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

Spotlight on Research: What's in (Half) a Face?

In the School of Psychology's new Spotlight on Research section, we focus on recent research conducted by Dr Darren Burke at our Ourimbah campus (pictured partly and wholly below!): 

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When we recognise someone, we integrate information from across their face into a perceptual whole, and do so using a specialised brain region. Recognising other kinds of objects does not engage such specific brain areas, and is achieved in a much more parts-based way.

In a recent review of the literature, we (Burke & Sulikowski, 2013) investigated how this face-specific mode of perception may have evolved by examining the evidence for face-based holistic processing in other species. A surprisingly wide variety of other animals can recognise each other from their “face”, but for most of these there is either evidence that they don’t do this “holistically” (dogs are an example) or insufficient evidence to claim that they do (typically because the experiments are poorly designed).

There is good evidence that some species of monkey are as affected by turning the face upside down as humans are (which is one index of holistic processing), and one species of monkey (Rhesus macaques) also show evidence of the “composite effect”. The composite effect refers to the fact that people find it difficult to recognise the top half of a face if it is shown lined up with the bottom half of a different face, because we can’t help integrating the two halves into a new whole. People have trouble recognising other primate faces when they are upside down, but only show the composite effect for human faces.

We also suggested that the original evolutionary origin of special holistic face processing might not be to recognise who’s who. There are actually lots of other sources of evolutionary important information in faces that require holistic integration. For example, detecting symmetry, and masculinity/femininity is important for mate-choice decisions, and subtle variations in facial configurations underpin many non-verbal communicative signals.

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For more information about this work, please see the following journal article:

Burke, D., & Sulikowski, D. (2013). The Evolution of Holistic Processing of Faces Frontiers in Psychology, 4 DOI: 10.3389/fpsyg.2013.00011

or contact Dr Darren Burke at Darren.Burke@newcastle.edu.au