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Could you imagine a world in which you played a CD for your infant, and they automatically became more intelligent just by listening to it? Wouldn't it make life so much easier to download Mozart on ITunes and score well on all your tests that way? What would you say if you were to know that there have been people that have actually believed this to be a fact?
The Mozart Effect was introduced to the world in the form of an article from the journal Nature. In this article, it was reported that "...college students who listened to about ten minutes of a Mozart piano sonata showed a significant improvement on spatial reasoning tasks compared with a group of students who listened to a relaxation tape." (Lilienfeld pg. 377) This 1993 study seemed to show that intelligence could be improved by simply listening to classical music. Though it was difficult to replicate by other researchers, and it never claimed to improve spatial reasoning over the long term, the Mozart Effect was utilized as justification for companies to sell Mozart CDs to families with infants.
Later research would suggest that short-term mental arousal could explain the Mozart Effect. This would explain why individuals listening to music that they themselves enjoy (whether it be Mozart or not) feel more alert versus those that are not listening to anything. Perhaps you feel more alert after reading a story that makes you feel excited. Personally, I feel more alert after watching a thrilling movie. Any such activities could potentially improve short-term spatial ability, though not your intelligence.
So, even if listening to mentally stimulating music (or performing any activity that is stimulating) only improves short term spatial ability, perhaps we could benefit from the Mozart Effect. Could we potentially score better on exams if we listened to classical music shortly before taking them? Though our intelligence would not have been improved from listening to the music, could we temporarily improve our spatial reasoning for such exams? In all honesty, it's really doubtful at this point. Though it your short term spatial reasoning would likely be improved by listening to stimulating music, it hasn't been proven to do so significantly in the least.
This article helps to explain why the Mozart Effect should be categorized as an urban legend, and how this pseudoscience bursted its way into public popularity. Though it would be fun if we could all improve our I.Q. scores by simply listening to music, the evidence isn't there to support this extraordinary claim.