Checklist for Autism in Toddlers- CHAT

Abstract

The Checklist for Autism in Toddlers (CHAT) is a seminal, brief behavioral screening instrument designed for the early detection of Autism Spectrum Disorder (ASD) and related pervasive developmental disorders in children aged approximately 18 months. Developed by researchers including Simon Baron-Cohen and Gillian Baird, the CHAT was revolutionary in its combination of both parent-reported behaviors (Section A) and direct clinical observation by a healthcare professional (Section B).

The scale focuses on key predictive behavioral markers, such as the ability to engage in joint attention, symbolic or pretend play, and basic social interaction skills. Its structure allows for rapid administration during routine developmental surveillance checks, facilitating timely referral for diagnostic assessment and early intervention services.

Keywords

Autism Spectrum Disorder, ASD, Toddlers, Screening, Early Detection, Joint Attention, Pretend Play, Psychological Assessment, Developmental Disorders.

Authors

Gillian Baird, T. Charman, A. Cox, Simon Baron-Cohen, J. Swettenham, S. Wheelwright, A. Drew.

Purpose

The primary purpose of the CHAT is to serve as a rapid, cost-effective, and standardized screening tool for identifying young children who exhibit early indicators associated with Autism Spectrum Disorder or other Pervasive Developmental Disorders (PDDs). It is specifically tailored for administration by primary care providers, such as General Practitioners (GPs) or Health Visitors (HVs), during standard developmental assessments typically conducted at the 18-month check-up.

Successful identification using the CHAT is intended to trigger immediate referral to specialist services. Early diagnosis and subsequent intervention are crucial steps in improving developmental trajectories and maximizing long-term outcomes for children on the autism spectrum.

Construct

The CHAT is designed to measure fundamental social and communicative deficits that are present early in life and are highly predictive of a later autism diagnosis. The instrument focuses on three core psychological constructs:

• Joint Attention: The ability to share attention with another person regarding an object or event. This is assessed through items requiring the child to follow a pointing gesture and to use pointing gestures to indicate interest to the clinician (protodeclarative pointing).
• Pretend Play (Symbolic Play): The capacity for imaginative and symbolic thought, which is assessed through items related to the child’s ability to engage in functional or imaginative play scenarios, such as pretending to drink tea.
• Social Reciprocity and Interest: The child’s innate interest in other children and enjoyment of basic reciprocal social games (e.g., peek-a-boo).

Validity

The original CHAT demonstrated high specificity, meaning that a child who screened positive was highly likely to receive a later diagnosis of ASD (low false positive rate). This high positive predictive value made the scale useful for identifying high-risk cases.

However, when used in general population screening, the CHAT historically exhibited lower sensitivity, suggesting that a significant number of children who were later diagnosed with ASD screened negative on the CHAT (high false negative rate). The scale’s strongest predictive validity lies in the five critical items (A5, A7, B2, B3, B4), which specifically target joint attention and pretend play deficits.

Reliability

The reliability of the CHAT is generally considered adequate for a brief screening instrument. The observational component (Section B) requires standardized training for clinicians to ensure high inter-rater reliability. When administered correctly by trained personnel, the observational items show good consistency.

Internal consistency (Cronbach’s alpha) is moderate, which is expected given the scale’s brevity and its design to measure distinct, though related, behavioral domains using dichotomous (Yes/No) responses rather than a continuous Likert scale.

Factor Analysis

Factor analysis of the CHAT typically reveals a structure that aligns closely with the two-part administration method. The items tend to coalesce around two main factors: Parent-Reported Socialization and Development (Section A) and Clinician-Observed Social Communication and Symbolic Function (Section B).

Crucially, the items related to protodeclarative pointing (Item A7/B4) and pretend play (Item A5/B3) consistently emerge as the strongest independent predictors, reinforcing the hypothesis that deficits in joint attention and imagination are core components of the construct being measured.

Instrument

Test Type: Screening Tool (Behavioral and Developmental Assessment)

Format: Combined Parent Questionnaire (9 items) and Clinical/Health Professional Observation (5 items). Dichotomous scoring (Yes/No).

Language Available: English (Original), widely translated and used in international studies.

Population Group: General pediatric population undergoing routine developmental surveillance.

Age Group: Toddlers, typically between 18 and 24 months of age.

Population Details: Primarily utilized in community health settings, such as primary care clinics and health visitor services, for universal screening purposes.

Test Methodology: The CHAT is designed for quick administration (approximately 5–10 minutes). Section A is completed by the parent or caregiver. Section B involves structured, specific tasks conducted by the clinician during the appointment, aimed at eliciting key behaviors like shared attention and symbolic play in a controlled environment.

Keywords

Screening Instrument, Early Intervention, PDDs, Simon Baron-Cohen, Child Development, Social Communication, Observation Scale.

Authors

Author ORCID Identifier: N/A

Affiliation Email addresses: N/A

Correspondence Address: N/A

Permissions & Fee and Test Year

The CHAT was initially developed and validated in the early 1990s. The scale is generally considered a non-proprietary instrument and is often utilized free of charge for clinical and academic research purposes.

Test Year: Initial publication and validation occurred between 1992 and 1996.

Permissions & Fee: Typically available free of charge for non-commercial clinical use. The instrument can often be found via the Autism Research Centre (ARC) website.

Reference’s

Baird, G., Charman, T., Cox, A., Baron-Cohen, S., Swettenham, J., Wheelwright, S. and Drew, A. (2001). Screening and surveillance for autism and pervasive developmental disorders Archives of Diseases in Childhood 84:468-475.

Items of the Checklist for Autism in Toddlers- CHAT

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.