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Tools for Autism Screening: The M-CHAT and POSI

Updated: Mar 2

If you're a parent, you've likely read about increasing rates of autism diagnoses in recent years and wondered how children are diagnosed, if your own child is at risk, and when and how often they should be screened. There's no one-size-fits-all answer, as diagnosis time and method can vary depending on the individual. Below we provide an overview of the typical process from concern to care.

In this article:

What Is Autism?

Autism, or autism spectrum disorder (ASD), refers to a group of conditions that affect social skills, speech, and nonverbal communication. People with autism may also engage in repetitive behaviors or have restricted interests.

There is not one single type of autism, but instead a spectrum of strengths and challenges that range from mild to severe.

Healthcare professionals categorize ASD into one of three levels based on the level of support a person needs:

  • Level 1: Needs support

  • Level 2: Needs substantial support

  • Level 3: Needs very substantial support

Based on their level of impairment, some people diagnosed with ASD may need a great deal of support with the tasks of daily living, communication, and/or social skills. Others are high functioning and live independent lives.

Facts and Figures About Autism

  • In 2021, the CDC reported that approximately 1 in 44 children in the U.S. are diagnosed with ASD.

  • Boys are four times more likely to be diagnosed with autism than girls. This works out to:

    • 1 in 27 boys

    • 1 in 116 girls

  • Most children are diagnosed after age 4, though autism can be reliably diagnosed as early as age 2. Early diagnosis is important to improve outcomes by beginning interventions early when the brain has the most neuroplasticity (ability to adapt).

  • 31% of children with ASD have an intellectual disability (IQ less than 70), 25% are in the borderline range (IQ between 71 and 85), and 44% have IQ scores in the average to above average range (IQ greater than 85).

  • Autism affects all ethnic and socioeconomic groups.

  • Minority groups tend to be diagnosed later and less often.

Adapted from Autism Speaks

Screening For Autism In Toddlers

Children usually demonstrate signs of autism—such as delayed language skills, limited social interaction, repetitive behaviors, or loss of previously acquired speech or social skills—by age 2 or 3.

However, they might show other developmental delays associated with autism by 18 months or even earlier.

The American Academy of Pediatrics (AAP) recommends that all children receive (1) developmental screening at 9, 18, and 24 or 30 months; (2) screening when concerns are raised at a surveillance visit; and (3) autism screening at 18 and 24 months.

However, not all healthcare providers conduct the recommended screenings. In fact, a 2012 study found that only 17.8% of physicians complied with the three screening recommendations.

If your healthcare provider does not screen your child at these well-child visits, do not hesitate to ask for a screening.

You can also complete an autism screening form online or on the Pathfinder Health app and share the results with your primary care provider if you have any developmental concerns for autism.

Just remember that these screening tools do not diagnose children with autism. Rather, they are a starting point for a conversation with your healthcare provider.

Screeners can help a parent advocate on behalf of their child using clinical data. Your provider can then refer you to a specialist such as a developmental pediatrician, neurologist, or psychiatrist to perform a diagnostic evaluation.

We discuss the two major screening tools used to screen for autism in toddlers—the M-CHAT and POSI—below.

Modified Checklist for Autism in Toddlers


The Modified Checklist for Autism in Toddlers (M-CHAT) or Modified Checklist for Autism in Toddlers, Revised (M-CHAT-R) is a 20-question screening test designed for children between 16 and 30 months old.

It consists of 20 questions—the same questions are used at every age administered—about a child's verbal and non-verbal communication (both expressive and receptive), interest and interactions with other people, ability to pretend, and sensitivity to sound and movement.

Each question is answered simply with "pass" or "fail." Every "fail" response receives one point.

  • A score of two or less means that the child is not currently considered at risk and should continue with regular screenings.

  • A score of three or more indicates that a child is at least at medium risk for ASD and a healthcare provider should perform a follow-up interview to clarify responses.

  • A score of eight or more indicates that the child is at high risk and their healthcare provider may refer them immediately for a diagnostic evaluation and early intervention services.

