Abstract: Conference papers are presented for nutrition scientists which emphasize the reciprocal interaction of the investigator's experimental interest (e.g., cardiovascular physiology, behavior) and the choice of the appropriate independent variable whereby nutritional status is to be defined. The material is covered under 3 sections. The 1st deals with the role of metals, in general, and iron, specifically, in nervous system metabolism. Sufficiently detailed knowledge of these pathways should allow for predictions of the types of behavioral and affective changes that might accompany iron deficiency. The 2nd section addresses the critical issue of how the independent variable, iron status) should be defined. The last section includes descriptions of the most recent studies on the functional effects of iron deficiency in animals and humans. Examination of the types of functional deficits permit delineation of possible biochemical mechanisms whereby iron status might influence behavior. (wz).