Development Xiaonan Liu

Why Study Development?

• “One great blooming, buzzing confusion” – William James (Learning is amazing!!)

• One way to understand human cognition is start at

the beginning

• Help our understanding of children and the learning process

Physical and Brain Development• In Utero:

• Zygote: conception-2 weeks• Embryo: 2 weeks-2 months (8 weeks)

• Cell differentiation• Fetus: 2 months to birth

• Functioning organ systems develop, early reflexes seen (e.g. non-nutritive sucking)

Fig. 5-2, p. 123

Fig. 5-3, p. 123

Physical and Brain Development• At birth, the human brain weighs

approximately 350 grams.• By the first year. the brain weighs

approximately 1000 grams.• The adult brain weighs 1200-1400 grams.

Physical and Brain Development

Physical and Brain Development• From birth:

• Reflexes:• Grasping• Rooting• Foot flexing

• Sensory• Discriminate high and low sounds, vowels,

mother’s voice• Very near-sighted, but can discriminate

brightness and color and track moving objects

Physical Development

• Gross motor skills• 7-8 months: sitting up• 8-10 months: crawling• 10-12 months: “cruising”• 12-15 months: walking• 2 years: hopping on one foot, kicking• 4 years: jumping rope, balancing on one foot

• Fine motor skills• 1 month: reflexive grasp• 4 months: reaching, hands at midline• 6 months: reach precisely, grabs at objects• 12-14 months: throwing objects• 2 years: unscrewing jars• 3 years: cutting with scissors, holding pencil• 6 years: writing, drawing shapes

Cognitive Development …and the Work of Jean Piaget

Important Concepts Within Piaget’s Model• Schemes: Mental model of the world that we use to

represent, organize, and interpret our experiences.• Assimilation: Integrating new experiences into an

existing scheme.• Accommodation: Changing or modifying a scheme

in order to incorporate a new experience.

Four Major Stages of Cognitive Development

1. Sensorimotor (0-2 years)2. Preoperational (2-7 years)3. Concrete Operations (7-11 years)4. Formal Operations (12+ years)

Sensorimotor Period• From birth to ~2 yrs old• Actions progress from

simple reflexes to deliberate movements

• Object permanence – realize object still exists even when it can’t be perceived

• The A Not B Error

Preoperational Period• From ~2 yrs to ~7 yrs• Learn to use symbols, signs

and language• Egocentrism – cannot

understand another person’s point of view

• Failure of conservation – do not yet understand that quantity remains the same despite appearance

Concrete Operational Period

• From ~7 yrs to ~11 yrs• Thinking becomes

systematic, quantitative and logical

• Success at all conservation tasks – number, solid quantity, liquid quantity

• Decentration of perception – ability to classify objects in terms of more than one dimension

Formal Operational Period• From ~11 yrs to adult• Apply logical and systematic

thought to abstract problems• Deductive reasoning – specific

conclusions based on general hypotheses

• Inductive reasoning – make generalizations based on specific observations

• Handling multiple variables simultaneously

Strengths of Piaget’s theory• Good “feel” for what children’s

thinking is like • Covers broad age span• Covers broad spectrum of

developments in children’s thinking

• Interplay of content & mechanism

Weaknesses of Piaget’s theory

• Methods• Underestimates

competence – children succeed earlier than predicted

• Can’t explain dissociations – success or failure depends on the way concept is tested

• Sometimes, no discrete stages - development occurs somewhat gradually or incrementally

Technique: Habituation

• Infants like to look at objects that are new and interesting to them

• Procedure• Familiarization: Object presented repeatedly until

infants no longer look at it much• New object introduced

• Method: Infants look longer at new object—allows testing of whether they perceive object as new or old

Kids sometimes smarter than you think: Occluded rod experiment

• 4-month-old infants familiarized with A, then presented with either B or C

• Results – Looked longer at C than B

• Conclusions• Broken rod more novel than

unbroken rod• Rod in display A was

originally perceived as unbroken

pr Y|X =freq XY freq X

Language Acquisition:Statistical Learning

Word segmentation

Statistical learning

PRE TTY BA BY

Continuations within words are systematicContinuations between words are arbitrary

