No new data needs to be collected. Use the data from both of last week's
magnitude estimation experiments
Weber's Law Experiment
Standard Motion Size: 3, 6, 12, 24, 48, 96
Number of Trials Per Level: 10
Width of Grating Cycle: 512
Grating Contrast: 100
This is a Forced-Choice method
Using the Magnitude Estimation Data from Week 2
Paragraph describing procedure
Use graph from last lab. Does the graph fit better with Fechner's
or Stevens' predictions? Look at the shape. Consider all of the
data together. Do not answer for each data set separately but the
answer must apply to both results together.
For Weber's Law Experiment
Calculate the JND for each standard motion size. Use the
Forced-Choice threshold equation
Your JND will already be ΔI.
Convert to ΔI/I.
Plot on a bar graph. X axis = I (standard motion size). Y axis = ΔI/I. So 6 bars.
Answer the following question: do the data fit Weber's Law or not?
Why or why not?
Worth 25 points
Point: Develop your skills at interpreting graphs, in particular, in how
data relate to theoretical ideas.