The Spectrum of Autism Symptoms

Common and Unusual Symptoms of Autism

Small boy looking out the window

Xesei/Getty Images

Autism spectrum disorder is diagnosed by specialists or teams of specialists who usually have significant experience. They use various tests to help determine if someone has the symptoms of the disorder. Then they select one of three levels of severity and 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 symptoms.

Universal Symptoms of Autism

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

  • Deficits in social communication and social interaction across multiple contexts
  • Deficits in nonverbal communicative behaviors used for social interaction
  • Deficits in developing, maintaining, and understand 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 symptoms must be present. In addition, the symptoms must not be explainable by another diagnosis.

For example, a person with deficits in communicative behaviors may be hard of hearing or have low vision, either of which would impair typical communicative skills. Finally, the symptoms must be significant enough to have a real impact on activities of daily life.

Autism Symptoms Are Hard to Nail Down

If you close closely at each of the symptoms 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 people with autism have difficulty with social communication and interaction. But what kind and level of difficulty? The possibilities are almost endless:

  • A person with autism 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 (inappropriately) using phrases they repeat from TV or movies. Or they may use TV-talk appropriately, but 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 treatments and expected outcomes are very different based on not only the severity but also the type of speech disorder.

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

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

So a person with autism 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 there are many people with autism who have average or above-average IQs, according to Autism Speaks: "An estimated 40% of people with autism are nonverbal, 31% of children with ASD have an intellectual disability (intelligence quotient [IQ] <70) with significant challenges in daily function, 25% are in the borderline range (IQ 71–85)."

It is a truism that people with autism 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, use complex software, or even handle a TV remote.

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.

Quite a few presentations of autistic people suggest that they are unemotional, or unable to form loving relationships. 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. People with autism, however, express these qualities in idiosyncratic ways, so that they can be hard to recognize.

Symptoms Shared By Typical Peers

There are many autism symptoms that are shared by people who are not autistic. They become symptoms of autism based, not on their existence, but on the degree to which they vary from what is considered "normal."

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

Stimming

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 typical (nail-biting, hair twirling, toe-tapping) to the clearly unusual (violent rocking, pacing, and even self-injury through headbanging or pinching).

Most people with autism stim, but then again most human beings stim in one way or another; most typically developing people learn, sooner or later, that while hair twirling is acceptable, violent rocking or twirling is not (though most children go through a stage during which they do a great deal of twirling).

Stimming is essentially harmless, but those people with exaggerated or unusual forms of stimming are subject to teasing, bullying, stares, and marginalization.

Social Difficulties

If most typically developing 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 typically developing 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 symptoms of autism, then, is not their existence but their quality and intensity.

Most typically developing 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.

People with autism may not recognize jokes at all or may have a very different idea of what's funny. But then again most people with autism can recognize and find the humor in pratfalls and physical humor.

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 people with autism experience sensory overload as a result of what most people consider to be normal stimulus—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.

People with autism 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 people with mild anxiety.

Restricted Interests and Behaviors

Restricted interests, behaviors, and routines are very common among people with autism—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 people with autism are (or can be) as flexible as many "typical" 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: a person with autism 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 nearly as diverse as the typical population. While some people on the spectrum have extreme symptoms that radically limit their ability to participate in typical activities, many do not.

While some people with autism have surprising or unusual symptoms, they are not typical of the disorder. The bottom line, as is often stated in autism circles: "When you've met a person with autism, you've met a person with autism."

Was this page helpful?
Article 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.

  3. Autism Speaks. Autism statistics and facts.

Additional Reading