High likelihood High likelihood

Low likelihood

Transitional probabilities

(freq) pretty(freq) pre .80

.0002(freq) tyba (freq) ty

versus

PRETTY BABY

8 months Infants can use statistical cues to find word boundaries

• Saffran, Aslin, & Newport (1996)• 2 minute exposure to a nonsense language

(tokibu, gopila, gikoba, tipolu)• Only statistical cues to word boundaries• Tested on discrimination between words and

part-words (sequences spanning word boundaries)

Experimental setup

tokibugikobagopilatipolutokibu gopilatipolutokibugikobagopilagikobatokibugopilatipolugikobatipolugikobatipolugopilatipolutokibugopilatipolutokibugopilatipolutokibugopilagikobatipolutokibugopilagikobatipolugikobatipolugikobatipolutokibugikobagopilatipolugikobatokibugopila

tokibugikobagopilatipolutokibu gopilatipolutokibugikobagopilagikobatokibugopilatipolugikobatipolugikobatipolugopilatipolutokibugopilatipolutokibugopilatipolutokibugopilagikobatipolutokibugopilagikobatipolugikobatipolugikobatipolutokibugikobagopilatipolugikobatokibugopila

tokibugikobagopilatipolutokibu gopilatipolutokibugikobagopilagikobatokibugopilatipolugikobatipolugikobatipolugopilatipolutokibugopilatipolutokibugopilatipolutokibugopilagikobatipolutokibugopilagikobatipolugikobatipolugikobatipolutokibugikobagopilatipolugikobatokibugopila

Results

0

2

4

6

8

Words Part-words

Loo

king

tim

es (

sec)

*

Information-Processing Theories

• Thinking = information processing• Representation of information• Processes - applied to representations• Constraints - memory limits constrain representation

and processing• Cognitive development = change in information

processing capability• Precise analysis of change mechanisms

• Change produced through continuous self-modification

• Outcomes of child’s actions change information processing in the future

Memory representations & capacity

• Leg-string Infants remembered that kicking made mobile move after 2 months

•Working memory span increases with age

Rehearsal as information processing

• Increase in rehearsal speed leads to increase in working memory capacity

• Older children do better on recall tests because they use rehearsal as a memory strategy

Social Development

Attachment• Infant forms a relationship with caregiver and uses

them as a secure base to explore the world• Harlow: monkeys are comforted by soft “contact comfo

rt”, not feeding.• Ainsworth: Strange situation

• Episode 1: Mother (or other familiar caregiver), Baby, Experimenter (30 seconds)

• Episode 2: Mother, Baby (3 mins)• Episode 3: Mother, Baby, Stranger (3 mins or less)• Episode 4: Stranger, Baby (3 mins)• Episode 5: Mother, Baby (3 mins)• Episode 6: Baby Alone (3 mins or less)• Episode 7: Stranger, Baby (3 mins or less)• Episode 8: Mother, Baby (3 mins)

Attachment Styles• Secure - Uses caregiver as a secure base for exploration. Upset

by departure of parent but easily calmed when they return and can continue to play.

• Resistant – Does not use parent as a secure base, often stays close to them. Upset when they leave but not comforted by their return.

• Avoidant – Little affect while playing. No visible stress upon parents departure, ignores them on return. Treats the stranger similarly to the caregiver.

• Disorganized – no clear attachment patter. Show freezing or repetitive behavior.

Strange Situation Results

Middle class kids:• 60% secure• 15% anxious/resistant• 10% anxious avoidant• 15% disorganized• But is it causal? unclear. (Could be due to child's

temperament?)

Theory of Mind

• Theory of Mind – the understanding that we have a mind (intentions, desires, knowledge, beliefs) and that other people have a mind of their own (2-5 yrs)

Moral Development: KohlbergA woman was near death from a special kind of cancer. There

was one drug that the doctors thought might save her. It was a form of radium that a druggist in the same town had recently discovered. The drug was expensive to make, but the druggist was charging ten times what the drug cost him to produce. He paid $200 for the radium and charged $2,000 for a small dose of the drug. The sick woman's husband, Heinz, went to everyone he knew to borrow the money, but he could only get together about $1,000 which is half of what it cost. He told the druggist that his wife was dying and asked him to sell it cheaper or let him pay later. But the druggist said: “No, I discovered the drug and I'm going to make money from it.” So Heinz got desperate and broke into the man's store to steal the drug for his wife. Should Heinz have broken into the laboratory to steal the drug for his wife? Why or why not