Perceptual Development

historical: enrichment theories

perceptual learning occurs by accrual of information (from blank slate to knowledge)

• behavioral stimulus-response theories

• piaget

nativist theories

• perceptual information in environment is impoverished and ambiguous

• perceptions are arrived at via construction of representations

• there is no link between perception and action

who made the differentiation theory

eleanor gibson

what is the differentiation theory

• perceptual information is rich and structured

• perceptions are arrived at via differentiation

differentiation

the ability to extract invariant elements from the constantly changing environment (ex: a red ball that is partially covered in a photo is still a red ball)

3 weeks—pattern perception

• poor contrast sensitivity

• prefers large, simple patterns

2 months—pattern perception

• can detect detail in complex patterns

• scans internal features of patterns

4 months—pattern perception

• can detect patterns even if boundaries are not really present

12 months—pattern perception

• can detect objects even if two thirds of drawing is missing

differentiation theory

• learning takes place by progressive distinctions among stimuli

• there is a fundamental reciprocity of perception & action

perceptual learning: affordances

• infant’s discovery of the possibilities for action offered, or afforded, by objects and situations (Gibson)

Gibson’s contributions of differentiation theory

• perception = cognition

• children use meaningful properties of the world as the basis for differentiating features of the perceptual stimulation

• experience/learning change our perceptions, and our perceptions change how & what we learn

mechanism for perceptual development

exploratory action (touching, reaching, crawling to things)

birth-1mo—depth perception

sensitivity to kinetic cues

2-3mo—depth perception

sensitivity to binocular cues

5-12mo—depth perception

• sensitivity to pictorial cues

• wariness of heights

kinetic cues (0-1mo)

• sensitivity to motion

• looming effect (back away from something that looks like it’s coming at you)

binocular depth cues (2-3 mo)

• images your left and right eye see are slightly different, what you perceive merges these inputs pic

pictorial depth cues (5-12 mo)

trees that are smaller show it’s far away, grass gets lighter as it’s further away, van overlapping shows it’s closer, etc

visual cliff

wariness of heights

intermodal perception

• piaget: sensory modalities are initially separate

• gibson: newborn already has some ability to integrate information from different sensory modalities

assessing auditory-visual intermodal perception

5 mo. babies look at screen that matches picture with the sound they hear

assessing visual-tactile intermodal perception

• change from 8 to 9.5 mo

• feeling something different from what they were seeing

• 9.5mo old knew it was different

• 8mo old maybe knew it was wrong, but didn’t have strategies to do something about it

speech perception in infants

• can detect sounds of any human language

  • prefer slow, clear, and high-pitched

  • prefer own mother’s voice

• statistical learning capacity for speech patterns and sounds

• human newborns can discriminate languages of different rhythmic families

  • so can rats & tamarin monkeys

~4mo for speech perception

discriminate within same rhythmic family

12mo for speech perception

• segment speech into words, pair word with object

  • <7% of speech directed at infant consists of single words

experience expectant process

• similar brain circuitry to adults

• too advanced to be based purely on auditory experience

• argues for experience-expectant modules to facilitate language acquisition

perceptual narrowing effect: speech & faces

• 0-6mo can distinguish speech sounds in all languages

• 9mo, less sensitive to speech distinctions in non-native languages

• similar pattern with face perception—6 mo olds can learn to recognize monkey faces, 9 mo olds don’t

what lobe of the brain recognizes faces?

temporal lobe

6 mo old temporal lobe

shows a different response to faces than to objects, and to mom’s vs. stranger’s face

inverted faces

babies do not recognize

infant emotion discrimination

7mo old infants discriminate them from upright negative faces

facial emotion processing in children

• infants discriminate positive and negative facial expressions at least as young as 7 mo of age

• discrimination of emotions within valence categories appears to take longer to develop, extending well into childhood and even early adolescence

0-5mo for emotion processing circuits

structural formation of neural circuitry

5-7mo for emotion processing circuits

experience-expectant functional development

8mo+ for emotion processing circuits

experience-dependent functional development