TEAM PROJECT 5:
PSYCHOLOGY
Mike, Jill, Ashley, Kel, Raina, Deepali,
Grace, Josh, Janet & Alice
CHANGE
DETECTION
BLINDNESS
What is it?
Change detection blindness is the
inability to notice changes in our
surroundings.


People are unable to detect changes if their
brains do not encode the data that they
perceive.
Normally, we expect a constant environment
around us, and thus, we do not necessarily
notice subtle changes that can occur.
Why do I care?
Change detection blindness tells us how
our visual/attentional system operates.
By seeing where our visual/attentional
system fails, we can understand the
underlying mechanisms behind how our
brain encodes our surroundings.
So throw me a bone here…
Change Detection Blindness most
commonly occurs at the movies:
 Films are usually taped out of
sequence and spliced together to
form a consecutive storyline
 There are often many unnoticed
editing errors
Popular Examples
“The Matrix”

Bullet dodging sequence
In the beloved motion picture, “The
Wizard of Oz,”

The length of Dorothy’s pigtails changes 5
times in 1 scene!!
And heeeeeeeeeere’s Dorothy!
Past Experimental Findings
In 1996, Daniel Levin and Daniel Simons
of Cornell University conducted a SLEW
of studies in CDB.
The first experiment tested subjects’
ability to detect changes in scenery and
peripheral details

Only 1 in 9 people noticed any change
Past Experiments cont’d…
Levin and Simons’ second experiment
involved a short clip with only an actor
change.

33% of the subjects noticed the change
A study conducted by Ronald Rensink
showed that people are more likely to
detect changes in vital central objects
rather than minor changes (1996).
Factors influencing CDB

Intentions of the observer
Incidental vs. intentional

Complexity of the scene
Visual
Dialogue and audio

Type and duration of changes
Our Experiment: Goals
Create a video that combines elements
from aforementioned studies:




Dynamic display
Central and peripheral changes
Instructions vs. no instructions
Varying degree and duration of changes
Subjects
Age 18 or older
Two groups, 5 males and 5 females
each
A. Uninstructed - “watch the clip”
 B. Instructed - “pay close attention
and watch for changes between
cuts”

And now you
are all our
guinea pigs
Sign the consent form!
And now our video…
• Please pay attention and
watch for changes
between scene cuts!
(please turn off all cell
phones at this time )
Here’s Your Questionnaire!
Did you notice any changes?
Now for the last part…
Can you identify the second actress?
YOU CAN DO IT!
Would you like a Debriefing Form?
Please
recycle
Now let’s check out
the KINKS…
Who cut the
cheese?
OOPS, I DID
IT AGAIN
Just hangin’
wit MY
BOYS
A QUICKIE Analysis
of the Results…
Percentage of changes
noticed
Comparison between groups
60
50
40
Trial two
30
Trial one
20
10
0
No Instructions
Group A
Instructions
Group B
Comparison of first trials
1.00
No instructions
Instructions
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
fruit basket
tie
plants
watch
water bottle
necklace
picture
cup
plate switch
shades
0.00
Sample Size
It was difficult to determine the statistical
reliability of our findings.
Ideally: a minimum of two groups of 20
Our study: a total of 20 volunteers ~ two
groups of 10

Cannot extend results to the general
population
0.80
fruit basket
1.00
tie
plants
watch
water bottle
necklace
picture
cup
plate switch
shades
HEY, how’d MY BOYS do?
female
male
0.60
0.40
0.20
0.00
Picture Identification
25%
15%
Face
Detail
10%
50%
Correct guess
Incorrect guess
As good as YOUR MOMMA’s
SEMI-SWEET pie (graph)
I think I’ll
call him…
MINISURACE
Take a CHILL PILL,
it’s almost over…
Discussion
After both viewings, the uninstructed
group found 48% of the changes while
the instructed subjects noticed 51%
Even after both viewings, why so few
detections?



Richness and complexity of scene
Exciting acting
Limited attention capacity
Discussion cont’d
Most significant change in the clip

The actor change was undetected
Presented subjects with pictures of the
first and second actors


15% of participants judged correctly based on
the face.
Additionally, 10% of participants guessed
correctly
Tying it together…
In the initial viewing, the instructed
noted 22% of the changes while the
uninstructed identified only 16% of the
changes
Changes (i.e. painting) that altered the
overall visual scene are more likely to
be identified
In our study, the actor change was less
likely to be noticed than peripheral
changes
Final Thoughts
Only 50% of the total changes were
detected


Two viewings
Further instruction
Do we have a poorly designed visual
system?
Ability to detect change
Perception

We are used to continuity in our environment.