Which line was longer?

The line on the top
The line on the bottom


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Did you notice any pattern in the background of dots on that last trial?

Yes
No


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Please answer the following questions even if you responded "no" to the previous question.
If you aren't sure of an answer or don't know, please just guess.


Which of these images best matches the dots you saw on the previous trial? Click to select.





How confident are you about your choice?

Not at all confident
Somewhat confident
Very confident


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Which of these images best matches the dots you saw on the previous trial? Click to select.




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This short survey asks you to provide some demographic information about yourself.
None of the information will allow us to identify you and it will be analyzed by combining across responses from many people.
Your responses will not affect your compensation for this HIT.


Do you identify as male or female?
Male
Female

What is your age?
Under 18
18 - 24
25 - 49
50 - 80
Over 80

Which best describes your vision?
My vision is normal. I don't need glasses or contacts.
I need glasses or contacts, and I wore them during the experiment.
I need glasses or contacts, but I wasn't wearing them during the experiment.


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Have you ever done a study like this before, where you were doing a difficult task, and something unexpected showed up? If so, please describe it briefly.

No
Yes


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You will be performing a difficult judgment task.

You will see a pair of lines, one of them slightly longer than the other, on top of a grid made of black and white dots.

Your task will be to judge which line is longer.

You will only have a brief moment to view the lines. A plus sign will appear to help guide your eyes to the right place before the lines show up.

This task is very difficult, so just do your best!

We have detected a screen that is too small to run this experiment.

If you are on a mobile device, please re-load this page on a larger device.

Your browser does not support the canvas element. Please re-load this page in another browser.

For this next (and final) trial, please ignore the lines and concentrate on the dots in the background.

Thank you for participating in our study!

Purpose of the Study

In this study, we are replicating a study originally done in 1997. In that study, it was found that even when people did not notice that the dots in the background were forming any kind of pattern, they were still influenced by the illusion they formed. Even though the two lines were the same length, one looked longer than the other because of the visual illusion in the background.

We are interested in how likely you were to notice that the dots formed a pattern while you were doing the line judgment task, and whether or not you were affected by the visual illusion.

Click the button below to finish the experiment and get your completion code. Thank you again for participating!