1. PSY 323 – Cognition
Chapter 10:
Visual Imagery

2. Visual Imagery Seeing in the absence of a visual stimulus
A type of mental imagery
The ability to recreate the sensory world in the absence of physical stimuli
Also, occurs in other senses
Paul McCartney of “The Beatles”
claimed that the song “Yesterday”
came to him as a mental image

3. Visual Imagery Try this:
Close your eyes and try to picture the back of a one dollar bill
Close your eyes and try to picture the front of a penny

4. How did you do?

5. Early Ideas About Imagery
Wilhelm Wundt
Early psychologist felt that images were one of the three basic elements of consciousness (sensation and feelings were the others)
First to adopt introspection
Click on picture for pronunciation 

6. Imageless Thought Debate
Much Controversy!
Over whether it is possible to have thoughts that are not accompanied by images
This debate occurred in the late 19th century and was critical to the introspectionist program because they studied imagery as a window into thought processes
If some thought was not accompanied by images, it was not clear how it could be studied

7. Good-bye imagery… John Watson Father of behaviorism
“Give me a dozen healthy infants…”
Felt that the study of imagery was unproductive
Psychology as the Behaviorist Views it.
John B. Watson (1913)
( )

8. Imagery and the cognitive revolution
Imagery Reenters Psychology
Refuted claims that imagery was impossible to study
Demonstrated imagery had functional role – as seen in memory tasks like paired associate learning
Key point of Paivio’s work – imagery impacts memory
89 years old
Major Turning Point - Allan Paivio’s studies (1960s)

9. Paivio’s Dual-Coding Theory
Memory is served by two systems:
Verbal
Nonverbal (visual)

10. Pavio’s Conceptual-Peg Hypothesis
Found concrete words easier to recall than abstract words due to imagery
Concrete nouns create mental images other words can “hang onto”

11. More Evidence…
Concrete or abstract adj-noun pairs Square-door, rusty-engine Subtle-fault, absolute-truth Free-recall (recall as many as possible) Concrete > Abstract Paired-Associate Learning (Square ____?) Concrete performance improved over free Abstract performance did not
Begg (1972)

12. Demonstrating that Imagery Exists
Shepard & Metzler (1971)
Procedure
Mental chronometry Task: participants saw two objects, had to indicate quickly whether the two objects were the same or different
Stimuli used in mental rotation experiment 

13. Demonstrating that Imagery Exists
Shepard & Metzler (1971)
Results
Time it took to indicate that they were the same object was directly related to how far the object had to be rotated
Interpretation
Imagery and perception share some of the same mechanisms
Note: First experiment to use quantitative methods in the study of imagery.

14. Imagery and Perception
Major question: Do imagery and perception share the same mechanisms?
Kosslyn (1973)
Procedure
Task: Memorize an image, then answer questions about whether certain parts appear in the image
Time it takes to say yes is related to distance between initial focus and correct part
Stimulus for image-scanning experiment 

15. Imagery and Perception
Results
It took longer for participants to find parts that are located farther from the initial point of focus
Interpretation
Evidence a spatial nature of imagery existed
They were scanning across the image of the object so it makes sense that parts located further away would take them longer to get to
Kosslyn (1973)

16. Imagery and Perception
Alternative Interpretation
Lea (1975)
Proposed that as participants scanned, they may have encountered other interesting parts, such as the cabin, and this distraction increased their reaction time
Kosslyn (1973)

17. Imagery and Perception
Alternative Interpretation
Lea (1975)
Proposed that as participants scanned, they may have encountered other interesting parts, such as the cabin, and this distraction increased their reaction time
Kosslyn (1973)

18. Imagery and Perception
Kosslyn et al. (1978)
Procedure
Task: Memorize an image, then answer questions about whether certain parts appear in the image
Time it takes to say yes is related to distance between initial focus and correct part
Island used in image-scanning experiment 

19. Mental scanning (Kosslyn et al. 1978)
Results
Participants scanning times were linearly related to the physical distances between locations
Interpretation
It wasn’t the distractions; spatial nature of imaging was the reason
Mental scanning time
Physical distance between locations

