Longitudinal factor analysis

A model is presented for factor analysing scores on a set of psychological tests administered as both pre- and postmeasures in a study of change. The model assumes that the same factors underlie the tests on each occasion, but that factor scores as well as factor loadings may change between occasions. Factors are defined to be orthogonal between as well as within occasions. A two-stage least squares procedure for fitting the model is described, and generally provides a unique rotation solution for the factors on each occasion.We thank M. W. Browne, R. P. McDonald, R. Pruzek, and the Managing Editor for their constructive comments.     

Behavioral discrimination of click intensity in cat

Avoidance conditioning procedures were used to train cats to discriminate intensity differences between successive clicks. The discriminative behavior was applied in a modified method of adjustment to determine a difference limen (DL) for click intensity. The obtained DLs were consistent within and between subjects, and averaged 4.4 db. This value is greater than previously reported intensity DLs for pure tones in cats.