Sensation & Perception : Development

Visual Acuity Measurementsq

Preferential Looking Technique

Visual Evoked Potential (VEP)

Preferential Looking Technique

Infants have spontaneous looking preferences

Visual Evoked Potential (VEP)

Measuring neural response to a visual stimulus

Poor

Visual acuity is ____ at birth.

• 20/400 to 20/600 at one month

Reasons for Low Acuity at Birth

Visual cortex is not fully developed

• Shape and size of cones are not fully developed

Infant Face Perception

Understanding infant sees using preferential looking effect

Human faces are among the most important stimuli in an infant’s environment

Gestalt Perceptual Organization

Perceptual Completion

Habituation

Perceptual Completion

_______ _______ is the perception of an object as extending behind occluding objects.

Habituation

One stimulus is presented to an infant repeatedly and the infant’s looking time is measured

Dishabituation

Increase in looking time when stimulus is changed

Kellman & Spelke Experiment

Infants showed dishabituation to two separated rods only in the movement condition

Johnson et al. Experiment

Perceivers followed the motion with their eyes while non-perceivers fixated on the non-moving element of the display

Subjective Contour

3-4 months

True

Capacity to imitate seems present from birth

Meltzoff (1995)

18 month-olds who witnessed the adult unsuccessfully perform the action performed as well as those who saw the adult successfully perform the action

False, may not

T/F : Perception of biological motion may depend on visual experience

Vallortigara (2005)

Examined the preferences of newly hatched chicks for different types of motion

Infant Color Vision

It is a complex problem to know what an infant really “sees”

• Chromatic color

  • Brightness

Bornstein et al. Experiment

Results showed that four-month infancts categorized colors like adults do

3 months

Infants are able to binocularly fixate at approx. _____ _____ old

Fox et al. Experiment

Infants could follow 3D object in random-dot stereograms

Granrud et al. Experiment

5 & 7 month infants were first familiarized with a large and small wooden object for 10 minutes

• Same types of objects were shown at the same distance, only the size was switched

  • 7 month infants reached for object, but 5 month infants did not

0 - 4 months

Sensitive to kinetic cues, physiological cues

4 - 6 months

Stereopsis

• Binocular depth cells

  • Necessary binocular vision experience

7 months

Pictorial cues

Smooth Pursuit

Newborn

10 weeks

Newborn

Short, jumpy, saccadic eye movement

10 weeks

Smooth & Anticipatory

Vergence

About 3 months, almost the same as adults’

Oisho et al. Experiment

6 month infants showed audibility curves similar to adults’ thresholds within 10 to 15 dB

DeCasper & Fifer Experiment

Infants recognize recordings of their native language versus a foreign language, or a previously heard story

Eimas et al. Experiment

Control group with no changes in sound showed decreased sucking throughout experiment

• Results reveal the same phonetic boundary seen in adults

Very Young Infants

“Citizens of the world”

Experience-Dependent Plasticity

Change in the brain’s ability to respond to specific stimuli that occurs as a result of a experience

Pascalis et al. Experiment

Adults looked longer at new human faces in a pair but not at new monkey faces

• However, 6 month infants discriminated between both the human and monkey face pairs, but 9 month infants did not

Sound Localization

Present at birth

• 20 degrees discrimination

Adults

Less than 1 degree discrimination

U-Shape Function

Great at birth and 4 months

• Poor at 2-3 months

Birth - 2 Months

Subcortical, reflex

2 - 4 Months

Cortical activity increases and it replaces subcortical activity as a dominant influence

4 Months

Cortical activity is sufficiently developed

Accurate localization

Kuhl & Meltzoff Experiment

Infants showed preference (74% of the time) for the face that corresponded to the sound

Steiner

Found that newborns can smell and discriminate between different olfactory stimuli

True

T/F : Newborns can discriminate between sour, sweet, and bitter stimuli

Mennella Experiment

Used combination of carrot juice and water to study infant preferences

Withdrawal

Major symptom of autism is _____ from contact with people.

Attention & Autism

People with autism can solve reasoning problems about social situations, but cannot function when placed in these situations.

Klin et al. Experiment

Autistic observers look at socially irrelevant stimuli in these situations

• Thus, where autistic individuals pay attention in a social situation may lead to perceiving the world differently

Pelphrey et al. Experiment

Results suggest that autistic people cannot read intentions of others

Presbyopia

Old vision

Far sighted

Vision

Presbyopia

Visual Acuity Decline

Accommodation Problem

Increased Sensitivity to Glare

Color Vision Decline

Cataracts

Depth Perception Decline

Dark Adaptation Curve

Increased sensitivity to glare

Light scatter

Color Vision Decline

Cone death

• Yellowing lens

Cataracts

Clouding lens

• Half of people in 80’s

• Sun exposure, diabetes

• Artificial lens replacement

Macular Degeneration

Blood flow to the macula is restricted

Hearing

Presbycusis

• 14%, 45 - 64 : Hearing Loss

  • More for the high frequency

Cell Death in the Inner Ear

Reduced Blood Supply

Stiffening in Basilar Membrane

Presbycusis

Old hearing

Touch & Pain

Lower sensitivity for touch

• Two points threshold sensitivity

Pain sensitivity is the same

Taste & Smell

Less accurate, higher threshold

• Fewer taste bud, connectors withered

Women is better than men