The relationship between emotion and cognition is complex, but often thought to be simple: emotion is frequently viewed as being distinct from cognition, and, often, an impediment to clear reasoning.  This view pervades philosophy, “common sense”, and neuroscience.  Luiz Pessoa’s book clearly shows that this idea is not well-supported by evidence. It is both a valuable overview of research in neuroscience and psychology on the relationship between cognition and emotion, and a well-crafted argument for a novel approach to understanding this relationship.  Much of contemporary work in this area accepts the traditional view that “emotional stimuli are processed initially by a dedicated, modular system that operates rapidly, automatically, and largely independent of conscious awareness” (p. 41), a view that Pessoa has characterized as the “standard hypothesis”.  This view also assumes that emotional and cognitive processing are largely separate and, in many cases, are in competition with each other.  Throughout the book, Pessoa draws on a wide variety of studies to debunk this view and support his alternative.  He also addresses the tension between localized and distributed accounts of brain function; whereas the “standard hypothesis” tends to accept a modular view of the brain, on which specific cognitive functions are localized to particular brain areas, he advocates a network view on which emotional and cognitive processing intersect in multiple ways.

The book begins with an introductory chapter that addresses the conceptual difficulties inherent in giving definitions of “emotion” and “cognition” and then surveys the organization of the book.  Chapter 2 discusses research on the function of the amygdala, perhaps the paradigm case of an “emotion center” in the brain.  More specifically, the amygdala is associated with fear processing, though Pessoa argues that this underestimates the complexity of the function of the structure.  Instead, he suggests, the amygdala is best understood as being involved in determining both what a stimulus is and what kind of behavioral response is appropriate to the stimulus.  In the following chapter, he looks specifically at the role of affect in visual perception, for which the amygdala is commonly thought to be crucial. The chapter contains an extensive review of the empirical literature on the role of affect in vision, which, on balance, does not support the standard hypothesis.  Pessoa traces the idea that the amygdala is the terminus of an automatic, subcortical route for emotion processing to its roots in rodent studies that showed that there is an auditory pathway in rats that bypasses the cortex and that is sufficient for some forms of Pavlovian conditioning (Le Doux, 1996).  While “[a] similar subcortical role is assumed to exist for visual information in primates, including humans” (Pessoa, p. 43), on balance, there is little to no support for this assumption.

Given this lack of support, Pessoa suggests replacing the standard hypothesis with a “multiple waves model” of emotion/cognition integration, on which there are multiple parallel routes for the processing of visual information, which include both cortical and subcortical regions.  This model also introduces the idea that understanding emotion processing, and its effects on cognition, requires focusing on networks of brain regions, rather than on individual, modular regions.  This idea is expanded on later in the book.

The next few chapters of the book continue to survey the literature on various aspects of emotional and cognitive processing, drawing together animal and human research, as well as including both purely behavioral studies and work that uses various techniques to study neuroanatomy and neurophysiology.  Throughout, Pessoa does an admirable job of synthesizing a great deal of research.  Chapter 4 examines the role of attention in the processing of cognitive stimuli, showing that the idea that emotion processing occurs “automatically” or “preattentively” is an oversimplification.  Moreover, this view fails to take into account the “endogenous” influence of an individual’s goals on even low-level perceptual processing.

Chapter 5 looks at the interaction of cognitive and emotional processing in the prefrontal cortex, showing that activity in even “quintessentially” cognitive areas like the dorsolateral prefrontal cortex is influenced by emotional stimuli. Here, Pessoa addresses the theory that emotion and cognition engage in competitive interaction, so that increased emotion processing reduces cognitive processing, and vice versa (Drevets and Raichle, 1998). Again, Pessoa shows that while this may be true in some cases, the relationship between cognitive and emotional processing is not that simple.

Chapter 6 considers the effects of motivation on both perception and cognition. Pessoa notes that while researchers have acknowledged that emotion and motivation are related, the tendency has been to study them independently of each other.  As he did in the case of emotion, Pessoa shows that motivation influences task performance.  Moreover, the relationship between motivation and attention turns out to be complex, and the two cannot be clearly separated.

Chapter 7 presents Pessoa’s dual competition model, on which “both emotional and motivational signals are integrated with perception and cognition so as to effectively incorporate value into the unfolding of behavior” (p. 159). Pessoa surveys a number of mechanisms by which emotional and cognitive processes may interact (relating back to the multiple waves model presented in Chapter 2) and again reiterates that brain areas involved in cognitive control respond to emotional stimuli.  In particular, networks of brain regions that are involved in the performance of specific tasks (such as the “attentional network”) interact with “valuation networks,” and do so via multiple communication mechanisms.  These include (1) direct connections between brain areas; (2) indirect communication via “hub” regions; and (3) neuromodulatory systems using, e.g., dopamine or norepinephrine.  Similarly, motivation influences both perception and cognition via multiple pathways.

Chapter 8 turns to an explicit discussion of a theme that has recurred throughout the book, which is the mapping of cognitive and perceptual functions in the brain.  Pessoa notes the long-standing tension between modular accounts of brain function that attempt to find specific brain regions associated with particular tasks, and holistic accounts that emphasize the importance of brain networks.  His own view is that a network approach is more promising, and in making this case, he describes work on both anatomical and functional connectivity among brain regions (cautioning that the latter cannot be easily inferred from the former).  He also argues that a network approach should not assume that the brain can easily be divided into discrete, non-overlapping networks, and also pointing out that there may well be multiple possible decompositions of brain regions into subnetworks, which may each be useful for different explanatory purposes.  He therefore concludes that it would be a mistake to search for the appropriate ontology of neural networks.

The final two chapters bring together the network perspective and the question of the relationship between emotion and cognition (Chapter 9) and then summarize the book’s arguments and present some implications of the framework it defends (Chapter 10).  Pessoa discusses several brain regions in some detail (including the basal forebrain, orbitofrontal cortex, and amygdala), emphasizing their connectivity with a number of other (cortical and subcortical) structures, and considering the implications of this architecture for the potential integration of emotional and cognitive processing.  The book concludes with a discussion of some of the implications for taking a “network perspective” on emotion and cognition, making explicit some ideas that had been previously suggested in passing.

In conclusion, this is an extremely valuable book, both as a resource for those who want to understand the current state of research on emotion and cognition, and as a coherent, well-supported challenge to the currently dominant understanding of the relationship between them.  Pessoa has done an excellent job of summarizing the extensive and diverse research literature and of using this summary to convincingly support both his critique of the field and his proposed alternative.  While the book is not light reading, and a solid background in neuroscience is likely necessary to fully appreciate Pessoa’s account, the argument is so clearly laid out that readers without such a background can readily understand his analysis.  Given the widespread acceptance of the “standard hypothesis” about emotion and cognition, this book deserves a wider audience.

References

Drevets, WC, Raichle, ME. Reciprocal suppression of regional cerebral blood flow during emotional versus higher cognitive processes: Implications for interactions between emotion and cognition. Cognition and Emotion 1998;12(3):353-385.

LeDoux, JE. The Emotional Brain N;ew York: Simon & Schuster. 1996.

© 2014 Robyn Bluhm

Robyn Bluhm, Ph.D., Philosophy & Religious Studies, Old Dominion University