Interoception: our hidden sense?

By Lara Orlandi


Bladder bursting? Craving a snack? Itchy? We experience these feelings via interoception, one of our far lesser-known senses. The vast majority of people have probably never even heard the term before, yet interoception plays such an integral part in our daily lives and our core wellbeing. By understanding interoception, we may gain insight into our physical and mental health, and why we often behave and act the way we do.


A visual representation of interoception [photo credits to the Weizmann Institute of Science]


So, what is interoception?


Scholars have varied slightly across the years in their attempts to define interoception, but an overarching concept remains constant. Interoception can be broadly explained as the sense that interprets the internal state of our body. We perceive signals from all of our organs, influencing our thirst, hunger, temperature and emotions. For instance, if a person’s heart is racing and their muscles have tensed up, then their interoceptive sense would tell them that they are afraid. Likewise, if your bladder is full, your brain would receive a signal telling it so, prompting the necessary response of emptying it. Interoception is specifically distinct from our exteroceptive sense, which is the detection of stimuli outside the body such as light or sound.


How does it work?


There are specialised sensory receptors all throughout the body that send neural signals to the insular cortex of the brain, which is located deep within the cerebral cortex. The cerebral cortex is primarily responsible for multiple higher level brain processes such as thought and memory. After the insular cortex interprets these signals, it produces a reactionary feeling, which is often followed by a behavioural response to counteract it. We develop our interoceptive skills from birth, honing our interpretation of bodily states so that we soon are able to self-regulate rapidly.


How is it measured?


Scientists can first measure interoception in terms of ‘interoceptive accuracy’, the ability to consciously perceive your internal conditions. This can be recorded through heartbeat detection tests in which the chosen internal condition is naturally your heartbeat. One test involves the individual counting how many heartbeats they feel in a set time period, which is in effect measuring the capability of internal measuring mechanisms. There is also an alternate test for interoceptive accuracy in which the subject must synchronise single heartbeats with external stimuli, such as tapping. It is important to note that both of these tests are difficult to validate as they may be affected by variables such as stress levels and sleep deprivation.


There is a second function of interoception which is ‘interoceptive attention’ which constitutes how often an individual notices their heart beating. Interoceptive attention is more difficult to measure concisely and distinguish. Scientists might attempt to investigate it by having a subject take a questionnaire at set intervals all throughout the day, noting how they feel and their internal observations.


Why does it matter?


On a fundamental level, interoception is intrinsic to homeostasis, which is the regulation of internal bodily conditions. An example of this is when a person's interoception informs them that they are thirsty. They will subsequently drink some water, aiding osmoregulation and returning the water content of their body to the desired level. Without interoception and a clear knowledge of what our internal environment needs, the operation of homeostasis would be significantly more difficult.


Interoception also extends outward towards social contexts; scientific studies have shown a connection between interoception and social interaction. One study (Werner et al., 2013) offered evidence of this relationship by placing participants in a position of social exclusion in a conversation. Participants with a higher interoceptive ability (IAcc) experienced a lesser negative impact in that situation, compared to their peers with a lower IAcc. All the participants had the same physiological reactions. They only reported variation in psychological damage, which leads us to conclude that it is not the physical internal reactions that determine our social stress, but rather our perception of these changes, i.e. interoception.


Other studies imply that our interoceptive abilities are adjusted in response to stressful situations. The ‘attentional switching hypothesis’ describes how in these contexts of exclusion, our body decreases its focus on interoception in order to extend its focus on exteroception, so that it may reintegrate itself into the group. This is evidenced by a study (Durlik and Tsakiris, 2015) that recorded how social exclusion, implemented through the Cyberball game, caused a decrease in IAcc.

These studies can both be true; people with a higher IAcc might be able to adapt to these scenarios more easily, and simultaneously these scenarios can cause fluctuations in IAcc, in multiple respects, interoception is strongly incorporated within social contexts.


Finally, interoception is arguably required for a deeper contentment within ourselves. Abraham Maslow proposed a hierarchy of needs in his paper entitled ‘A theory of human motivation.’ In this explanation, he suggested that our basic physiological needs must be satisfied first in order for us to transcend to satisfy our love and belongingness needs, as well as esteem and self-actualization needs. Following this proposition, given we rely upon interoception for physiological regulation, we by extension require it also in order to reach a satisfactory livelihood and reach a deeper sense of belonging with ourselves.



Sources

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