The topics treated in The brain and emotion include the definition, nature, and functions of emotion (Ch. 3); the neural bases of emotion (Ch. 4); reward, punishment, and emotion in brain design (Ch. 10); a theory of consciousness and its application to understanding emotion and pleasure (Ch. 9); and neural networks and emotion-related learning (Appendix). The approach is that emotions can be considered as states elicited by reinforcers (rewards and punishers). This approach helps with understanding the functions of emotion, with classifying different emotions, and in understanding what information-processing systems in the brain are involved in emotion, and how they are involved. The hypothesis is developed that brains are designed around reward-and punishment-evaluation systems, because this is the way that genes can build a complex system that will produce appropriate but flexible behavior to increase fitness (Ch. 10). By specifying goals rather than particular behavioral patterns of responses, genes leave much more open the possible behavioral strategies that might be required to increase fitness. The importance of reward and punishment systems in brain design also provides a basis for understanding the brain mechanisms of motivation, as described in Chapters 2 for appetite and feeding, 5 for brain-stimulation reward, 6 for addiction, 7 for thirst, and 8 for sexual behavior.

The brain and emotion treats emotions as states elicited by reinforcers (reward or punishment), but it is unclear how this view can do justice to the diversity of emotions. It is also unclear how such a view distinguishes emotions from states such as hunger and thirst. A complementary approach to understanding emotions may begin by considering emotions as aspects of social cognition.

Rolls's book, The brain and emotion is an important and valuable contribution to our understanding of the brain mechanisms that underlie emotional processes. Its explanatory value is less obvious when it comes to psychological and philosophical issues concerning the nature of emotions.

I criticize Rolls's account of what makes emotional states conscious.

Rolls defends a higher-order thought theory of phenomenal consciousness, mapping the distinction between conscious and non-conscious states onto a distinction between two types of action and corresponding neural pathways. Only one type of action involves higher-order thought and consequently consciousness. This account of consciousness has implausible consequences for the nature of stimulus-reinforcement learning.

Motivation and emotion are not clearly defined and differentiated in Rolls's The brain and emotion, reflecting a widespread problem in conceptualizing these phenomena. An adequate theory of emotion cannot be based upon reward and punishment alone. Basic mechanisms of arousal, agonistic, and prosocial motives-emotions exist in addition to reward-punishment systems.

This review focuses on the theory of emotion outlined in Chapter 3 of Rolls's The brain and emotion. It is proposed that Rolls's emphasis on a relatively simple neurobiologically derived emotion scheme does not allow him to present a comprehensive account of emotion. Consequently, high-level cognitive processes, such as appraisal, end up being retained in the theory despite Rolls's skepticism about their utility. An argument is put forward that the concept of appraisal in the emotion literature is more than semantic convention and actually allows us to talk about multiple functional-level routes to the generation of emotion – a characteristic of the latest generation of theories in the cognition-emotion literature.

I express two concerns with the theory of emotion that Rolls provides: (1) rewards and punishers alone fail to explain the basic emotions; (2) Rolls needs to clarify his notion of the intentionality of emotions. I also criticize his theory of consciousness, arguing that it fails to explain qualia, and that ironically it is emotions which make this most evident.

The concept of emotion as defined by Rolls is based upon reinforcement mechanisms and their underlying neural networks. He shows how these networks process signals at many levels, through both separate and convergent pathways essential for adaptive action. While many behavioral issues related to emotion are omitted from his review, he succeeds admirably in summarizing both the “current state of the art” in single unit analyses and in pointing out how future research directions may be crafted.

The book contains a masterly review of Rolls's single-neuron research reflecting rewards. It places that research in the context of the neo-behaviorist theory of emotions. That theory provides a useful first approximation to emotion-eliciting conditions but has little to tell about emotions as motivational states or response dispositions: nor does it give a rationale for what are considered to be primary rewarding stimuli.

Rolls emphasizes the role of emotion in behavior. My commentary provides some balance to that position by arguing that stored social knowledge dominates our behavior and controls emotional states, thereby reducing emotions to a subservient role in behavior.

Rolls discusses various adaptive explanations of physiological processes and the emotions. We give a critical analysis of some of these from the perspective of behavioural ecology. While agreeing with the approach adopted by Rolls, we identify topics that could have been better presented by making use of the existing literature.

Rolls presents a good integrative summary of the neural bases of emotions, adds new findings and insights, and takes a stance on controversial issues such as separate or distinct brain systems for processing emotion information and for planning and action. This commentary raises questions about his explanations of emotion activation, response to novelty, the evolution of emotions, and the phenomenal experience of emotions in human consciousness.

Rolls presents a theory of emotion based on the premise that emotions are evoked by events that are capable of being instrumental reinforcers and punishers. As support for this theory is drawn almost entirely from experiments in non-human primates, valuable insights into the relationship between punishment and reinforcement systems, and the nature of instrumentality, may have been overlooked.

Rolls's preliminary definitions of emotion and speculative restriction of consciousness, including emotional sentience, to humans, display behaviorist prejudice. Reinforcement and causation are not by themselves sufficient conceptual resources to define either emotion or the directedness of thought and motivated action. For any adequate definition of emotion or delimitation of consciousness, new physiology, such as Rolls is contributing to, and also the resources of other fields, will be required.

Rolls's presentation of emotion as integral to cognition is a welcome counter to a long tradition of treating them as antagonists. His eduction of experimental evidence in support of this view is impressive. However, we find his excursion into the philosophy of consciousness less successful. Rolls gives syntactical manipulation the central role in consciousness (in stark contrast to Searle, for whom “mere” syntax inevitably falls short of consciousness), and leaves us wondering about the roles left for emotion after all.

Rolls uses evolutionary theory and behavioral learning theory in his analysis of emotion. We believe that both theories are greatly underutilized, leaving an incomplete description of the nature of emotion and its neural foundation.

Rolls's book depends significantly on a definition relating emotion to reward and learning. This definition confuses two separable concepts, and may result in the exclusion of notions of emotion and motivation from lower animals that may possess limited learning capacities. A more useful definition might revolve around the notion that emotions are states that function to optimize the performance of behavior.

Examples of terror generated by an aircraft disaster, of human courtship behaviour, and of the application of laboratory techniques to the commercial training of animals suggest (1) that emotion is simply the subjective counterpart of (objective) motivation (so that separate brain mechanisms would be an embarrassment) and (2) the apparent involvement of reward and punishment is a consequence of the excessively narrow range of experimental procedures used and has no foundation in the design of the brain.

The representation of events, in primates at any rate, is a separate process from their emotional evaluation. The same holds for cognitive evaluation. Here too representation and evaluation are separate operations. Acknowledging the symmetry leads to the notion of free representation.