Affective responses to music have been shown to be influenced by the psychoacoustic features of the acoustic signal, learned associations between musical features and emotions, and familiarity with a musical system through exposure. The present article reports two experiments investigating whether short-term exposure has an effect on valence and consonance ratings of unfamiliar musical chords from the Bohlen-Pierce system, which are not based on a traditional Western musical scale. In a pre- and post-test design, exposure to positive, negative and neutral chord types was manipulated to test for an effect of exposure on liking. In this paradigm, short-term (“mere”) exposure to unfamiliar chords produced an increase only in valence ratings for negative chords. In neither experiment did it produce an increase in valence or pleasantness ratings for other chord types. Contrast effects for some chord types were found in both experiments, suggesting that a chord’s affect (i.e., affective response to the chord) might be emphasised when the chord is preceded by a stimulus with a contrasting affect. The results confirmed those of a previous study showing that psychoacoustic features play an important role in the perception of music. The findings are discussed in light of their psychological and musical implications.