āIf there is an āinvisible handā at work it is that empathy matures and consciousness expands to fill the temporal and spatial boundaries set by the new energy regime. Empathy becomes the thread that weaves an increasingly differentiated and individualized population into an integrated social tapestry, allowing the social organism to function as a whole.ā āThe Empathic Civilizationā by Jeremy Rifkin.
Sensitivity is a normal part of life. There are days when even the strongest of us may feel overwhelmed by the pressures of life, the world, our children, our bosses, and our heartbreaks. On the positive side, even the crankiest of humans may sometimes be overtaken by spontaneous joy, delight in small pleasures, a favorite song, or the sight of a belovedās face. However, the degree and frequency to which any individual experiences an amplified sense of, and perhaps oversensitivity to, the world and others varies. Some of us may feel very sensitive to things every day. We may become strongly affected by othersā moods, hear every note in a song, and become bothered or delighted by the slightest of things. For others, it may take a great deal of stress, an extreme situation, or a specific trigger to induce a strong reaction. This enhanced sensitivity to the environment is also known as sensory processing sensitivity (SPS), differential susceptibility, vantage sensitivity, high environmental sensitivity, and biological sensitivity to context (see Greven et al., 2019 for review). In addition to greater responsiveness to the environment, SPS is also characterized by enhanced awareness, empathy, depth of processing, and self-reflection (Aron & Aron, 1997; Acevedo, Aron, & Aron, 2018; Acevedo, Aron, Pospos, & Jessen, 2018).
At some level we all know that people vary in their sensitivity. I remember years ago, when talking to a nutritionist because I was having some gastrointestinal issues, the implicit nature of SPS came across in a very subtle way. At the time, I was having trouble digesting many foods which, once upon a time, had never bothered me. Suddenly, I could not eat many foods without experiencing pain and bloating. After completing a long list of questions, the nutritionistās diagnosis was not irritable bowel syndrome, nor a wheat allergy, nor a gluten intolerance. She proceeded to tell me in not so many words that she thought I was ātoo sensitive.ā The example she gave went something like this, āBianca, my dad is the type of person who can have his finger chopped off and he will continue to do his job as if nothing has happened. On the other hand, my mother will cry when she gets a papercut.ā Although I was relieved to learn that I didnāt have a chronic disease or a serious issue, I was mildly disappointed because there is no remedy for high sensitivity. It took years of trying different things to get my digestive system back to homeostasis. Eventually, Ayurveda, the ancient Indian practice of nutrition, is what worked for me; as well as figuring out that wheat was the culprit of many of my digestive issues.
Indeed, we all have varying degrees of sensitivity that is subject to change depending on the big and small circumstances of our lives, our life stage, and the types of activities we engage in. For example, mind-body practices, such as meditation, may enhance oneās awareness of and sensitivity to the environment. However, for some individuals, (approximately 20%ā30%), high sensitivity is their baseline. It is not a disorder and there is no cure for it. You canāt take a magic pill to make it go away. If you are having challenges at work, or with your health, or your romantic partner, it is more likely than not that your boss, doctor, and even your romantic partner may misunderstand you, misdiagnose you, not get you, or flat out not have the mental or emotional bandwidth to support you. They may simply think that youāre over-reactive, dramatic, eccentric, difficult, neurotic, or anxious. However, the flip side is that when SPS expresses itself adaptively, highly sensitive individuals engage in deep thinking, make better decisions, ponder spiritual questions, and engage in meaningful work (Aron & Aron, 1997; Aron, Aron, & Jagiellowicz, 2012). Thus, many people may deem those with the trait to be creative, gifted, empathic, nurturing, mystical, and intuitive.
Many of us may not be aware that we have the trait or that there is a genetic, biological basis for our sensitivity. SPS may be especially hard to identify in those of us that are extraverts or high sensation seekers [roughly 30% of highly sensitive persons (HSPs)] (Lionetti et al., 2018). Others may have been shunned for their high sensitivity, especially men (Falkenstein, 2019), so they learned to repress, deny, or hide it. And even for those who have a robust self-esteem about their sensitivity, they may not make a big show of it, but instead suffer silently when the world feels overwhelming. Also, they donāt boast, brag, or give themselves enough credit when their sensitivity results in great acts of kindness, creativity, insight, and love. Indeed, many highly sensitive individuals suffer from low self-esteem (Aron et al., 2010) as studies have shown significant correlations between high SPS and low self-esteem (Acevedo, Aron, & Aron, 2018; Acevedo, Aron, Pospos, et al., 2018). Some has been written about this topic, for example, see Dr. E Aronās book, The Undervalued Self. Also, stigma, low self-esteem, and shame are commonly experienced by highly sensitive individuals as a result of knowing, whether implicitly or explicitly, that they are ādifferent,ā a minority, and being misunderstood.
