The Spectrum of Autism Symptoms

Common and Unusual Symptoms of Autism

Autism spectrum disorder is clinically diagnosed by specialists or teams of specialists who usually have significant experience. They use various tests to help determine if someone has the symptoms, or traits, of the disorder. Then they select one of three levels indicating the amount of support the autistic person needs, and they can select from a slew of specifications (such as intellectual disability) that may or may not be present.

But even all those tools don't provide enough information to help a parent, teacher, or therapist accurately envision a particular individual's strengths, challenges, behaviors, or needs. Just as significantly, they have no real role to play in choosing the most appropriate treatments or predicting outcomes over the lifespan.

In fact, an autism spectrum disorder diagnosis tells you remarkably little about any individual person, their particular challenges and strengths, or the therapies that would help them cope with or overcome any difficulties they experience in navigating non-autistic society.

Autism "Symptoms" vs. "Traits"

Autism is a type of neurodivergence, in which a person's brain functions in ways that are different than what's considered "neurotypical." Increasingly, neurodivergence is seen as a difference rather than an illness, and its characteristics are thought of as traits rather than symptoms.

Universal Symptoms of Autism

Verywell / Laura Porter

Universal Symptoms of Autism

Everyone with an appropriate autism spectrum diagnosis has certain traits, described in the American Psychiatric Association "Diagnostic and Statistical Manual of Mental Disorders Fifth Edition" (DSM-5). The diagnostic criteria for autism include the following:

  • Deficits in social communication and social interaction across multiple contexts
  • Deficits in nonverbal communicative behaviors used for social interaction
  • Deficits in developing, maintaining, and understanding relationships
  • Restricted, repetitive patterns of behavior, interests, or activities
  • Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior
  • Highly restricted, fixated interests that are abnormal in intensity or focus
  • Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment

All of these symptoms, of course, can occur in someone who is not autistic. To qualify for an autism diagnosis, therefore, all of the traits must be present. In addition, the traits must not be explainable by another diagnosis.

For example, a person with differences in communicative behaviors may be hard of hearing or have low vision, either of which would impair verbal or written communicative skills. Finally, the traits must have a real and consistent impact on the person’s lived experiences and activities of daily life.

Autism Symptoms Are Hard to Nail Down

If you close closely at each of the traits of autism, you'll recognize that they are very general. They also depend on a shared understanding of what is "normal." The diagnostic criteria provide a range of possible ways in which the symptoms can present themselves, but even these don't begin to cover the range of possibilities.

For example, all autistic people have difficulty with social communication and interaction. But how does that difficulty present? The possibilities are almost endless:

  • An autistic person can be completely unable to use spoken language.
  • They may be able to speak and write fluently but have a hard time recognizing sarcasm or jokes.
  • They may be able to speak but only using phrases they repeat from TV or movies. They may be unable to craft their own unique phrases and sentences.
  • They may be able to speak and write fluently but have an unusual "prosody" (flat or unusual vocal tone).
  • They may be able to speak moderately well but use unexpected phrases that are unusual for their age or their situation (a 10-year-old using the term "indubitably," or an adult talking about a preschool television show).
  • They may be able to learn to use new words and phrases at an unusually slow rate, or they may never learn to use new words or phrases at all.

The appropriate therapies and expected outcomes are very different based on not only the presentation but also the type of speech disorder.

Surprisingly, autistic people with lesser differences in communication may find it harder to manage in typical settings than people with more differences—because they are more aware of their challenges, of others' judgments, and of their social mishaps when they occur.

The same wild diversity of expression is the same for many other autism criteria. For example, while some autistic people are hypersensitive to sound and light, others are hyposensitive—meaning that they barely notice sensory input that would overwhelm non-autistic peers.

So an autistic person in a crowded concert hall might find the music physically painful, enjoyable, or barely noticeable.

Well-Known But Uncommon Symptoms

It's easy to be fooled by the media into thinking that unusual autistic abilities, behaviors, or interests are actually universal among people on the spectrum. For better or worse, however, many of these are not only universal—they are relatively rare.

The 1988 movie "Rainman" led many to assume that autism is characterized by outstanding feats of memory and calculation. This ability, called savant syndrome, is actually quite rare: Only about 10% of people on the spectrum have savant abilities. Of those, most (like the character in "Rainman") are unable to use those skills in real-world situations.

Several TV shows and documentaries as well as the media in general suggest that people on the spectrum have above-average intelligence. While many do, a large percentage have an intellectual disability with significant challenges in daily function.

It is a cliche that autistic people love and are good at technology. While there are certainly people on the spectrum that fall into this group, a great many do not. In fact, a large percentage of autistic people have little or no ability to code, operate complex software, or use household electronics.

