In mixed electroacoustic music it is common to find the erroneous conception according to which interaction should base itself exclusively on the fusion between instrumental writing and electronic devices, whereas the contrast between these sound spheres is as significant as the fusional states. Although fusion may be seen as the most important ingredient for an efficacious compositional strategy concerning interaction, it is actually through contrast that the identities of spectral transfers in mixed composition can be evaluated by the listener. This text intends to introduce a discussion about the many possibilities offered by the morphology of interaction between acoustic sources and electroacoustic resources and structures. In this sense it tries to identify intermediate types between the extremes of pure fusion and pure contrast, which can be established by the composer that sees in interactive music one of the most advantageous poetic realms of electroacoustic music.