The way we think and interpret what we live through is closely connected with the words we have available to describe our experiences. We often use particular concepts for lack of more precise ones. Words, however, are not neutral: they give meaning, they influence and shape the way we understand our reality and how we explain what is happening inside us.
In this spirit, many people perceive themselves as introverted or shy, or avoid being in crowds, attributing it to anxious traits in their character. In 1997, however, Elaine Aron published a paper developing her theory about a trait shared by many people: a high degree of sensory processing sensitivity (HSP). This theory was born out of her clinical observation that a proportion of the population (estimated at around 15–20%) shows this particular trait, and it has been supported by subsequent studies (Aron & Aron, 1997; Costa-López et al., 2021).
Many people were described by parents or teachers as overly sensitive or shy children while growing up. But what others translated as sensitivity or shyness was, for some children, a higher degree of activation related to the depth and range of their processing of information — both from the external environment (sounds, textures, visual stimuli such as lights) and from the internal one (pain, hunger, preoccupation with thoughts or feelings). This is not sensitivity in the sense of how easily someone is offended or takes things the wrong way, but depth of perception and processing of subtle sensory information. The neurobiological system of these people is more sensitive to processing sensory stimuli and to the intensity of changes in them, whether noise, smells or lights.
We can observe that not everyone is affected in the same way by what happens in the environment. Some people — myself included — are easily unsettled by the sound of a loud engine or a sudden car horn in the street, while others do not register it as disturbing at all.
Sensitivity to stimuli means there is heightened activation of the organism in response to what is happening in the environment, but also greater overload and fatigue when there is an abundance of stimuli, people, noise and so on — which can become exhausting for the nervous system. This characteristic of nervous system functioning is also observed in other animal species, and has been found to exist at relatively stable rates within those species.
Sensitivity to stimuli includes, beyond stimuli from the external environment and pain or hunger, other people’s moods, the experience of listening to music or looking at works of art. The organism has a more intense awareness of internal experiences, which can show itself when watching films or videos containing violent or frightening scenes. It also relates to the arousal of the organism when it has to perform within a short space of time. There is also observed avoidance of conditions likely to provoke intense stress, and particular sensitivity to the moods and needs of others. What is normal for some people and does not disturb them — loud music, sirens, bright lights, smells, or being among many people — can be too intense for someone with high sensory sensitivity.
Some people walk into a space and notice details that pass others by: the mood of the people there, the friendships or hostilities between them, the quality of the air, the personality of whoever decorated the room. Some, then, appear to perceive nuances that go unnoticed by others. This is not a matter of sharper senses — hearing and vision, for example, are not better — but of a difference in the way the organism perceives, filters and processes information.
In general there is a difficulty in tolerating what other people tolerate without being disturbed, because of this difference in the abundance of stimuli and the depth at which they are perceived. What is moderately stimulating for many people is far more intensely stimulating for people with high sensory sensitivity.
On the other hand, because the nervous system is more easily aroused, people with this trait may need more time in calm or solitude to return to a state of balance and emotional regulation. Moving away from overstimulation helps the nervous system to re-regulate and recover energy. As one client described it to me, during breaks at her university she needed to withdraw from people, and often at the end of the day she came home tired from all the stimuli she took in and processed daily. Time at home, too, was synonymous with a personal refuge of calm and the absence of intense external information.
It is important to note that high sensory sensitivity is not a mental disorder, but a normal temperamental trait found in a proportion of the population. This way of perceiving the environment does not mean only greater vulnerability to overstimulation; it is also, in a way, a gift — an innate mode that, if properly cultivated and cared for, can be a useful compass in life. It also often appears alongside a greater capacity for empathy, creativity, heightened attention to detail and a richer imagination.
Psychotherapy can help with recognising and better understanding this trait, and with exploring ways of regulating arousal. Through this process, people can recognise which conditions help them and what they need in order to function in balance, making use of the possibilities that accompany this heightened sensitivity while operating at optimal levels of arousal.
Elaine Aron has created a questionnaire you can complete to see where you fall on the HSP spectrum. Parents can also complete the questionnaire on behalf of their child:
Take the Adult Sensitivity Self-Test
For children:
Highly Sensitive Child Test (Parent Version)
References:
Aron, E. N., & Aron, A. (1997). Sensory-processing sensitivity and its relation to introversion and emotionality. Journal of Personality and Social Psychology, 73(2), 345–368.
Aron, E. N. (1996). The Highly Sensitive Person: How to Thrive When the World Overwhelms You. New York, NY: Harmony Books.
Costa-López, B., Ruiz-Robledillo, N., Ferrer-Cascales, R., Albaladejo-Blázquez, N., & Sánchez-SanSegundo, M. (2021). Relationship between Sensory Processing Sensitivity and Mental Health. Medical Sciences Forum, 4(1), 19. https://doi.org/10.3390/ECERPH-3-09064
