development mid #2 3/6/2012 12:39:00 PM
CHAPTER 6: Early cognitive foundations: sensation, perception & learning
Sensation and Perception
SensationProcess by which sensory receptor neurons detect info. and transmit
it to the brain
PerceptionProcess of interpreting the sensory input
Nature vs. Nurture
o Empiricists Infants must learn to interpret sensations (nurture)
o Nativists Many basic perceptual abilities are innate (nature)
Enrichment vs. Differentiation
o Enrichment Theory (Piaget) we must add to sensory stimulation by
using, stored knowledge in order to perceive a meaningful world.
Cognition enriches sensory stimulation.
Differentiation Theory (Gibson)
o our senses provide all we need to interpret experiences, perception
involves detecting distinctive features/cues in the sensory stimulation.
Children learn to detect distinctive features
Ways which 2+ objects can differ (size, coloiur, shape)
Methods that use behavioural and physiological responses to study sensation and
perception in infants:
(1) Preference method
o presenting 2+ stimuli and observing which stimulus the infant prefers.
One looked longer at = preference
o Shortcoming If an infant shows no preferences, it is not clear if they
failed to discriminate them or found them equally interesting.
(2) Habituation Method
o decrease in response to stimulus that is familiar from repetition.
Stimulus presented repeatedly until infants response habituates
Discrimination ability is tested by presenting a second stimulus and
Dishabituation increase in responsiveness that occurs when
stimulation changes (can detect difference). o researchers must pay careful attention to the familiarization time line of
each infant being tested.
(3) Evoked Potentials
o a change in patterning of the brain waves that indicates that an
individual detects (senses) a stimulus
Observe changes in activity for different stimuli
Changes = have ability to discriminate
(4) High-Amplitude Sucking
o the ability of infants to make interesting events last by varying the rate
at which they suck on a pacifier.
Baseline sucking rate is established
Increased rate of sucking causes sensory stimulus to be introduced
Suck at a high rate interested
Sensory Capabilities and the Brain
Touch, Temperature, and Pain
o Due to receptors in the skin, they are:
Sensitive to touch
Sensitive to warmth, cold, temperature change
Sensitive to pain
In very rare cases, a baby will be born unable to feel pain
there are techniques to try to reduce pain for newborns
o Hearing is not great at first improves over first 4-6 months
Use evoked potentials
o Detect differences in loudness, duration, direction, and pitch o Attentive to voices especially mothers
Use high amplitude sucking suck faster for mothers voice.
Even fetuses show a higher heart rate to mothers voice
o Distinguish speech sounds (phonemes)
smallest meaningful sound units that make up a spoken language.
Recognixe repetitive words
o Otitis media is common
bacterial infection of the middle ear that produces mild to
moderate hearing loss.
Almost all children diagnosed atleast once
o Auditory localization U-shape function, disappears, then reappears.
o React to noxious odours turn away, unpleasant look
o Can recognize scent of mother (olfactory signature)
Ex. breast pad expeirment
o Have taste preferences (sweet tooth!)
o React with facial expressions for different tastes
o Some people are super tasters
o Least mature sense
o Sensitivity to brightness (Pupillary reflex)
o Track motion (faces the most)
o Colour (trouble discriminating Blue, greens & yellows from white)
o Low Visual acuity persons ability to see small objects & fine detail
Very young infant trouble accommodating (focus distances)
o Sharper visual contrasts amount of light/dark transition in a stimulus.
Common vision problems:
o Nearsightedness (myopia)
o Farsightedness (hyperopia)
Less common problem:
o Blindness Visual Perception in Infancy
Pattern and Form
o Early preference for: (0-2 mos)
High contrast patterns (sharp boundaries between light & dark)
See best moderately complex, high-contrast, motion!
o Later form perception: (2 mos-1 year)
Perceiving objects as wholes
Face preference and recognition
complex discriminations (object & surroundings)
heavily rely on motion cues (rod example)
8 months- no longer need kinetic cues
Perception of 3D Space