Phys Growth 13

What is Comfort vs. Contradictions?

• Comfort vs. Contradictions

  • Contradictions such as being motion sick – the body cannot make sense of the two different stimuli present

What is Sensation vs. Perception?

• Sensation

  • Neural activity triggered by a stimulus that activates a sensory receptor and results in sensory nerve impulses travelling along the sensor nerve pathways to the brain

• Perception

  • Selection, organization, and integration of sensory information

  • Interpretation of stimuli

  • Involves all senses, but vision is very important

How is our sight developed?

• Visual Sensation aka Visual Acuity

  • How we can read content

• Develops post-natally; at 1 month information is useful but not refined (5% of adult acuity, 20/400)

• Color vision and luminally (???) present at birth, but discrimination improves in first months

• Perception improves with maturation of underlying physiological processes

• Visual experience necessary for development of vision

How does aging effect eye sight?

• Natural Changes and Eye Diseases

  • Impact quality of visual info to the CNS

  • Can impact performance of daily skills

• Diseases and Congenital Issues

  • Presbyopia

  • Cataracts

  • Glaucoma

  • Age-related maculopathy

What are the signs of a visual problem?

• Lack of hand-eye coordination

  • EX) Cutting with scissors, not able to trace a pattern could mean disorders

• Squinting

• Under or overshooting for objects

  • EX) Unable to hit target correctly in ballistic skills

• Unusual head movements especially in infants

What is Space Perception?

• Perception of 3D space is necessary for most movements

• Visual info received by receptors in the retina in 2D

  • We interpret in 3D

• Depth perception - a person’s judgment of the distance from self to an object or place in space

What are the sources for space perception?

• Retinal Disparity

  • Differences in the images received by the two eyes as a result of their different locations (finger in front, close one eye open other and then repeat)

• Motion Parallax

  • Change in optical location for objects at different distances during viewer motion

  • “Changing of location due to motion itself”

    • EX) Driving down a highway, something further will be smaller, something closer will be bigger

• Optic Flow (still unsure, look it up)

  • Receiving information in different ways

  • Changes in the pattern of optical texture, a transformation of the optic array, as a viewer moves forward or backward in a stable environment

When do we perceive the space around us?

• 1 month: blinking when object is approaching

  • Demonstrates that they perceive the object is getting closer, and not only that, it is getting bigger

• 6 to 14 months

  • Visual cliff experiments of Walk and Gibson

How do we perceive our objects? (LONG)

• Figure-and-Ground Perception

  • Ability to see an object as a distinct from the background

  • Perception of edges leads to extraction of the objects from the environment

  • Improvement between 4 and 6 years and again between 6 and 8 years

• Whole-and-Part Perception

  • Ability to discriminate parts of a picture or an object from the whole, yet integrate the parts into the whole, perceiving them simultaneously

  • Before 9 years, children have difficulty integrating objects that form a whole. They see one or the other at different times

• Size Constancy

  • Being able to render the size and diameter of an object despite the image projected in our retinas

  • Newborns have this

• Spatial Orientation

  • Orientation or position of objects as they are located in space or in a 2D drawing

  • 3 - 4 years: differentiate directional extremes (i.e. high-low, front-back)

  • 8 years: differentiate obliques and diagonals but may still confuse left and right

How do we assess an infant’s perception?

• Visual Preference

  • Simultaneous presentation of two stimuli

  • If the child looks at one stimuli longer, it is assumed that he can distinguish between the two and that he prefers that one

• Habituation

  • Stimulus presented repeatedly until interest is decreased by habituation

  • A new object is presented

  • If the child looks at the new stimulus, it is assumed that he can distinguish between the two

How do we perceive motion?

• Very important for motor development

• Specialized cells in the visual cortex for movement detection

• Newborns perceive movement, but direction is not perceived before 8 wks

• Speed detection threshold is higher until 6 weeks

• Older adults also have a hard time detecting movement that is close to the detection threshold

* You are moving around in a crowded city (walking or in a car). Give examples of how space or object perception would come into play. (practice question)

talk to yourself bro

How does our proprioception develop? Is it the same as kinesthesia?

• Essentially our 6th sense

• Provides info about:

  • Position of body parts in relation with the rest of the body

  • Body movements

• Proprioception vs Kinesthesia

  • Not the same thing

  • Proprioception - being aware of body in space

  • Kinesthesia - awareness of how the body is moving in space

What are the Kinesthetic receptors?

• Muscle Spindles

  • Parallel to muscle fibers

  • Sensitive to stretching of muscle

    • Increases contraction in response to stretch

• Golgi Tendon Organs

  • Located at the junction of tendon and muscle

  • Detects tension at tendon

  • Informs CNS of change in force

  • Impartial role in maintaining muscle tone

• Joint Receptors

  • Located in joint capsules

  • Most respond to extremes in joint amplitude

  • Detection of the limit of the articulation

  • “Last ditch mechanism in the body” typically responds to severe amplifications in the joint (i.e. rolling the ankle)

How does kinesthetic sensation develop?

• Infantine reflexes are stimulated by proprioceptive receptors

  • Presence of the reflex demonstrates that the corresponding receptor is functioning

  • At birth, responds to touch

  • Labyrinthe righting reflex appears around 2 months – a vestibular function

• Development of cutaneous receptors follow this order:

  • Oral, genital, palmar, and plantar

  • Cephalocaudal and proximodistal development

What is Tactile Recognition?

• Recognizing an object and its characteristics by touching it

  • 4 yrs - child can purposefully manipulate without vision

  • 5 yrs - child can explore characteristics of the object

  • 6 yrs - exploration becomes systematic (follows a plan)

  • 8 yrs - cutaneous memory and object recognition is improved, speed of tactile recognition is also imrpvoed

What is Body Awareness (Perception of the Body)?

• Fundamental aspect of proprioception: knowledge and localization of different body parts, their relations, capacities, and limitation

• By 6 yrs, about ⅔ of children can identify major body parts (hand, nose, knee, etc)

• By 9 yrs, mistakes are rare in identifying body parts

• This ability depends on language, conceptual capacities, and other sensory modalities

What is Spatial Perception?

• The ability to draw conclusions about one’s own space/position including in relation to objects

• Egocentric Localization:

  • Localization of an object in space in relation to one’s own body

• Objective Localization:

  • Localization of an object using reference points other than one’s own body (i.e. reading a map)

• Before 1 year, only egocentric localization

• Objective localization develops between 12 - 16 months

• Both types are used in the adult

What does the ear consist of? Is Hearing perfect at birth?

• Consists of the ear (outer, middle, and inner ear)

  • Internal develops first, close to adult form by 3 months pre-natal

  • Outer and middle ear formed by mid-fetal life

  • Fetus responds to loud noises or could also be due to vibrations

• Hearing is not perfect at birth

  • Gelatinous substance is loose but becomes viscous as we age

  • Absolute threshold is ~60 decibels higher for a newborn than an adult (normal voice vs. whispering)

  • Cannot differentiate intensity of noises or frequency of sounds like an adult

How does auditory sensation develop in adults?

• Presbycusis - decrease in hearing sensitivity, happens naturally due to degradation of the brain, demyelination, or exposure to heavy/loud sounds

• Absolute threshold increases, therefore sound must be louder (whispers become harder to detect)

• Decreased ability to hear higher frequency sounds