Key issues in generating a psychological-testing protocol.

An individual's behavior is created by an amalgam of genetic, environmental, cultural, and historical variables working in concert and changing over time. Variations in nutrition are one class of environmental factors. Linking these to outcome effects requires carefully designed studies. Many considerations are involved, and this paper draws attention to some of the fundamental ones. Psychological and behavioral functions tend to be complex, in part because they are affected by a wide range of variables. Almost any given state--a particular constellation of psychological characteristics displayed by an individual at a given time--can be produced in a variety of ways.