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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.
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