I wanna share what I think to be Feldman Barret's positive account from the paper "The Emotion Paradox", rather than dealing with the details of the evidence she presents for it.
Emotions are interoceptions. They are the body's perception of itself (through some modalities, like "somatovisceral information"). That means what we leverage to explain perception applies to emotion. Perception is task relative; what you see depends upon what you're doing; and mediated by a bunch of things. Your past experiences, what you've learned, how you conceptualise stuff. What you've learned influences what you see, what you're doing influences what you see, how you talk about what you see influences what you see. Those effects of "what you've learned", "how you conceptualise stuff" and "what you're doing" get put into the process of valuation.
Valuation is one part of how our bodies do emotions. The other part is core affect. Core affect, inn Barret's words is:
Core affect has been characterized as the constant stream of transient alterations in an organism’s neurophysiological state that represent its immediate relation to the flow of changing events
Core affect (i.e., the neurophysiological state) is available to consciousness and is experienced as feeling good or bad (valence) and to a lesser extent as activated or deactivated (arousal).
Core affect and valuation run in parallel all the time. Insofar as emotion is concerned, we are core affect machines and valuation machines. Valuation draws on resources outside core affect, and it modulates (or mediates) the emerging experience of emotion. The extra resources are anything that we could bring to bear to contextualise information; all these extra resources can be labelled as concepts. They're not only the "clear distinct ideas" of Russel, they're more general representations.
How they work together is that core affect updates its environmental and bodily information quickly, valuation updates itself a bit more slowly. If the environment and the body are food, core affect is chewing, valuation is digestion, emotion is the whole thing insofar as it's bodily.
To be able to label a state of core affect "anger", we have to have the cognitive resources in place not just to categorize it, but to devote enough of our attentional and representational resources to it that that a categorization ("I feel angry") emerges as an individuated description of our emotional state. As Barrett puts it, emotions are "perceptual symbols", like "red".
I argue that the process of categorization is fundamental to both color and person perception
and draw a parallel between these categorization processes and the way in which people use their knowledge of emotion categories to shape an experience of
emotion.
The usual folk psychology ways we talk about emotion are all post categorisation; we have distinct but overlapping (descriptions of) states like happiness, anger, shame, horniness. What we learn about these categorisations, the folk psychology stuff, influences how we feel. This intervention of resources outside core affect upon our emerging experience of emotion through learning simultaneously makes it discursively/culturally mediated and something that can be honed and practiced, a skill. Husserl called phenomenology "relearning how to see", Barrett may suggest that we can relearn how to feel.
The intervention learning has upon the emerging experience of emotion is not limitless; the processes that constitute core affect are linked to how the body is extremely likely to typify its own sensations/state; the body is predisposed to some emotions and responses. There are some biological primitives (central pattern generators) that valuation acts improvisationally upon, draws boundaries between, and leverages contextual information to interpret and prescribe what to do upon their (and core affect's) basis.
The way I've written it above may suggest that core affect and valuation are still reactive; they are means for digestion of environmental stimuli, and this always goes stimulus->response or behaviour->feeling. This isn't true; valuation is predictive/prescriptive, and this is fleshed out in some of her later work. In the paper "The Theory of Constructed Emotions", Barrett leverages Bayesian brain ideas about concepts and perception to refine how emotions are predictive/prescriptive, not simply reactive. Emotion is in some regard anticipated behaviour that is expected to be effective and salient in summarising our body's situation (including current task and goals).
I hypothesize that in assembling populations of predictions, each one having some probability of being the best fit to the current circumstances (i.e., Bayesian priors), the brain is constructing concepts (Barrett, 2017) or what Barsalou refers to as ‘ad hoc’ concepts (Barsalou, 1983, 2003; Barsalou et al., 2003). In the language of the brain, a concept is a group of distributed ‘patterns’ of activity across some population of neurons.
Valuation becomes a patterning of core affect(s); patterning is always going on in the emerging experience of emotion, so it modulates emotion; emotions are a "what's now? what's next" rather than just a "this just happened", and "this just happened" is part of informing "what's now? what next?".
As Barrett puts it:
A brain can be thought of as running an internal model that controls central pattern generators in the service of allostasis (for more on pattern generators, see Burrows, 1996; Sterling and Laughlin, 2015; Swanson, 2000). An internal model runs on past experiences, implemented as concepts. A concept is a collection of embodied, whole brain representations that predict what is about to happen in the sensory environment, what the best action is to deal with impending events, and their consequences for allostasis (the latter is made available to consciousness as affect). Unpredicted information (i.e. prediction error) is encoded and consolidated whenever it is predicted to result in a physiological change in state of perceiver (i.e. whenever it impacts allostasis). Once prediction error is minimized, a prediction becomes a perception or an experience. In doing so, the prediction explains the cause of sensory events and directs action; i.e. it categorizes the sensory event. In this way, the brain uses past experience to construct a categorization [a situated conceptualization; (Barsalou, 1999; Barsalou et al., 2003; Barrett, 2006b; Barrett et al., 2015)] that best fits the situation to guide action. The brain continually constructs concepts and creates categories to identify what the sensory inputs are, infers a causal explanation for what caused them, and drives action plans for what to do about them. When the internal model creates an emotion concept, the eventual categorization results in an instance of emotion.