Does not become quiet or smile when spoken to (0–3 months)
Does not notice sounds in the environment (4–6 months)
Does not vocalize excitement and displeasure (4–6 months)
Does not respond to simple requests and directions such as “no” and “come here” (1 year)
Does not recognize words for common objects (1 year)
Does not produce beginning sounds such as /p/, /b/, /m/ (1–2 years)
Does not point to pictures when named (1–2 years)
Does not say new words each month (1–2 years)
Does not seem to understand simple 1-step instructions (1–2 years)
Others have difficulty understanding his or her speech
Does not talk during pretend play such as saying “Beep-Beep” when playing with cars (2 years)