Chapter 9

• Sensation is a physiological process that is the same for all of us
• Sensation is a 3 step process that involves our sensory receptors detecting a stimulus and then sending this unprocessed sensory information to the brain
• Perception is the process of selecting, organising and interpreting sensory information to be able to understand it
• Perception is a psychological process that is different for all of us
• Sensation process

  1. Reception - detect sensory info - external stimuli
  2. Transduction - convert energy into electrochemical energy that the brain can utilise
  3. Transmission - sending electrical impulses to the relevant brain region
• Perception process

  1. Selection - feature detection cells filter impulses by selecting some + filtering out others
  2. Organisation - brain assembles the selected impulses into a pattern or form that can be recognised
  3. Interpretation - giving meaning to the impulses based on what we have sensed
• Attention is voluntary (conscious) or involuntary (unconscious) tendency to focus awareness on a specific stimulus and ignore other stimuli
• Automatic processing - requires little conscious awareness and mental effort
• Controlled processing requires high levels of awareness
• Sustained attention - attention over a prolonged period of time without being distracted
• Divided attention - rapidly switching the focus of your awareness between tasks

  • Faster with automatic processes
• Selective attention - choosing the focus of your awareness while ignoring other stimuli

  • can be intentional or automatic
• Depth perception - ability to see 3D space and accurately judge distances using environmental cues
• Binocular cues - both eyes work together to provide brain with depth and distance information
• Retinal disparity - each retina receives a slightly different image, seperate images fuse together to form one overall image - results in 3D sight
• Convergence - both eyes tun inward as objects move closer, to maintain focus
• Monocular cues - depth perception cues that rely on information from only one eye
• Accomodation - lens changing shape to maintain focus, when object is close to lens it is more rounded
• Pictorial cue - create impression of depth on a flat surface where depth doesn't exist
• Linear perspective - apparent convergence of parallel lines create illusion on increasing distance
• Interposition (overlap) - object partially obscures/blocks another object, is perceived as being in front of, and therefore closer than the other object
• Texture gradient - amount of perceptible detail decreases as distance from observer decreases
• Relative size - tendency to perceive object that produces the largest retinal image as being closer to us, object with smallest retinal image as being further away (two objects must be expected to be the same size)
• Height in the visual field - object located closer to horizon is perceived as being further away than objects located further away from the horizon
• Gestalt principles - rules used to organise seperate elements of a visual stimulus into meaningful patterns or whole forms
• Figure-ground - imaginary contour line to group and seperate features of a stimulus so that per of a stimulus appears to stand out as an object against a plainer background
• Figure (the object) Ground (plain background)
• Closure - mentally filling in the gaps in an incomplete figure
• Similarity - similar feature = a group
• Proximity - closeness = a group
• Size constancy - size of an object remains the same despite changes in the retinal image
• Shape constancy - actual shape of object remains the same despite changes in the retinal image
• Brightness constancy - level of brightness stays the same under changing light conditions
• Orientation constancy - an objects true orientation is unchanged despite changes in the retinal image
• Social factor - culture