PHIL/PSYCH 256, Week 6


6a Images: Introduction


Do heart experiment: B, turned on back, with V underneath, with line removed = heart.

How do we do this? Is it of general value? When do you find yourself using images?

- scientists such as Einstein report extensive use of imagery

- and engineers too, e.g. Tesla running experiments

Vision is complicated: Optical illusions.


But you can't trust introspection: we have no direct access to our images. History:

1. Introspectionist (psychologists in late 19th century)

2. Behaviorism made whole question of imagery suspect. In philosophy too: Ryle.

3. But with rise of cognitive science, the issue resurfaced: Paivio, Shepard, Kosslyn.

4. But images continue to have critics: Pylyshyn.

Positions in the imagery debate

Depictionists: we really do use picture-like images.

Descriptivists: no, it's all really verbal, but just seems pictorial because we're running through it as if it is pictorial.

How can we choose between these? Can descriptivists account for everything?

Problem with naive depictionists: the mind's eye cannot simply have a homunculus inside, because then you still have to explain how the homunculus has images.

Representational power of images:

Is there anything in an image that couldn't be put into words? And vice versa?

Computational power

1. What things are easier to do with images? Harder?

2. Visual operations: zoom, scan, rotate, flip.

3. Note difficulty of modeling vision computationally.

4. Images useful in problem solving, e.g. ape swinging rope to get banana.

5. Many analogies are visual, e.g. solar system: atom.

6. Imagery and learning? Are some things easier to learn by imaging?

Sports and imagery.

7. Easier to do spatial operations, e.g. rotation, on visual representation.

8. Visual abduction, e.g. Tesla: run mental model.

Kosslyn's model:

1. Images are quasi-pictorial.

2. Images are similar to what is displayed on a CRT screen.

3. Representation preserves distances.

4. 2-dimensional array that can be scanned.

Glasgow's model

1. 3-dimensional arrays

2. nested: e.g. map of Europe

3. many operations defined on arrays

Graphical models: David Croft

1. objects represented by organized graphs

2. define rotation and other objects

3. apply to analogical problem solving

4. this is both depictive and descriptive

Multimodal nature of concepts: Barsalou

Concept of car is not just a verbal description, but includes visual and other kinds of representations.

6b Imagery: Psychological reality

Kinds of evidence for importance of imagery:

1. Anecdotes

- everyday life: ask students

- tactile imagery: blind artist

- scientists

- Beethoven wrote his 9th symphony after he became deaf

2. Computational considerations

- abstract arguments

- actual models

3. Psychological experiments, e.g. reaction times

4. Neurological experiments

- brain activation

- deficits

Kosslyn & Koenig, Wet Minds, 1992,

Ch. 4: Visual Cognition

Evidence exists that imagery can be used many ways

A. Access information in memory

1. Imagery techniques greatly improve memory,

e.g. remember shopping by imagining walking

through the grocery store

2. Brain scans: visual areas in the brain are also activated during mental imagery. Visual mental imagery resulted in large increases in blood flow in the occipital lobe and other areas used in high-level visual perception.

3. Brain damage: there are patients who can use shapes but not spatial relations and vice versa. These patients have corresponding impairments in perception.

4. Scanning experiments: reaction times.

5. Image generation: Imaging L is faster than F which is faster than

Speculation: imagery may have developed for use in recognizing objects.

B. Reasoning using imagery

1. E.g. Finke's heart example: people can generate creative new images.

2. Image transformation: rotate N left 90 degrees.

3. Brain scans show visual areas active.

4. Symbolic reasoning done imagistically, e.g. "taller than".

See also: Imagination and mental imagery

C. Using Imagery to Learn Skills

E.g. in sports.

D. Using Imagery to Comprehend Language

E.g. directions to get from one place to another.

E. Effects of Brain Damage

Defects in imagery tend to go with defects in vision.

Image generation deficits in some people

Typically have damage in left posterior part

of brain.

Image generation and transformation are carried out

by multiple subsystems on both sides of the


Key points from Glasgow and Papadias

Phil/Psych 256

Computational Epistemology Laboratory.

Paul Thagard

This page updated Oct. 15, 2015