Chapter 13 Sensory 1 and 2 Flashcards
No study of motor development is complete without the study of the relationship between?
perception and action
Perception:
is a multistage process that takes place in the brain and includes selecting, processing, organizing and integrating information received from the senses
Sensation:
neural activity triggered by a stimulus activating a sensory receptor
sensory nerve pathways to the brain
Perception
multistage process in the CNS
identical sensations can yield different perceptions
3 parts of the sensory system
visual, kinesthetics and auditory
What sense to we rely on the most?
Vision
How much sensory info is channeled through vision?
80%
is it the most or least mature sense as a newborn?
least
Acuity?
Sharpness of sight
In the first month what is acuity like?
20/400 (5% of adult level)
infants can differentiate facial feature at 20 inches
acuity by age 5 and 10?
20/30 by age 5 and 20/20 by age 10
Visual changes with aging?
declines with vision have implications for skill performance and everyday living tasks
Symptoms of visual problems? Any age
lack of hand eye coordination, squinting, under or overreaching for objects, unusual head movements
Visual perception involves perception of?
space, objects, and movement
Perception of space requires and where does the information come from?
requires perception of depth and distance
information comes from retinal disparity, motion parallax and optic flow
Perception of objects?
objects attributes are size, shape and motion
Perception of space? what age do infants perceive depth?
by 6 month infants perceive depth
depth perception is refined to adult like levels in adolescence
more older adults fail depth perception tests than younger adults
Sclera?
a tough, opaque tissue that serves as the yes protection outer coat and provided shape; the white of the eye
Iris:
the coloured part of the eye, regulates amount of light entering the pupil
pupil:
Center of iris. opens and closes to regulate amount of light entering the eye
Retina:
a very thin layer of light sensitive tissue that lines the inner part of the ye. It is responsible for capturing the light rays that enter the eye
Cornea:
Transparent outer layer of the eye , which bulges forward. Primary structure focusing light entering the eye (fixed focusing)
Lens:
a crystalline lens located just behind the iris. second most powerful structure focusing light entering the ye (adjustable focusing)
Ciliary muscles:
tiny muscles that dilate and constrict the pupil size; alters shape of lens
Retina:
Consists of 2 types of photoreceptors; cones and rods
Rods:
black, white, grey, form and shape. Very sensitive and can help us see in the dark
Cone:
sense colour and need more light
How many rods?
120 million
How many cones?
6 mil
Are all visual structures in place at birth?
Yes
When light strikes the rods and cones in the retina what happens?
transduce to electrical impulses
Where does the information from electrical impulses go?
Crosses optic chiasm in forebrain in front of the hypothalamus)
After crossing optic chiasm where does the info go?
information arrives at the lateral geniculate nucleus within the thalamus
What happens at the lateral geniculate nucleus within the thalamus?
spatial organization of the visual scene is detected
After info is done in the lateral geniculate nucleus where does it go?
primary visual cortex
After primary visual cortex where is info sent?
sent to superior colliculus where it is integrated with other incoming sensory inputs
What does the integration allow for?
Allows for hand/eye coordination. also plays a role in attention and visual perception
Visual information is reflection in 3 characteristics:
acuity, accommodation and contrast sensitivity
How do we measure acuity?
Snellen Test
Hyperopia?
Far sighted: eyeball is shorter than normal (objects focus beyond the back of the eye)
Hardening of the lens (with age) increase hyperopia
Myopia?
Near sighted: eyeball is longer than normal (image falls short of the retina)
Astigmatism?
a defect in the eye caused by deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus
How common is astigmatism?
1 in 3 people have some degree of it
Newborn vs adult eye?
Newborns eyeball is short and the distance between the retina and the lens is reduced
results in temporary hyperopia
during the 1st year cornea is not symmetrical (astigmatisms and difficulty focusing)
ciliary muscles are weak; therefore few newborns cannot shape their lens to accommodate for shifting place of focus for visual targets
When can newborns best adjust lens for
5-10 inches away
Contrast sensitivity:
referes to the ability to resolve spatial structures from fine to course at various levels of contrast and the ability to perceive differences in light levels
What is contrast sensitivity critical for?
detection and recognition of shapes
Contrast sensitivity in newborns:
newborns have poor contrast sensitivity but can detect many object, improves rapid in the first 6 months
What patterns to babies perfer?
