Perceptual development in children & studied in animals

• What is perception?

  Perception - organisation and interpretation of sensory information
• What is the nativist view of perception?

  • Humans are born with at least some genetically predisposed perceptual abilities even if not immediately evident and only appear later
• What is the constructivist view of perception?

  • Perceptual abilities develop through learning as we make sense of the sensations we experience so are born with little or no perceptual abilities
• What is the interactionist view of perception?

  • Born with strong predisposition to develop certain perceptual abilities for survival but these develop in response to experiences
• Outline development of depth perception

  • 3 dimensional - ability to perceive depth or distance promotes survival
  • Brains can interpret depth cues - features of environment that give info about where objects are and how far
  • Perceive objects as constant even though we see them from different angles e.g. open door still looks like a door
• What are constancies?

  • Object remains unchanged even though we may perceive them as changed
  • E.g. Colour, shape, size
• Give examples of depth cues

  • Linear perspective
  • Height in plane
  • Superimposition
  • Texture gradient - less detail further away
• Outline research into role of nature

  Bower:

  • Tested ability of babies 8-17 days old to perceive depth / distance in recognising object coming towards them
  • Showed 2 cube shaped objects, 1 larger than other
  • Each watched as moved from within 20cm and smaller object within 8cm - images projected to retina same size
  • Often raised arms & heads in response to closer object showing they can distinguish between them and shows some degree of depth perception present few days after birth
• Outline research into role of nurture

  Hudson:

  • Showed 2D drawing to South African children & adults who had primary education and those who did not
  • Hunter appears to point spear in general direction of elephant & antelope with depth cues in image implying what really aiming at - elephant smaller & higher up
  • School ppts - hunter aim at antelope
  • Unschooled ppts - chose elephant - implies depth perception learned through experience and unschooled had less

  
• Outline face perception in babies

  Fantz:

  • Newborns - black & white of human face
  • Babies looked at image on left longer
  • Young babies showed no preference for correct image over scrambled but did at 3 months - perception but not present at birth
  • 1 week prefer patterned surfaces to plain
  • 2 months preferred 3D to flat

  
• What did Fantz say about how face perception develops in babies?

  Fantz:

  • Babies preference for human faces develops at same time as changes in how they scan faces
  • 1 month - look intently at edges or contours
  • 2 / 3 months - look at centre of face probably controlled by neural circuits in the development of the cerebral cortex - when babies perceive human faces rather than collection of human parts
• Outline preferential looking

  • Fantz - babies look at things they find interesting
  • Measure amount of time spent looking at 2 stimuli (quan)
  • Longer on 1 is preference and indicates they can distinguish between
  • Can video babies eye movements for reasonably objective & accurate measures (inter-rater)
• Outline Habitutation

  • Babies spend longer looking at something novel but once used to it they become habituated and look elsewhere
  • Present stimulus to baby and record how long baby looks and when they look away the stimulus is taken away for short time & presented again
  • Repeated until look less and less
  • Become habituated as used to it and when look for longer time again they are dishabituated
• What is an EEG?

  • Correlating brain activity with perceptual development
  • Can be recorded using geodesic sensor net over head

  Farzin:

  • Used G Net with 128 sensors to measure steady state visual potentials (spike in brain activity from visual stimuli) in babies when they see faces
• Outline dark rearing

  • Rear infant animals in dark to investigate development of perception to see if nature or nurture - done by Blakemore & Cooper
  • Dark reared deprived of perceptual stimulation
  • If capable of same perceptual feats as light it suggests perception is innate
  • Some researchers do dark to light rearing to see impact of experience and if perception recovers it shows nurture