  Western tonality provides a hierarchy of stability among melodic
scale-degrees, from the maximally stable tonic to unstable chromatic notes.
Tonal stability has been linked to emotion, yet systematic investigations of
the associations between the hierarchy of melodic scale-degrees and perceived
emotional valence are lacking. Here, we examined such associations in three
experiments, in musicians and in non-musicians. We used an explicit task, in
which participants matched probe tones following key-establishing sequences to
facial expressions ranging from sad to happy, and an implicit speeded task, a
variant of the Implicit Association Test. Stabler scale-degrees were associated
with more positive valence in all experiments, for both musicians and
nonmusicians. This notwithstanding, results significantly differed from those
of a comparable goodness-of-fit task, suggesting that perceived tonal valence
is not reducible to tonal fit. Comparisons of the explicit and implicit
measures suggest that associations of tonality and emotional valence may rely
on two distinct mechanisms, one mediated by conceptual musical knowledge and
conscious decisional processes, the other - largely by non-conceptual and
involuntary processes. The joint experimental paradigms introduced here may
help mapping additional connotative meanings, both emotional and cross-modal,
embedded in tonal structure, thus suggesting how extra-musical meanings are
conveyed to listeners through musical syntax.
