Developmental Psychology: Infant Perception Basics

Visual Development

• Infants' visual development is not as underdeveloped as previously thought
• Babies scan their surroundings and focus on interesting things from birth
• Research methods are used to assess infant perception, including preferential looking and habituation paradigms

Methods in Infant Research

• Preferential Looking Paradigm: Assess infant preference for one stimulus over another. Two stimuli are presented side-by-side, and researchers measure how long the baby looks at each one
• Habituation Paradigm: Repeatedly present a stimulus to an infant until the baby becomes bored (habituates) or loses interest. Then researchers present a new stimulus. If the infant's interest is renewed (dishabituation), it shows they can distinguish between the original and new stimuli

What do babies see at birth?

• Previous assumptions were that infants' vision was almost non-functional at birth, but recent evidence shows this is inaccurate
• At birth, infants visually scan their environments and pause to look at things
• Researchers must get creative to assess what infants can see

What is interesting to infants?

• Infants prefer to look at complex and highly saturated stimuli (strong colors).
• Familiarity is also an important factor.

Habituation Paradigm

• The habituation paradigm takes advantage of a baby's inborn attraction to novelty
• Repeatedly showing a baby the same stimulus will eventually lead them to lose interest
• If the baby then shows renewed interest when a new stimulus is presented, it suggests the baby can distinguish between the two

Familiarity vs. Novelty

• Generally, infants prefer familiar stimuli
• Repeated exposure to a stimulus will lead to a shift in their preference towards novelty.

Summary of Visual Development

• Preferential-looking: Two stimuli are presented to infants, and researchers record where the infant looks longer. This indicates a preference.
• Habituation: A stimulus is repeatedly shown until the infant is no longer interested. Then another stimulus is introduced to see if the infant's interest is recovered. This indicates discrimination.
• Both paradigms are used to assess an infant's ability to distinguish between different stimuli

Visual Acuity and Colour Perception

• Poor visual acuity at birth, infants prefer high-contrast visual stimuli.
• Infants' color vision gradually improves and matures by 5 to 8 months, reaching adult-like levels.
• At birth, visual acuity is poor, but by 8 months, it approaches adult levels.
• Inability to discern details at birth is due to immature cone cells in the retina
• Cone cells are light-sensitive cells in the retina responsible for fine details and color vision.

Development of Visual Acuity

• Visual acuity improves gradually until 8-12 months after birth.
• Infants' vision becomes sharper over time with maturation

Color Perception

• At birth, infants' vision is primarily grayscale.
• Color perception develops to adult-like levels by 5 months of age due to maturing cones and visual cortex neural connections.

Visual Scanning

• Infants start visually scanning their environment from birth
• Early on, eye movements are jerky, but smooth visual tracking develops in stages.
• Smooth visual tracking and following movement is fully developed by 8 months.

Face Perception

• Newborns have a preference for faces and face-like stimuli over non-face stimuli
• This suggests a potential innate mechanism for face perception.
• Infants show preference for stimuli that are top-heavy, as opposed to bottom-heavy.

Why are infants drawn to faces?

• Hypothesis: Infants might have a generalized preference for top-heavy stimuli, not only faces.
• Researchers presented babies with upright faces, upside-down faces, and scrambled or top-heavy/bottom-heavy faces.
• Results indicated babies prefer upright faces over upside-down faces, and faces with a top-heavy arrangement to faces with bottom-heavy arrangement.

Seeing Mom's Face

• Within days after birth, babies prefer their mothers' faces over other women's faces.

Becoming a Face Specialist

• Over the first year of life, infants gradually develop specialization in face recognition
• Improved ability to distinguish between faces that are frequently experienced versus those less frequently seen.

Other-Race Effect in Infants

• Infants show an easier time distinguishing faces of their own race compared to other races.
• This preference is not innate but a result of exposure and experience. Frequent exposure to faces from one's own racial group leads to better recognition of those faces.
• Three-month-old babies can generally distinguish amongst all racial faces
• Nine-month-olds can better discriminate between faces from their own race.

Perceptual Narrowing

• Perceptual narrowing is the tuning of perceptual mechanisms in infants to specific sensory inputs within their environment
• This improvement in perceiving common stimuli comes at the expense of the ability to discriminate stimuli not frequently encountered
• It is due to synaptic pruning, where less used neural connections are eliminated.

Recap: Synaptic Pruning

• Synaptic pruning eliminates unused neural connections, improving efficiency
• Follows the "use it or lose it" principle.
• Rapid synaptogenesis occurs after birth leading to hyperconnectivity, which is later pruned

Face Perception in Children with ASD

• Children with autism spectrum disorder may have difficulties recognizing faces, including avoiding eye contact.
• Toddlers with ASD have displayed preferences towards geometric shapes over faces
• In infants, preference for non-faces could be an early indicator of ASD later in their lives.

Summary of Face Perception

• Infants have a preference for faces, especially their mothers' faces, from birth
• This preference is likely not innate but a result of a general preference for top-heavy stimuli
• By 9 months of age, infants become specialists in recognizing faces.

Object Perception

• Perceptual constancy is the ability to recognize objects as staying constant in size, shape, and color despite changes in retinal image.
• Infants exhibit evidence of perceptual constancy from birth.
• The ability to distinguish between objects is called object segregation. Movement is a key cue.

Perceptual Constancy in Infants

• Studies using habituation paradigms show that infants as young as newborns can perceive objects as being the same, regardless of changes in retinal image due to changes in distance.

Object Segregation in Infants

• The ability of infants to identify separate distinct objects is called object segregation
• Infants show evidence of object segregation as early as four months of age.
• Research suggests this ability is dependent on experience and perceptual development, not purely innate

Depth Perception

• Binocular disparity is the slightly different retinal image from each eye used to perceive depth, developed by 4 months of age.
• Infants depend on binocular disparity for depth perception
• Infants need both eyes for binocular vision; it can be impacted by visual experiences.
• Monocular cues for depth perception (size, overlap, etc) emerge around 6 months, and are dependent on visual experience and improvement in visual acuity

Sensitive Period for Binocular Vision

• A sensitive period for binocular vision from birth to age three exists.
• Infants that don't receive normal visual input during this time may not develop appropriate binocular vision and will encounter issues with depth perception.

Visual Development Timeline

• A summary of visual development progresses from birth to 9 months of age, demonstrating the progressive development of infants' vision

The Nature and Nurture of Visual Development

• Some visual abilities are innate, including perceptual constancy and preference for top-heavy stimuli
• Other abilities depend on experience and maturation in the brain

This quiz explores the fundamentals of infant perception, including methods used to study it and key concepts such as depth perception and sensitive periods. You will encounter questions about paradigms like preferential looking and habituation, as well as important developmental phenomena. Test your knowledge on what makes infants unique in their perceptual abilities.