Vividness of Mental Imagery: Vividness of Mental Imagery: Individual Variability can be Individual Variability can be

Measured ObjectivelyMeasured Objectively

Xu Cui, Cameron B. Jeter, Dongni Yang, Xu Cui, Cameron B. Jeter, Dongni Yang,

Read Montague, David M. EaglemanRead Montague, David M. Eagleman

Presented by:Jordan McNeely

Introduction Introduction

Can subjective reports be verified through Can subjective reports be verified through any objective measure?any objective measure?

Introduction cont.Introduction cont.

Accumulating evidence suggests that the Accumulating evidence suggests that the primary and secondary visual cortices are primary and secondary visual cortices are

widely activated during mental imaging widely activated during mental imaging tasks. tasks.

Past research has indicated that visual Past research has indicated that visual cortex activation and vividness of mental cortex activation and vividness of mental

imagery has a positive correlation.imagery has a positive correlation.

Introduction cont.Introduction cont.

The current study is testing to see if a The current study is testing to see if a subjective measure of the vividness of subjective measure of the vividness of mental imagery can be corroborated by mental imagery can be corroborated by objective measures such as fMRI scans objective measures such as fMRI scans

and color word naming tasks. and color word naming tasks.

Method: SubjectsMethod: Subjects

8 subjects participated in this study 8 subjects participated in this study (6 male, 2 female)(6 male, 2 female)

They ranged in age from 25-31They ranged in age from 25-31

Method: Experiment 1Method: Experiment 1

Vividness of visual imagery (VVI) measurementVividness of visual imagery (VVI) measurement

They were given set of 16 standardized They were given set of 16 standardized visualization tasks and were ask to rate the visualization tasks and were ask to rate the vividness of what they saw in their mind’s eye on vividness of what they saw in their mind’s eye on a scale of 1-5a scale of 1-5

(Note: a low VVI score indicates more vividness (Note: a low VVI score indicates more vividness and a high score indicates less vividness)and a high score indicates less vividness)

Method: Experiment 2Method: Experiment 2

Color word identifying taskColor word identifying task

For each trial, the background of a computer For each trial, the background of a computer screen turned either yellow, orange, or purple screen turned either yellow, orange, or purple

32ms later, the word “yellow”, “orange”, “purple”, 32ms later, the word “yellow”, “orange”, “purple”, or no word appeared in the center of the screen or no word appeared in the center of the screen for 32 ms, the presented word was always blackfor 32 ms, the presented word was always black

Participants reported on a keyboard which of the Participants reported on a keyboard which of the words, or no word, they saw words, or no word, they saw

Participants each completed 120 trials Participants each completed 120 trials

Method: Experiment 3Method: Experiment 3

fMRI imaging fMRI imaging

Participants wore sleeping masks during fMRI Participants wore sleeping masks during fMRI scansscans

The participants were given a visualization task The participants were given a visualization task and asked to begin visualizing at an auditory and asked to begin visualizing at an auditory “go” signal and to stop visualizing at an auditory “go” signal and to stop visualizing at an auditory “stop” signal“stop” signal

Each trial was 10s and there was a rest period of Each trial was 10s and there was a rest period of 10s between each trial10s between each trial

Participants each completed 24 trials Participants each completed 24 trials

Method: fMRIMethod: fMRI

Region of interest Region of interest was Brodmann was Brodmann areas 17 and 18. areas 17 and 18. Better known as Better known as the primary and the primary and secondary visual secondary visual cortices cortices respectively. respectively.

Method: fMRI cont. Method: fMRI cont.

BOLD signal of the whole brain gray matter BOLD signal of the whole brain gray matter was subtracted from the BOLD signal of was subtracted from the BOLD signal of

the visual cortex.the visual cortex.

This was done to ascertain the activation of This was done to ascertain the activation of the visual cortex relative to the activation the visual cortex relative to the activation of the whole brain during the visualization of the whole brain during the visualization

task. task.

Results Results

A significant negative A significant negative correlation was found correlation was found between activation in between activation in the visual cortices the visual cortices and subjective VVI and subjective VVI scores. scores.

rr= -0.73, = -0.73, pp=0.04 =0.04

Results cont. Results cont.

A significant positive correlation was found A significant positive correlation was found between VVI score and congruent versus between VVI score and congruent versus

incongruent performance on the color incongruent performance on the color word identification task.word identification task.

rr= 0.73, = 0.73, pp= 0.04= 0.04

Results cont.Results cont.

Results cont.Results cont.

A significant A significant negative correlation negative correlation was found between was found between visual cortex visual cortex activation and activation and congruent versus congruent versus incongruent incongruent performance on the performance on the color word color word identification task.identification task.rr= -0.77, = -0.77, pp= 0.03= 0.03

DiscussionDiscussion

The correlation between the subjects visual The correlation between the subjects visual cortex activation and their score on the cortex activation and their score on the

naming task may indicate that people with naming task may indicate that people with more vivid mental imagery have increased more vivid mental imagery have increased interaction between the parts of the brain interaction between the parts of the brain that code for color perception and color that code for color perception and color

naming. This could lead to difficulty naming. This could lead to difficulty differentiating between what color they differentiating between what color they

saw and what color word they saw. saw and what color word they saw.

Discussion cont. Discussion cont.

The correlation between VVI score and The correlation between VVI score and visual cortex activation is very important visual cortex activation is very important

because it shows that a subjective because it shows that a subjective experience can be measured, not only experience can be measured, not only

objectively, but biologically. objectively, but biologically.

Discussion cont.Discussion cont.

Future researchFuture research

Will these findings translate to other Will these findings translate to other subjective experiences?subjective experiences?

What other thoughts or feelings can be What other thoughts or feelings can be measured using imaging techniques and measured using imaging techniques and what part of the brain would they be what part of the brain would they be located in?located in?

Critique Critique

No mention of specifics on subjectsNo mention of specifics on subjectsAverage of 54Average of 54±3% accuracy identifying ±3% accuracy identifying

presented wordpresented wordOnly 8 subjects does not give your Only 8 subjects does not give your

correlations much powercorrelations much power

CritiqueCritique

If the question of the study had been If the question of the study had been “Does visual cortex activation increase “Does visual cortex activation increase during mental imaging exercises relative to during mental imaging exercises relative to the whole brain” the answer would have the whole brain” the answer would have been no.been no.

What else transpires during mental What else transpires during mental imaging?imaging?