patterns with the most contrast
cannot see contrast in more complex patterns (prefer more bold)
Preferential looking:
infants look at new or novel objects over familiar ones
Explain habituate
attention wander from objects to which the infant has habituated
researchers habituate an infant ti an object then present a familiar object and a new one
infants can detect a difference, they tend to look at the new object
What do we use to assess fixations and eye movements
eye tracking
Fixation (scan path):
start around edges (1 month)
progress to relevant areas of human expression (2 months )
Saccades (eye movements):
no eye movements for newborns, must move head
saccades appear before smooth pursuits
Smooth pursuit:
4-5 months will exhibit approaching movements with upper body as if attempting to receive an object
5-6 years will begin tracking in horizontal plane
8-9 years can track an arc
maturity in smooth pursuit achieved at 12 year
Braille reading and reorganizing
brain has the ability to reorganize cortical areas that are otherwise unused for optimal efficiency
What did sadato et al find in terms of braille reading?
increased blood flow to occipital lobe primary visual cortex, decrease in regional cerebral blood flow in these same areas with the same task in sighted individuals
What is a downside to the 3-finger reading technique?
cortical smearing of the representation of those three fingers and increased zone cortically, but they are now prone to misperceiving von Fray hairs
3 major aspects of visual perception?
- perception of space/depth
- objects
- motion
What is a powerful depth cue?
shadows
perception of space depensd on? a d the info comes from?
depends on judgement if depth and distance
Information comes from experience software
When do infants blink (to shows object coming towards them)
around 1 month
What is the most famous evidence that depth perception is innate?
infants b/w 6-12 month failed to cross the cliff
Perception of Objects:
Realization that objects continue to exist when they are no longer in view
Object permanence
Fantz, 1961 object perception study
ages 4 days to 5 months, shown pairs of faces measured time spent fixated on each one
realistic face were looked at the most compared to scrambled and blank (least)
What does this study suggest?
the ability to recognize faces is either innate or learned shortly after birth
When it comes to whole or parts children usually?
detect the whole or detect the parts, will detect both but never at the same time
When does integration of whole and parts occur
by age 9
Perception of motion: object constancy
distance and object perception interact
adults perceive that objects retina their size even if the retinal image size changes because their distance from the observer changes
When does motion perception develop?
starts to develop 1-3 months of age and continues through childhood
Kinesthetics is the “__” sense
the 6th sense
What does the kinesthetic or proprioceptive system give us info about?
our body parts in relation to each other
position of the body in space
our body’s movement
nature of objects that we interact with
Is muscle memory a thing?
No
The stages of learning body parts
themselves, others than a doll
ages that children learn body parts:
9 month = nose, eyes
18 months = ears, hands, feet
7 years = minor parts (ankles, wrists, shins)
9 years = all parts of the body
internal awareness and laterality?
internal awareness that there are two sides to the body and that these sides are different
involved development of the ability to use one side or both sides of the body to make desired movements
By how old can children identify/label left and right parts of the body?
8-9 years old
Lateral preference (dominace)
infants show early hand preference when reaching but not always predictive of their adulthood handedness
What age of true lateral preference?
3-4
How do they know which hand they prefer?
a child who has developed lateral preference will experience “feelings” (perceptions) when one side does not feel natural
the tactile system?
sense of touch
Haptic?
refers to the sense of touch that occurs on the skin with the movement of the body
involves skin receptors stimulated by touch, pressure, temperature and pain
tactile perception?
refers to the ability to detect and interpret sensory info cutaneously (of or on the skin)
Proprioceptors?
the various kinesthetic receptors located in the periphery of the body
what the the 2 types of proprioceptors?
somatosensors and vestibular apparatus
somatosensors
located in the muscles, muscle tendon junctions, joints, ligaments, under the skin
vestibular apparatus
in the inner ear
where are the senory receptors fo audity located?
utricle and saccule (inner ear)
Absolute threshold:
minimal detectable sound an individual can hear at least half the time (higher db threshold for newborns)
Are newborns sensitive to noise?
Newborns are more sensitive to loud sounds b/c ear canals are smaller
Presbycusis:
loss of hearing sensitivity (loss of hair cells that do not regenerate)
How many hair cells do we start with?
3500 inner hair cells
intermodal perception?
integrating separate perceptual systems
Do we need to integrate or are the systems unified from the start?
Hard to know but some support the second view that there are areas of the brain which simultaneously respond to multiple sensory inputs
