Lecture 02 - Perceptual and Motor Development

What is the difference between sensation and perception?

sensation is the process of receptors being stimulated and info being sent to brain

perception is what you make of sensation

• no perception without sensation

Do newborns have a good sense of smell at birth? How do we know?

Newborns have a good sense of smell at birth

• Positive response to pleasant smells

• Negative response to unpleasant smells

What do we know about smell in newborns?

• Studies that show that babies will prefer odours of the stuff that the mother ate during pregnancy

• Early on, babies have a capacity to smell but they can also retain and have a memory of smells

• Smell goes directly to olfactory bulb (brain)

  • We rely on sense of smell (animals particularly) for survival value

What types of tastes are infants generally attracted to? Why?

most infants have a sweet tooth

• they react to sweet substances by smiling, sucking, etc.

sugars = carbohydrates = energy

What is connection between infant’s taste and breast milk?

sensitive to changes in taste of breast milk

typically nurse more after their mother has consumed a sweet tasting substance

What is infants’ hearing like?

• Infants hear well but not quite as well accurately as adults

• Auditory system is fine tuned for pitches in range of human speech

• Preference for music

When do infants develop full vision?

takes longest to develop

takes about 3 months to have full colour vision

• that is when the 3 kinds of cones and associated circuits are working

What is visual acuity? What is this like for newborns? How do we test this?

Visual acuity = ability to distinguish details

• Newborns and 1-month-olds see at 6 meters what normal adults see at 60-120 meters

  • How to test this:

    • Present them with blank spot, or circle with grading. See where the child looks (preferential looking towards the graded circle). Making the grading progressively sharper until it looks similar to black dot

      • Narrower space between grading bars = higher acuity

• Acuity improves rapidly from one month to one year

When do infants have adult-like colour perception?

by 3-4 months

When can children integrate sensory info? What does this mean?

by 8 months

• They can recognize something that they touched and match it to what they see (felt firetruck in bag and then see firetruck and connect these)

• Detect relations between visual and auditory info

• Link body movement to musical rhythm

What is “common fate” in the Gestalt principles of motion perception?

If two objects move together, a child perceives them as one object.

How can children perceive objects using colour? Texture? Edge line?

If objects share the same colour, texture, edge line children are more likely to perceive them as part of the same object

What challenge does shape constancy pose for infants? At what age do children typically develop shape constancy?

They may think objects seen from different angles are different

• around 8 months the child understands that this is the same object just at different angles

What do infants prefer to look at, and how does this change by 3 months?

Infants like faces; by 3 months, they focus on features (eyes, nose, lips)

• fixation points of eyes, lips (using eye-tracking)

In particular, what object do infants prefer looking at (think distorted faces)?

prefer face-looking objects

prefer an outlet face to a mixed up human face

What does greater retinal disparity between the left and right eyes’ images signal?

That an object is close

At what age do infants begin using retinal disparity as a depth cue?

Around 4 to 6 months.

What are depth pictorial cues?

we also develop depth perception by learning cues

What is the texture gradient cue for depth?

nearby objects have coarse, distinct texture; distant objects appear finer and less distinct

What is interposition cue for depth?

nearby objects partially obscure more distant ones

What is linear perspective cue for depth?

parallel lines converge in the distance; the closer together they appear, the farther away the object is

What is the relative size cue for depth?

nearby objects look larger than distant ones

What was the visual cliff experiment? What did it tell us?

e.g. with infants and checker board platforms

as young as 1 ½ months, babies are afraid to go over cliff

• they already have perception of depth

What are motor skills?

coordinated movement of the muscles and limbs

What are some examples of motor skills for adults?

learning a new sport

learning to drive standard

gymnasts learning a triple tuck

How are babies at motor skills? Why?

everything is new for a baby

babies move all limbs together 

• they have not learned to inhibit limbs while moving others 

What are motor skills jointly learned with?

habitual movements

• from the striatum

Is everyone’s motor development timeline the same?

no!

large individual differences in rate of motor progress

What are gross motor skills?

walking, running, jumping, catching, swinging

balance improving

gait (manner of walking) is smoother and rhythmic

upper and lower body skulls combined in more refined actions

greater speed and endurance

How do gross motor skills develop?

through play

What are fine motor skills?

self help: dressing, eating

drawing and printing

pincing

How do fine motor skills develop?

through daily routine

What is the sequence of fine motor skill development and what ages do these occur?

pre-reaching

• newborn

ulnar grasp

• 3-4 months

• reaching or grabbing

transferring object from hand to hand 

• 4-5 months

pincer grasp

• 9 months

• precisely grabbing something between thumb and index

Definition of reflexes:

unlearned responses triggered by a specific form of stimulation

What do infant reflexes indicate? What occurs if they don’t develop or remain for too long?

reflexes indicate whether the newborn’s nervous system is working properly

• if these or other reflexes are weak or missing altogether, a thorough physical and behavioural assessment is required

• also a sign of neurological problem if they are present too long

What is the Babinski reflex?

sole of foot stroked → fans out toes and twists foot in 

prepares baby for balance when standing

disappears at 9 months-1 year

What is the blinking reflex?

flash of light or puff of air → closes eyes

permanent reflex

What is the grasping reflex?

palms touched → grasps tightly

weakens at 3 months; disappears at1 year

What is the moro reflex?

sudden move or loud noise → startles and throws out arms and legs and then pulls them toward body 

disappears at 3-4 months

What is the rooting relfex?

cheek stroked or side of mouth touched → turns toward source/opens mouth and sucks

important for feeding

disappears at 3-4 months

What is stepping reflex?

infant held upright with feet touching ground → moves feet as if to walk

disappears at 3-4 months

What is sucking reflex?

mouth touched by object → sucks on object

disappears at 3-4 months

What is swimming reflex?

placed face down in water → makes coordinated swimming movements

disappears at 6-7 months

What is tonic neck reflex?

placed on back → makes fists and turns head to right

disappears at 2 months

Which reflexes prepare the newborns to get nutrients they need to grow?

rooting

sucking

→ Ensures newborn is prepared to start a diet of life-sustaining milk

Which reflexes prepare newborns to avoid unpleasant stimulation?

blink reflex

withdrawal reflex = pulls limb away from painful stimulus (permanent)

→ Protects newborn from harmful or uncomfortable experiences

Which reflex prepares newborns for larger voluntary motor activity?

stepping reflex

early basis for voluntary locomotion

List all 12 developmental milestones:

FCCRSSSSCPSW

first creepy crawly rattle ssssnake climbed perfectly still wavy

0 = fetal posture

1 = chin up

2 = chest up

3 = reach and miss

4 = sit with support

5 = sit on lap, grasp objec

6 = sit alone

7-8 = stand with help

7-8 = crawl

8 = pull to stand by furniture 

11 = stand alone

12 = walk alone

When a child learns a new skills, what 4 things is it a joint product of?

1. CNS development

2. body’s movement capacity

3. child’s goals

4. environmental support for the skills

How can cultural variations effect motor development?

early movement opportunities

child-rearing practices

• In West Africa, mother encourages early walking by having baby walk up her body

environmental stimulation