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  • 1. A2 Psychology – PERCEPTION (PSYA3) For the exam in June you need to know: Subject: Theories of perceptual organization Gregory’s top down/indirect theory of perception Gibson’s bottom up/direct theory of perception Development of perception The development of perceptual abilities, including depth/distance, visual constancies. Perceptual development, including infant and cross-cultural research Face recognition and visual agnosias Bruce and Young’s theory of face recognition, including case studies and explanations of prosopagnosia Name: __________________________ Made notes? Revised?
  • 2. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 3. THEORIES OF PERCEPTUAL ORGANISATION Theory 1: GIBSON’s DIRECT THEORY OF PERCEPTUAL ORGANISATION 1. Why does Gibson’s model fit with evolutionary psychology? 2. Does that suggest that his model believes perception is due to nature or nurture? 3. What is the optic array? 4. What does this picture show? And how would we use this information to make sense of the world? 5. What does this picture show? And how would we use this information to make sense of the world? 6. How is this artist using texture gradient to their advantage in this painting? 7. What are affordances? 8. Why is Gibson’s theory described as a direct theory of perception?
  • 4. Evaluation of Gibson’s theory _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 5. SPOT THE MISTAKES! Outline and evaluate Gibson’s theory of visual perception Gibson stated that the environment provides so much rich information that there is no need for bottom-up processing. His theory is sometimes known as the ‘Ecological Theory’ because of the claim that perception can be explained solely in terms of the information we receive from the environment. The starting point for Gibson’s Theory was that the pattern of light reaching the eye, known as the optic array, provides ambiguous information about the layout of objects in space. This information comes in many forms. It contains invariant unambiguous information that enables the observer to process depth and constancies e.g. texture gradient. Perception involves ‘picking up’ the rich information provided by the optic array in a direct way with little/no processing involved. However, optic array doesn’t explain how we’re able to perceive what objects are or how they should be used. The first type of data Gibson identified from the optic array is the optic flow pattern. This is the effect where the point you’re travelling towards seems to move and the rest appears to be stationary. In the case of pilots, this provides them with clear information about their direction, speed and altitude. Another important aspect of the theory is that there is no need to interact with your environment e.g. an observer can obtain valuable information about the environment by staying still. In addition, Gibson’s theory has been tested in real life situation therefore it has high ecological validity. Gibson also argued that the important aspects of optic array remain the same when the observer moves around their environment. They are known as invariants. According to Gibson, the invariants helps is to estimate accurately the size of any object whether it’s close or far away. An example of an invariant is texture gradient. Another aspect is affordance. In Gregory’s theory, the use of objects is determined by direct sensory information provided by the stimulus. He argued that many objects have directly perceivable properties e.g. chairs afford themselves to be sat on. This is supported by Warren and Hannon (1988) who produced films consisting of patterns of moving dots, stimulating the optic flow that would be produced if someone were moving in a given direction. As Gibson predicted, the participants
  • 6. used the optic flow information to make accurate judgements of the direction in which they were heading so people could afford movement to the person without lots of information. Van den Berg and Brenner (1999) found that we two eyes to use the optic flow pattern. However, it is found that judgement about direction is more accurate with one eye, rather than two. This is due to binocular disparity. The slight difference in images on the retina of each eye allows a person to obtain additional information about relative depth of objects. Gibson’s theory is a highly ecologically valid theory as it puts perception back into the real world. A large number of applications can be applied in terms of his theory e.g. training pilots, runway markings and road markings. It’s an excellent explanation for perception when viewing conditions are clear. Gibson’s theory also highlights the richness of information in optic array and provides an account of perception in animals, babies and humans. Gibson’s approach is supported by the existence of visual illusions in which perception is inaccurate. Gibson dismissed visual illusions as unecological as they are not used in everyday life and are artificial. Gibson’s theory also can’t explain the influence of situation and culture and it doesn’t explain perception from an individual’s perspective. His theory is reductionist as it seeks to explain perception solely in terms of the environment. There is strong evidence to show that the brain and long term memory can influence perception. In this case, it could be said that Gregory’s theory is far more plausible. Gibson’s theory also only supports one side of the nature nurture debate, that being the nature side. Again, Gregory’s theory is far more plausible as it suggests that what we see with our eyes is not enough and we use knowledge already stored in our brain, supporting both sides of the debate. Once you have changed the text so it is accurate, mark the essay and identify what is missing…
  • 7. Theory 2: Gregory’s theory of perception watch the film on Gregory and answer the following questions… 1. What was it about the case study that inspired his theory? 2. How does Gregory explain the hollow face illusion? Outline Gregory’s theory of perceptual organization _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 8. Use ideas from Gregory’s theory to explain these visual illusions… 1. the Necker cube 2. The Muller-Lyer illusion 3. The Ames Room 4. Old woman/ Young woman illusion 5. The Ponzo illusion
  • 9. Evaluation of Gregory’s theory of perceptual organisation _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 10. From what you have learnt already, how would you compare and contrast Gibson and Gregory? Gibson No need for cognitive input (i.e. expectations) Gregory Indirect Theory of Perception (combining visual stimuli with previous knowledge) Bottom-up Theory of Perception (visual stimuli are enough for perception) Nature (no need for learning – objects we see afford to be used – i.e. a chair affords to be sat on) Constructivist Approach (we need to build on what our eyes present to us in order to construct a meaning for what we see). High ecological validity (looks at perception in the real world i.e. pilots landing planes) Reductionist (simplifies perception to visual stimuli alone) Can explain our perception of ambiguous stimuli (i.e. visual illusions) Disregards the need to understand ambiguous images Visual perception is seldom in error, allowing us to move at high speed and perform complex actions with great accuracy Supporting evidence use ecological “natural” stimuli.
