What evidence do the researchers of the Mozart Effect experiment offer as a test of their hypothesis? Is this evidence empirical (observable)? Is it valid?
I'm assuming that you're referring to the original Mozart Effect study (Rauscher et al., 1993). It is a study which has been drastically over-generalized. In that study, researchers had adults listen to Mozart for 10 minutes, and then gave them the Stanford-Binet IQ test. They found that performance on a spatio-temporal task (visualization of folding paper into particular patterns under a time limit) increased by about 8-9 ...
Summarizes the findings of the original study of the Mozart effect.