20. Imagery Debate: Is imagery Spatial or Propositional
Kosslyn’s experiments were convincing, but there was yet another alternative explanation
Pylyshyn (1973)
Felt results are based on propositional mechanisms, not on spatial representation
Mental images are created by the same mechanism that creates language
Ushered in the imagery debate (still going on)

21. Imagery Debate: Is imagery Spatial or Propositional
Basic idea: just because the experience is spatial doesn’t mean the underlying representation is
Spatial experience of mental images could be an epiphenomenon
Information could be encoded with language (propositional representation) or with images (depictive representations) – can’t tell

22. How Does Phlyshyn Explain Kosslyn’s First Set of Results?
Tacit-knowledge explanation
People in the mental scanning task behave based on what happens in a real scene
Participants unconsciously use knowledge about the world in making judgments
In the real world it takes longer to travel greater distances
Simulate this behavior in the experiment

23. Against Propositional Representation
Finke & Pinker (1982)
Procedure
Short presentation of simple display with 4 random dots, followed (after 2-sec delay) by an arrow
Participants had to say whether the arrow pointed to one of the dots in the first display (gone now)
See next slide 

24. Demo of Finke & Pinker (1982)

25. Against Propositional Representation
Results
Longer responses for greater distances
Interpretations
No time to convert to propositions, no meaning in the dots (except spatial relations)

26. Size in the Visual Field
As you move closer to objects in the real world:
Object fills more of your visual field
Details are easier to see
Kosslyn (1978) used these facts to investigate mental imagery
Stimuli used in this experiment 

27. Size in the Visual Field
Procedure
Task: Imagine two objects, moving close enough so that the bigger object fills most of visual field
Answer questions about one of the animals
Question about the animal when it was bigger than the other animal
Question about the animal when it was smaller than the other animal
Kosslyn (1978)

28. Results
Participants were asked to imagine animals, such as an elephant and a rabbit next to each other.
The experimenter asked “Does a rabbit have whiskers?”
RT = ms
Participants were asked to imagine animals, such as a fly and a rabbit next to each other.
The experimenter asked “Does a rabbit have whiskers?”
RT = ms
Kosslyn (1978)

29. Size in the Visual Field
Interpretation
Since participants answered the question about the rabbit more rapidly when it filled more of the visual field, it can be inferred that mental images are spatial just like perception
Kosslyn (1978)

30. Size in the Visual Field
Kosslyn also asked participants to create mental images of different sizes
Larger images activated more of V1 (early visual areas) - just like perception
Kosslyn (1978): fMRI Study

31. Imagery Neurons Some neurons respond to seeing certain objects
Those neurons can fire when that object is imagined in the brain
Perception
Imagery
Kreinman et al. (2000)

32. Brain Imaging LeBihan et al. (1993)
Compared the brain areas that are activated at three times:
When a person observed perceptions of actual visual stimuli (perception)
When the person was imagining the stimulus (imagery)
When visual stimulus was not present; no imagery was performed

33. Brain Imaging
LeBihan et al. (1993)
Brain activity in area V1

34. Apparently its not the end of the debate…
Pylyshyn (2001)
Argues that just as the spatial experience of mental images is an epiphenomenon brain activity can also be an epiphenomenon
Posits that brain activity in response to imagery may indicate that something is happening, but may have nothing to do with causing imagery

35. Transcranial Magnetic Stimulation
Researcher allows a magnetic field to be applied to his skull and thus disrupt the activity of neurons in a particular region
See video clip 
Video illustrates basic procedure used by Kosslyn et al. (1999)

36. Kosslyn et al. (1999) The perception task:
Participants were asked to indicate which of the stripes in two of the quadrants was longer (e.g., are the stripes in 3 longer than stripes in 2?)
The imagery task:
= the perception task, but they were asked to close their eyes and make judgments based on their mental image of the display
Kosslyn et al. (1999)

37. Kosslyn et al. (1999) Manipulations:
TMS was directed to the visual area while participants were making judgments
TMS was directed to another part of the brain while participants were making judgments
Results
TMS slowed responses both in the imagery and perception conditions
Kosslyn et al. (1999)

38. Transcranial Magnetic Stimulation
Interpretation
The perception and imagery tasks are carried out by the same brain areas
Kosslyn et al. (1999)

