Soft-Assembled Mechanisms for the Unified Theory

Do connectionist and dynamic-systems models converge on a unified theory? The answer depends on the kind of mechanism that the two models attempt to unravel. Two views of mechanism avail themselves to contemporary scientists. One view of mechanism represents cognitive activity as reducible to a cognitive architecture of separate cognitive components. Another view sees cognitive activity as emergent and highly dependent on fine details of the contexts in which behavior emerges. We will argue in this chapter that connectionist and dynamic systems models complement each other and collectively move toward a unified theory of development if they subscribe to the second view of mechanism, one that treats behavior as soft assembled in the immediate context. The chapter organization is as follows. In section Where Models Converge in Stalemate, we address why models aimed at reducing behavior to cognitive components cannot make clear headway. The argument is that a reduction of behavior requires human performance to be relatively context free. Yet, as we show with the example of balance task performance, human performance is highly context dependent, even in the sterile laboratory context of balance experiments. In section Taking Context Effects Seriously, we elaborate on what such context dependence could mean. While not conclusive on its own, strong context dependence is consistent with the idea that cognitive activity is softly assembled to suit the immediate task environment. Soft assembly offers a plausible alternative to hard-assembled cognitive functions—functions that exist prior to and independently of the task context. We review more pointed evidence for soft assembly and discuss why models that take soft assembly seriously—connectionist or dynamic systems— anticipate the unified theory.