Lecture 17: Imagery

Snoopy example

• image snoopy

• focus on his feet, are his ears round? → tool longer to answer

• focus on his head, are his ears floppy?

People’s RT is proportional to the space between the two points (scanning the visual image)

Kosslyn

tested wheter imagery is truly “image-like” or “propositional”

• participants studied a map with 7 landmarks

• He found that the farther subjects were asked to “scan”, the longer they took to respond.

Mental rotation

showed 2 images and asked if they are the same or different shapes

• easier when the angle between the two shapes is smaller

What does visual imagery do for us?

• help with memory

Subjects who rated themselves as “good visualizers” scored about 20% better than subjects who rated themselves as “poor visualizers”
Davis Marks (1973)

• Showed pictures of items, and asked questions like

• What number was written on the golf ball? What was the time on the clock?

• Participants were also asked to report the “vividness” of each of the test images

Measuring vivdness of imagery

VVIQ - questionaire that asks you to choose the rating that matches the imagery you see based on a discription

Neural correlates of imagery (Leila Reddy 2010)

Participants were scanned using fMRI while viewing or imagining items

• Activity in ventral-temporal areas could be used to predict both viewed and imagined categories

• Activity in retinotopic areas could only predict viewed categories

Synesthesia

the perception of a stimulus produces a different impression than its physical representation

• ex. seeing a black A letter as red

Inducer

The stimuli (black A)

• often letters and numbers

• overlearned ordered sequences

Concurrent

The thing they see (red A)

• can be perceptual in nature

Variation among inducers

• 4 = green

• four = each letter a different color

• IV = each a different color

Synesthesia mappings

• letters → colors

• numerical sequences → spatial arrangements

• musical notes → colors

• spoken words → colors

• words → tastes

One way round - seeing red won't conjure a specific letter

We all experience some cross modal associations

• Misophonia: sound → emotion

• Takete or Baluba: people around the world match shapes with the same words

What makes synesthetes special?

Responses are automatic, fixed over time, and highly specific

Measuring synesthesia

• Color matching

• modified stroop tasks

• show a bunch of letters and ask for the pattern the ‘2’ make, easier to syntehes since ‘2’ would be in different colors than the ‘5’

Color matching

• Participants adjust a color (e.g. with 3 knobs, or picking from a color wheel) to match each grapheme

• Repeat within and across sessions

• Test reliability (within and across sessions)

Modified Stroop task

Letter naming condition

• Showed letters in consistent colors (the colors that the syntheses see the letter in, ex. A in red), inconsistent colors, and netural colors

Ink naming condition

• Same consistent and inconsistent trials, but the neutral showed a random object in color

RT was faster in consistent → neutral → inconsistent compared to control subjects who had no difference in RT

Experiments by Witthoft and Winawer

a synesthete claimed to have learned his associations from a childhood toy

• tested lots of synesthetes over time using the color matching task to see if there are common letters that they chose for letters

Some aspects of synesthesia are learned

How synesthesia is created?

There is a genetic component

• can’t just train someone to be a synesthete by pairing items lots of times

When does synesthesia develop?

• when kids learn to count and say the alphabet

• when they learn months and days of the week

• when they learn to read music