Hello, please help me with this question about Weber's Law. You will use the formulas separately for each of the target size conditions. It is important to sort the trial-by-trial data according to the target size. If you mix together trials from different conditions, you will get incorrect answers.
Trial Target circle radius (pixels) Matching circle radius (pixels) 50.0 45.9 10.0 10.8 30.0 31.1 50.0 47.3 30.0 28.5 OUT 10.0 10.7 10.0 11.5 (0 00 10.0 11.0 30.0 32.3 10 10.0 11.8 11 10.0 11.4 12 30.0 29.9 13 50.0 47.1 14 50.0 47.8 15 10.0 11.9 16 30.0 32.7 17 30.0 30.3 18 30.0 32.3 19 10.0 12.4 20 50.0 47.5 21 50.0 48.8 22 50.0 48.9 23 10.0 11.9 24 30.0 29.8 25 30.0 31.6 26 30.0 32.2 27 50.0 48.2 28 10.0 11.6 29 50.0 50.3 30 50.0 52.3How robust is this effect? Are there limits to this effect? Weber's Law holds for many different stimuli, tasks, and conditions. You may not nd the expected pattern of results if you do not really try to match the circle sizes. Not trying to do your best may introduce so much variability from trial to trial that the effects of Weber's Law will be impossible to detect. Formulas To calculate the standard deviation we will use a formula that makes it clear that the standard deviation is similar to an average distance from the mean value. There are other formulas that are easier to calculate but are not as easy to understand. To begin, you need to calculate the mean value of a set of scores: 21:1 Xi 71. X : where n is the number of scores. The mean is then used to compute the sum ofsquares, 88, which is the sum of the squared deviations for each score and the mean. " i 2 SS : Z (X; , X) . 7221 To compute the standard deviation, we divide the SS by n-1 and take the square root: #38 s: n71 You will use these formulas separately for each of the target size conditions. It is important to sort the trialby-trial data according to the target size. If you mix together trials from different conditions, you will get incorrect answers. Use the trial-bytrial data to answer these questions. Question Answer Sum of squares for when the target is 10: S (The difference between your answer and the correct value must be less than 0.01.) The mean of matching circle radius values when the target is 30: I (The difference between your answer and the correct value must be less than 0.01.) :' The standard deviation of the matching circle radius when the target is 30: :| (The difference between your answer and the correct value must be less than 0.01 ._) Sum of squares for when the target is 50: S (The difference between your answer and the correct value must be less than 0.01.)