The aim of this book is multifold. One of the aims of this volume is to shine a light on the science of sensitivity so that individuals with the trait and others can come to understand it as a normal variation that does not need fixing, shunning, or special accommodations. It is simply a variation, like being right-handed versus left-handed, or being tall versus short. These variations all serve a purpose and many have remained in our gene pool because they have helped with species survival in some way.
To achieve these aims, this book describes theory, research, validated assessment tools, and clinical issues related to high sensitivity. It may serve as a practical manual for the assessment of SPS which may be particularly useful to clinicians, educators, physicians, and health care workers. It may also serve as a tool for researchers and instructors, providing them with background, theory, and science on SPS to date, so they may apply the measures and ideas in their research and/or the classroom.
Another goal of this volume is to provide a comprehensive scientific analysis of SPS so that more individuals may learn to understand and have a greater respect for this trait, rather than seeing it as a weakness or deficiency. This may help future generations to simply ābeā of their kind and realize that when those with the trait are nurtured, they have much more to offer, and the world to gain. However, itās important to realize that it is pretty standard and normal for humans to have preferences, both slight and strong. Also, the problem with any minority is that humans have a hard time not falling into one group or another. It makes things, situations, and people easier to process cognitively when they are compartmentalized so that we can quickly size things (and people) up without taking the extra cognitive effort to unpack it all. Indeed, this is yet another strategy that has helped our species to survive.
1 The science of sensory processing sensitivity
According to scientists, there are a few big questions that remain to be answered, āWhat is the origin of life?ā, āWhat is the universe made of?ā, āIs there intelligent life beyond our planetā, and āWhat is the source of human consciousness?ā. I would argue that the topic of this book indirectly addresses the last of these questions as it largely deals with a scientific explanation of SPS: an innate, genetically based trait that is characterized by enhanced awareness and responsivity to the environment and other individuals. Other cardinal features of SPS include heightened awareness, enhanced responsivity to the environment, and greater depth of processing, self-reflection, empathy, and intuition. Coincidentally, some of the characteristics attributed to SPS overlap with those that scientists consider to engender āmental consciousness,ā such as the ability to be aware that one is experiencing something. Mental consciousness is thought to be distinct from creature consciousness (or wakefulness) in that it involves awareness that a stimulus is present, awareness that oneās self exists, and awareness that it is oneās self that is sensing, behaving, and solving problems (Ledoux & Brown, 2017). Therefore, by gaining a better understanding of the biological mechanisms underlying SPS, we may inadvertently contribute to solving āthe hard problem of consciousness.ā
In seminal research on the neural basis of SPS, it was discovered that as a function of the SPS trait, greater brain response was shown in brain regions associated with awareness, memory, self-other processing, and empathy (Acevedo et al., 2014; Acevedo, Jagiellowicz, Aron, Marhenke, & Aron, 2017; Jagiellowicz et al., 2011). Applying some of this knowledge to understanding the hard problem of consciousness may help scientists, for example, by providing them with a more narrow focus of brain regions that may be targeted for the study of mental consciousness. Also, perhaps by focusing our examinations on individuals, who are both highly sensitive and well adjusted, thanks to good-enough childhoods and not-too-stressful lives, we may gain a better understanding of the expression of the trait in its purest form. Indeed, in positive environments, high SPS persons can be quite content, calm, and well-adjusted. Not that I mean to say that highly sensitive people are always more calm or aware than others, but again, such work is needed. Another issue is that most of the world sees dysfunction more readily because unhappy individuals tend to complain more, and express their stress, discomfort, and anxiety. On the other hand, highly sensitive individuals tend to like their āsolitude,ā so we may not see them at their best. Again, such work may further advance the scientific understanding of consciousness.
2 The history of sensory processing sensitivity
The road to a scientific understanding of SPS has not been linear. It has taken interesting twists and turns. In its infancy, the systematic study of what we now call SPS was lar...