Sunday, May 07, 2006

The Microeconomics of Anticipation

OR: The Kiss and the Shock and Patterns of Inferotemporal Preference.

The Neurocritic is not an economist and is not fond of the field of neuroeconomics. Nonetheless, to understand the narrow definition of "dread" used by Berns et al. (2006) in their article, "Neurobiological Substrates of Dread," one needs to consult some old articles on economic theory:

"...the term 'savouring' referes to positive utility derived from anticipation of future consumption; 'dread' refers to negative utility resulting from contemplation of the future."

As one can discern from my previous two "meta-commentaries" on this article, I was bothered by the pretentiousness of a title claiming to have a neurobiological explanation of the very complex affective state known as "dread." The construct under study here would seemingly be better described as "anticipation," specifically anticipation of a well-defined cutaneous shock to the dorsum of the left foot.

The paper by Berns et al. aims to explain why people will sometimes choose to delay gratification and to speed up the receipt of unpleasant outcomes (most specifically, the latter... although I would imagine a corporation-sponsored study on the former will be forthcoming from some lab or other).1 Anyway, the act of waiting (or anticipation) can take on positive or negative dimensions.

George Loewenstein
Anticipation and the valuation of delayed consumption.
The Economic Journal 97: 666-684 (1987).
This paper presents a model of intertemporal choice that incorporates "savoring" and "dread" -i.e., utility from anticipation of delayed consumption. The model explains why an individual with positive time preference may delay desirable outcomes or get unpleasant outcomes over with quickly, contrary to the prediction of conventional formulations of intertemporal choice. Implications of savoring and dread for savings behavior, empirical estimation of discount rates, and public policy efforts to combat myopic behavior are explored. The model provides an explanation for common violations of the independence axiom as applied to intertemporal choice. Copyright 1987 by Royal Economic Society.

My problem with the Berns et al. study is with the interpretation of their results:

The manifestation of dread in the more posterior elements of the pain matrix informs our understanding of what dread is and how it impacts decision-making. ... Although dread is usually thought of as an emotion based on fear and anxiety (Berridge, 1999), our localization of dread tothe posterior elements of the matrix suggests that dread has a substantial attentive component. (p. 756)
Here, the authors commit the logical fallacy known as "reverse inference" by inferring the participants' emotional state from the observed pattern of brain activity. They discount the role of the amygdala in "dread" because both moderate and extreme dreaders showed elevated hemodynamic responses there during the unpleasant interval of waiting for the shocks.

Taken together, the anatomical locations of dread responses suggest that the subjective experience of dread that ultimately drives an individual's behavior comes from the attention devoted to the expected physical response (SI, SII, the caudal ACC, and the posterior insula) and not simply a fear or anxiety response.

So anticipation of pain is "attention," not fear and anxiety. It's a little early to make that conclusion.

Can cognitive processes be inferred from neuroimaging data?
Russell A. Poldrack
Trends in Cognitive Sciences
Volume 10, Issue 2 , February 2006, Pages 59-63

There is much interest currently in using functional neuroimaging techniques to understand better the nature of cognition. One particular practice that has become common is ‘reverse inference’, by which the engagement of a particular cognitive process is inferred from the activation of a particular brain region. Such inferences are not deductively valid, but can still provide some information. Using a Bayesian analysis of the BrainMap neuroimaging database, I characterize the amount of additional evidence in favor of the engagement of a cognitive process that can be offered by a reverse inference. Its usefulness is particularly limited by the selectivity of activation in the region of interest. I argue that cognitive neuroscientists should be circumspect in the use of reverse inference, particularly when selectivity of the region in question cannot be established or is known to be weak.
see Geoff Aguirre for earlier commentary on reverse inference:

Functional Imaging in Behavioral Neurology and Cognitive Neuropsychology
Geoffrey Karl Aguirre
In: T. E. Feinberg & M. J. Farah (Eds.), Behavioral Neurology and Cognitive Neuropsychology. (2003). New York: McGraw Hill.

1 it might be difficult, however, to conduct an actual fMRI study using Loewenstein's hypothetical as the positive reinforcer: obtaining a kiss from the movie star of your choice.

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2 Comments:

At May 07, 2006 1:34 AM, Blogger Chris said...

It looks like there were all sorts of typical cog neuro errors. For example, inferring that the amygdala wasn't involved because both groups showed increased responese there. Of course, we don't know what that response means, or what exactly it's doing, so how can we infer that the same thing was happening in the amygdala in both groups? But so much of any localization based on neuroimagining data depends on getting rid of common areas of response that it's not clear what cog neuro would be if it didn't get rid of them.

 
At May 07, 2006 5:22 PM, Anonymous bgp said...

It still seems funny to me that people are trying to tout "neurobiological explanation of [insert subjective experience here]." Be that dread, happiness, the smell of roses, the sound of a violin string. Better references to the phenomena described might be "the neurobiological correlates that we derived from fancy neuroimaging hocus-pocus when our subjects felt [insert subjective experience here]." Great post, by the way.

 

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