PERCEPTUAL DEVELOPMENT

CHAPTER 5

◦ Key battleground of nature vs. nuture debate◦ Nativism (inborn) vs. empiricism (skills are

learned) WAYS OF STUDYING EARLY PERCEPTUAL

SKILLS◦ Preference technique devised by Robert Fantz◦ Baby given two options, researchers track which

one they look at more◦ Another option habituation

Baby shown an object until habituated A similar object is then shown to see if baby notices

whether it is different

THINKING ABOUT PERCEPTUAL DEVELOPMENT

EXPLANATIONS OF PERCEPTUAL DEVELOPMENT◦ Arguments for Nativism

Researchers have found more and more skills already present in newborns and very young infants

Newborns don’t have to be taught what to look at Studies comparing preterm babies shows importance of

maturation age on perceptual development◦ Arguments for Empiricism

Research that shows some level of experience needed Aslin – maintenance (ie. decrease of visual perception) Attunement – deprivation of visual experiences in early

stages

◦ Integrating the Nativist and Empiricist Positions Development of perceptual skills is result of

interaction between inborn and experiential factors (ie. nature AND nuture

Similar to hardware and software Making visual discriminations is hardware Specific discriminations and number of separate objects

will depend on experience

SEEING◦ Until 25 to 30 years ago, many medical texts stated

infants were blind◦ Visual acuity

Infant’s at birth is 20/200 to 20/400, but improves rapidly during the first year

Most reach 20/20 by about 2 years of age Infants see quite well close up

◦ Tracking Objects in the Visual Field Following a moving object Initially inefficient but improves rapidly Some tracking at 2 months, but shift at around 6 to 10

months

SENSORY SKILLS

◦ Colour Vision Cells necessary to perceive red and green are clearly

present by 1 month, perhaps at birth, blue probably present at that time as well

HEARING AND OTHER SENSES◦ Auditory Acuity

How newborns hear better than how they see Children’s hearing improves up to adolescence Within general range of pitch and loudness,

newborns hear as well as adults With high-pitched sounds, acuity is less than adult

◦ Detecting Locations Determining general location of sound exists at birth and

improves Sounds arrive at one ear before another Newborns will turn their head Specific locations not well-developed

27 degrees at 2 months, 12 degrees at 6 months, 4 degrees at 18 months

◦ Smelling and Tasting As in adults, intricately related Newborns appear to respond differently to the four tastes

◦ Sense of Touch and Motion The best developed of all Considerable fine-tuning occurs in first year

LOOKING◦ Depth Perception

Binocular cues – involving both eyes Pictorial information – monocular cues

ie. linear perspective (railroad tracks seemingly getting closer)

Kinetic cues – objects near you move more than objects farther

kinetic information perhaps used beginning at 3 months

Binocular cues used at about 4 months Pictorial cues used at about 5 to 7 months

The Gibson/Walk visual cliff experiment

PERCEPTUAL SKILLS

◦ What Babies Look At From the beginning, babies look at the world in a non-

random way In first 2 months, focused on where objects are Between 2 to 3 months, focus on what an object is as

opposed to where Begin noticing patterns, horizontal/vertical, big/small

◦ Faces: An Example of Responding to a Complex Pattern Little indication that faces are uniquely interesting to

infants Face processing as young as 3 months Prefer attractive faces and prefer mother’s face Recognition of voice directs attention to face

LISTENING◦ From 1 month, infants can discriminate between sounds◦ By 6 months, can discriminate between two-syllable words

Male or female doesn’t matter COMBINING INFORMATION FROM MANY SENSES

◦ Intersensory integration and cross-modal transfer◦ Cross-modal as early as 1 month, more common at 6

months◦ Intersensory is important in infant learning

Better able to recognize a new stimulus then with either stimulus alone

◦ Preference for looking at visuals that match with a sound◦ Not a completely automatic process

IGNORING PERCEPTUAL INFORMATION◦ Child must acquire set of rules called perceptual

constancies ie. size constancy, shape constancy, colour

constancy◦ OBJECT constancy

Remain the same even when sensory information has changed

Babies show this at 3 or 4 months and become more skilled

◦ When learning to read, child has to unlearn some shape constancies (ie. b and d, p and q)

INDIVIDUAL DIFFERENCES IN PERCEPTUAL SKILLS◦ Like physical development, perceptual

development shows significant individual variations

◦ Faster habituation by 4 to 5 months is associated with higher IQ at 3 or 4 years of age

OBJECT PERCEPTION◦ Babies are born with built-in assumptions

ie. connected surface principle◦ Other skills are learned through experience

Babies “hypotheses” are modified based on experiences

Infants’ understanding of objects is the foundation upon which object concept is constructed and applied to real-life interaction over the first 3 years

THE OBJECT CONCEPT

OBJECT PERMANENCE◦ Strongly emphasized in Piaget’s theory

Stages in the Development of Object Permanence First sign is at 2 months of age Child develops schema or expectation about

permanence not developed enough to lead to searching for an object

Changes at 6 to 8 months By 12 months, objects continue to “exist” even when no

longer visible

◦ Object Permanence and Cultural Practices Progression toward object permanence across first

18 months quite similar

EARLY DISCRIMINATION OF EMOTIONAL EXPRESSIONS◦ Infants begin to pay attention to social/emotional

cues at about 2 or 3 months More when face is turned toward them

◦ Also beginning to notice and respond differently to variations in others’ emotional expressions

◦ By 5 to 7 months, can begin to read one “channel” – facial or vocal

◦ Later in year one, develop “social referencing” responding to cues and reacts with equivalent concern or fear

PERCEPTION OF SOCIAL SIGNALS

CROSS-CULTURAL COMMONALITIES AND VARIATIONS◦ Similarity with same “basic” emotions

ie. fear, happiness, sadness, anger and disgust◦ Cultures have different rules about which

emotions may be expressed and which must be masked