W3.1 - Perceptual + Motor Development

How is infant perception tested?

Infant perception is tested using habituation → present an infant the same stimulus until bored, then introduce a new stimulus to observe if their attention increases.

Habituated vs. dishabituated

habituated - used to something (so they become bored) ;

dishabituated - renewed interest when a new stimulus is introduced (dec. bored)

What is the least mature sense at birth?

Vision - due to a lack of visual stimulus in utero and underdeveloped retinal and cortical connections.

What is visual actuity? What pattern can an infant distinguish best?

Visual actuity is the clarity of an infants vision. Infants can best distinguish black and white stripes with wide width.

When does color perception develop and how?

At birth, NB can only see in black, white & red and by 3-4 months, they can see the same colors as adults as the specialized neurons in the retina need experience to develop & view wavelengths.

In what order do the colors from wavelengths develop?

1. long (red & orange)

2. medium (green & blue)

3. short (blue & violet)

How do infants’ eyes track their environment?

NBs take in information thru Saccades, which are quick, simultaneous eye movements that allow them to take in a lot of information. Their eyes jump from subject to subject or when following an object.

Why do newborns have saccades?

Newborns have saccades bc their retina lacks structure and has muscular limits on ability to control these movements. → disorganized & easily tiring (but fully developed by 2 mo.)

How are infants tracking objects?

At 1 month, infants track the outside edges or contours of an object and by 2 months, they engage in smooth tracking able to scan contours & inner parts of the face.

How do infants percieve faces?

Infants percieve faces by starting at the outer edges (chin, hairline, & eyes @ 1 mo.) then start at the top and between the eyes and mouth (3 mo.) & prefer real faces

Can infants’ face perception species specific?

Perceptual narrowing - infants don’t know what is & isn’t important so they pay attention to everything but overtime, start to pay attention to important stuff only. At 6 mo., they can discriminate between human & monkey faces but by 8 months can only discriminate humans.

Do infants have racial preferences with face perception?

Yes, infants tend to perfer the face of the race/ethnicity they have most exposure to (caucasian bby prefers caucasion) and its developed by 3 months.

Why can infants develop a race preference with face perception?

The more a child is in contact with a specific race, the more they pay attention to internal contours & features that correlate w/race. → need frequent contact with multiple to not develop a preference

When does an infant begin to percieve an object in motion?

at 4 mo. an infant cannot anticipate movement → at 6 mo. they start to use cues to anticipate movement

When do infants develop depth perception?

Infants use monocular (1 eye for depth) cues (like interposition & texture gradients) → develop depth perception at around 4 mo.

Define Interposition

cue to depth, use of edges to percieve depth

How can interposition be observed in an infant?

a 4 mo. old should look longer at a triangle than the rectangle because they use the edges as a cue

How can the impact of texture gradients be seen in infants?

Using the visual cliff paradigm, an infant who has depth perception won’t want to cross the deepside of the cliff

What is the most mature sense at birth?

Hearing → in the first few days of life, they’ll turn towards sound, get startled easily, & can distinguish sounds, languages, & rhythms

Do infants react to smell?

Infants react to strong smellls only, but by 1 week, can recognize mom’s breast milk & amniotic fluid

How is an infant’s sense of taste like?

they prefer sweet over bitter, sour, salty, or neutral → by 4 mo. start preferring salt but tend to nurse more if mom eats vanilla

Describe an infant’s sense of touch.

Nerves are the same proportion as adults → experience pain & are sensitive to temperature → can be seen thru grimace & withdrawal reflex

How do infants integrate their senses?

Using intersensory redundancy → perceptions are best when info is redundant to multiple senses

ex) 1 mo. - can visually recognize a pacifer only touched before; 3 mo. can match voice w/emotion

Why can’t infants & kids pay selective attention?

BC the frontal lobe is late to develop → lack executive control

How can we keep a infant/child’s attention?

by issueing reminders, decreasing distractions, make important info salient (small list of tasks)

How do motor skills develop?

head to trunk → hands to feet → midline to extremeties → gross to fine muscles

When do infants gain head control?

• NB - turn side to side while on back

• 2-3 mo. - lift while on stomach

• 4 mo. - sit w/support

What is involved in developing self motion?

the vestibular system (inner ear) & visual proprioception (sensors in periphery) are needed for balance → improves w/experience

How is visual proprioception tested?

The moving room study - kids w/locomotor experience: will posturally, compensate to peripheral movement while pre-loco will fall (walls move forward, percieve falling)

Explain the relationship between perception & movement.

an interactive exchange - need experience to incorporate perceptual info into controlled movement

How does carrying help with motor development?

carrying provides vestibular & proprioceptive stimulation → earlier dev. walking/crawling

How do reaching skills develop?

Reaching initially random → voluntary ~ 3 mo. → improves w/depth perception & increase control of body

Ulnar vs Pincer grasp

ulnar grasp involves fingers closing against palm (hand) while pincer is between index & thumb (developed thru increase coordination)

When does handedness appear?

Preference emerges by 13 mo.

• connected to language localization, handedness depends on the opposite side of lang. areas

• increase capacity of dominant hemisphere in relation to skilled motor