Sensory Processing Sensitivity (SPS) is the official term for the trait of the Highly Sensitive Person, which was identified and extensively studied by Dr. Elaine Aron in the mid-1990s. It describes individuals with heightened sensitivity to sensory input, emotional stimuli, and social environments. Since the term was introduced by Dr Elaine Aron, a vast amount of research has been carried out to expand and refine our understanding of the trait. Below is a list of related terms and definitions for describing and furthering our understanding of the trait - I find these terms are really helpful to gain a more cohesive an holistic understanding of the trait.
Related Terms
Environmental sensitivity, as described by Dr Michael Pluess, is a concept rooted in trait sensitivity, which highlights how people vary in their responsiveness to external stimuli due to biological and psychological differences. Dr Pluess emphasises that environmental sensitivity is not solely about vulnerability to adverse conditions but also encompasses heightened receptiveness to supportive and enriching environments.
A closely related term is that of differential susceptibility - a theory developed by Jay Belsky and further explored with Dr Pluess, which suggests that individuals are not merely vulnerable to adverse environments but also uniquely positioned to thrive in supportive and nurturing ones. In this framework, heightened sensitivity makes them more malleable, for better or worse, depending on the quality of their surroundings. This perspective underscores the dual potential of sensitivity, highlighting the benefits in positive environments and the challenges in negative ones. The research suggests that specific genes that contribute towards sensitivity function less like ‘vulnerability factors’ and more like ‘plasticity factors’ - in other words, sensitivity doesn’t make us more vulnerable, but it makes us more adaptable.
Related to the above is the concept of vantage sensitivity, which is a psychological framework that explains individual differences in responsiveness to positive environmental influences. Introduced by Michael Pluess and Jay Belsky in 2013, it suggests that some individuals benefit significantly from positive experiences such as psychological interventions, while others have minimal or no benefit under similar conditions.
Exploring Other Perspectives
Smolewska et al. (2006) expanded the original Highly Sensitive Person (HSP) construct, developed by Elaine Aron, by proposing a three-factor model of sensory processing sensitivity (SPS). Their main criticisms and contributions of the original HSP scale were that it lacked dimensional nuance. Dr Elaine Aron originally described sensory processing sensitivity as a unitary construct, implying that HSPs possess a single, cohesive trait. Smolewska et al. argued that the concept of sensitivity is multifaceted and cannot be fully captured as a single characteristic. They identified three distinct components within the SPS framework: Ease of Excitation (EOE), Low Sensory Threshold (LST), and Aesthetic Sensitivity (AES) describe the key components that make up the HSP trait. Each factor contributes to how sensitive individuals experience and respond to their environment, including sensory, emotional, and aesthetic stimuli.
1. Ease of Excitation (EOE)
EOE is the tendency to become easily overstimulated or overwhelmed by external stimuli. This factor measures how quickly an individual reacts to stimuli and the intensity of their response. Individuals with high EOE can become easily excited, agitated, or stressed when exposed to strong or prolonged sensory inputs, such as loud noises, crowded places, or even complex social situations. A person with EOE might feel overwhelmed at a busy party with loud music, numerous conversations, and flashing lights, while others may not experience the same level of discomfort.
2. Low Sensory Threshold (LST)
LST refers to the sensitivity of an individual to subtle sensory stimuli, including sights, sounds, smells, and textures. Those with a low sensory threshold are more attuned to and affected by sensory input than individuals with a higher threshold. Individuals with a low sensory threshold are often aware of stimuli that others might overlook or find irrelevant. This can manifest as a heightened sensitivity to light, sound, touch, or other environmental cues. While this sensitivity allows for deeper processing of information, it also means that everyday environments can feel more intense or even overwhelming for the individual. An individual with low sensory threshold may be disturbed by the faint sound of a ticking clock in a quiet room, while others may be unaware of it altogether.
3. Aesthetic Sensitivity (AES)
AES refers to the heightened sensitivity to and appreciation of beauty, art, nature, and other aesthetic experiences. This factor is characterised by a strong emotional response to stimuli such as music, visual art and natural landscapes. Individuals with high AES often experience profound emotional reactions to beauty and art, leading them to be deeply moved by aesthetic experiences. This sensitivity can contribute to greater creativity, appreciation for nature, and emotional richness, but it can also lead to overstimulation if the aesthetic input is too intense or constant. A person with AES might feel deeply moved or even tearful when viewing a beautiful sunset or listening to an emotional piece of music.
These three factors work together to create the profile of an HSP, where the individual is highly attuned to their sensory and emotional environment, experiencing it in more vivid and intense ways than most people. Understanding these factors helps to clarify the breadth and depth of Sensory Processing Sensitivity, offering insights into why HSPs might feel overwhelmed or respond emotionally to the world around them.
The original HSP model was criticised for focusing heavily on negative or overstimulating experiences. Smolewska et al. pointed out that sensitivity also includes positive elements, such as the ability to deeply appreciate art, music, and nature (captured by AES). This reframes sensitivity as not purely a vulnerability but also a potential strength.