  • 11. DEVELOPMENT OF PERCEPTION watch the film and answer the following questions… 1. Why do children not have a perfect visual system as soon as they are born? 2. Why do they have good hearing and smell senses? Development of Perceptual Abilities 1. Depth perception? a. What is depth perception? b. How do we see depth? What cues do we use? 2. Visual constancies? a. What are visual constancies? b. How do we see the world as constant? Visual Constancies Depth perception What Would Gibson say about… What would Gregory say about…
  • 12. Infant studies that show perceptual development 1. Gibson and walk wanted to see if depth perception is innate. They tested infants ability to use motion parallax. What is this? 2. Outline the procedure that Gibson and Walk used 3. How were they able to draw the conclusion that depth perception is innate? 4. What were the problems with saying that depth perception is innate in Gibson and Walk’s study? 5. How did G & W overcome this problem? (think animal studies) 6. Campos did his study to show that babies of 2 months were able to perceive depth. How did he know that they could perceive depth?
  • 13. 7. Could his findings be explained by nurture? Explain why. 8. Campos did another study where he showed that babies responded to the mothers face when they were about to cross the cliff. What does this tell us about the original G & W study? Why might the babies have refused to cross the cliff (other than because of perceiving depth)? 9. Why would Bowers suggest infants have size constancy if they looked at the 30cm squared cube positioned at 3m away, compared to the 90 cm cube at 3m? 10. What are the 2 possible explanations for the development of perceptual abilities that we can take from Bower’s study? (one to do with learning, one to do with innate capabilities) 11. Why is it difficult to rely on infant studies to tell us whether perceptual abilities are innate?
  • 14. Cross Cultural Studies on perceptual development You must also be able to outline and evaluate cross cultural studies on the development of perceptual abilities… What did they do? Muller-Lyer illusion in different cultures Hudson Turnball Allport and Pettigrew What does this show? Evaluation of study (relate to a perceptual ability)
  • 15. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 16. FACE RECOGNITION AND VISUAL AGNOSIAS Model of face recognition by Bruce and Young You must be able to describe and evaluate this model describe and evaluate case studies on problems with face recognition Describe this model… __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________
  • 17. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 18. Bruce and Young’s Face Recognition Model – Case Studies Objective: To identify relevant case studies that support Bruce and Young’s face recognition model. Read through the following case studies and identify which component of the model they are testing. 1. Malone et al (1982) found one patient who was able to recognise photographs of famous politicians (14 out of 17 correct), but had severe problems matching unfamiliar faces. Another patient could match unfamiliar faces but had great difficulty recognising photographs of famous faces (5 out of 22 correct). What are some of the issues of relying on case studies to tell us about face recognition or prosopagnosia? 2. Mr W could make accurate copies of line drawings of faces. He could correctly identify facial expressions and he could identify photographs showing the same expression. Mr W could also identify unfamiliar faces. When shown faces taken from different views he could correctly identify the same face when shown pictures of a person as full-face and threequarter views. However, when shown pictures of ten famous faces he could only identify one. If he was told the names of familiar people he could describe them. (studied by Bruyer et al 1983) 3. Bowers and Heilman (1984) described a patient that could identify pairs of pictures of unfamiliar faces and could also match photographs of facial expressions, however they could not identify the emotions expressed by the people in the photos. 4. D could not recognise familiar faces nor could she identify facial expressions, but she could perform at a normal level on an unfamiliar face matching task, if given enough time. D could also judge what sounds were being mouthed in photographs of speaking people and she was susceptible to the McGurk illusion. She also had problems recognising familiar places and she could not recognise her own handwriting. (studied by Campbell, Landis and Regard 1986) (later we will determine which of these people could you diagnose as having prosopagnosia)
  • 19. watch the film and answer the following questions… 1. What do we learn about Bruce and Young’s model from the McGurk Illusion? 2. What do we learn about Bruce and Young’s model from the work on infants and face recognition? What does the work of Caroline Blais tell us?
