Characteristics of SPS as graphically summarized by Greven et al. (review article, 2019)[1] A person with a high measure of SPS is said to be a highly sensitive person (HSP).[2][3]
Sensory processing sensitivity (SPS) is a temperamental or personality trait involving "an increased sensitivity of the central nervous system and a deeper cognitive processing of physical, social, and emotional stimuli".[2] The trait is characterized by "a tendency to 'pause to check' in novel situations, greater sensitivity to subtle stimuli, and the engagement of deeper cognitive processing strategies for employing coping actions, all of which is driven by heightened emotional reactivity, both positive and negative".[3]
A human with a particularly high measure of SPS is considered to have "hypersensitivity", or be a highly sensitive person (HSP).[2][3] The terms SPS and HSP were coined in the mid-1990s by psychologistsElaine Aron and her husband Arthur Aron, who developed the Highly Sensitive Person Scale (HSPS) questionnaire by which SPS is measured.[3] Other researchers have applied various other terms to denote this responsiveness to stimuli that is seen in humans and other species.[4]
According to the Arons and colleagues, people with high SPS make up about 15–20% of the population.[2] Although some researchers consistently related high SPS to negative outcomes,[3][5] other researchers have associated it with increased responsiveness to both positive and negative influences.[6][7][8][9] Aron and colleagues state that the high-SPS personality trait is not a disorder.[10][11]
Origin and development of the terms
Elaine Aron's book The Highly Sensitive Person was published in 1996.[12] In 1997 Elaine and Arthur Aron formally identified[13]sensory processing sensitivity (SPS) as the defining trait of highly sensitive persons (HSPs).[3] The popular terms hypersensitivity (not to be confused with the medical term hypersensitivity) or highly sensitive are popular synonyms for the scientific concept of SPS.[2] By way of definition, Aron and Aron (1997) wrote that sensory processing here refers not to the sense organs themselves, but to what occurs as sensory information is transmitted to or processed in the brain.[13] They assert that the trait is not a disorder but an innate survival strategy that has both advantages and disadvantages.[10][11]
Elaine Aron's academic journal articles as well as self-help publications for the lay reader have focused on distinguishing high SPS from socially reticent behavior[14] and disorders[11][15] with which high SPS can be confused;[16] overcoming the social unacceptability that can cause low self-esteem;[16] and emphasizing the advantages of high SPS[17] to balance the disadvantages emphasized by others.[5][16][18]
In 2015, journalist Elizabeth Bernstein wrote in The Wall Street Journal that HSPs were "having a moment," noting that several hundred research studies had been conducted on topics related to HSPs' high sensitivity. The First International Scientific Conference on High Sensitivity or Sensory Processing Sensitivity was held at the Vrije Universiteit Brussel.[19] By 2015, more than a million copies of The Highly Sensitive Person had been sold.[20]
Earlier research
Research pre-dating the Arons' coining of the term "high sensitivity" includes that of German medicine professor Wolfgang Klages, who argued in the 1970s that the phenomenon of sensitive and highly sensitive humans is "biologically anchored" and that the "stimulus threshold of the thalamus" is much lower in these persons.[21] As a result, said Klages, there is a higher permeability for incoming signals from afferent nerve fibers so that they pass "unfiltered" to the cerebral cortex.[21]
The Arons (1997) recognized psychologist Albert Mehrabian's (1976, 1980, 1991) concept of filtering the "irrelevant", but wrote that the concept implied that the inability of HSPs' (Mehrabian's "low screeners") to filter out what is irrelevant would imply that what is relevant is determined from the perspective of non-HSPs ("high screeners").[13]
Attributes, characteristics and prevalence
Boterberg et al. (2016) describe high SPS as a "temperamental or personality trait which is present in some individuals and reflects an increased sensitivity of the central nervous system and a deeper cognitive processing of physical, social and emotional stimuli."[2]
People with high SPS report having a heightened response to stimuli such as pain, caffeine, hunger, and loud noises.[5] According to Boterberg et al., these individuals are "believed to be easily overstimulated by external stimuli because they have a lower perceptual threshold and process stimuli cognitively deeper than most other people."[2] This deeper processing may result in increased reaction time as more time is spent responding to cues in the environment, and might also contribute to cautious behavior and low risk-taking.[2]
SPS involves responsiveness to both environmental adversity and positive environmental aspects, respectively modeled by the diathesis–stress model and the vantage sensitivity framework.[22]
The HSP Scale, initially (1997) a questionnaire designed to measure SPS on a unidimensional scale, was subsequently decomposed into two,[23][24] three,[25] or four[26] factors or sub-scales.[2] Most components have been associated with traditionally accepted negative psychological outcomes[2][3] including high stress levels, being easily overwhelmed, increased rates of depression, anxiety, and sleep problems, as well as autistic traits;[2] the diathesis–stress model focused on increased vulnerability to negative influences.[6] However, the differential susceptibility theory (DST)[6][7] and biological sensitivity to context theory (BSCT)[8] and sensory processing sensitivity (SPS)[27] suggest increased plasticity in terms of responsiveness to both positive and negative influences; and the vantage sensitivity (VS) concept emphasizes increased responsiveness to positive experiences.[9][28] Researchers such as Smolewska et al. (2006) said positive outcomes were more common in individuals with high aesthetic sensitivity, who tend to experience heightened positive emotions in response to rewarding stimuli and more likely to score high on "openness" on the Big Five factors model.[29]
