Infant Depth Perception

• University course PSY2020 Lecture 2 study notes on Prenatal, Infancy & Brain development by Ting-Yat Wong, PhD on Jan 15 2024.

Group Presentation & Individual Paper

• Students will analyze the development of a chosen movie character through the lens of developmental psychology as a group project, due March 12.
• The analysis focus includes psychological growth, behavioral changes, and effects of external factors
• The individual paper, due April 9, requires an autobiographical analysis report demonstrating an understanding of psychological theories related to personal development.
• The report should be limited to 1,200 words.
• Include personal experiences, and analyze how developmental theories and research explain your journey

Question and Discussion

• Babies who walk early are not necessarily inclined to be especially bright.
• The average 2-year-old is about half of their adult height.
• Most children walk when they are ready, and no amount of encouragement will enable a 6-month-old to walk.

Maturation and Development: Height and Weight

• Expect a rapid increase in height and weight over the first two years of life.
• Growth becomes more gradual during middle childhood.
• Puberty (early adolescence) will herald rapid growth spurts for children.
• At age 10 ½, girls start their growth spurt, with boys starting about 2 ½ years later, growing faster than girls once they begin.

Body Proportions

• Cephalocaudal development involves head-downward growth.
• At birth, head and legs each constitute 25% of body length.
• By adulthood, the head is 12%, and legs reach 50% of body length.
• Proximodistal development involves center-outward growth, with internal organs developing before limbs.
• This trend reverses during puberty.

Human Brain Facts and Neuron Units

• The human brain has 100 billion neurons
• Each neuron are connected to 10 thousand other neurons
• The brain weighs about 2% of the body weight but consumes about 20% of the body's total energy.
• The brain contains about 86 billion neurons, each connected to around 7,000 other neurons. These send between ten and 100 signals every second.
• Neurons are nerve cells which contain axons, dendrites, a myelin sheath, and glial cells
• Axons send electrical signals across synaptic gaps, via neurotransmitters.
• Dendrites receive signals from different neurons.
• The myelin sheath is a layer of fat cells that helps impulses travel faster along the axon.
• Glia, which nourish neurons and encase them in myelin, exist throughout life.

Myelinization

• The process by which axons are coated with a fatty substance, myelin.
• Myelin sheaths act as electrical insulators, speeding up neural signal transmission.
• It allows for faster, more efficient neural communication.
• It is critical for cognitive, motor, and sensory functioning.
• Disruptions in myelinization can lead to neurological disorders, e.g., multiple sclerosis.
• It begins prenatally and continues through childhood and adolescence.
• Different brain regions undergo myelinization at different rates, e.g., sensory and motor areas before higher-order regions.
• Myelinization is vital for normal brain and behavioral development.
• Early experiences, such as nutrition and stimulation, can influence myelin growth.
• Understanding myelinization aids in diagnosing related disorders.

Brain Development During Pregnancy

• Neurons develop during the 1st trimester
• Neurons multiply in the 1st trimester
• Neurons Migrate in the 2nd trimester
• Neurons branch and form synapses in the 3rd trimester
• Pruning (apoptosis) occurs in the 3rd trimester
• Synapses reorganize during the 3rd trimester
• Myelination also occurs during the 3rd trimester

Connectivity in Early Life

• Brain connectivity increases significantly from birth through the first two years of life.

Reisen Research Findings

• Prolonged dark rearing led to permanent deficits in vision and perceptual abilities
• Normal visual function could not be fully restored, even with later exposure to light
• Beyond seven months, atrophy of retina and optic nerve was irreversible
• Early visual stimulation helps maintain normal sensory and cognitive growth

Brain Structure

• Frontal lobes govern movement, personality, thinking, and intentionality.
• Occipital lobes control vision.
• Temporal lobes govern language processing, hearing, and memory.
• Parietal lobes govern spatial location, attention, and motor control.

Gray and White Matter

• Gray matter and white matter are named due to their appearance during dissection.
• Gray matter is primarily composed of neuronal cell bodies, dendrites, and synapses, involved in processing information and controlling muscle movements using sensory perception. It has a Grayish color due to lack of myelin.
• White matter consists of myelinated axons facilitating communication between brain areas and fast signal transmission in the brain, and has a White color due to the myelin sheath.

Brain Development Across Lifespan

• Variations in brain structure impact function throughout life.

Sensation and Perception

• Sensation is the detection of sensory stimulation.
• Perception refers to the interpretation of sensory input.
• It is the mental process of sorting out, interpreting, analyzing, and integrating stimuli from the senses and brain.

