1Infant Perception-IILast class:I. Face PerceptionII. CategorizationIII. Depth Perception ( we will finish today)Today:IV. Object SegregationV. Cross-Modal PerceptionVI. ConclusionsC. Fear of heights?Visual cliff: deep and shallow sidesCampos et al.2 groups:--Experienced crawlers (9 mos)--Beginning crawlers (7 mos)15 per groupResults:Experienced:15/15 cross shallow0/15 cross deepBeginning: 15/15 cross shallow10/15 cross deep (most!)Related results:--Babies (in harness) go off a high table!(Rader et al.)--Phone survey of parents: babies crawl off high surfaces (e.g., tables, couches, beds, changing tables)Initial Interpretation:--Beginning crawlers have depth perception, but NO fear of heights!--How does fear develop?--Falls and near falls--Social referencing2• Uncertainty: --with 12-inch drop:-infants use social referencing-if parent poses fear, infants don’t cross deep side-if parent poses joy, infants cross deep side• Certainty:--with 40 inch drop:-infants ignore parent posing joy -infants don’t cross deep side--with 4 inch drop:-infants ignore parent posing fear-infants cross deep side--Autonomous thinkers!New Interpretation:--Campos: Beginning crawlers have depth perception, but NO fear of heights!--but new evidence by Adolph (assigned reading article) suggests a somewhat different conclusion:Infants do not learn fear of heights once and for all.Rather, infants learn what is safe vs. unsafe for eachposture (e.g., sitting, crawling, walking) separately!• 12-month-old experienced crawlers do not crawl into drop (confirms Campos), BUT:• 12-month-olds novice walkers walk into drop!!!• 18-month-olds experienced walkers do not walk into dropKretch & Adolph readingFocus: 90-cm dropD. Conclusions--Young infants have some depth perception at birth --How well they see depth depends on cues available--Infants learn implications of depth (e.g., drop-off) separately for each postureIV. Object SegregationWhere does each object begin and end in a scene?3A. Adults: many sources of infoone such source is Featural information:e.g., shapepatterncolortextureetc.If surfaces on either side of the screen have the same features, then same objectPartly occluded display:If surfaces on either side of the screen have different features, then different objectsPartly occluded display:4B. Infants?Needham et al.4 mosViolation-of-expectation Method:--Show two test events: expected: consistent with expectationunexpected: violates expectation--If look reliably longer at unexpected event, have expectationSimilar ConditionMove-Together EventMove-Apart EventResults:--look reliably longer at apart than attogether event-- see red surfaces as 1 box• Assume similar features mean one objectDissimilar ConditionMove-Together EventMove-Apart EventResults:--look reliably longer at together than atapart event-- see red and green surfaces as 2 boxes• Assume different features mean different objects5C. Conclusions--By 4 months, use featural info to organize visual scenes--However, not at 3 months—infants learn touse featural info to organize visual scenesbetween 3 and 4 monthsIII. Cross-modal PerceptionFocus: Auditory-visual perceptionA. Do newborns orient toward sounds?Yes, as long as…--held properly--sounds not too intense--sounds not too briefB. Do infants know what sights and sounds go together? Spelke and Owsley3.5 mos and olderPlay mom’s or dad’s voice on speakerMOM DADBABYMATCH voice to parent!!Kuhl and Metzolf4 mos-MATCH sound to face!!-extended to 2 months!See silent videotapes of same woman saying“a” or “ee”Hear “a” or “ee” on central speakerC. How do infants attain theirauditory-visual knowledge?--Association--Anything else?Adults can detect synchronyCan infants also?6Spelke4 mosFam: 100 sec Donkey soundtrack100 sec Kangaroo soundtrackTest: several 5 sec segments of Donkey & Kangaroo soundtracksslowfastPredictions:--If only association: ZIP!--If can detect synchrony: MATCH soundtrackto movie!Results:--MATCH each soundtrack to its movie!--Can detect synchrony--Extended to many other eventsExample of other events: Lewkowicz and Ghazanfar--at 4 and 6 months, infants can match vocalization and face of rhesus monkey--fail at 8 and 10 months, because of perceptual narrowing in processing of cross-species faces, vocalizations, or bothlong coo(affiliative encounter)short grunt (threat call)VI. Conclusions--Infants’ perceptual world is not fundamentallydifferent from that of older children and adults--From birth, they possess a rich set of perceptual abilities that are elaborated, fine-tuned, and shaped by experience--But do infants think about the world as we do? Is their cognitive world qualitatively similar to ours, or is it fundamentally different?--The developmental researcher who first promoted the idea that infants and young children are fundamentally different thinkers than older children and adults was the Swiss psychologist Jean Piaget--We now turn to a discussion of his influential theory on cognitive development--Next, we will examine how Piaget’s theory has been revised over time7Piaget’s TheoryI. BackgroundII. A stage theoryIII. The pre-operational stageI. Piaget’s theory: Background• Personal details--1896-1980, Switzerland--1918: Ph.D. in zoology--1919-1920: went to Paris to study psychology; hired in Alfred Binet’s lab to giveIQ tests to children--1921: back to Switzerland to start his life’s work!--married, 3 children• Why such impact?--created the field of cognitive development--produced very broad theory:-age range: infancy to adolescence-topics: all aspects of cognition(e.g., causality, time, space, logic, categorization, concepts,symbols, imagination, play, moral judgment)• Why such impact (cont’d)?--found tasks that were easy to do and thatreplicated with children around the world--made radical claims about the process of cognitive development!• Three radical claims1. Child plays active role in knowledge acquisition: Constructivist view --not a vessel in which society poursknowledge, moral norms, etc.(against Freud)--not a passive entity (e.g., ball of clay) shaped by rewards and punishments (against Skinner)• Three radical claims (cont’d)2. Major qualitative discontinuities in cognitive development: Stage viewchildren are fundamentally different thinkers than adults8• Three radical claims (cont’d)3. No innate cognitive basis to development(against Chomsky)--only general tendencies for adaptationand