Sensory-Perceptual Development1 Flashcards
no study of motor development is complete without _
the study of the relationship between perception and action
*vision & perception slide
What class activity did we do about perceptions?
series of visual illusions, which one we saw first
define perception
a multistage process that takes place in the brain and includes selecting, processing, organizing, and integrating information received from the senses
define sensation
- neural activity triggered by a stimulus activaating a sensory receptor
- sensory nerve pathways to the brain
define perception
- multistage process in the CNS
- identical sensations can yield different perception
what 3 sensory systems did we discuss?
visual, kinesthetic, auditory
sensory systems function as _
individual structural constraints
we rely on what sense more than any other?
visual
- 80% of all sensory information is channelled through the visual system
- however, it is the least mature of newborn senses
*note in babies smell is dominant, but once developed we rely on vision
define acuity
the sharpness of sight
describe acuity
- in the first month, acuity is 20/400 (5% of adult level)
- infants can differentiate facial features at 20 inches
- acuity is ~20/30 by age 5 and 20/20 by age 10
describe visual changes with aging
declines with vision have implications for skill performance and everyday living tasks
list the symptoms of visual problems (any age)
- lack of hand-eye coordination
- squinting
- under or overreaching for objects
- unusual head movements
perception of space requires _
perception of depth and distance
for perception of space, information can come from
-retinal disparity
- motion parallax
- optic flow
describe the object attributes in perception of objects
size, shape, motion
describe the perception of space (hint: think development of depth perception)
- by 6 months, infants perceive depth
- depth perception is refined to adult like levels in adolescence
- more older adults fail depth perception tests than younger adults (ex. driving tests)
describe the sclera
a tough, opaque tissue that serves as the eye’s protective outer coat and provides shape; the ‘white of the eye’
describe the iris
the coloured part
- regulates amount of light entering the pupil
describe the pupil
centre of iris, opens and closes to regulate amount of light entering the eye
describe the retina
a very thin layer of light-sensitive tissue that lines the inner part of the eye
- it is responsible for capturing the light rays that enter the eye
describe the cornea
transparent outer layer of the eye, which bulges forward
- primary structure focusing light entering the eye
describe lens
a crystalline lens located just behind the iris
- second most powerful structure focusing light entering the eye
describe the ciliary muscles
tiny muscles that dilate (widen) and constrict (narrow) the pupil size; alters shape of the lens
the retina consists of _
2 types of photoreceptors
- rods and cones
describe rods
black, white, grey, form and shape
- very sensitive and can help us see in the dark
describe cones
sense colour and need more light
how many rods do we have
~120 million
how many cones do we have
~6 million
all visual structures are in place at _
birth
what happens to light energy in the eye? (hint: pathway of light to the brain)
- light energy strikes rods and cones in the retina
- transduced to electrical impulses
- information crosses at the optic chiasm
- information arrives at the lateral geniculate nucleus within the thalamus
- from there to the primary visual cortex
- info sent to superior colliculus where it is integrated with other incoming sensory inputs
define the optic chiasm
x-shaped space in the forebrain in front of the hypothalamus
what happens at the LGN
the spatial organization of the visual scene is detected
sending info to the superior colliculus and integrating it with other sensory inputs allows for_
hand/eye coordination
- also plays a role in attention and visual perception
detail of visual information is reflected in 3 characteristics
acuity
- accomodation
- contrast sensitivity
define acuity, how is it measured?
ability to see fine detail
- measured using the snellen test
describe the snellen test
“normal” vision is 20/20
- first # = test distance (ft)
- second # = average person could read the letters from x ft away
what does the score 20/40 on the snellen test mean?
*can see the same detail at 20 feet that the average person can see at 30 ft away, worse vision
what 3 conditions did we discuss under the topic of accomodation?
- hyperopia (far sighted)
- myopia (near sighted)
- astigmatism
describe hyperopia. What happens with age?
