Instructions for Mueller-Lyer
The line in the frame above is the standard. Your task is to compare each horizontal line segment below to the standard. Judge the length of each horizontal line segment only, not including the fins. Compare each horizontal line below to the standard above. Call the standard 100. If you think that the horizontal line below equals the standard, type 100 in the space provided. If the horizontal line seems larger than the standard above, use numbers larger than 100, in proportion to its apparent length; e.g., if it seems 5% longer than the standard, record 105. If the line below seems smaller than the standard, use numbers below 100; for example, if it seems 5% shorter, use 95. The larger the line looks, the larger the number you should type in as your judgment of the line's length.
Warmup Trials Mueller-Lyer