How do major and minor chords affect emotion:
The early stages of processing that are involved suggest that major and minor chords have deeply connected emotional meanings, rather than superficially attributed ones, indicating that minor triads possess negative emotional connotations and major triads possess positive emotional connotations.
How does the major and minor keys affect the sound of music:
Most of the time, when all else is held constant, music in a major key is judged as happy while minor key music is heard as sad. I say most of the time because it's not true across the board. Minor music can be happy even if people do not understand the lyrics, such as in Van Morrison's 'Moondance'
