Processes of sensation&perception

• Perception definition⇒ Three processes of perception- selection (feature detectors), organisation and interpretation (both based on visual perception principles)- are specific to vision
• 1. Selection

  • Millions of stimuli enter the eye and it is impossible to process them all at once, so we are selective about what we give our attention to

  At this stage of the process, the image is broken up by specialised cells called feature detectors (cells in the optic nerve and primary visual cortex that individually respond to lines of a certain length, angle or direction to break up an image for visual perception)
• 2. Organisation

  • Our visual cortex in the brain recognises information so that we can make sense of it
  • We do this by using the following visual perception principles
  • Gestalt principles

  -Depth cues

  • Once the image is reassembled using these principles, it travels along two pathways simultaneously to the temporal lobe to identify the object and to the parietal lobe to judge where the object is in space
• 3. Interpretation

  • This is the process whereby the visual stimulus is given meaning
  • The temporal lobe identifies the stimulus by comparing incoming information with information already stored in memory
  • Past experiences, motives, values, and context help us to understand what we are looking at by contributing to our perceptual set.
  • While information is sent to the temporal lobes it also travels to the parietal lobes which assist in judging where the object is in space
• Cocktail party effect

  • models of explaining memory

  process of memory- encoding, storage, and retrieval

  multi-store model of memory (Atkinson and Shiffrin)

  sensory register: duration capacity and encoding

  
• Processes of sensation

  1. Reception
  2. Transduction
  3. Transmission
• Process of perception

  1. Selection
  2. Organisation
  3. Interpretation
• Sensation Definition= process of your sensory organs receiving information from the environment and then sending it to the relevant parts of the brain
• Perception definition= three processes of perception- selection (feature detectors), organisation and interpretation (both based on visual perception principles)- are specific to vision
• 1/3 process of sensation

  1. Reception

  • Light enters the eye through the cornea
  • Then it passes through the pupil
  • The lens then focuses the light onto the retina
  • The retina contains photoreceptors- which are light-sensitive cells called rods and cones
• 2/3 process of sensation

  2. Transduction


  The electromagnetic energy that we know as light energy, is converted by the rods and cones into electromagnetic nerve impulses. Allows the visual information to travel along the fibres of the optic nerve to the brain.
• Optic nerve


  The two tracts of neurons that transmit visual information from the eyes to the occipital lobes of the brain
• Photoreceptors (rods and cones)


  • Organised into groups
  • These groups form receptive fields
• Receptive fields


  A particular region of the visual space
• Visual information processing


  1. Retina identifies visual stimuli

  2. Passes information via rods or cones to bipolar cells

  3. Then to the retinal ganglion cell
• Retinal ganglion cell


  A type of neuron that is located near the surface of the retina; visual information from the photoreceptors is received by the retinal ganglion cells
• 3/3 process of sensation

  3. Transmission

  • the next task is for the rods and cones to send the nerve impulses along the optic nerve to the primary visual cortex in the occipital lobes, at the very back of the brain where specialised receptor cells respond as the process of visual perception continues
• Photoreceptors:

  • detects visual stimuli
  • the rods (125000000 in each eye) are photoreceptors that are particularly sensitive to black and white, and we typically use these at night
  • the cones (6500000 in each eye) are involved in providing clear colour vision and rely on bright light to function
  • cones are used more than rods in daylight
• 1/3 Process of Perception

  1. Selection

  • Millions of stimuli enter the eye and it is impossible to process them all at once, so we are selective about what we give our attention to
  • At this stage of the process, the image is broken up by specialised cells called feature detectors (cells in the optic nerve and primary visual cortex that individually respond to lines of a certain length, angle or direction to break up an image for visual perception)
• 2/3 process of perception

  2. Organisation

  • Our visual cortex in the brain recognises information so that we can make sense of it
  • We do this by using the following visual perception principles

  -Perceptual constancies

  -Gestalt principles

  -Depth cues

  • Once the image is reassembled using these principles, it travels along two pathways simultaneously to the temporal lobe to identify the object and to the parietal lobe to judge where the object is in space
• 3/3 process of perception

  3. Interpretation

  Visual stimulus is given meaning
• Temporal lobe


  Identifies the stimulus by comparing incoming information with information already stored in memory
• Perceptual set


  • Past experiences, motives, values, and context help us to understand what we are looking at
• Information processing

  1. Information is sent to the temporal lobes

  2. Information also travels to the parietal lobes which assist in judging where the object is in space
• Patients with parietal lobe damage


  • Able to recognise an object, but they may constantly bump into furniture or misjudge picking up their knife and fork