The suggestion of an underlying dimension in mental imagery despite low correlations among objective spatial and self report measures was investigated using data from two independent samples of 131 college students. The first study revealed some factorial independence in imagery aptitude, while the second study investigated individual patterns of imagery ability in four mutually exclusive groups through analysis of variance procedures with repeated measures on four cognitive tasks. Interpretations from results of these two studies tentatively support differential attributes. Neurological literature suggests that: (1) major components of nonverbal cognition may be mental manipulation of external objects in space, imaginal body movements, and nonverbal conceptual representations; (2) this diversity complicates the construct of mental imagery; and (3) different neural centers in both left and right hemispheres are probably being tapped in various operationalizations of imagery aptitude. (Author)