39. Neuropsychological case studies
Removing Part of the Visual Cortex
Farah (2000)
Patient M. G. S
An educated young woman
Her right occipital lobe removed as treatment for a severe case of epilepsy.
The mental walk task was given before and after the operation

40. Removing Part of the Visual Cortex
Mental Walk Task
She visually imagined walking toward an animal; And estimated how close she was when the image began to overflow
“Overflow” means that the mental image was too big so that she could not see the entire animal at once in her mental image
Farah (2000)

41. Before the operation After the operation Farah (2000)
Mental walk test: before and after the operation.
Before the operation, she could mentally walk to the image of a horse within 15 feet before “overflowing”.
After the operation, she could mentally walk to the image of a horse within 35 feet before “overflowing”.
Explanation:
Removing part of the visual cortex reduced the size of her field of view.
 The visual cortex is important for imagery
Farah (2000)

42. Other case studies
Perceptual problems are accompanied by problems with imagery
People who have lost the ability to see color due to brain damage are also unable to create colors through imagery
People who have unilateral neglect in perception also have unilateral neglect in imagery

43. Perceptual Problems are accompanied by problems with imagery
Uilateral Neglect
Brain damage to attentional centers of the brain (right parietal lobe)
Patients ignore half the visual field
Oftentimes, the left half of the visual field is ignored
Right hemisphere brain damage = Left visual field impairment

44. Perceptual Problems are accompanied by problems with imagery
In typical experiments with unilateral damaged patients, the patient is asked to identify objects held up
Objects on left & right: Only right object seen
Object only on the left: Left object is seen
Almost as if right field takes precedence
Unilateral Neglect 

45. Does this work for imagery, too?
Unilateral neglect patients ignore half of the visual field. But what about imagery?
Bisiach & Luzzatti (1978)
Researchers asked an Italian patient to imagine standing in the Piazza del Duomo in Milan (familiar to patient)
See next slide 

46. The Piazza del Duomo in Milan
When the patient imagined himself standing at A, he could name objects indicated by a’s.
When he imagined himself at B, he could name objects indicated by b’s.
Bisiach & Luzzatti (1978)

47. Perceptual Problems are accompanied by problems with imagery
Results
“Face north. What do you see?”
Only describes things on his right
“Turn around. What do you see?”
Only describes things on his right (but was on the left originally!)
Interpretation
Neglect works on imagery, too!
Bisiach & Luzzatti (1978)

48. Dissociations What does a double dissociation prove?
Perception OK, Imagery Poor
Guariglia et al. (1993) - Unilateral neglect only for imagery, not for perception
Farah et al. (1988) - R.M. could recognize objects and draw them, but could not draw objects from memory (requires imagery)

49. Neuropsychology: Perception Poor, Imagery OK
Berhmann et al. (1994) - C.K. could not name perceived objects but could draw detailed pictures from memory
“Fencer’s Mask”
“Rose Twig”
“Feather Duster”
Drawn by C.K.

50. ANOTHER CASE OF Double Dissociation

51. Conclusions form the imagery debate
Imagery and perception are closely related
Some shared mechanisms; not all
fMRIs confirm this; brain activation is not complete
Perception is stable; imagery fragile
Harder to manipulate mental images
See image below
Chalmers & Reisberg (1985)

52. Using imagery to improve memory
How does imagery help improve memory for two things?
Researchers investigated bizarreness and interactivity
Wollen et al. (1972)
Remember two words
Participants told to use one strategy out of a possible four
See next slide 

53. Using imagery to improve memory
Wollen et al. (1972)

54. Using imagery to improve memory
Results
Interacting > Noninteracting
Bizarre = Nonbizarre
Bizarreness had no effect
Interactivity did
Wollen et al. (1972):

55. Pegword Technique Associate to-do items with concrete nouns
Rhyme number words with concrete nouns
One--bun
Two--shoe
Three--tree
Four--door
Five--hive

56. Pegword Technique Example
First thing you have to do: go to the dentist
One--bun
Associate dentist with bun

57. Credits
Some of the slides in this presentation prepared with the assistance of the following web sites:
archlab.gmu.edu/people/jthompsz/9-VisualImagery_2.ppt
wps.prenhall.com/wps/media/objects/923/945327/9.ppt
memoryandcognition.wikispaces.com/file/.../Imagery_Ch10.p...