1Perception• Normal perceptual development requiresnormal perceptual experience.• Infant actively seeks necessary stimulation.• Perceptual development is influenced by thecultural context.How do we know?• Habituation– Repeatedly present stimuli until infant’s responsedeclines, or habituates– Present novel stimuli.– If infant response increases=> baby can tell the difference between old andnew stimuli.• Preferential-looking– Present two visual stimuli side-by-side– If infants look longer at one of them=> baby can tell the difference between the two.2How do we know?• Operant Conditioning– Condition infant to respond to a stimulus.– Present novel stimuli.– If infant does NOT respond to novel stimuli=> baby can tell the difference between old andnew stimuli.Perception• Taste and Smell• Hearing• Touch Temperature and Pain• Vision• Integrating sensory information3Auditory Perception• Infant auditory system is well developed atbirth, but hearing does not achieve adult leveluntil 5 to 8 years.• Auditory localization: Newborns can turntoward the direction of the sound.• Remember The Cat in the Hat?Touch• Oral exploration - Infants explore the worldorally for the first few months.• Manual exploration - From 4 months on,infants begin to rub, finger, probe, and bangobjects.• Increase in manual control facilitates visualexploration.4Visual Acuity• Visual acuity is the sharpness of vision.Visual Acuity• Visual acuity is the sharpness of vision.• Newborn’s cones are still developing.– Infants have poor contrast sensitivity; they can seepatterns only when composed of highly contrastingelements.– Newborns do not perceive a richly colorful world.• Color vision is mature by 2-3 months of age.• By 8 months, infants’ vision is comparable toadults’.5Visual Scanning• Infants are attracted to moving stimuli, but badat tracking.• By 2–3 months, infants can track slow movingobjects smoothly.Visual Scanning• 1-month-olds focus on outer contours.• 2-month-olds scan interiors thoroughly.6Object Perception• Perceptual constancy: Although our retinalimages of people and objects change as theymove away from or toward us, our impressionof the person or object stays the same.• Object segregation: Ability to perceiveboundaries between objects.• Infants seem to have perceptional constancyand the ability to do object segregation.Object Segregation• By 2 months, based on common movement.7Object Segregation• By 8 months, based on general knowledge.Depth Cues Used by Infants• Optical expansion: (by 1 month) The visual imageincreases as an object comes toward us, causing thebackground to be occluded.• Binocular disparity: The closer the object, the moredifferent the retinal images of it from the two eyes willbe.• Stereopsis: (suddenly, about 4 months) The processby which the visual cortex combines the differentneural signals from each eye to create depth perception.• Monocular (pictorial) cues: (by 6-7 months) Theperceptual cues of depth that can be perceived by oneeye alone.– Relative size– Object interposition8Intermodal Perception• Infants are able to combine information fromtwo or more senses.• Very young infants link oral and visualexperiences.• As they get older, infants integrate visual andtactile explorations.• Infants at about 4 months can integratespeaking sounds with a picture of lips moving.• Continues to improve during childhood andadolescence.Childhood & Adolescence• Learning how to use senses moreintelligently.• Attention– Longer attention span– Selective attention– Systematic attentionAdulthood• Sensory and perceptual capacities