Newborn Sensory Capabilities

• Vision is the least-developed, but infants can accommodate brightness, discriminate some colors, and track moving targets.
• Hearing develops the ability to turn in the direction of sounds but are are less sensitive to softer sounds than adults
• Taste: Prefer sweet solutions and can discriminate sweet, salty, sour, and bitter tastes.
• Smell: Can identify a variety of odors, and turn away from unpleasant ones and can identify their mother when breast-fed
• Touch: They can sense touch, temperature change and recognize pain.

Visual Development

• Visual acuity refers to the clarity or sharpness of vision, i.e., the ability to perceive fine detail.
• Newborns can see stripes 30 times wider than adults.
• Development includes detecting brightness, but vision is the least mature sense.
• By birth they can see 1/10 inch (2.54mm) wide at one foot (30.48cm) away
• By 2 months they can see 1/2 of the width seen at birth
• By 4 months they can see 1/4 of the width seen at birth
• By 8 months they can see 1/8 of the width seen at birth
• By 4-5 years is said to be Adult-like (i.e., 1/30 of the width seen at birth)
• Early vision impacts how infants interact with their environment.
• The ability to distinguish and categorize different wavelengths of light as distinct colors is importand
• Newborns have a limited color discrimination.
• 2-3 month olds - Infants begin to distinguish between red, green, blue, and yellow.
• By 3-4 months vision is comparable to an Adalt
• A babies perference a prefernce for bright, saturated colors over pastels

Depth Perception Development

• Kinetic cues: Looming is where an object appears to get larger and signals that it is closer.

• Motion parallax: Objects closer to you move across your field of vision faster than distant objects

• Development in use of 3 classes of cues: Kinetic, Binocular, and Monocular

• Kinetic cues begin from birth, and have sensitivety to motion cues

• Binocular cues begin around 3–4 months, and develop stereopsis

• Monocular (pictorial) cues occur around 6-7 months.

• Infants use linear perspective, interposition, and texture gradients to judge depth.

• Binocular cues such as convergence rotate inward when looking and a slight binocular disparity for things close to them

• Common types include: Linear Perspective, Interposition (Occlusion), Relative Size, Texture Gradient, and Shading and Lighting.

Visual Cliff Experiments

• Gibson & Walk's 1960 experiment investigated depth perception in infants, where infants are placed on the shallow side
• Campos et al. researched it again and were further able to group the results based on the infants crawler experience

Pattern and Forms

• They show a prefernce for high contrast patterns and face-like stimuli
• Fantz's 1961 test indicates infants prefer complex stimuli and moderately complex stimuli
• Early vision in infancy explain the prefernce

Hearing During Infancy

• Hearing is relatively well developed
• Fetus can respond to soudns around the third trimester
• Can discrimate Volume, Pitch and Duration
• Infants are sensitive to phonemes
• Recognize certain words when they hear them often

Smell and Taste During Infancy

• Smell is well developed at birth
• The innate sweet tooth of babies show that they can discrimiate the differfent tastes
• Taste is influsencede based on what the mother ate during pregnancy

Preferences

• Smell: Shows perfernce to Mothers breast milk
• Taste: Prefers sweet

Touch during Infancy

• The sense developes even before birth
• Can respond to the differnt tactile stimuli (light touch, pain)
• There has proven benefits when doing skin to skin contact
• Realses calm, and supportive growth when gently touched

Intermodal Perception

• Auditory-visual perception for a person.
• Helps match the face that heard and sounds together
• 1 month olds have the weakest intermodal perception
• By 4 month the hearing and vision modes start intermodal matching

Intersensory Redundancy Hypothesis

• Amodal Properties includes those that features detectable by multiple senses
• Learning is enhanced when there is a redundancy in the two different senses
• Selectivity attention when they have these redundant properties that are presented

Cultural Influences

• Language and become familiar with the the specifc sounds that are important to the the culture
• A familiarty with owns cutures music and tone

Reflexes

• Rooting Reflex: They head turn to see somthing when something is near ther cheek
• Sucking Reflex: They create a rythmic motion when somthing touches their mouth to ensure they take their nutrients in
• Moro (Startle) Reflex: When there is a suddning noise to a saftey reflex, the babys hands come togther.
• Blink Reflex: When somthing is approuching the face quickly, it is to help with blinking the eyes

Basic Learning in Infancy

• There is change in bahvior that is from experience that stays
• Learning is the cause and affect
• There are certain stimulus that is a repeated response over time
• Dishabituation helps with what the baby wants to look at
• Pavlov's classical conditioning is where a a stimulus and a response are paired together
• The conditioned stimulus is what brings forward that habit
• Social Cognitive Theory by Albert Bandura describes the ways in which people learn from and utilize their environments.
• Observational learning where they the baby can mimic what they see
• From a model of behavior
• Reciprocal interactions among three fators: personal factor, behavioral factor, and environmental factor at 14-26 months old
• The Baby Doll experiment is to observe that one learns though imitating the actions