PSYC 4220 1st Edition Lecture 11 Outline of Last Lecture I II III Physical Development Brain Development Enrichment of the Brain Outline of Current Lecture I Assessing Infant Perceptual Abilities II Infant Vision III Infant visual preferences IV Infant depth perception V Infant hearing VI Infant speech perception VII Infant taste VIII Infant smell Current Lecture Assessing Infant Perceptual Abilities Preferential looking measures which stimuli an infant prefers to look at Assume stimulus they look at longer is the one they prefer Preference for on stimulus implies ability to tell them a part No preference either couldn t tell them a part or just liked both equally Preferential looking is used but not as much as others because no way to determine why baby looks at two stimuli for same amount of time if there is no difference in timing Habituation losing interest stimuli that is presented over and over if you expose a baby over and over again they will do something called an orienting response when they see something new Heart rate decreases when they see something new Once you ve showed them something 2 or 3 times they probably won t have the orienting response heart rate won t change but when you then show them something new again they will again respond with orienting response Used to test if infant can tell difference between two stimuli If infant grows bored with one stimulus then shows renewed interest in new stimulus must be able to tell items apart Instead of heart rate monitor they might instead look to see if baby stops sucking on pacifier Evoked potentials measure electrical activity on scalp to determine brain activity Changes in patterns of brain waves can detect stimulation High amplitude sucking methods infants learn to vary their sucking rate to make stimuli appear As baby sucks fast the projector will show the new stimulus It s a habituation study where they use the pacifier as a measure of habituation Infant Vision Can detect changes in brightness at and can detect large differences between colors at birth Prefer blues greens Can t discriminate different shades of same color until after 4 months Can t track slow moving objects Distance vision poor but improves rapidly over 1st 6 months At birth 20 200 to 20 600 By 6 months 20 20 Infant Visual Preferences Prefer faces especially human ones circles curves patterned objects Contour sharp boundaries between light and dark Movement though slow is best Moderate complexity All these preferences are innate or inborn A few hours after birth babies already have a preference for their own mother s face Infant Depth Perception Infants have depth perception blink when objects approach face Habituate to same stimuli presented at different depths Visual cliff infants 6 months or older 90 cross shallow less than 10 cross cliff 2 months old heart rate dropped when over deep side indicating interest but not fear suggests they can perceive change in depth but aren t afraid of falling Infant Hearing hearing better developed than vision can localize sounds but not as well as adults are as good as adults by 1 hearing preferences complex sounds infant directed speech high pitched expressive voice prefer mother s voice to other people s but don t prefer dad s voice to to other males prefer mother s language to other languages Infant Speech Perception born with ability to distinguish between phonemes smallest units of sound of all your languages lose sensitivity to phonemes not used in native language by one year recognize mother s voice within 3 days after birth little recognition preference for father s voice even at 4 months preferences for passages lullabies read by mother during last 6 weeks of pregnancy by 4 months turn head toward sound of own name Infant Taste can distinguish between tastes at birth born preferring sweet disliking bitter produce different facial expressions for different tastes preferences can be altered by early diet Infant Smell olfaction smell works well at birth prefer smell of own amniotic fluid by 6 days turn head away from unpleasant odors similar smell preferences to adults by 3 years old same preferences can make very subtle distinctions recognize mother by odor