HIT (Heuristic Identity Theory) proposes that identity claims between psychological processes and neural mechanisms are advanced as heuristics that serve to guide further research. Emphasizing the thoroughly hypothetical character of identity claims in science, HIT focusses on the way that proposed identifications of psychological and neural processes and structures contribute to the integration and improvement of our neurobiological and psychological knowledge. Hypothesized identities advance research by suggesting new avenues for the empirical investigation of both mind and brain. The resulting empirical findings motivate scientists at both levels to tinker with their conceptions of the pertinent processes and structures. As even the brief discussion of visual processing demonstrates, these hypothetical identities evolve in response to on-going research. Explanatory and predictive successes are what justify these identity claim and what make additional theoretical and evidential resources available in future research.