Since then, a new HSP scale has been developed by researchers (but it has still yet to be published, as of January 2025). This scale attempts to make up for previous limitations by acknowledging the more positive aspects of the trait. However, below I share some perspective on what I still believe to be still missing from our understanding of the SPS and the highly sensitive person.
What is Still Missing
There are large aspects of sensitivity that are still not discussed or indicated in the Highly Sensitive Person scale/s. Dr Elaine Aron speaks to the spiritual inclination of Highly Sensitive People, and has previously stated in a blog post in 2011 that HSPs have a thinner boundary between the conscious, unconscious and collective unconscious (Aron, 2011). Yet, the lived experience of the highly sensitive person and the potential correlation between HSPs and their heightened propensity for spiritual experiences, awakening experiences, and their deep attunement to personal or collective suffering is not widely discussed.
The HSPs tendency to experience psychological distress and it’s potential catalyst for psycho-spiritual transformation also appears to be left out of the literature. Finally, what the purpose of the temperament is - beyond ‘surival’ - is also not explored in detail. I propose sensitivity has a purpose that goes beyond survival of the species but relates to our evolution of consciousness and psycho-spiritual awakening. Here, I will describe some concepts, which seem to be highly correlated to the construct of sensitivity. There are also so many questions behind the the contributing factors of high sensitivity. Although it’s understood to be an innate and genetic trait - I propose we need to explore the intergenerational aspects of the trait and how trauma or intergenerational trauma may play a role in the evolution of the trait.
Transliminality & Porous Boundaries
Research has highlighted a connection between sensitivity and transliminality, the ability for psychological material to cross thresholds of consciousness (Thalbourne & Houran, 2000). Sensitivity is considered a key component of the transliminality personality construct which appears closely linked to Hartmann’s (1991) concept of ‘boundary thinness.’ Boundary thinness refers to openness and ease of accessing altered states of consciousness, often associated with increased anomalous experiences (AEs) and sensory overload (Simmonds-Moore, 2009). Individuals with thinner boundaries are more likely to report experiences such as numinous dreams, mystical states, intense emotional responses, and sensory sensitivity (Roxburgh, Vernon, & Schofield, 2023; Rabeyron & Watt, 2010).
Given their heightened sensitivity to both external and internal stimuli, it is reasonable to expect that individuals scoring higher on sensory processing sensitivity (SPS) might also exhibit thinner boundaries. This suggests a potential overlap between SPS, boundary thinness, and transliminality, particularly in relation to anomalous experiences.
The propensity for Spiritual Awakening Experiences & Post-Traumatic Growth
Considering the fact that HSPs may have thinner psychological boundaries (as related to Hartmann’s concept of "boundary thinness"), they are also more likely to be open to altered states of consciousness, mystical experiences, or transcendent moments. This openness can facilitate spiritual awakenings, where individuals feel a heightened sense of connection to something greater than themselves. In addition, differential susceptibility, which is highly related to the construct of HSP, suggests that individuals vary in their sensitivity to environmental influences, meaning some people are more sensitive to both positive and negative stimuli than others. This concept can be linked to the HSPs potential for spiritual emergence, awakening or psycho-spiritual growth because it highlights how individuals with high sensitivity may respond more intensely to transformative experiences, which are often catalysts for spiritual or psychological development. Spiritual awakening refers to a gradual and often enriching process of emergence where one experiences a deeper sense of connection with the self, others, and the universe. It is characterised by heightened awareness, intuitive insights, expanded perceptions, and transformative shifts in one’s worldview. Trauma, difficult life experiences, stress or adverse childhood experiences, grief and loss often trigger the spiritual awakening process or can result in spiritual crisis. Again, since HSPs are more impacted by challenging life events but are more likely to respond to interventions because of their vantage sensitivity, I propose they are more likely to experience spiritual crisis but have the potnetial for psycho-spritiual transformation.
Borderland Consciousness
Jerome Bernstein’s theory of borderland consciousness (Berstein, 2015) offers a framework for understanding heightened sensitivity within a broader cultural and psychological context. Rooted in his work as a Jungian psychoanalyst and his engagement with Indigenous wisdom, his theory on borderland consciousness describes a state of being that bridges two distinct paradigms: the linear, materialistic worldview that dominates Western culture and the holistic, interconnected worldview of Indigenous traditions. Individuals with borderland consciousness navigate and integrate both of these approaches, often feeling an internal tension between the two where they seek to navigate their deep, intuitive understanding of the world with the more rational, scientific framework that dominates modern society. Like Highly Sensitive People, those with borderland consciousness are acutely attuned to the suffering of others, the collective unconscious, and the environment. This sensitivity allows them to perceive societal and ecological disruptions, often on a visceral level.