- far sighted
- eyeball is shorter than normal (objects focus “beyond” the back of the eye)
- hardening of the lens (with age) will increase hyperopia
describe myopia
- near sighted
- eyeball is longer than normal (image falls short of the retina)
on the topic of myopia, what type of lens corresponds to a positive or negative prescription?
concave - negative
convex - positive
describe astigmatism
- a defect in the eye caused by a deviation from spherical curvature which results in distorted images, as light rays are prevented from meeting at a common focus
ex. claire’s eyeball is shaped like football
how often does astigmatism occur?
about 1 in 3 people have some degree of astignmatism
what structural differences happen in the cornea of newborns?
during the first year, cornea is not symmetrical
(astigmatisms and difficulty in focusing)
what structural differences happen in the ciliary muscles of newborns?
ciliary muscles are weak; therefore, few newborns cannot shape their lens to accommodate for the shifting plane of focus for visual targets
- newborns can best adjust for targets 5-10 inches away
newborns can best adjust for targets_inches away
5-10
define contrast sensitivity
refers to the ability to resolve spatial structures from fine to course at various levels of contrast and the ability to perceive differences in light levelso
contrast sensitivity is critical for the detection and recognition of _
shapes
what patterns do babies prefer (contrast sensitivity)
- babies prefer the pattern with the most contrast
- newborns cannot see the contrast in more complex patterns (therefore, prefer to look at more bold patterns)
- by 2 months, contrast sensitivity has improved considerably
*small contrast = blurs together
describe preferential looking
- infants look at new or novel objects over familiar ones
- attention wanders from objects to which the infant is habituated
- researchers habituate an infant to an object then present a familiar object and a new one
- if infants can detect a difference, they tend to look at the new object
define habituation*
the state of having adapted to stimuli/toy
what can we use eye tracking for? (assessment of vision and perception)
- we can use eye tracking to assess fixations and eye movements (visual search behaviour)
describe fixations
- scan paths
- start around edges
- progress to relevant areas of human expression
describe saccades
eye movements
- no eye movements for newborns, must move head
- saccades appear before smooth pursuits
describe smooth pursuit
- 4-5 months will exhibit approaching movements with upper body as if attempting to receive object
- 5-6 years will begin tracking in a horizontal plane
- 8-9 years can track an arc
- maturity in smooth pursuit achieved at ~12 years old
describe braille reading (pt1)
- consider individuals who are blind, and are proficient in Braille reading at an early stage in life
- their brain has the ability to reorganize cortical areas that are otherwise unused
- for optimal efficiency
**instead of area of brain being dormant, neuroplasticity to use that space for touch receptors for ppl who are blind
describe braille reading (pt2)
- sadato et al. (1996) found an increase in blood flow in the occipital lobe primary visual orte in people who are blind during braille and touch discrimination tasks
- there was a decrease in regional cerebral blood flow in these same areas with the same task in sighted individuals
describe some of the strategies used in braille reading
- different strategies for # of fingers used during Braille reading
- for 3-finger reading techniques, there is a cortical ‘smearing’ of the representation of those 3-fingers & an increased zone cortically
- however, these individuals are now prone to misperceiving von Fray hairs
*for someone who’s blind, their 3 fingers are interpreted as 1 in the brain, made for efficiency
list the 3 major aspects of visual perception
1) perception of space/depth
2) perception of objects
3) perception of motion
a very powerful depth cue is _
shadow
describe depth perceptions
-our brains are organized to perceive what we see in terms ofour everyday experiences (reflection of light from objects tells us about the object’s location, size, shape, colour, etc.)
- sometimes, even for adults, this info can be misleading
define optic flow
the continuous change that occurs in the optic array (ie. pattern light makes when it strikes the retina) due to a moving object
define motion parallax
objects in space change location on our retina as we move or as they move
- objects moving at a constant speed in front of us will appear to move faster or slower depending on their distance to us
*objects closer have a shorter distance to travel in visual field
*objects farther away are perceived as moving slowing because they stay in visual field longer
define depth perception
the ability to use visual cues in order to perceive the distance or 3-dimensional characteristics of an object
perception of space depends on judgment of _. This info comes from _
depth and distance
- experience software
describe experience software
- infants have the mechanics in their retina and motion parallax, but they lack experience
- can infants perceive depth from birth? Is depth perception innate? How much is experience a rate limiter on depth perception?
*depth perception is refined to adults like levels in adolescence
infants blink from about 1 month of ange when shown _ (experience “software)
an object that appears to be approaching
- thus, object is perceived as moving towards the not merely increasing in size
what is the most famous evidence that depth perception is innate? (experience software)
- infants between 6-12 months failed to cross the “cliff”
- this suggests they possessed at least some of the elements of depth perception
what did we learn from the video that showed baby’s not crossing over a fake cliff?
the fear reponse actually seems to be learned
(ie. need to know about surfaces when crawling)
define object permanence (perception of objects)
realization that objects continue to exist when they are no longer in view
describe the perception of objects
ability to perceive an object’s attributes (size, shape, motion) & relate this to ourselves and to other objects
- much to do with the development of contrast sensitivity (ability to distinguish patterns)
newborns have poor contrast sensitivity but can _
detect many objects
- face perception
what was used to study face perception?
