Our brain is constantly keeping track of the experience of our body in the environment, enabling us to determine where we are, how we feel, and respond appropriately. How does this work? Let’s find out!
Researchers parse the experience of our body into three domains: exteroception, proprioception, and interoception. Are you familiar with these terms? What type of information do each of these domains contribute to the experience of the body in the image below?
- Exteroception refers to information about the body’s external environment, like auditory and visual information. In the above image, this would include the hum of moving water that dampens the rest of the sound in the environment.
- Proprioception refers to information about the position and movements of the body. In the above image, this would include the movement of your arms and legs while treading underwater.
- Finally, interoception refers to information about the internal state of the body, like our heartbeat and digestive signals. In the above image, this includes “air hunger” or feeling a lack of air in your lungs.
In this article, I will first examine how these three domains interact and contribute to the experience of our body in the environment. Second, I will zoom in on interoception, how it serves homeostasis (i.e., our body’s tendency to maintain a stable equilibrium or balance), and its role in the experience of emotions. Interoception is vital to our well-being, and researchers are hopeful it will lead to new insights about mental health. Let’s start!
Our brains continuously integrate exteroceptive, proprioceptive, and interoceptive information to maintain a representation or image of how/where our body is (Quigley et al., 2021; Seth, 2013; Simmons et al., 2013). Why does the brain need to integrate information from all three domains? Well, as you will see, any one domain is insufficient on its own.
Imagine you feel your heartbeat start to quicken (interoception) but you have no exteroceptive or proprioceptive information to give you helpful context. How might you interpret this change in your heartbeat?
An increase in heart rate can accompany many experiences, like exercise or an infection. However, your response to an increase in heart rate during exercise is very different than when you are experiencing an infection. Without contextual information, it is difficult to interpret and respond to this experience of a quickening heartbeat.
Now imagine you become aware of your heart beating faster and start to gather other contextual information. For example, you smell fresh baked bread and hear the bustle of a busy restaurant (exteroception). You also notice your knees are bent sitting in a booth (proprioception). Maybe you are sitting across from a date (exteroception). With this context, you might interpret your increased heart rate as nervousness. In this example, I have described exteroception, proprioception, and interoception as conscious experiences, and sometimes they are. However, our brains are constantly tracking and integrating information from these three domains even when we are not consciously aware of it!
So, our brain continuously integrates exteroceptive, proprioceptive, and interoceptive information to interpret our body in the environment and respond appropriately. In contrast, when researchers study these domains, they often examine them separately to better understand each domains unique contributions. Let’s take a closer look at interoception, how it serves homeostasis (i.e., our body’s tendency to maintain a stable equilibrium or balance), and is fundamental to our experience of emotions.
Interoception is vital to homeostasis, meaning the regulation of physiological conditions to “set points” or a narrow range of values that facilitate survival. For example, adult humans’ temperature ranges from 97.7 to 99.5 °F. The brain receives interoceptive information about temperature to assess whether homeostasis is maintained or if a regulatory response is needed. If our temperature has risen above the ideal homeostatic range, our brain initiates a response, such as sweating, removing an article of clothing, or both. Thus, interoception is vital to our physical health and survival. However, researchers have also highlighted the role interoception plays in many other functions, including the experience of emotions, sense of self, and cognitive processes (Gu & FitzGerald, 2014; Seth, 2013; Tsakiris & Critchley, 2016).
Researchers have been exploring the role of interoception in emotions for many years, starting with foundational theories from James & Lange that emotions are the result of physiological reactions (e.g., racing heart) to an event (James, 1894; Lange, 1885). Modern theories of emotion build on this idea, where emotions are thought to be the result of experiencing an interoceptive sensation (e.g., shortness of breath, flushing of cheeks), then integrating contextual cues (exteroceptive and proprioceptive information) to appraise or name what we are experiencing, such as “I am embarrassed” (Barrett, 2013; Barrett & Bar, 2009).
Let’s further break down the pathway to experiencing an emotion (see Figure 2). We can think about our brain moving from low-level interoceptive information (stimuli) to more abstract high-level interpretations that reach conscious awareness and offer meaning (Barrett, 2017).
First, we have interoceptive stimuli, which are internal signals reflecting the current state of the body.
Affect is derived from incorporating all of these interoceptive stimuli together. Affect has two dimensions: valence (i.e., ranging from pleasant to unpleasant) and arousal (i.e., ranging from low to high levels of alertness). Affect offers a summary about the current state of the body across all of its systems (see Figure 1).
Finally, when we use the word emotion, we are often referring to the categorization of affect into emotion concepts such as “anger” or “excitement” (Quigley et al., 2021), which are influenced by culture (see my previous blog to learn more). For example, if someone is experiencing unpleasantness and higher levels of arousal/alertness, along with other contextual cues, they might label their current state as “angry” (see Figure 3).
However, there is no one-to-one mapping between interoceptive sensations and specific emotions. For instance, increases in heart rate can accompany many emotional experiences, including anger, fear, and excitement. As such, interoceptive information serves as one, albeit important, building block of emotion (Bechara & Naqvi, 2004; Pollatos et al., 2007; Zamariola et al., 2018). Interoceptive information is still ambiguous without exteroceptive, and proprioceptive information, cultural factors, and previous experience taken into consideration.
Taken together, three domains, exteroception, proprioception, and interoception, contribute to the experience of our body in the environment. Their integration is vital for our brain to make sense of what we are experiencing. Most research has focused on exteroceptive processes. However, since the 2000’s, there has been a steep increase in interoception research, as researchers continue to recognize the importance of this process for our daily functioning. As you have read, interoception contributes to important human experiences such as our emotions, sense of self, and mental health broadly. Eventually researchers hope to see interoception research inform interventions for various clinical disorders.
Edited by Brianna Best and Liz Rosdeitcher
References:
Barrett, L. F. (2017). How emotions are made: the secret life of the brain.
James, W. (1894). Discussion: The physical basis of emotion.
Lange, C. G. (1885). The mechanism of the emotions. The Classical Psychologists, 672–684.
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