Bernstein argues that borderland consciousness often arises in individuals who have encountered trauma, leading to a sensitivity that makes them particularly attuned to the deeper, often unconscious dynamics of the human condition. This heightened awareness is not just psychological but also spiritual, as those with borderland consciousness are deeply aware of the interconnection between all things which shifts their way of relation to self, others and the world. Like Highly Sensitive People, individuals with borderland consciousness often find themselves feeling "out of sync" with mainstream society as their experiences and insights transcend traditional Western categories. Bernstein’s theory highlights the importance of integrating Indigenous wisdom into modern psychology, to address the split between rationality and intuitive, embodied knowing within Western culture. In both Highly Sensitive People and those with borderland consciousness, there is the potential for transformation and healing, not only for the individual but for the collective.
Conclusion
Sensory Processing Sensitivity (SPS) provides a profound framework for understanding how certain individuals interact with and are shaped by their internal and external environments. Through the pioneering work of Dr. Elaine Aron and subsequent researchers, the concept has evolved to highlight not only the challenges of heightened sensitivity but also the HSPs potential for positive transformation.
The exploration of HSP alongside related concepts, such as environmental sensitivity, differential susceptibility, and vantage sensitivity, has expanded our appreciation of how sensitive individuals can thrive under supportive conditions. Also, the nuanced components of SPS, which include Ease of Excitation (EOE), Low Sensory Threshold (LST), and Aesthetic Sensitivity (AES) shed light on the multifaceted nature of this trait, balancing its challenges with its strengths.
Despite these advancements, critical gaps remain, particularly in understanding the spiritual, transpersonal and transformative dimensions of sensitivity. Concepts related to spiritual awakening experiences and the theory of borderland consciousness point to deeper layers of sensitivity that intertwine with spirituality and our role in the collective. These areas need to be explorated further along with the lived experiences of highly sensitive individuals and their potential contributions to personal and societal transformation.
Ultimately, sensitivity is not a vulnerability but a dynamic trait with the capacity for personal and collective transformation that can foster a deeper connection with the world.
References
Aron, E. (2011). The priestly part of our being "Priestly Advisors" Part II: Individuation. The Highly Sensitive Person. Retrieved from https://hsperson.com/the-priestly-part-of-our-being-priestly-advisors-part-ii-individuation/
Aron, E. (1996). The Highly Sensitive Person: How to Thrive When the World Overwhelms You. New York: Broadway Books.
Bernstein, J. (2015). Living in the Borderland: The Evolution of Consciousness and the Challenge of Healing Trauma. London: Routledge.
Belsky, J., & Pluess, M. (2009). Differential susceptibility to environmental influences. Psychological Bulletin, 135(6), 885–908. https://doi.org/10.1037/a0017376
Pluess, M., & Belsky, J. (2013). Vantage sensitivity: Individual differences in response to positive experiences. Psychological Bulletin, 139(4), 901–916.
Roxburgh, E. C., Vernon, D., & Schofield, M. B. (2023). Exploring boundary thinness and its relation to sensory processing sensitivity and anomalous experiences. Journal of Parapsychology, 87(1), 50–65.
Rabeyron, T., & Watt, C. (2010). Paranormal experiences, trauma, and boundary thinness: A study of sensory processing sensitivity. Journal of Nervous and Mental Disease, 198(8), 614–621. https://doi.org/10.1097/NMD.0b013e3181e0866e
Smolewska, K. M., McCabe, S. B., & Woody, E. Z. (2006). A psychometric evaluation of the Highly Sensitive Person Scale: The components of sensory-processing sensitivity. Personality and Individual Differences, 40(6), 1269–1279. https://doi.org/10.1016/j.paid.2005.09.022
Simmonds-Moore, C. A. (2009). The role of boundary thinness, transliminality, and sensitivity in explaining anomalous experiences. Personality and Individual Differences, 47(7), 658–662. https://doi.org/10.1016/j.paid.2009.05.008
Thalbourne, M. A., & Houran, J. (2000). Transliminality, the questionnaire measurement of thin boundaries, and their correlates. Journal of Transpersonal Psychology, 32(1), 1–13.
About the Author
Jules De Vitto has a BSc in Psychology, MA in Education and MSc in Transpersonal Psychology, Consciousness and Spirituality and is an accredited transpersonal coach, trainer and experienced educator. She is the founder of the Highly Sensitive Human Academy - a central hub that offers courses, coaching, articles and a podcast for Highly Sensitive People. She helps those who identify with the traits of high sensitivity to navigate emotional overwhelm, step into their authentic power and align with their true purpose in life.
She is a published author and wrote one of a series of books on Resilience, Navigating Loss in a time of Crisis. Her research has also been published in the Transpersonal Coaching Psychology Journal and Journal of Consciousness, Spirituality, and Transpersonal Psychology.
In addition to her academic and coaching pursuits, Jules has spent years engaging in deep transformative healing work. She is a Reiki Master and Teacher and has completed Michael Harner’s Shamanic Practitioner Training through the Foundation of Shamanic Studies and a Grief Ritual Leadership Training with Francis Weller.
Jules is passionate about creating community for Highly Sensitive People and embracing the full spectrum of our emotional and sensory capacities rather than trying to ‘fix’ ourselves. Deepening the connection to our sensitivity enables us to open our hearts and form better relationships with ourselves, others and the world.
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