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Visual Trickery

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Aubree Carr

on 28 November 2016

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Transcript of Visual Trickery

The McCollough Effect is a contingent (subject to change) color after effect, which can be seen by looking at something as simple as ruled paper. To create the after effects a vertical grating of one color and a horizontal grating of another color are needed, along with the test gratings. To see an after effect, there must be a primary action, which in this experiment is a person alternatively looking at the horizontal grating (first color) and vertical grating (second color) for a period of time to see the after effect on the b&w gratings.
Experimental Question
Who is impacted most by the McCollough Effect:
I am predicting there will be a difference between male and females, with females responding better.
Some extra information
Visual Trickery : An Experiment about the McCollough Effect
By Aubree Carr
The McCollough Effect was originally described by Celeste McCollough in 1965 and has been an on-going investigation since.
The Effect has been documented to last for long hours and even overnight in some cases, with the worst documented effect lasting 3 months. However, it has been proven that the longer you look at the colored images the longer you will see the hazy colors on the test grating.
My assumption is based on visual research which indicated that the vision of a male is more sensitive to moving objects and detail change while female vision is more perceptive to color changes.
These are images of what was used to demonstrate the McCollough Effect!
Test grating
Vertical green grating
Horizontal red grating
Control Group:
Experimental Group:
Independent: Length of demonstration shown to participant.
3 males and 3 females will participate to test for replication.
The experiment will be conducted for a 2-day period for a total of 4 demonstrations. (1-morning and 1-evening per day)
This is basically what I did...
Set up the demonstration with laptop (used maximum brightness)
Took each participant one at a time (Male, Female, Male order) and explained the test to their understanding, than I began the demonstration & stopwatch simultaneously
The subject than focused on the demonstration for 2 minutes straight. (Music was allowed)
After 2 minutes of focusing, the demonstration was stopped and a printout of the test grating was given to the participant while starting the stop watch to record how long it took to stop seeing the effect.

These steps were repeated for all of the participants!
These were the results for the female and male groups. Both morning and evening demonstrations. I also included the average of how long each female/male group took to stop seeing the effect in minutes.
Day Two: Morning & Evening
Day One: Morning & Evening
Here's what I found:
Day One Morning Averages
Males: 7.25 minutes
Females: 7.67 minutes
Day One Evening Averages
Males: 8.17 minutes
Females 7.75 minutes
Day Two Morning Averages
Males: 7.92 minutes
Females: 8.33 minutes
Day Two Evening Averages
Males 8.75 minutes
Females: 8.83 minutes
Entire Day-One Average
Males: 7.71 minutes
Females: 7.67 minutes
Entire Day-Two Average
Males: 8.33 minutes
Females: 8.58 minutes
To conclude, my hypothesis was partially supported. However, I would say there is not sufficient evidence to support that the female groups eyesight would return to normal faster than the male group. On day one the female group average was slightly faster than the male group. However, on the second day the results were opposite.
Therefore, I hypothesize that the female groups eyesight will return to normal faster than the male group
Why does the McCollough Effect Matter?
It helps scientists learn about the visual system and how information is represented.
Play an important part in sensory adaptation. Which basically means the more you are exposed to something the less you notice it. (your nose)
Learn about the ability to alter perception.
Different age groups.
Try using different colors. (Green & Red are complementary, does it matter?)
Different sized grids. (thick/thin lines)
Color adaptation of edge-detectors in the human visual system, by C. McCollough, appeared in Science, 149, 1115-1116.
Extroversion and the McCollough Effect, Nicola A. Logue and William Byth, British Journal of Psychology (1993)
The McCollough effect reveals orientation discrimination in a case of cortical blindness by G.Keith Humphrey1, Melvyn A. Goodale2, Maurizio Corbetta3, Salvatore Aglioti4, Volume 5, Issue 5, May 1995, Pages 545–551
There is little-known about the effect but it is a remarkable optical illusion.
Something interesting about the effect is it makes your perception of color different from reality.
Dependent: Length of abnormal eyesight from demonstration
Full transcript