Keep in mind, however, that even a finding of “high risk” on a screener is not an official ASD diagnosis–only a diagnostic evaluation by a specialist can provide a diagnosis.


The M-CHAT questionnaire has been revised to include follow-up questions and is now identified as the Modified Checklist for Autism in Toddlers, Revised with Follow-Up (M-CHAT-RF).

The M-CHAT was originally designed to maximize sensitivity, meaning that it would detect as many cases of ASD as possible and produce many false positives—children who are identified as "at-risk" by the M-CHAT but not later diagnosed with ASD.

To reduce the number of false positives, the doctors who created the M-CHAT revised it to include follow-up questions to be administered to children originally identified as medium or high risk.

These follow-up questions consist of a flow chart for each of the twenty M-CHAT questions that include both positive and negative examples and clarify the frequency of certain behaviors.

Because the M-CHAT-RF has added significant clarity to the original, make sure that you are using the latest version if you wish to screen your child.

Parents Observations of Social Interactions

The Parent’s Observations of Social Interaction (POSI) is one component of the age-specific Survey of Wellbeing of Young Children (SWYC) questionnaire that healthcare providers administer at the 18, 24, and 30-month well-child visits.

It consists of seven questions—the same at all ages—focused on a child's communication (both expressive and receptive) and play.

The parent answers by specifying the type and frequency of different social behaviors. If the parent selects one or more responses that fall in the last three columns, the question is scored as “1”; otherwise, it is scored as "0."

At the end of the test, a total score of three or more points indicates that a child is “at risk” and should receive additional evaluation or investigation.

Comparing the M-CHAT and POSI

Although the M-CHAT and POSI both screen for autism, they include different features and score results in different ways:

A set of two sub-studies examined and compared the reliability and validity of the POSI and M-CHAT with clinical evaluations performed by a healthcare provider. Both studies looked at how each screening tool compared in terms of sensitivity (the ability to catch the most true instances of a disease without missing anyone) and specificity (the ability to reduce false positives). The findings of the two sub-studies were as follows:

The sub-studies concluded that even though the POSI is a shorter evaluation tool, it compared well to the M-CHAT and may serve as an efficient way to screen for autism in toddlers.

Why Is It Important to Screen Early?

1. Early identification optimizes child outcomes

The first five years after your child’s birth are crucial to their health, well-being, and the overall trajectory of their life. In fact, 90% of your child's brain develops by age five.

This is the time when it has the highest neuroplasticity (the brain’s ability to essentially "rewire" itself to function in a different way). This flexibility means that treatment has the greatest impact during the early years, especially birth to age three.

So if the results of an M-CHAT or POSI screening suggest that your child is at risk, don't delay! Although autism may sound scary, it's important to remember that early diagnosis, treatment, and therapies can provide many benefits for your child and give them the best possible outcome.

These services can help your child learn the skills they need to be successful in school and life, reducing the need for more costly special education and related services later on.

In fact, some children who are diagnosed with autism and begin treatment at an early age progress so much that they are no longer on the autism spectrum when they are older. The key is to identify concerns at the earliest possible age.

Some of the benefits of beginning autism treatments and services at the earliest possible age include:

  • Improved communication

  • Improved social skills

  • Increased ability to participate in daily activities

  • Improved academic performance and educational attainment

  • Increased independence and self-reliance

Beginning these services early can also play a vital role in supporting parents and caregivers. It builds their competence and confidence, which helps them provide the best possible care and support for their children in the long term.

2. Services available to young children and their families

There are numerous publicly-funded and private resources, services, and support programs available to babies and young children with developmental delays and disabilities–including autism–as well as their families.

If your child is diagnosed with autism, there are many ways to maximize their learning and growth.

A type of therapy called Applied Behavior Analysis ("ABA") is specially designed for children with autism spectrum disorder and helps develop communication, self-help, and social skills, among others.

ABA and other therapies based on it are the most researched and commonly used behavioral interventions for autism.

Many children diagnosed with autism also benefit from other interventions, such as speech and occupational therapy to help them function in daily life.

