Perception

• perception: the process of receiving information from the senses and interpreting it in a way that is meaningful
• sensation: the perception of stimuli by the sensory receptors in the body
• Sensation is our body's way of detecting a stimulus in the environment whereas perception is how our brain organises and interprets the sensations.
• The two main types of depth cue are monocular (single eye) cues and binocular (two eyes) cues
• depth perception: the ability to judge the distance of objects in the visual field from the eye
• binocular depth cues: cues that are only detected when both eyes are used
• monocular depth cues: cues that can be detected using one eye
• types of monocular depth cues - height in plane, relative size, occlusion & linear perspective
• height in plane: objects higher up appear further away than those lower down
• relative size: smaller things appear closer than larger ones
• occlusion: an object partially blocking another object appears nearer than it does if it doesn’t block anything else
• linear perspective: lines that are parallel appear to get closer together and come to a point in the distance
• types of binocular depth cues - retinal disparity & convergence
• retinal disparity: difference between the view of the left and right eye gives the brain information about depth and distance
• convergence: eyes point close together when an object is close. muscles work harder so you know distance and depth
• visual illusion: a perceptual phenomenon that causes the brain to misinterpret visual information
• ponzo illusion: a misinterpreted depth cue. Perceive horizontal line higher up as longer than vertical line

  
• muller-lyer illusion: a misinterpreted depth cue. the two vertical lines are the same length but the line with the outgoing fins are seen as longer

  
• rubin's vase: ambiguous figure. it is a face and a vase. both pictures are correct, the brain alternates between the two

  
• ames room: a misinterpreted depth cue. the room is in a shape of a trapezoid. people are seen as different sizes even though they are the same size

  
• size constancy: objects perceived as constant size despite size on retina changing with distance
• misinterpreted depth cues: objects apparently in the distance scaled up by the brain to look normal size, causes visual illusions e.g. ponzo illusion & muller lyer illusion
• ambiguous figures – two possible interpretations of image, brain can’t decide which is correct. e.g. necker cube & rubin’s vase
• fiction: seeing something which is not there e.g. kanizsa triangle – illusory contours create impression of a second triangle
• gibson's theory of perception: the environment gives us all the information we need to perceive the world
• gibson believes that sensation & perception are the same and the eyes detect everything we need without having to make inferences.
• gibson's theory emphasises the role of nature in perceptual processes
• gibson's theory has difficulty in explaining cultural differences in perception
• innate perception - is the ability to perceive stimuli without any prior experience or training
• gibson's theory can explain examples of innate perception
• gregory's constructivist theory of perception - we use past experiences to interpret the world around us. it contrasts gibson's theory and proposes that sensation and perception are not the same. this strongly suggests that perception develops more from nurture than nature.
• gregory's theory sees perception as a construction - the brain uses incoming information and information we already know to form a guess/hypothesis.
• gregory's theory - emphasises the role of nurture in perceptual processes
• gregory's theory - sees sensation and perception as separate processes
• gregory's theory - can explain how culture might influence how we see something
• gregory's theory - struggles to explain examples of innate perception
• Gibson's theory


  Perception happens directly because the visual environment gives us all the information our brain needs. Sensation and perception are the same thing.
• Optic flow patterns


  • The point we are moving towards stays stationary whilst the rest of the view seems to rush away from it
  • If there is no 'flow', the brain knows we are not moving
• Motion parallax


  A monocular depth cue that helps us understand the speed of movement. Objects closer to us in our visual field are moving faster than objects further away from us.
• Gibson says we do not learn to perceive the world around us. Our perceptual abilities are innate and allow us to deal with our surroundings without the need of past experiences.