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Perceptual development

Difference sensation and perception

• Sensation: processing of basic information from the external world via receptors in the sense organs and brain  »  five different senses: sight, hearing, taste, touch and smell
• Perception: processing of organizing and interpreting sensory information about the objects, events and spatial layout of the world around us

Visual development

Multiple steps to perception:

• Processing basic information (sensation)
  • Refers to all the properties of a stimulus (e.g. color, orientation, contrast, spatial frequency)
  • The properties are processed in your brain in the visual cortex
  • The properties enter the eye, after which the information is send to the Lateral Geniculate Nucleus (LGN) and then processed to V1 (striate cortex) in the visual cortex
  • Preferential looking technique: the check the eyesight of an infant (newborn) » if an infant looks longer at one picture this means two things: The infant can discriminate between the two things and the infant prefers the picture it looks longer at
    
    • Measures visual acuity (how sharp someone can see) » used for testing spatial frequency and contrast
    • Relation spatial frequency and contrast: if the spatial frequency increases, it’s more difficult to see the contrast and if the contrast becomes very low, we also cannot see a pattern anymore
• Object segregation » the ability of seeing/identifying different objects.
  
  • Three relevant processes:
    
    • Border detection: we need to see where an object ends and another object/the background begins
    • Integration/grouping: we need to know which elements belong to one object
    • Figure-ground segregation: we need to segregate the object from its background
  • Gestalt theory: the whole is more than the sum of its parts. Our mind organizes and interpret visual input according to certain grouping principles
    
    • Proximity: objects close to each other are grouped together
    • Similarity: elements that are similar are grouped together regardless of their proximity
    • Figure ground: distinguish between the background and the foreground
    • Continuity: we tend to follow the smoothest path when following a line
    • Closure: we tend to fill in the gaps
    • Connectedness: objects that are connected are seen as a whole, are grouped together
  • The grouping principles determine whether we detect an object or not
  • Saccadic eye movement: ‘jumpy’ eye movements, no straight line
  • Smooth tracking: smooth eye movement, can only when following an object (emerge around 7/8 weeks)
  • Starts around 6 months and develops throughout childhood and children become more accurate and faster in segregation
  • Segregation is important for object recognition » it helps objects recognition because the processes of border detection, integration and figure-ground segregation are important to see the actual object and to recognize the object
  • In the brain: the information is send from V1 (in the visual cortex) to other specific areas, which is done through feedforward connections. The specialized areas also send information back to V1 (feedback connection) » segregation happens in this process (of sending information back)
• Object recognition (perception)
  
  • Our brain is specialized in seeing objects » we have very specialized places in the brain when we see different objects (e.g. an area that’s activated when seeing a face)
  • Babies have a preference for face-like images from the moment they’re born
  • Perceptual narrowing: our perception is shaped by our experiences. Our perception to objects that we encounter frequently is improved, whereas our perception to objects encounter infrequently is declined » we become specialized in what’s relevant to us » it makes our brain more efficient
  • Object recognition also helps segregation

Auditory perception

• Hearing develops mostly prenatally
  • 9 weeks: ears begin to develop
  • 16 weeks: some sounds can be detected
  • 24 weeks: baby will turn head towards voices
• Development: threshold for sound detection is higher, especially higher frequencies, which means that speech will not be heard clearly in the first six months of life. Auditory localization needs to develop after birth

Intermodal perception

• Our senses don’t work independently from each other. We integrate information from different senses and this determines our perception of the world (intermodal perception)
• It’s not just combining information, but information from one sense can influence the perception of the other