Fig. 9. Exploratory Factor Analysis of different cocaine self-administration modalities.

A) Schematic of behavioral measures used in factor analysis with individual z-scores. C) Visual representation of factor loadings onto the 3 extracted factors (of 6 identified), which collectively describe 70% of total variance. B) Scree plot depicts eigenvalues for all components extracted. Filled symbols denote significant values (eigenvalue > 1) selected for further analysis.