In this paper we extend finite state machines to allow expressions in Plausible Logic for labelling transitions. As a result, we enable the design of behaviours that incorporate non-monotonic reasoning with a high-level software development tool. Using a cognitive software architecture that supports the efficient implementation of a developing/ programming environment, we automatically translate graphical designs of behaviour into executables that run on board autonomous robots. The graphical designs are obtained by demonstrating the transformation of the state machine into a Behavior Tree does not lose information and enhances modularisation of logic descriptions. We illustrate this with a description of the rapid development of the behaviour of a friendly poker player on an Aibo that interacts with humans.