Mapping of open-field behavior in rats and integration of various independent study results

Open field behavior of four treatment groups was plotted on a map by factor scores which were derived from principal component analysis. The treatment consisted of electric shock, extensive stroking, testing under a very dim-light condition, or testing after habituation to the field. Five measures were used: ambulation, penetration into the inner square, rearing, defecation, and urination. The first two principal components accounted for 93% of the total variance in the data. By using the four treatment groups for reference, the manner in which results of independent studies can be plotted on a map, and how the interpretation of results can be facilitated, were demonstrated with some examples. A table composed of scores of eta squared for the four groups was also presented for reference and to facilitate integration of the results of various independent studies.