The affect system has been shaped by the hammer and chisel of adaptation and natural selection such that form follows function. The characteristics of the system thus differ across the nervous system as a function of the unique constraints existent at each level. For instance, although physical limitations constrain behavioral expressions and incline behavioral predispositions toward a bipolar (good—bad, approach—withdraw) organization, these limiting conditions lose their power at the level of underlying mechanisms. According to the authors ' model of evaluative space ( J. T. Cacioppo & G. G. Berntson, 1994; J. T. Cacioppo, W. L. Gardner, & G. G. Berntson, 1997), the common metric governing approach—withdrawal is generally a single dimension at response stages that itself is the consequence of multiple operations, such as the activation function for positivity (appetition) and the activation function for negativity (aversion), at earlier affective processing stages.

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Purpose can be characterized as a central, self-organizing life aim. Central in that when present, purpose is a predominant theme of a person’s identity. Selforganizing in that it provides a framework for systematic behavior patterns in everyday life. As a life aim, a purpose generates continual goals and targets for efforts to be devoted. A purpose provides a bedrock foundation that allows a person to be more resilient to obstacles, stress, and strain. In this paper, we outline a theoretical model of purpose development. Besides outlining various essential ingredients to creating a purpose in life, we describe three broad pathways. The first process is proactive involving effort over time and only resulting in a purpose after gradual refinement and clarification. The second process is reactive involving a transformative life event where a purpose arises and adds clarity to the person's life. The third process is social learning- involving the formation of purpose through observation, imitation, and modeling. Our aim is to stimulate more research on this higher-level construct in the architecture of personality.