Morrison's research work centered on statistical mechanics within theoretical physics, the many-body problem, and the relationship between microscopic and macroscopic physics. In collaboration with John Garrison and Jack Wong, Morrison made a significant contribution in 1972 by demonstrating "the absence of long-range order in quantum systems in two dimensions, such as in thin superfluid helium films, due to the breaking of a continuous symmetry." He also worked on the application of "current algebra" to the geometry of macroscopic quantum flows in superfluid helium.