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Human development
A. Normal perceptual development
Earliest to mature (essentially “adult like” by 2 months)
Temporal resolution (CFF)
Light sensitivity
Motion sensitivity
Present by 4-6 months
Color vision
Stereopsis
Maturing later (6+ months)
Spatial vision (VA, contrast sensitivity, vernier acuity)
Refractive error
Accommodation and convergence
Form perception
B. Normal motor development
Gross motor and language development
General sequences in motor skills:
Rolling over: 2-4 months of age
Sitting without support: 5 to 7 months
Standing while holding on to support: 5-10 months
Pulling self to stand: 6-10 months
Standing well without support: 10-14 months
Walking well: 11-14 months
General sequence in language
Babbling
Words
Sentences
Oculomotor
Consistent eye turn: NEVER normal
Large vergence and accommodative errors in younger infants
Saccadic errors in younger infants
Nasal bias in OKN and pursuit until about 6 months of age
Vestibular function should be mature shortly after birth
Visual perceptual-motor
Piaget stages
Sensorimotor (0-2 years): lack of fully developed object
permanence (realization that objects continue to exist when not
present
Preoperational (2-7 years): beginning of internalized thought
processes; logical thought not yet fully developed; beginning of
sense of self
C. Normal cognitive and social development
Piaget’s stage of “concrete operations”: use of logical rules, begins fairly
abruptly at about the time children start school
Marked by ability to “conserve” or realize that the amount of a
material does not change unless something is added or taken away
even though its form may change
Stage of “formal operations” begins around adolesence
Ability to use abstract concepts, more flexible thought processes,
deal with hypothetical situations
Social
Infants--temprament differences apparent early in life
Facial muscles mature at birth; infants can smile, pout, etc.
Attachment of infant and a consistent caretaker important
“Terrible twos”: beginning of self awareness; become possessive
of toys, etc., more complex social behavior
School age: friendships become important, especially with peers
of same sex and age
D. Effects of early environmental restrictions
Plasticity--not all functions begin to be plastic at the same time
Not all cease to be plastic at 7 years
Critical periods beginning at birth
Absolute light threshold
Temporal resolution (CFF)
Peak contrast sensitivity
Color vision
Grating acuity
Critical periods beginning between 3 and 4 months and continuing well
into later childhood
Directional discrimination (motion)
Stereopsis
Critical periods complete by 6 months
Absolute light threshold
Temporal resolution (CFF)
Peak contrast sensitivity
Animal models
Only means to know effects on ocular dominance distribution and ocular
dominance columns
Both present at birth
Deteriorate if normal binocular vision is impaired
unilateral occlusion and strabismus have largest
ffects
Light and pattern deprivation
Unilateral pattern deprivation alone can shift cortex to monocular state
Monocular and binocular deprivation
Monocular deprivation has more serious effects than binocular early in life
Refractive error
Uncorrected monocular AND binocular errors lead to amblyopia
Hyperopic errors: more serious than myopic errors
Smaller amounts need correction for normal development
Strabismus
Altenating: normal VA but reduced stereo
Unilateral, constant: both VA and stereo reduced
Cataract
Unilateral even more serious than bilateral
Unilateral ptosis is also serious