The modified checklist of autism in toddlers (MCHAT) adheres to a list of informative questions about the child. The answers to these questions indicate whether the child needs evaluation by a specialists to detect his/her neurological development.

The Autism Behavior Checklist is a 57-item questionnaire that is undertaken by parents or teachers of the patient. The ABC is divided into five subscales for evaluation purpose. These include sensory behavior, social relating, body and object use, language and communication skills, and social and adaptive skills.

The Autism Observation Scale is used to determine autism in infants who have an older sibling with autism. It is a play-based, semi-structured design which allows identifying early signs of autism in infants in the age group of 6 to18 months. There are seven activities that provide behavior observing opportunities in the areas such as visual tracking, disengagement of attention, orientation to name, reciprocal social smiling, differential response to facial emotion, social anticipation and imitation.

This test is designed for parents to identify autism spectrum disorder in their child. It contains 50 items across five areas associated with autism spectrum disorders such as social skills, attention switching, attention to detail, communication and imagination. The rating needs to be done by the parents by using either ‘definitely agree’ or ‘definitely disagree’.

When specialists refer a child after evaluation for possible autism spectrum disorder, a structured interview called the Autism Diagnostic Interview-Revised (ADI-R) is conducted with the parents of the child. Anyone who has achieved a mental growth of 18 months can take up this interview and it deals with areas of reciprocal social interaction, communication and language, and patterns of behavior.

The ADI-R is conducted in an informal set-up like home and has 93 questions which need to be answered in a span of 1-2 hours. This investigator-based interview questions are open ended and provide all the information required to determine a valid rating for each behavior. Parents and caretakers need to enthusiastically participate in the test as their inputs are valued by the evaluator. 

Autism Diagnostic Observation Schedule is a series of structured and semi-structured tasks that allows social interaction between the examiner and the subject. The subject’s behavior is observed and determined by the evaluator who assigns these to predetermined observational categories. The scores of the analysis are determined by the observations of subject’s behavior and pre-determined observations.

Generally, ADOS takes 30 to 60 minutes to evaluate the subject. For the subject to show social and communication behaviors characteristic of autism, the examiner provides a series of opportunities. There are four modules and each subject is evaluated from activities of one module. The modules are selected on the basis of the developmental and language level of the subject. 

Childhood Autism Rating Scale is a 15-item behavior rating scale that helps to identify children with autism. It also helps in identifying the degree of autism affect in a person from mild, moderate to severe. The Scale is convenient to evaluate child over 2 years of age. There are five prominent items for diagnosing autism that are included in CARS. Each of these items includes a specific characteristic, ability or behavior. By observing the child and evaluating inputs from parents’ report, the rating of the child is given on each of the five items. The rate scale is marked on a 7 point scale, and the rating of the subject determines the severity of autism in the child. 

The Gilliam Autism Rating Scale is used to identify autism in individuals from the age group of 3 to 22 years. The items for GARS are based on four subtests such as Stereotyped Behaviors, Communication, Social Interaction and Developmental Disturbances.

The first 3 core subtests describe and measure the behavior of the subjects and the fourth test developmental disturbances allows inputs from parents.

The GARS-2 is a revised version of GARS screening tool. Developed by Dr. James E. Gilliam, this also serves to track autism in subjects between the ages of 3-22 years. Unlike the first version, GARS 2 has three subtests to screen the individual. It includes 42 questions to screen individuals and can also track the severity of each case from mild, moderate to severe. 

The Childhood Asperger Syndrome Test is a questionnaire designed for parents to screen for Asperger Syndrome and other social and communication disorders. The test consists of a 37-item questionnaire for parents to be answered in either ‘yes’ or ‘no’, and questionnaires for children in the age group of 4 to 11 years old.