Research in evolutionary biology provides evidence that the trait of SPS can be observed, under various terms, in over 100 nonhuman species,[2][4] Aron writing that the SPS trait is meant to encompass what personality psychologists have described under various other names.[30] Conversely, Aron has distinguished SPS from what she considers it is not, explicitly distinguishing[31] high SPS from possibly similar-appearing traits or disorders (such as shyness,[16][32]sensation-seeking,[33]sensory processing disorder,[15] and autism[10]), and further, that SPS may be a basic variable that may underlie multiple other trait differences[13] (such as introversion versus extraversion[31]). Contrary to common misconception, according to Aron HSPs include both introverts and extroverts,[34] and may be simultaneously high-sensation seeking and cautious.[33]
In humans and other species, responsive and unresponsive individuals coexist and consistently display different levels of responsiveness to environmental stimuli, the different levels of responsiveness having corresponding evolutionary costs and benefits.[4] This observation parallels Aron's assertion that high SPS is not a disorder, but rather a personality trait with attendant advantages and disadvantages.[10][11] Accordingly, Aron cautions medical professionals against prescribing psychoactive medications to "cure" the trait, which may or may not coexist with an actual disorder.[35]
A 2015 longitudinal study based on army medical records of Swedish men showed a correlation between low resting heart rate and violence and criminality, with the authors theorising that lower sensitivity to stimulation resulted in increased likelihood of risk-taking and sensation-seeking behaviour – effectively a low sensitivity counterpart to SPS.[39]
HSP Scale score patterns in adults were thought to be distributed as a dichotomouscategorical variable with a break point between 10% and 35%,[15] with Aron choosing a cut-off of the highest-scoring 20% of individuals to define the HSP category.[2] A 2019 review article stated that findings suggest people fall into three sensitivity groups along a normal distribution sensitivity continuum.[1]
^ abcdefgBooth, Charlotte; Standage, Helen; Fox, Elaine (1 Dec 2015), "Sensory-processing sensitivity moderates the association between childhood experiences and adult life satisfaction", Personality and Individual Differences, 87: 24–29, doi:10.1016/j.paid.2015.07.020, PMC4681093, PMID26688599
^ abcWolf, Max; Van Doorn, G. Sander; Weissing, Franz J. (2008). "Evolutionary emergence of responsive and unresponsive personalities". PNAS. 105 (41): 15825–15830. doi:10.1073/pnas.0805473105. PMC2572984. PMID18838685. "Such differences in responsiveness (also termed coping style, reactivity, flexibility, plasticity) have been documented in many organisms including ... humans" (n. 15 citing Aron & Aron (1997, SPS) and n. 16 citing Belsky et al. (2007, differential susceptibility)). Boterberg et al. (2016) cites Wolf et al. (2008) for the statement: "research in evolutionary biology provides evidence that the trait of SPS can be observed in over 100 nonhuman species."
^ abcBoyce, W. Thomas (2016). "Differential Susceptibility of the Developing Brain to Contextual Adversity and Stress". Neuropsychopharmacology. 41 (1): 141–162. doi:10.1038/npp.2015.294. PMC4677150. PMID26391599.
"(T)here is an emerging scientific consensus on how 'sensitivity to context' may be instantiated with an intricate and compelling neuroscience" (p. 149). "... a now substantial corpus of evidence ... documenting differences in susceptibility at the levels of temperament and behavior ("The Highly Sensitive Person at p. 146), neuroendocrine physiology, brain structure and function ("Cortical sensory processing sensitivity" at p. 149), neuronal sensitization and responsivity, and allelic and epigenetic variation within genomic structure" (p. 157).
^ abcdAron, E.N. (2006). "The Clinical Implications of Jung's Concept of Sensitiveness". Journal of Jungian Theory and Practice. 8: 11–43. CiteSeerX10.1.1.490.9371. Discussion re nervous system is, inter alia, in "Prelude to Research" at p. 14.
^ abcdAcevedo, B; Aron, E; Pospos, S; Jessen, D (April 2018). "The functional highly sensitive brain: a review of the brain circuits underlying sensory processing sensitivity and seemingly related disorders". Phil. Trans. R. Soc. B. 373 (1744): 20170161. doi:10.1098/rstb.2017.0161. PMC5832686. PMID29483346. (I)n this review, we compare the neural regions implicated in SPS with those found in fMRI studies of Autism Spectrum Disorder (ASD), Schizophrenia (SZ) and Post-Traumatic Stress Disorder (PTSD) to elucidate the neural markers and cardinal features of SPS versus these seemingly related clinical disorders. We propose that SPS is a stable trait that is characterized by greater empathy, awareness, responsivity and depth of processing to salient stimuli. We conclude that SPS is distinct from ASD, SZ and PTSD in that in response to social and emotional stimuli, SPS differentially engages brain regions involved in reward processing, memory, physiological homeostasis, self-other processing, empathy and awareness. We suggest that this serves species survival via deep integration and memory for environmental and social information that may subserve well-being and cooperation.
