Highly sensitive person (HSP) refers to a personality trait involving increased sensitivity of the central nervous system and deeper cognitive processing of physical, social, and emotional stimuli. While not an officially recognized clinical diagnosis, the concept of sensory processing sensitivity has gained popularity as a way of explaining why some people seem to be more deeply affected by their environments and relationships. This article examines the evidence for HSP and whether it can be considered a valid construct.
What is High Sensory Processing Sensitivity?
The term “highly sensitive person” was first coined in the 1990s by psychologist Elaine Aron to describe individuals she identified as having increased sensitivity to physical, emotional, and social stimuli. According to Aron, HSPs process information more deeply and exhibit increased emotional reactivity. Key characteristics include:
- Becoming easily overwhelmed by external stimuli like bright lights, loud noises, crowded spaces, or strong scents
- Noticing subtleties in the environment that others miss
- Easily startled or rattled by unexpected stimuli
- Feeling deeply moved by arts, music, or nature
- Experiencing unpleasant sensory input more intensely
- Needing extra down time to recharge from too much stimuli
- Disliking violent or shocking content
- Feeling strong emotional responses to other people’s moods
- Being conscientious with great attention to detail
While HSP is viewed as an inborn trait, the degree of sensitivity can vary across different situations and life stages. Estimates suggest 15-20% of people have high sensory processing sensitivity.
Is there evidence for a biological basis?
While no specific gene has been identified, research suggests there may be genetic underpinnings to sensory processing sensitivity. Studies have found the following:
- HSP self-reports are fairly consistent over time, suggesting an inherent trait rather than a transient state.
- Identical twins are more likely to share HSP traits compared to non-identical twins or unrelated people.
- Adoptees are more similar in sensitivity to biological parents than adoptive parents.
- Brain imaging shows HSPs have increased activation in regions related to awareness, integration of sensory information, empathy, and planning.
This indicates high sensitivity likely has some biological and heritable origins, though environment clearly plays a role as well.
Is HSP related to established disorders?
While some clinicians apply an HSP diagnosis, it does not appear in the Diagnostic and Statistical Manual (DSM) or International Classification of Diseases (ICD). However, research suggests overlap and comorbidity between high sensitivity and certain disorders including:
- Anxiety disorders: Heightened sensitivity to stressors is linked to social anxiety, generalized anxiety, and post-traumatic stress.
- Depression: Difficulty coping with overstimulation may increase depression risk.
- ADHD: Sensory sensitivity is common in ADHD, though impulsivity is usually low in HSPs.
- Autism: Autism involves sensory processing differences, though social motivation tends to be lower than HSPs.
The heightened sensory-emotional reactivity of HSPs likely represents one pathway that may underpin multiple diagnostic categories when more impairing.
How is HSP assessed?
No clinical interviews or medical tests exist to diagnose HSP. Self-report questionnaires have been developed to measure the construct including:
- The Highly Sensitive Person Scale (HSPS)
- The Highly Sensitive Child Scale
- The Adult Sensory Processing Sensitivity Scale
These tools assess sensitivity across domains like stress reactivity, emotional intensity, sensory discomfort, attention to detail, and ease of overwhelm. However, no cutoff scores are universally accepted for determining HSP status.
Strengths of HSP Measures
- Demonstrate good internal reliability.
- Relate as expected to brain function and personality traits like neuroticism, introversion, and empathy.
- Link to outcomes like depression in expected directions.
Limitations of HSP Measures
- Lack norms and consistent cutoffs to qualify someone as highly sensitive.
- Susceptible to response bias if someone desires the HSP label.
- Not yet demonstrated to have predictive power distinguishing HSPs from general population.
Is high sensitivity adaptive or problematic?
Views differ on whether HSP represents:
- An advantage evolutionarily, with deeper processing of context and heightened threat response.
- A risk factor making people more prone to overwhelm and negative emotionality.
- A temperament difference that may be adaptive or problematic depending on context.
Research overall suggests sensory sensitivity is a double-edged sword with upsides and downsides:
Potential advantages
- Noticing subtleties and making meaningful connections
- Thinking deeply before acting
- Empathizing and connecting emotionally
- Appreciating arts, nature, and beauty
- Conscientiousness and attention to detail
Potential disadvantages
- Easily overwhelmed by noise, crowds, deadlines
- Slow recovery from upsetting events
- Prone to anxiety or depression when overstimulated
- Withdrawing or avoiding due to high arousal
- Hyperfocusing at cost of missing the big picture
Overall, HSPs likely have capabilities both well suited and problematic for certain environments or situations.
Is HSP a valid construct?
Evaluating the validity of HSP hinges on several considerations:
Does HSP describe a coherent, distinct trait?
Yes, self-report scales show good internal consistency and relate as expected to other traits like introversion and neuroticism. Brain imaging also reveals distinct functional patterns in HSPs.
Is HSP heritable and stable over time?
Twin studies suggest genetics contribute substantially to high sensitivity. Self-reports also remain fairly stable into adulthood, indicating an innate trait rather than temporary state.
Does HSP have adaptive or detrimental effects?
While heightened sensitivity can impair functioning in some contexts, it also relates to positive outcomes like conscientiousness and creativity. Overall, HSPs appear to have specialized strengths alongside greater vulnerability to overarousal.
Can HSP be reliably and validly measured?
Self-report scales consistently assess the same underlying trait. However, lack of norms or cutoffs makes it difficult to determine clinically significant levels of sensitivity. Blind raters would improve reliability.
Does HSP reliably predict outcomes or treatment response?
More research is needed on whether HSP status predicts life outcomes or response to treatments. Early indications are promising, but clinical utility remains to be seen.
Is HSP distinct enough from existing diagnoses?
While HSP shares traits with anxiety, ADHD and autism, it also demonstrates unique characteristics not defined by other disorders.
Conclusion
In summary, high sensory processing sensitivity appears to describe a coherent and likely innate trait involving deeper cognitive processing and heightened emotional reactivity to stimuli. Preliminary evidence is promising for HSP as a valid construct that may inform psychiatric vulnerability and personalized treatment. However, important gaps remain in demonstrating its clinical utility as a diagnostic category. More research is still needed on the predictive power, measurement properties, heritability, and neurobiology of sensory processing sensitivity across the lifespan. But despite limitations, HSP represents a promising framework for understanding personalized traits of oversensitivity that can pose both strengths and impediments in everyday life.