No, Being Autistic Is Not the Same as Being Highly Sensitive

Two women sitting on rock facing a lake and mountains.

Source: Roberto Nickson on Pexels.

Co-authored by Rachel Samson, M.Psych and Erin Bulluss, Ph.D

The internet is now the primary residence of popular or “pop” psychology; concepts and theories about human experiences, supposedly based on psychology that find acceptance among the public.

Both autism and high sensitivity have found their way into this arena with thousands of pop psychology pages, websites, videos, articles, and social media accounts. Often these focus on areas of overlap between autism and high sensitivity and suggest these might be the same thing with two different names.

Both the diagnostic criteria for autism and the measures assessing for high sensitivity include sensory experiences that differ from most of the population. According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders,¹ one of the diagnostic criteria for autism is:

Hyper- or hypo-reactivity to sensory input or unusual interests in sensory aspects of the environment (e.g., apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement).

The validated self-report highly sensitive person scale^2,3 includes items such as "I am easily overwhelmed by things like bright lights, strong smells, coarse fabrics, or sirens close by," "I am easily overwhelmed by strong sensory input," and "I am bothered by intense stimuli, like loud noises or chaotic scenes."

While there is certainly a major overlap in sensory processing experiences of both autistic and highly sensitive individuals, specifically sensitivity to sensory information, this does not mean they are the same thing.

As clinical psychologists with a special interest in neurodiversity—one who is autistic and one who is highly sensitive, our clinic receives a high volume of referrals for clients who are highly sensitive and/or autistic and who are seeking formal assessment or informal help in untangling their particular flavour of neurodivergence.

Often undiagnosed autistic people seeking our services have absorbed misinformation and identify (or have been identified) as highly sensitive, resulting in missed diagnosis and, subsequently, a lack of access to required supports. There can be a reluctance to let go of the identity of being a highly sensitive person and embrace autistic identity instead, due to stigma and misunderstanding surrounding autism. Therefore, creating a barrier to self-acceptance that limits mental health and wellbeing.

We also hold concerns about highly sensitive people being misdiagnosed as autistic by professionals who are not trained in assessing temperament and high sensitivity, which may lead to poor self-understanding and mismatched supports.

Sensitivity

Sensitivity is a heritable and evolutionarily conserved temperament trait.⁴ Temperament is defined as biologically based individual differences in reactivity and self-regulation.⁵ Just as humans differ from one another on their level of introversion and other temperament traits, people also vary in how sensitive they are. It is estimated that around 30 percent of the population is highly sensitive.⁶ High sensitivity presents equally in males and females and has been observed in over 100 species, including humans, monkeys, dogs, fish, and insects.^{7,8,9,10,11,12,13,14,15}

The scientific term for sensitivity is sensory processing sensitivity (SPS), though people are often more familiar with the popular psychology terms highly sensitive person (HSP)¹⁶ and highly sensitive child (HSC).¹⁷ While we talk about “high sensitivity” as a category, research shows SPS forms a continuum from low sensitivity to high sensitivity.⁶

Highly sensitive people, compared to those who are less sensitive, tend to have:

• a greater response to stress,
• a greater capacity for noticing subtleties in their environment,
• deeper cognitive processing of physical, social, and emotional stimuli,
• greater emotional reactivity to positive and negative information, and
• a tendency to become more easily overstimulated.¹⁸

High sensitivity is considered a phenotypic marker of an underlying greater biological sensitivity to the environment and a more reactive central nervous system. Individuals across species vary in their sensitivity to the environment, with some individuals being more strongly affected by their environment and others being less affected.

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In other species of animals, approximately 20 percent of the population is more responsive to the environment and has been labeled high-reactive.¹⁹ Variations in environmental sensitivity are understood to increase the group’s ability to adapt to the environment^20,21 as highly sensitive individuals across species can detect opportunities and risks that can promote the safety and wellbeing of the larger group.

