Some interesting reading, but their findings are not supported by any substantial evidence. However, I guess you could assess the various major/minor keys in relation to periods in classical music history, e.g.
C major:Completely pure. Its character is: innocence, simplicity, naivety, children's talk
This corresponds well with some of the simplistic (pure/harmonic, some might say naïve) traits of the Classical era. Think for example of some of Mozart's famous sonatinas for piano, many of them are in C major, with few or no key variations.
F# major:Triumph over difficulty, free sigh of relief uttered when hurdles are surmounted; echo of a soul which has fiercely struggled and finally conquered lies in all uses of this key
B major:Strongly colored, announcing wild passions, composed from the most glaring colors. Anger, rage, jealousy, fury, despair and every burden of the heart lies in its sphere
F# and B are often used in impressionistic works, and if you consider some of the adjectives above, they correspond well with the characteristics of impressionism (color, freedom, passion).
On the basis of this you could hypothesize that the various keys connote different ranges of emotions - from a historical point of view at least!
However, as CD mentions, there are several methodological considerations. One could argue that it is scientifically impossible to prove anything about keys and related emotionality, simply because the connotations of keys are subjective! Furthermore, there are no differences in terms of taxonomy between the various keys. C major and and B major contain the same intervals in terms of intonation, so are they really different from each other??? They might as well produce the same connotations for the audience?
I think a more interesting analysis would concern the emotional connotations of intervals. What emotions does a third and fifth bring up respectively?
But again, it is pointless do this kind of research without fitting it into a general picture...
