Instructions for Ratios of Differences in Darkness


In this experiment you are asked to consider the difference in darkness between two dot patterns and compare that with the difference in darkness between two other dot patterns. Your task is to estimate the ratio of the first difference (on the left) to the second difference (on the right).

You will make your judgments using the following scale for judging ratios of differences:

12.5=the difference on the left is 1/8 as large as the difference on the right
25=the difference on the left is 1/4 as large as the difference on the right
50=the difference on the left is 1/2 as large as the difference on the right
100=the difference on the left is equal to the difference on the right
200=the difference on the left is twice the difference on the right
400=the difference on the left is four times the difference on the right
800=the difference on the left is eight times the difference on the right

Feel free to use numbers in between or more extreme to reflect your judgment of the ratio of the darkness difference between the two patterns on the left as a ratio of the darkness difference between the two patterns on the right.

Look at the first warmup, W1 below. Notice that the two differences are the same. In that case, the ratio of the two differences would be 1, so you should type the number 100 in the space provided next to that trial. Look at trial W2. This represents a large difference on the left, divided by a small difference on the right. You should respond with a number greater than 100. But how large does the ratio of the two differences in subjective darkness seem to you? Is the first difference twice as great, three times as great, four times as great, six times as great, eight times as great, or what? You would enter a number that is 100 times the ratio. Now look at warmup W3. Here the difference on the left is less than that on the right, so the ratio is less than 1, so you will use a number less than 100 here. If you thought the difference between the two patterns on the left is 1/2 as great as the difference on the right, you would type 50; if the difference on the left seems 1/4 the difference on the right, type 25, and so on.

Warmup Trials Ratios of Differences in Darkness


W1.
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These two differences are the same, so the ratio is 1, and you should type 100.

W2.
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The difference on the left is greater than the difference on the right, so you will judge how many times bigger it is and enter that number (greater than 100 in the box).

W3.
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In this case, the difference on the left is smaller than the difference on the right, so the ratio will be less than 1, and your response should be less than 100.

W4.
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In this case, the difference on the left is greater than the difference on the right, so the ratio will be greater than 1, and your response should be greater than 100. If the left difference seems twice as big, type 200; four times as big, type 400, etc.

W5.
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Which is bigger? By how much? What is the ratio of the difference on the left to the difference on the right?
Please RE-READ the instructions and warmups one more time before you begin. The purpose of this study is to measure subjective values. We are interested in your subjective experience of darkness differences, rather than any computations on actual number of dots. You are asked to form the impressions of two subjective differences and to judge the ratio of differences.
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17. What is your age? years.
18. Gender: Are you Male or Female?
Female
Male

19. How many years of Education have you completed? Put 12 for High School Diploma
Put 16 for college diploma (bachelor's degree).
put 20 for doctorate degree (Ph.D., M.D., etc).
Education:
20. Nationality (country of birth):
21. Comments:

Please check your answers. When you are done, push the button below.

Thank You!