUST PUBLISHED: Decision Making - Monkey See, Monkey Do (But Not Like a Human)

A great deal is known about how we make simple decisions, right down to the way neurons in our brains connect to translate the things we sense into the responses we make. Some of the most important neural studies of decision-making have used monkeys as an analogue for humans. The broader scope of methodology which can be used with primates has provided information far beyond that obtainable from human experimentation. However, conclusions based on animal experiments may not always translate to humans.

Recent work using single cell recordings from monkeys (Bonnet macaques) drew a particularly strong conclusion about human decision making – that all current theories about how decisions are made were wrong, in spite of these theories having decades of support from empirical studies in humans. This conclusion was supported by analysis of how the monkeys responded to instructions to change their decision-making strategy. There was an apparent disconnect between the way the neural recordings from the monkeys’ neurons changed between strategy conditions and the way theories of human decision-making suggested those changes should occur.

In a re-analysis of the monkey data, Peter Cassey, Andrew Heathcote, and Scott Brown came to a different conclusion; the disconnect is not between cognitive and neural accounts of decision making, but between the decision-making strategies employed by humans and those employed by monkeys, even in the same – and very simple! – task. When we allowed both behavioural and neural data to inform our analysis, it was apparent that the monkeys from these experiments were just not making decisions in the same manner as humans.

There is a cautionary tale here - the failure to properly account for inter-species differences, even for processes assumed to be analogous, such as simple perceptual decisions, can lead to incorrect conclusions about the nature of humans. The commonly-used analogy between human and monkeys in simple decision-making appears to break down once strategic choices enter the picture.

For further details, please see the following open-access article:

Cassey, P., Heathcote, A., & Brown, S. (2014). Brain and Behavior in Decision-Making PLoS Computational Biology, 10 (7), 1-7 DOI: 10.1371/journal.pcbi.1003700