For the intimate fusion of touch, temperature and sometimes also taste and smell sensations into a single unified total impression raises the question of whether we do not have here Gestalt qualities which are built up upon a foundation belonging to several sensory regions. As can easily be recognized, it is just as possible that a complex of, say, touch and temperature sensations should provide the foundation for a Gestalt quality as should a complex of sound sensations. Indeed no a priori objection can be raised even against the idea that there should exist sound-colour-Gestalten spanning the data of the senses of sound and vision as something like a bridge - even though we do not believe that we can detect anything of this sort in sensation.
— CHRISTIAN VON EHRENFELS