Sensation & Perception Flashcards
Sensation
the processing of basic information from the external world by the sensory receptors
-> bottom-up processing
Perception
The process of organizing and interpreting sensory information
-> top-down processing
How to study infant’s sensory & perception?
- Preferential-looking: show 2 stimuli at the same time to see what infants prefer to look at
- Habituation: repeatedly show a stimulus until response declines
- Operant conditioning: reward infant with stimulus to see which stimulus they prefer
How to know if the infant can distinguish/sense?
If the infant’s response increases when a novel stimulus is presented, the researcher infers that the baby can discriminate between the old and new stimuli
Vision Acuity in infants
sharpness of visual discrimination
development:
- 8 months: similar to adults
- 6 years: full adult acuity
how to test: comparing the duration baby (reaction to new stimulus) looks at black-white striped square vs. gray square of same size and brightness
Contrast sensitivity in infants
The ability to detect differences in light & dark area
birth -> 2 months: prefer images with high visual contrast
reason for poor contrast sensitivity:
- underdeveloped fovea
- cone cells (light-receptors) differ from adults’ in size, shape and spacing
Colour vision in infants
2-3 months: similar to adult colour vision (colour discrimination)
Infants can discriminate between two bright, vivid colors better than between two faint, pastel colors
Scanning & tracking development in infants?
Scanning:
- 1 month: scan perimeter of shapes
- 2 months: perimeters and interiors of shapes
Tracking: although start tracking since birth but can’t follow object motion until 2-3 months of age
Face recognition in infants?
From birth, infants are drawn to faces because of a general bias toward configurations with more elements in the upper half than in the lower half
What is surprising about facial recognition in 6-month-old infants?
6-month-old infants are better at distinguishing between monkey faces than 9-month-olds and adults
-> less used to seeing only human faces
Facial preferences in infants?
- Prefer caregiver’s face
- Understand significant of facial expressions
- Beauty bias: look longer at (more) attractive adults -> attractiveness affect behaviours: infants interact more positively with people with attractive faces
Pattern perception in infants?
Two-month-old infants can analyze and integrate separate elements of a visual display into a coherent pattern
-> study: invisible square by arranging 4 circles with 90-degree angles
What are 3 characteristics of objects perception?
- Perceptual constancy: perception of objects being constant in size (despite contradictory images)
- Object segregation: can perceive if overlapping image is made of 2 or more objects or not based on physical cues (e.g. gravity)
- Depth perception: ability to register a visual image of an object is 3D (using optical expansion, stereopsis and monocular cues)
Key developments of depth perception in infants?
1 month: optical expansion
4 months: stereopsis
6-7 months: sensitive to monocular/pictorial cues
19 months: pictorial representation - stop treating images of 3D objects as real objects
Optical expansion?
First appear in 1-month-old infants
A depth cue in which the object image increases, indicating that they are getting close
Stereopsis?
First appear in 4-month-olds
Visual ability to perceive the world in 3D by combining visual signals from binocular disparity (difference in what is seen from left & right eyes)
Monocular/pictorial cues
The perceptual cues of depth that can be achieved by one eye alone.
Including:
1. Relative size (larger is closer)
2. Interposition (overlapping)
3. Linear perspective (convergence of parallel lines).
Auditory perception in infants?
Takes 5-6 years for infants to reach the same level in adults.
Good at recognizing subtle differences in human speech
Auditory localisation: newborns will turn toward sound, especially with repeated sound
Perception of sounds? (phonemes)
2-month-olds can recognise between 2 difference phonemes by measuring baseline sucking rate as responses to auditory stimulus
Measure by using habituation
Perception of music?
Evidence suggests a biological foundation for music perception
Evidences:
1. 31-week-olds heart rates calm down when listen to Brahms lullaby
2. Singing keep 7-10 months old infants calm twice as long as speech
3. Strong preferences for pleasing music sound similar to adults
4. Infants respond to rhythm and temporal organization in music
5. Sensitive to melody (even withs pitch-change)
Tastes & Smell in infants?
- Preference for sweetness
- Newborns prefer their own amniotic fluid and their mothers’ breast milk
- Newborns facial expression after tasting various substances are similar to adults’ (innate abilities)
Touch sensory in infants?
- birth -> 4th month: oral exploration - infants will put everything into their mouth
- 4 months: increase in hand movements
Intermodal perception
Very young infants can link sight and sound, oral and visual experience, and visual and tactile experience
Evidence for intermodal perception in infants?
- 2-months old prefer video that correspond to the sounds they are hearing when 2 videos are played
- 5-months old infants can link facial expressions with emotion in voice
- Infants can recognize shape of ring by connecting visual to touch
