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milestonesSOME COGNITIVE ATTAINMENTS OF INFANCY

A P P R OX I M A T E E X P L O R A T I O N /A G E P R O B L E M S O LV I N G O B J E C T C O N C E P T I M I T A T I O N C A T E G O R I Z A T I O N

Birth–1 month

1–4 months

4–8 months

8–12 months

12–18 months

18 months–2 years

� Categorization of per-ceptually similar stimuli

� Beginning categoriza-tion of objects by func-tion and behavior

� Categorization of manyobjects by function andbehavior

� Categorization of socialstimuli (for example,emotional expressions,human versus nonhu-man movement patterns)

� Active object sortinginto a single category

� Active object sortinginto two categories

� Imitation of adults’facial expressions andgestures (see Chapter 4)

� Deferred imitation of adults’ facial expressions after 24 hours

� Deferred imitation of adults’ actions onobjects after 24 hours

� Deferred imitationacross changes in con-text and after one toseveral months

� Imitation of actions anadult tries to produce,even if these are notfully realized

� Deferred imitation ofeveryday behaviors inmake-believe play

� Awareness of size andshape constancy (seeChapter 4)

� Use of motion and spatial arrangement toidentify objects (seeChapter 4)

� Some awareness ofobject permanence

� Use of shape, texture,and color to identify objects (see Chapter 4)

� Ability to retrieve anobject from the firstlocation in which it ishidden

� Ability to search in sev-eral locations for a hid-den object (A–B search)

� Ability to find an objectmoved while out of sight(invisible displacement)

� Newborn reflexes

� Exploration with limitedmotor skills, such ashead turning and sucking

� Exploration with bettercoordinated motor skills,such as kicking, reaching,and grasping

� Limited anticipation ofevents

� Exploration using well-coordinated reaching,grasping, swiping, bang-ing, and other manualbehaviors

� Intentional, or goal-directed, behavior

� Improved anticipation ofevents

� Problem solving by analogy to other similarproblems

� Exploration of objects byacting on them in novelways

� Experimenting withactions when solvingproblems

� Sudden solutions toproblems, without overt experi-mentation with actions.

Note: These milestones represent overall age trends. Individual differences exist in the precise age at which each milestone is attained.

III C O G N I T I V E A N D L A N G U A G E D E V E L O P M E N T

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