^Kaufman, Scott Barry (May 4, 2015). "Shades of Sensitivity". Scientific American. Archived from the original on December 8, 2015. Kaufman explains Smolewska et al. (2006).
^ abKlages, Wolfgang (1978). Der sensible Mensch : Psychologie, Psychopathologie, Therapie (The Sensitive Human: Psychology, Psychopathology, Therapy) (in German) (1 ed.). Stuttgart, Germany: Enke. p. 133. ISBN978-3432898711. OCLC6710563. Klages distinguishes between sensitive and highly sensitive people, classifying artists and "high intellectuals" as an example of the latter.
^Pluess, Michael (September 2015). "Individual Differences in Environmental Sensitivity". Child Development Perspectives. 9 (3): 138–143. doi:10.1111/cdep.12120. "...perhaps the most significant contribution shared across all three frameworks [SPS and DST, BSC] is the notion that sensitive individuals differ not only in their response to environmental adversity but also in response to positive, supportive aspects of the environment".
^Boterberg et al. (2016): overreaction to stimuli (OS) and depth of processing (DP).
^Smolewska et al. (2006): Aesthetic Sensitivity (AES, having greater awareness of beauty), Low Sensory Threshold (LST, easily unpleasantly aroused by external stimuli), and Ease of Excitation (EOE, easily overwhelmed by stimuli); results showing the (unidimensional) HSP Scale was "a valid and reliable measure of the construct of SPS"). Liss et al. (2008).
^Per Boterberg et al. (2016), a "theoretical redefinition" by E. Aron, Psychotherapy and the Highly Sensitive Person (2010): "DOES" acronym: Depth of processing, Overstimulation, Emotional intensity, Sensory sensitivity.
^Smolewska, Kathy A.; McCabe, Scott B.; Woody, Erik Z. (2006). "A psychometric evaluation of the Highly Sensitive Person Scale: The components of sensory-processing sensitivity and their relation to the BIS/BAS and "Big Five"". Personality and Individual Differences. 40 (6): 1269–1279. doi:10.1016/j.paid.2005.09.022. See also Kaufman, Scientific American (2015).
^Paraphrasing Aron and citing Wolf re different names for same or equivalent concepts:
From "Adult shyness: ..." (2005): weak nervous system (Pavlov), low screening (Mehrabian), augmenting (of stimulation; Petrie), reducing (of evoked potential; Buchsbaum, Haier, & Johnson), reactivity (Strelau), avoidance temperament (Elliot & Thrash), and nondisinhibition or reflectivity (Patterson & Newman), and what child temperament researchers have described as inhibitedness (Kagan), infant (or innate) shyness (Cheek & Buss; Daniels & Plomin), reactivity (Rothbart; Strelau), and threshold of responsiveness (Thomas & Chess).
From "The Clinical Implications of Jung's Concept of Sensitiveness" (2006): innate sensitiveness (Jung),
From "Adult shyness: ..." (2005): arousal focus (Feldman), and the physiological differences underlying introversion and extroversion (Eysenck; Stelmack; Stelmack & Geen).
From Wolf et al. (2008): coping style, reactivity, flexibility, plasticity, and differential susceptibility.
From "'The Power of (Shyness)' and High Sensitivity..." (2012): (re introversion) 30% of HSPs are social extroverts.
From "Adult shyness: ..." (2005): SPS doesn't inherently possess shyness' fear of negative social evaluations.
From p. 2 of "The HSP in love" (<=2007): an HSP who is also a High Sensation Seeker will find ways to have novel experiences without taking ill-considered risks.
From "The Clinical Implications of Jung's Concept of Sensitiveness" (2006): (re autism) HSPs are very aware of social and emotional cues and relate well socially once familiarity is achieved.
^Aron, Elaine N. (1996). "9. Medics, Medications and HSPs". The Highly Sensitive Person. Broadway Books. pp. 194–197. ISBN9780806536705. Especially subsections "A Caution About Medical Labels for Your Trait" through "Instant Arousal-Stopping Medications".
^Licht, Cecile L.; Mortensen, Erik L.; Knudsen, Gitte M. (2011). "Association between Sensory Processing Sensitivity and the 5-HTTLPR Short/Short Genotype"(PDF). Center for integrated molecular brain imaging. Archived(PDF) from the original on June 6, 2012. ● Licht, C., Mortensen, E. L., & Knudsen, G. M. (2011). "Association between sensory processing sensitivity and the serotonin transporter polymorphism 5-HTTLPR short/short genotype." Biological Psychiatry, 69, supplement for Society of Biological Psychiatry Convention and Annual Meeting, abstract 510.
