An infant is expected to say their first words at 12-15 months, show object permanence, walk unassisted, and can exhibit separation anxiety. At 4-6 months, infants start to babble or repeat sounds. At 7-11 months, infants can imitate sounds but not usually say their first word yet. At 16-18 months, toddlers are expected to be able to say around 10 words.

An infant starts imitating sounds, using gestures, and responding to their own name and simple instructions at 7-11 months. By 12-15 months, an infant is expected to say their first words. At 4-6 months, infants start to babble or repeat sounds but don't yet respond to their own name. At 1-3 months, infants are only cooing or gurgling in response to attention.

Edward Titchener (1867-1922) was a member of the structuralist field of thought. He and the other structural psychologists aimed to reduce psychological phenomena down to its basic mental processes.