Plateaus and Asymptotes

One hundred twenty years ago, the emergent field of experimental psychology debated whether plateaus of performance during training were real or not. Sixty years ago, the battle was over whether learning asymptoted or not. Thirty years ago, the research community was seized with concerns over stable plateaus at suboptimal performance levels among experts. Applied researchers viewed this as a systems problem and referred to it as the paradox of the active user. Basic researchers diagnosed this as a training problem and embraced deliberate practice. The concepts of plateaus and asymptotes and the distinction between the two are important as the questions asked and the means of overcoming one or the other differ. These questions have meaning as we inquire about the nature of performance limits in skilled behavior and the distinction between brain capacity and brain efficiency. This article brings phenomena that are hiding in the open to the attention of the research community in the hope that delineating the distinction between plateaus and asymptotes will help clarify the distinction between real versus “spurious limits” and advance theoretical debates regarding learning and performance.