  • 20. Evaluation of Bruce and Young… Evidence for the model (explain why it supports the model) Evidence against the model (explain why it challenges the model) ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________
  • 21. ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ Determine whether the following are true or false… B&Y model may be ethnocentric TRUE / FALSE Don’t use the Victoria Beckham example from the textbook to explain how the Cogntive System works TRUE / FALSE B&Y said that face recognition is innate TRUE / FALSE B&Y is a representation of how face recognition works TRUE / FALSE Gauthier challenges B&Y TRUE / FALSE The McGurk illusion needs to be explained if you mention it in your essay TRUE / FALSE
  • 22. Explanations of Prosopagnosia You must be able to explain how this disorder comes about and evaluate those explanations. You also (obviosuly) need to understand what prosopagnosia is… _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 23. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________
  • 24. ESSAY PLAN: Discuss two explanations of prosopagnosia (24 marks) Prosopagnosia is a difficulty in identifying faces. This essay will discuss two explanations of prosopagnosia and will consider whether it is a face specific problem or a difficulty in recognising objects that have similar properties. Explanation 1 – Faces process separately The brain has a specific area dedicated to processing and recognising faces. Evidence from case studies of people with neurological problems. Some people with brain damage can recognise objects but not faces and others show the opposite problems. This suggests a specific area of the brain dedicated to recognising faces. Evidence for Explanation 1 Bruce and Young’s model of face recognition assumes that face recognition is separate to object recognition. Case studies of people with prosopagnosia provide evidence for the model and hence evidence that faces are processed differently to objects. More evidence for the model Farrah studied a man with prosopagnosia called LH. LH and controls were presented with various faces and pairs of spectacles. They were then given a memory test to see how many they could recall. LH performed at about the same level as the normal controls when recalling the spectacles. But he was worse at recalling the faces. He could therefore recognise objects but not faces. Suggests that there is a specific area of the brain dedicated to recognising faces that is different to the area used for recognising objects. Brain imaging techniques Research shows that an area called FFA (fusiform face area) is active when people are recognising faces. Less active when they are recognising objects. Research shows people with prosopagnosia have damage to their FFA. Suggests people process faces in a different area of the brain to the one used for objects. Hence prosopagnosia is a specific problem with recognising faces. Explanation 2 – Faces are just objects that look very similar Some researchers have questioned whether face recognition is distinct from object recognition. They suggest that people may have difficulty recognising faces because faces look very similar to each other. It may be that people with prosopagnosia have lost the ability to distinguish between very similar objects, rather than lost the ability to recognise faces.
  • 25. Evidence for Explanation 2 A farmer could no longer recognise faces after he had suffered brain damage. He could not recognise the cows in his herd either, even though he could do this before. Study supports the idea that face recognition is not specific to faces and is no different from trying to identify similar objects such as cows. Evidence Gautier et al computer generated a set of artificial objects they called greebles. They designed them so that like faces they were all similar only differing in small ways. Before testing people were trained to ensure that they could recognise individual greebles. In one study participants were tested whilst in a brain scanner. They found that people were using the same part of the brain to recognise greebles as people normally use to recognise faces, the FFA. This suggests that people are not born with a specialised area of the brain dedicated to recognising faces. If this is correct then it follows that people who have difficulty recognising faces should also have difficulty recognising greebles. However, a patient with prosopagnosia could recognise greebles but could not recognise faces. Suggests that faces and greebles do not use the same brain mechanisms. Hence prosopagnosia is a problem specifically with recognising faces. Methodology Problems with case studies Only test one person. Results from case studies cannot be generalised to the wider population. Damage to the brain of each person will be different. Some damage is very localises e.g. bullet wounds, other damage is extensive e.g. from strokes. Makes it difficult to precisely identify the problems caused by any one part of the brain. Ethical problems (issues and debates**) Researchers must be careful not to distress patients when testing them They must get informed consent and if the patient cannot give this themselves then a guardian or other responsible adult should do so Researchers must maintain confidentiality both for the sake of the patient and also their families This is done by referring to the patient by their initial e.g. HM Issues and debates Nature nurture debate. Explanations do not explain whether we are born able to identify faces or whether we learn this skill. However there are case studies of people who have face recognition problems as children suggesting we may be born with some ability to recognise faces.
  • 26. SAMPLE ESSAYS OF PERCEPTION 1. Outline and evaluate theories of perceptual organisation (24 marks) 2. Outline and evaluate Gibson’s theory of perceptual organization (24 marks) 3. Outline and evaluate Gregory’s theory of perceptual organization (24 marks) 4. Discuss the development of perceptual abilities. Include examples from infant and cross-cultural studies in your answer. (8 marks + 16 marks) 5. Discuss research into perceptual development. (8 marks + 16 marks) 6. Discuss the role of cross cultural research in perceptual development (8 marks + 16 marks) 7. Discuss the role of infant studies in perceptual development (8 marks + 16 marks) 8. Critically consider explanations for the development of depth perception (24 marks) 9. Critically consider explanations for the development of visual constancies (24 marks)