Autism

Autism is a lifelong neurodevelopmental divergence present in around 2 percent of the population;^22,23 initially defined within the medical model and thus framed as a form of pathology, autism is increasingly viewed as part of the naturally occurring neurodiversity of humankind.²⁴

The DSM-5¹ defines autism spectrum disorder as:

• the presence of marked socio-communicative and socio-emotional divergence

along with some combination of:

• sensory processing differences
• capacity for hyper-focus
• intensity and/or specificity of interests
• preference for sameness and predictability
• repetitive or ritualistic behaviours

To be diagnosed within the medical model, these experiences must be present in some form starting in early childhood and significantly limit how the individual functions in current socio-cultural expectations.

The variation in presentation among autistic people has led to autism being erroneously presented as a spectrum that encapsulates all experiences on a scale of “typical” to “severely autistic.” In reality, autism is categorically distinct and underpinned by structural differences in brain development beginning in utero and leading to significant divergences in processing across various areas. It is not possible to be a “little bit autistic,” just as it is not possible to be “a little bit pregnant”; you either are autistic or you aren’t.

Differentiation of Autism and HSP

Similarities

Sensory Processing

While sensory processing is the main similarity between autism and high sensitivity, there are some differences in how this presents. While highly sensitive individuals tend to experience hyper-reactivity to sensory information, autistic individuals may have either a hyper- or hypo-reactivity to sensory information, a combination of both, or neither.

Capacity for Empathy

High empathy is also frequently included in lists of characteristics and anecdotes of the HSP, reflecting the underlying reactivity to the environment and subsequent ability to notice subtleties.

Many autistic people relate to the experience of high empathy. Because historically it was believed that autistic people characteristically lacked empathy, many autistic people instead relate to descriptions of high sensitivity. Now we understand that autistic people do not inherently lack empathy; research shows on the neural systems level, activation of the empathy network is comparable to that of non-autistic people.²⁵

Differences

Nature of Phenomenon

Both autism and high sensitivity are examples of neurodivergence. Sensitivity is a temperament trait that occurs along a continuum; high sensitivity reflects heightened reactivity to the environment and thus heightened experiences.

Autism is a neurodevelopmental divergence that is either present or not. Differences in brain structure and connectivity result in qualitatively different ways of experiencing oneself and the world, including heightened experiences.

Prevalence

The prevalence of autism is currently estimated at around 2 percent of the population.^22,23 While many people believe the actual prevalence might be higher due to misdiagnosis and missed diagnosis, it is very unlikely that the accurate prevalence of autism would be over 20 percent of the population, which is the proportion of the population of a variety of species that research has consistently identified to be highly sensitive.

Processing Style

Human brain imaging research using fMRI has shown an association between high SPS and increased activation of brain regions involved with depth of processing. High sensitivity is associated with a depth of processing, meaning relevant information may take longer to process and feel more intense. ²⁶

On the other hand, autistic people have both a higher perceptual capacity²⁷ and hyperconnectivity across brain regions,²⁸ meaning a greater volume of information from the environment is processed at any given time,²⁹ whether directly relevant or not. This indicates a breadth—as well as a depth—of processing in autistic people.

Impact of Environment

While autistic people have more fixed but idiosyncratic neurodevelopmental trajectories and require lifelong accommodations to flourish, the developmental trajectories and outcomes of HSPs are strongly influenced for better and for worse depending on the environment.

Research has shown that highly sensitive individuals have poorer developmental outcomes and an increased likelihood of behavioural and psychological difficulties in stressful and unsupportive early environments.^{19,30,31,32,33,34,35} Conversely, in supportive and highly nurturing early environments, highly sensitive people have the capacity to flourish and may have better developmental trajectories than less sensitive individuals.^19,30,34,35

In contrast, autistic people require supports and accommodations to thrive in modern society.²⁴ Where there is not the capacity for the environment to adapt to and accommodate the needs of the autistic person, the environment is then disabling and significantly impacts and limits the functional capacity and wellbeing of the autistic person.

By understanding the conceptual and experiential differences between autism and high sensitivity, rather than simply focusing on the similarities, we can recognise these are two distinct—yet potentially co-occurring—neurodivergences that both add to the necessary neurodiversity of humankind.