Under Contract N6onr-23810 with the Office of Naval Research. The opinions expressed are our own and are not necessarily shared by the Office of Naval Research. These studies are under the direction of J. P. Guilford. Paul R. Christensen is assistant director. Robert C. Wilson has been principally responsible for the conduct of this particular study. Donald J. Lewis contributed to the development of hypotheses and tests. Raymond M. Berger made substantial contributions to the development of the tests.

The authors are very much indebted to the Personnel Research Laboratory, Human Resources Research Center, Air Training Command, Lackland Air Force Base, Texas, for making the testing possible, and in particular to Dr. Lloyd G. Humphreys, Director, and to Mr. William B. Lecznar, Technical Aide.

Acknowledgement is made to Gordon Taaffe for the supervision of much of the statistical work connected with this study and to Norman W. Kettner for carrying out the extractions of factors and for valuable assistance on the rotations of axes.

A fuller discussion of this factor analysis is given by Wilson (16).

hfc: hypothesized factor content (see preceding outline for key to the hypotheses).

We are indebted to Professor L. L. Tburstone for his permission to reproduce tests 35, 36, 37, 39, 40 and 43. Sentence Gestalt I (test 27, 53) is patterned after a test developed by H. M. Grayson. We wish to thank Constance D. Lovell for making available to us a number of classes in beginning psychology for preliminary experimental testing.

Tests included as reference tests because of the known factor content.

The correlation matrix, the centroid factor matrix, and the rotated factor matrix have been deposited with the American Documentation Institute, 1719 N. Street, N.W., Washington 6, D. C. Order Document No. 4156 remitting $1.25 for 35 mm. microfilm or $1.28 for 6 by 8 inch photocopies.