Sensory & Motor Development
Part 1: Sensory Development
What is the perceptual world like in first six months of life?
- Newborn baby
- 4 week old (1 month) baby
o Little interaction
- 6 month old baby
o Still unable to speak, likes making sounds
o Likes to put things into his/her mouth
o Likes to pick up and hit objects
o Is engaged with his/her world
- These babies do very little. Barely reach for objects at 6 months. How can we tell what their
perceptual world is like?
o Chemical senses: smell and taste
o “Cognitive” senses: Hearing & Vision
- Response to chemical composition of gases
- Adults can discriminate up to 10,000 different chemical substances!
o Perceptions may change to distinguish more differences if one becomes associated with
an object more frequently eg. Wine taster can taste the difference between each wine
- Adult taste organized around 4 dimensions
o Bitter (at the back of tongue)
o Sour (at the back sides)
o Salty (front sides)
o Sweet (at the tip)
*There is a special relationship between smell and taste
Eg. a smell can bring back a taste from 15 years ago
Taste in newborns
- Facial reactions to sweet, sour, and bitter tastes in 2 hour olds
o Reaction to sweet sample
Someone put something in my mouth
Aaah but its sweet…nice! o Reaction to sour sample
Lemon juice! Sour!
O shaped mouth
o Reaction to bitter sample
N shaped mouth
o No distinct facial expression for salty taste
Smell Discrimination in newborns
- When exposed to sweet smells (honey or chocolate), newborns look relaxed and content (btw,
newbornds don’t really smile…)
- When exposed to foul or strong smells (rotten eggs or ammonia), newborns frown or turn away
Smell memory in newborns!
- Fetuses form memory for smell of amniotic fluid!
o Experiment was done to moisten one of mother’s breasts with amniotic fluid
o 23/30 newborns spontaneously choose breast with amniotic fluid
Babies have a preference for what the mothers ate while she was pregnant
Taste & Smell in newborns
- Taste: almost all in place at birth
o By 2 hours of life, 3 or 4 basic tastes are discriminated
- Smell: already memorable
o Some discrimination of smells
o Smell memories can be formed in the fetus!
- In adult, auditory system turns oscillating waves of air into sounds
- Some combinations of sounds are special: music
o Pattern in the air are sensitive to our ears
- What do infants hear when we play music to them?
Consonant vs. dissonant music
- Difference between two pieces = relations between notes
o We like some sequences of notes (consonant) better than others (dissonant)
- Why do we have a preference?
- Is it because it’s what we’re used to hearing?
- Or is our auditory system built to prefer
o Consonant music is the music we know of today, that we listen to Musical appreciation in 2 to 6 month olds
- How to make a baby control music
o Seat baby in front of a plexiglass box with bull’s eye picture in it
o Observers in separate room look at when baby looks at box
o When baby looks at box, observers press button to turn on lights in box to attract baby’s