The lack of invariance problem and the goal of speech perception

The overall goal of speech perception research is to explain how spoken language is recognized and understood. In the current research framework it is usually assumed that the key to achieving this overall goal is to solve the lack of invariance problem. But nearly half a century of sustained effort in it variety of theoretical perspectives has failed to solve this problem. It is argued that this lack of progress in explaining speech perception is not, in the first instance, due to the failure of individual theories to solve the lack of invariance problem, but rather to the common background assumption that doing so is in fact the key to explaining speech perception.