Stability analysis of traffic flow from the perspective of human-in-the-loop dynamics forms the main motivation of this paper, in which we pursue the natural necessity of considering memory capabilities of the human drivers. In particular, the paper is concerned with the effects of control decisions based on short-term memory, which can be represented by some distribution functions. Such a model assumes that control decisions of human drivers are based on the stimuli they continuously receive from a set of continuous points distributed over the history. With memory effects, the main objective is to understand, over a fundamental car-following traffic model, the stability features of the flow and is to introduce some physical insight from the arising analysis. Especially, scenarios in which how stability is affected by the number of vehicles are practically of interest. ©2007 IEEE.