How do we see our world?

How do we see?
1. Perception
  1. Is a psychological process which happens in our brain during which the brain makes sense of the visual image detected by our eyes.
2. Retina
  1. The light sensitive layer at the back of the eye.
3. Rods
  1. A visual receptor that is sensitive to dim light
4. Cones
  1. A visual receptor that is sensitive to bright light and colour.
5. Vision
  1. Our eyes work by detecting rays of light that are reflected or emitted by objects. This is a biological process that happens in our eyes.
6. Perceptual Processes
  1. The unconscious way people interpret and understand what they see or notice.
The optic nerve and the brain
1. What causes the blind spot?
  1. Blind Spot
    1. The point in the retina where the optic nerve leaves the eye, and as there is no room for rods and cones, no light is detected.
  2. The blind spot contains no rods and no cones
2. Optic chiasma
  1. The cross - shape where some of the information from the left and right eye crosses over to pass into the opposite side of the brain.
3. Visual cortex
  1. The area at the back of the brain that interprets visual information.
Seeing Depth
1. Depth cues
  1. Monocular
    1. One eye - there are five monocular cues.
      1. Size constancy
        We perceive an object as the same size even when its distance from us has changed.
        Distant things are scaled UP
        Nearby things are scaled DOWN
      2. Relative size
        Smaller objects are perceived as further away than larger ones.
      3. Texture gradient
        When you look at a scene, close up he textured surface is very detailed. Further away it is less clear.
      4. height-in-the-plane
        The objects at the bottom of your field of view is close to you. In the area at the top of the field, the objects are further away.
      5. Superimposition
        When one object is covering another it tells us that the thing you can see must be nearer than the partly hidden object.
      6. Linear perspective
        Parallel lines appear to converge (meet) in the distance
  2. Binocular
    1. Uses two eyes to perceive distance
      1. Stereopsis
        The greater the difference between the view seen by the left eye and the right eye, the closer the viewer is looking.
  3. The visual 'cues' that we use to understand depth or distance.
Gestalt Laws
1. 'The whole is worth more than the sum of its parts'
2. Figure - ground
  1. A small, complex, symmetrical object (the figure) is seen as separate from a background (the ground)
3. Similarity
  1. Figure sharing size, shape or colour are grouped together with other things that look the same.
4. Proximity
  1. Objects which are close together are perceived to be related
5. Continuity
  1. Straight lines, curves and shapes are perceived to carry on being the same.
6. Closure
  1. Lines or shapes are perceived as complete figures even if parts are missing.
Illusions
1. Visual illusions
  1. A conflict between reality and what we perceive.
2. Fiction
  1. Illusory contour
  2. An illusion caused when a figure is perceived even though it is not present in the stimulus.
3. Colour after-effects
  1. An illusion caused by focusing on a coloured stimulus and perceiving opposite colours immediately afterwards.
4. Distortion
  1. Where our perception is deceived by some aspect of the stimulus. This can affect the shape or size of an object.
5. Ambiguous figure
  1. A stimulus with two possible interpretations, in which it is possible to perceive any one of the alternatives at any time.
Gestalt theory of illusions
1. Muller-Lyer
  1. Closure
    1. This works with circles as well as fins. This suggests that in perceiving the figure as whole, we tend to 'add' the fins/circles to the central lines. This can pull the shape together, so it looks smaller, or (if it extends beyond the central line) stretches it out and makes it look longer.
2. Kanizsa triangle
  1. Fiction
  2. Closure
    1. Our perception makes a 'whole' shape using closure. We complete the edges to make a familiar shape (a triangle). This is the 'figure' of the figure-ground relationship.
3. Rubin's Vase
  1. Ambiguous Figure
  2. Figure - ground
    1. When we identify a 'figure', it is separate from the 'ground'. Normally any part of the image cannot be both; it can only be figure or ground. If we encounter a situation where something could be either figure or ground, it becomes ambiguous so we see an illusion.
Experiments and design
1. Descriptive statistics
  1. Mode
    1. An average that is the most common score or response in a set
  2. Mean
    1. An average that is calculated by adding up all the scores in a set and dividing by the number of scores
  3. Bar chart
    1. A graph with separate bars. Usually there is one bar for each condition in an experiment
  4. Median
    1. An average that is the middle number in an ordered set of data
  5. Range
    1. Shows the spread of a set of data by looking at the biggest and smallest scores
  6. Ways to summarise results from a study. They can show a typical average score of how spread out the results are.
2. IV
  1. The factor which is changed by the researcher in an experiment to make two or more conditions
3. DV
  1. The factor which is measured in an experiment
4. Experimental (Participant) design
  1. Independent groups design
    1. Different participants are used in different conditions in each experiment..
  2. Repeated measures design
    1. The same participants are used in all the conditions in an experiment
5. Hypothesis
  1. A testable statement of the difference between the conditions of an experiment. It describes how the IV will affect the DV
6. Controls
  1. Ways to keep variables constant in all conditions
Palmer (1975): Schemas and perception
1. Schemas
  1. We have a framework of knowledge about objects/people that affects our perception of information and memories.
2. Perceptual set
  1. The tendency to notice some things more than others. This can be caused by experience, context or expectations.
3. Reconstructive memory
  1. Recalled material is not just a 'ccpy'. Information is stored and when it is remembered it is 'rebuilt', so can be affected by extra information and schemas we might already have.
4. AIM
  1. To find out whether context would affect perception
5. PROCEDURE
  1. 64 Students tested in a laboratory experiment were shown visual scenes like a kitchen for 2 seconds (to provide context)
  2. Appropriate
  3. Inapproproate
  4. Inappropriate, different object
  5. No context
6. RESULTS
  1. The participants correctly identified the most objects after seeing an appropriate context (82%) and the least after seeing an inappropriate context (40%)
7. CONCLUSION
  1. Expectations affect perception. People have a perceptual ser based on context which affects how accurately they recognise objects.
  2. EVALUATION
    1. Strengths
      1. Controlled how long participants saw the object for.
      2. Clear instructions so they knew exactly what to do.
    2. Weaknesses
      1. As some data couldn't be used, there were fewer results
      2. The participants were told what they would be doing, this may have caused them to try harder.
Bartlett (1932): Schemas and remembering stories
1. Serial Reproduction
  1. A task where a piece of information is passed from one paticipant o te next in a chain or 'series'
2. Repeated Reproduction
  1. A task where the participant is given a story or picture to remember. They then recall it several times after time delays.
3. AIM
  1. To investigate how information changes with each reproduction and to find out why it changes.
4. PROCEDURE
  1. All participants read 'The War of the Ghosts' (deliberately unfamiliar story).
5. RESULTS
  1. Form
    1. Once a story has a particular outline it sticks. eg. the order of events
  2. Details
    1. Information such as names & numbers are lost. If remembered they become stereotyped.
  3. Simplification
    1. Events are made less complex. This can change the meaning.
  4. Addition
    1. Inaccurate details are added to the story.
6. CONCLUSION
  1. Unfamiliar material changes when it is recalled. It becomes shorter, simpler and more stereotyped. This may be due to the effect of schemas on memory.
  2. Strengths
    1. Both tests were repeated to show patterns
    2. Other stories used were not individual
  3. Weaknesses
    1. By using unfamiliar material, he could not be sure the changes would always occur
    2. Not always retested over the same time gaps, so could not be compared fairly.

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How do we see our world?

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	Created by Leah Firmstone over 9 years ago