preference method
describe the preference method
- ages 4 days to 5 months
- shown pairs of faces, measured time spent fixated on each one
- realistic faces, scrambled faces, and blank faces
- infants of all ages look mostly at the realistic facem and least at the blank face
what did the preference method show us?
suggests that the ability to recognize faces is either innate or learned shortly after birth
describe whole and part
a young child might report only seeing a heart or a face, and not the individual components (or the reverse)
- do not see the whole object made up of familiar pieces
when does integration usually occur? (whole and part)
integration usually occurs by age 9
- children usually detect the whole OR detect the parts
describe object constancy
- distance and object perception interact
- adults perceive that objects retain their size even if the retinal image size changes because their distance from the observer changes
describe the development of object constancy
- motion perception starts to develop
- continue to develop throughout childhood
- however, the development of motion perception in early childhood is not well understood, requires more research
What is the 6th sense?
kinesthetic
- kinesthesisis derived from the greek words ‘to move’ and ‘sensation’
the kinesthetic system gives us _ sense
body sense
- how we move in our environment
- identify the objects we’re interacting with
-provides our sense of force, heaviness and effort
think about walking through a fun house at a far, your visual system and kinesthetic are giving you _ information
conflicting
the kinesthetic system gives us information about what 4 things? Also provide an alternative name for kinesthetic
proprioceptive
- our body parts in relation to each other
- position of the body in space
- our body’s movements
- nature of objects that we interact with
do we have muscle memory?
no
- there is no literal memory in the muscles (otherwise you could replicate the golf swing after the golf swing simulator)
what is our body concept?
-knowledge of hte body parts
age of onset of body concept is directly related to _
how much time is spent teaching the information
we first learn body parts on _, then progress to parts on _, then a _ (kinesthetic sensation/body concept)
first learn body parts on themselves, then on others, then a doll
list the 4 notable periods in the development of body concept
9 months = nose, eyes
18 months= ears, hands, feet
7 years = minor parts (ankles, wrists, shins)
9 years = identify all parts of the body
internal awareness and laterality plays a key role in both _ and _
btoh movement and academic success
- by 8-9 years old, can correctly identify/label left and right parts of the body
describe lateral preference (lateral dominance)
- infants show early hand preference when reaching, but this is not always predictive of their childhood handedness
- true lateral preference by age 3-4
- a child who has developed “feelings” (perceptions) whenone side does not feel natural
describe the tactile system
- sense of touch
define 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, temp, pain
describe tactile perception
refers to the ability to detect and interpret sensory information cutaneously (of or on the skin)
define proprioceptors
the various kinesthetic receptors located in the periphery of the body
what are the 2 types of proprioceptors?
1) somatosensors
2) vestibular apparatus
describe somatosensors
located in the muscles, muscle-tendon junctions, joints, ligaments, under the skin
describe the vestibular apparatus
in the inner ear
describe the auditory system
although it is not as important to skill performance as vision or kinesthetic, auditory informaiton is still valuable for accurate performance
- people often use sounds as critical cues to initiate or time their movements
hearing involves which parts of the ear?
external, middle and inner ear
define the absolute threshold
the minimal detectable sound a hearer can sense at least half of the time the signal is sounded
how is the absolute threshold different as a newborn?
- is about 60 d higher for newborns than for adults
- so, a newborn can detect an average speaking voice, but an adult can detect a whisper
define presbycusis
a loss of hearing sensitivity
describe presbycusis
- physiological degeneration, or exposure to environmental noise
- people are born with a fixed # of cochlear hair cells that do not regenerate
- hair cells killed by excessive noise exposure at any point in life result in a permanent loss
describe auditory perception
- we get so much information from sound:
- people leaving/approaching
- location of an event
- material of an object
Intermodal perception integrates _
perceptual systems
ex. auditory-visual, visual-kinesthetic, auditory-kinesthetic
*IMAX movies feeling so life-like, those of us that tend to get motion sick might not enjoy these
intermodal perception involves the collaboration of _ and coordination of _
- collaboration of the senses to aid perception
- coordination of information from different sensory modalities
define sensation, perception and where info is coming from in intermodal perception
sensarion:physical stimulation of the sensory receptors
perception: interpreting this sensory information
*sensory information from the environment
a major technical issue where psychologists are divided, is the extent to which perception relies on the _
information from the environment