If your healthcare provider detects a concern, they can refer you to the appropriate type of specialist or services.

Additionally, parents can self-refer to Early Intervention Services (EIS), publicly funded programs provided by the states.

A doctor's referral is not required for EIS.

You can even seek EIS before your child receives a diagnosis–it is available to any child with a developmental delay. If you are concerned about your child’s development, you can find more information and links to EIS on the Pathfinder Health app or the CDC website.

Frequently Asked Questions

1. What is the official autism test?

There is no official autism test. Autism screening tools, such as the M-CHAT, can be helpful for gathering clinical data that can form the basis for a referral to a specialist, who will perform a diagnostic evaluation based on behavior and developmental history.

2. What is the gold standard test for autism?

There is no one perfect test for autism. The Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview-Revised (ADI-R) provide standardized, objective data and are screening tools used as part of a comprehensive evaluation by a specialist.

3. Is there a free autism test?

You can access the M-CHAT screening tool for free online. To receive a reliable diagnosis, you need an evaluation by an autism specialist. You can complete the screening, evaluation, and diagnosis process (if necessary) for free through your city/county, school system, or Child Find.

4. Can you test for autism online?

There are autism screening tools, such as the M-CHAT, available online. However, these do not test for autism, but rather indicate if additional evaluation is warranted. An evaluation by an autism specialist is the only way to receive an accurate diagnosis.

5. What is the best age to test for autism?

Although some children may show signs of autism as infants, most autism screening tools are developed for children 18 months and older. However, it is still important to screen for autism early, especially if you have concerns, to learn if your child is at risk.

6. How do doctors test for autism?

There is no lab test for autism. Rather, doctors perform a comprehensive evaluation that considers standardized diagnostic tools and takes into account the child’s developmental history and behavior.

7. What is the CARS test in autism?

The Childhood Autism Rating Scale (CARS) is used to distinguish between children with autism and those with other developmental delays. It rates 15 different behaviors and produces a composite score ranging from non-autistic to severely autistic.

8. What is the AQ test for autism?

The Autism Spectrum Quotient (AQ) is a questionnaire used to screen for autism in adults (over 16). The AQ is self-administered and has 50 questions. It is not meant to diagnose autism, but can form part of a more thorough evaluation.

9. What is the ADOS test for autism?

The Autism Diagnostic Observation Schedule (ADOS) is a standardized second tier screening tool used to assess children’s behavior across certain categories for use in diagnosing autism. The assessment is based on the examiner’s direct interaction with the child.

10. What test can confirm a diagnosis of autism?

Doctors assess whether a child demonstrates certain types of social communication and interaction deficits and engages in restricted, repetitive patterns of behavior as set out in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

11. Can you genetically test for autism?

Genetic testing cannot diagnose autism, which is caused by multiple genetic and environmental factors. However, genetic testing can identify genes associated with autism in particular cases and can provide insights for treatment or prevention of related conditions.

A Closing Thought

Most importantly, remember that if your child does receive an autism diagnosis, they are still the same child. An autism diagnosis is simply the means of accessing the best possible treatment and services for both your child and your family.

But the earlier the intervention, the better the outcome will be for your child–so don't delay if you have any concerns.

And remember that you are not alone–there are many resources available to help your child learn and thrive!


1. Arunyanart W, Fenick A, Ukritchon S, et al. Developmental and Autism Screening: A Survey Across Six States. Infants & Young Children: July/September 2012 - Volume 25 - Issue 3 - p 175-187.

2. Autism Speaks. Autism and Health: A Special Report by Autism Speaks (2017) available at


4. Smith NJ, Sheldrick RC, Perrin EC. An Abbreviated Screening Instrument for Autism Spectrum Disorders, available at

5. Zwaigenbaum, L., Bauman, M. L., Choueiri, R., Kasari, C., Carter, A., Granpeesheh, D., et al. (2015). Early intervention for children with autism spectrum disorder under 3 years of age: Recommendations for practice and research. Pediatrics, 136(Suppl 1), S60–81.


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