Many sources show or describe people on the spectrum as being able to think visually in complex ways. While most people on the spectrum are visual thinkers, however, the ability to (for example) mentally manipulate three-dimensional objects is unusual.

One blatantly wrong misconception is that autistic people are unable to form loving relationships. Quite a few presentations of autistic people suggest that they are unemotional. They also suggest a lack of humor and empathy.

There are people on the spectrum who do seem to fall into these categories. Most, however, have strong emotions and emotional attachments; many are very funny, and most are at least sympathetic if not empathetic. Autistic people, however, express these qualities in different ways, so they can be hard for non-autistic people to recognize.

And, of course, many non-autistic people appear unemotional and unempathetic, as well.

Symptoms Shared By Non-Autistic Peers

There are many autistic traits that are shared by people who are not autistic. They become markers of autism based not on their existence but on the degree to which they vary from what non-autistic society considers normal.

Of course, "normal" is in the eye of the beholder. Thus it can be hard to determine whether a behavior indicates a person is "autistic." To a degree, it's a matter of how the behavior is expressed rather than whether it is expressed. For example:


Stimming, which is short for self-stimulation, refers to sounds and movements that have no purpose other than self-calming or self-stimulation. These can range from the more common (hair twirling, toe-tapping, and nail-biting) to the less common (swaying or rocking, continuous repetition of a phrase or song line, and self-injury through headbanging or pinching).

Most autistic people stim, but then again most human beings stim in one way or another. Most people learn, sooner or later, that while hair twirling is accepted in neurotypical society, rocking or twirling is not (though most children go through a stage during which they do a great deal of twirling). In response, autistic people either mask their traits or are unable or unwilling to conform.

Almost all forms of stimming are harmless and they offer benefits to the person stimming, but doing so is stigmatized and people with less-common forms of stimming are subject to teasing, bullying, stares, and marginalization.

Social Difficulties

If most non-autistic people were socially competent all the time there would be no such thing as self-help books, matchmaking services, romantic breakups, or divorce. In fact, reality TV shows would cease to exist.

Many non-autistic people have a hard time reading unspoken signals that say "I like you" or "I am romantically interested in you." What makes these qualities become traits of autism, then, is not their existence but their quality and intensity.

Most non-autistic people can recognize a joke—based partly on their understanding of body language, partly on their understanding of human situations, and partly on their grasp of subtle differences that can make a situation funny. Autistic people may not recognize jokes at all or may have a very different idea of what's funny.

Sensory Dysfunction

If you've ever been overwhelmed by loud noise, bright lights, crowds, or even smells, you know what it's like to experience sensory overload. Many autistic people experience sensory overload as a result of what most people consider to be normal stimuli—that is, fluorescent light bulbs, emergency buzzers, crowded parties, and the like.

But many people without autism have similar issues, and some people (such as those who live with migraines or tinnitus) may have quite extreme responses to sensory input without being autistic.

Autistic people may also be undersensitive to sensory input and crave loud noises or the sensation of being squeezed. Interestingly, weighted blankets, once considered to be therapeutic tools for people with sensory dysfunction, are now popular for those with mild anxiety.

Restricted Interests and Behaviors

Restricted interests, behaviors, and routines are very common among autistic people—and among people in general. Autistic people may carry these qualities to an extreme (eating nothing but chicken fingers, or becoming agitated when bedtime is pushed back by ten minutes).

But many autistic people are (or can be) as flexible as many non-autistic people who prefer sameness and routine. Similarly, it can be hard to distinguish between a "normal" fascination with video games and an "autistic" fascination; the differences lie more in how the fascination is expressed than in the fascination itself.

That is: an autistic person may find it difficult to talk about anything except the favored interest, discuss the interest in a rapid monotone, and assume that others are as interested in the topic as they are.

A Word From Verywell

It's important to remember that autism spectrum disorder is not a monolithic disorder; people on the spectrum are as diverse as the non-autistic population. While some people on the spectrum have symptoms, or traits, that radically limit their ability to interact comfortably with non-autistic people, many do not.

And while some autistic people have rare savant traits, these are not typical of being autistic. The bottom line, as is often stated in autism circles: "When you've met an autistic person, you've met an autistic person."

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013.

  2. Treffert DA. The savant syndrome: an extraordinary condition. A synopsis: past, present, futurePhilos Trans R Soc Lond, B, Biol Sci. 2009;364(1522):1351-7. doi:10.1098/rstb.2008.0326.

Additional Reading

By Lisa Jo Rudy
Lisa Jo Rudy, MDiv, is a writer, advocate, author, and consultant specializing in the field of autism.