We are an intensely social species--it has been argued that our social nature defines what makes us human, what makes us conscious or what gave us our large brains. As a new field, the social brain sciences are probing the neural underpinnings of social behaviour and have produced a banquet of data that are both tantalizing and deeply puzzling. We are finding new links between emotion and reason, between action and perception, and between representations of other people and ourselves. No less important are the links that are also being established across disciplines to understand social behaviour, as neuroscientists, social psychologists, anthropologists, ethologists and philosophers forge new collaborations.

Cognitive neuroscience of human social behaviour.

Neuroeconomics uses knowledge about brain mechanisms to inform economic analysis, and roots economics in biology. It opens up the "black box" of the brain, much as organizational economics adds detail to the theory of the firm. Neuroscientists use many tools— including brain imaging, behavior of patients with localized brain lesions, animal behavior, and recording single neuron activity. The key insight for economics is that the brain is composed of multiple systems which interact. Controlled systems ("executive function") interrupt automatic ones. Emotions and cognition both guide decisions. Just as prices and allocations emerge from the interaction of two processes—supply and demand— individual decisions can be modeled as the result of two (or more) processes interacting. Indeed, "dual-process" models of this sort are better rooted in neuroscientific fact, and more empirically accurate, than single-process models (such as utility-maximization). We discuss how brain evidence complicates standard assumptions about basic preference, to include homeostasis and other kinds of state-dependence. We also discuss applications to intertemporal choice, risk and decision making, and game theory. Intertemporal choice appears to be domain-specific and heavily influenced by emotion. The simplified s-d of quasi-hyperbolic discounting is supported by activation in distinct regions of limbic and cortical systems. In risky decision, imaging data tentatively support the idea that gains and losses are coded separately, and that ambiguity is distinct from risk, because it activates fear and discomfort regions. (Ironically, lesion patients who do not receive fear signals in prefrontal cortex are "rationally" neutral toward ambiguity.) Game theory studies show the effect of brain regions implicated in "theory of mind", correlates of strategic skill, and effects of hormones and other biological variables. Finally, economics can contribute to neuroscience because simple rational-choice models are useful for understanding highly-evolved behavior like motor actions that earn rewards, and Bayesian integration of sensorimotor information.

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Neuroeconomics: How Neuroscience Can Inform Economics

Using a multiround version of an economic exchange (trust game), we report that reciprocity expressed by one player strongly predicts future trust expressed by their partner—a behavioral finding mirrored by neural responses in the dorsal striatum. Here, analyses within and between brains revealed two signals—one encoded by response magnitude, and the other by response timing. Response magnitude correlated with the “intention to trust” on the next play of the game, and the peak of these “intention to trust” responses shifted its time of occurrence by 14 seconds as player reputations developed. This temporal transfer resembles a similar shift of reward prediction errors common to reinforcement learning models, but in the context of a social exchange. These data extend previous model-based functional magnetic resonance imaging studies into the social domain and broaden our view of the spectrum of functions implemented by the dorsal striatum.

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Getting to know you : Reputation and trust in a two-person economic exchange

We review recent developments in neuroeconomics and their implications for economics. The paper consists of six sections. Following the Introduction, the second section enumerates the different research methods that neuroscientists use evaluates their strengths and limitations for analyzing economic phenomena. The third section provides a review of basic findings in neuroscience that we deemed especially relevant to economics, and proposes a two-dimensional dichotomization of neural processes between automatic and controlled processes on the one hand, and cognitive and affective processes on the other. Section four reviews general implications of neuroscience for economics. Research in neuroscience, for example, raises questions about the usefulness of many economic constructs, such as 'time preference' and 'risk preference'. It also suggests that, contrary to the assumption that humans are likely to possess domain-specific intelligence - to be brilliant when it comes to problems that the brain is well evolved for performing and flat-footed for problems that lie outside of the brains existing specialized functions. Section 5 provides more detailed discussions of four specific applications: intertemporal choice, decision making under risk and uncertainty, game theory, and labor-market discrimination. Section 6 concludes by proposing a distinction between two general approaches in applying neuroscience to economics which we term 'incremental' and 'radical'. The former draws on neuroscience findings to refine existing economic models, while the latter poses more basic challenges to the standard economic understanding of human behavior.

In spite of the remarkable progress made in the burgeoning field of social neuroscience, the neural mechanisms that underlie social encounters are only beginning to be studied and could-paradoxically-be seen as representing the "dark matter" of social neuroscience. Recent conceptual and empirical developments consistently indicate the need for investigations that allow the study of real-time social encounters in a truly interactive manner. This suggestion is based on the premise that social cognition is fundamentally different when we are in interaction with others rather than merely observing them. In this article, we outline the theoretical conception of a second-person approach to other minds and review evidence from neuroimaging, psychophysiological studies, and related fields to argue for the development of a second-person neuroscience, which will help neuroscience to really "go social"; this may also be relevant for our understanding of psychiatric disorders construed as disorders of social cognition.

/pdf/toward-a-second-person-neuroscience-3cc8z1fj3t.pdf

Toward a second-person neuroscience.

http://www.ccnl.emory.edu/greg/Hyperscan%20Final.pdf

Hyperscanning: Simultaneous fMRI during Linked Social Interactions

A new methodology for the measurement of the neural substrates of human social interaction is described. This technology, termed “Hyperscan,” embodies both the hardware and the software necessary to link magnetic resonance scanners through the internet. Hyperscanning allows for the performance of human behavioral experiments in which participants can interact with each other while functional MRI is acquired in synchrony with the behavioral interactions. Data are presented from a simple game of deception between pairs of subjects. Because people may interact both asymmetrically and asynchronously, both the design and the analysis must accommodate this added complexity. Several potential approaches are described. © 2002 Elsevier Science (USA)

Igor Karpov

Papers

Hyperscanning: Simultaneous fMRI during Linked Social Interactions

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