Emotions, while ubiquitous across species and one of the most common topics of conversation, are still, it seems, misunderstood.
Do emotions have biological roots and, if so, where? And how do physiological factors influence how emotions are felt, expressed, and understood?
For Ralph Adolphs and David J. Anderson, developing a comprehensive science of emotions began with trying to create a framework that is scientifically rigorous, inclusive, cumulative, and yet provides clear operationalization of the relevant concepts of emotions.
Their new book, The Neuroscience of Emotion: A New Synthesis, offers a new way to understand emotions, one that will leave you thinking differently about how emotions work and why they are so important.
“If you are most people, you feel convinced that, because you have emotions, you know a lot about what emotions are, and how they work. We believe you are almost certainly wrong,” write Adolphs and Anderson.
We wrongly assume many things about emotion, and gaining insight into emotion means moving past these assumptions. For one thing, there are many more than four primary emotions, and they are not irreducible.
The authors address this, saying, “There is scant evidence that “joy”, “fear”, or “anger” are irreducible and do not share component parts. Equally plausible is an alternative view in which each of these emotions is made up of a collections of components, or building blocks, some of which are shared by other emotions.”
What neuroscience offers is a way to understand what underlying mechanisms generate emotions, and further, to explain them through their underlying mechanisms.
One example is the feeling of disgust, which the authors explain evolved to help animals avoid poisonous or contaminated food.
Emotions, however, go much further than the reflex-like reaction to a noxious food. Often overlapping with other states, such as motivation, arousal, and drive, emotions serve as adaptive functional states that lie somewhere between reflexes, volitional, and deliberate action.
One way to understand emotions more clearly is to separate them into two classes: building blocks of emotions and features of emotions.
“All emotion states have most of the building blocks, and we can find precursors to emotions states in simpler organisms that already show many of the properties of building blocks. Features, on the other hand, are more elaborated, derived, and variable properties of emotions, and not all emotions have them,” write Adolph and Anderson.
Emotion states can also be related to one another and integrate information from multiple sources over time. One example is what is known as the “drift-diffusion” model, which describes how we reach a decision threshold depending on how rapidly sensory information is accumulated.
Emotions, however, are not generalizable. The authors write, “Given the highly varied and multimodal sensory inputs that can carry information relevant to a particular emotion (for example, predictors of a threat that could induce a state of fear) there is no simple formula that determines which stimuli cause an emotion, let alone which stimuli cause one type of emotion rather than another.”
Similarly, studying emotions means distinguishing between emotion states, called internal brain states, and feelings, the conscious and subjective experience of those emotions.
While we might not agree on whether animals have feelings, we can study their emotion states to help us better understand the function of our own emotions.
The authors write, “Darwin believed, and we agree, that emotional expression (whether produced in the face, the body, or both) was an evolutionary conserved function, and that its particular manifestations in different species provide insights to how emotions evolved.”
Asking questions like: Do flies engage in sex because it is rewarding or reinforcing to them, or simply because they are genetically programmed to do it? will help us better understand the internal states of motivation, arousal, and drive, as well as our own subjective feelings of love, lust, anger, and rage.
Separating emotion states from the conscious experience of feelings also helps us understand how sensory stimuli can go undetected and still induce an emotion. One example the authors give is fear conditioning in humans, where conditioned autonomic responses emerge — which is a form of emotional learning.
Shedding light on the often misunderstood topic of emotions, The Neuroscience of Emotion: A New Synthesis offers a truly scientific approach to understanding emotions, one that is as thought provoking as it is comprehensive.
The Neuroscience of Emotion: A New Synthesis
Princeton University Press, June 2018
Hardcover, 376 pages