Standard errors for rotated factor loadings

Beginning with the results of Girshick on the asymptotic distribution of principal component loadings and those of Lawley on the distribution of unrotated maximum likelihood factor loadings, the asymptotic distribution of the corresponding analytically rotated loadings is obtained. The principal difficulty is the fact that the transformation matrix which produces the rotation is usually itself a function of the data. The approach is to use implicit differentiation to find the partial derivatives of an arbitrary orthogonal rotation algorithm. Specific details are given for the orthomax algorithms and an example involving maximum likelihood estimation and varimax rotation is presented.This research was supported in part by NIH Grant RR-3. The authors are grateful to Dorothy T. Thayer who implemented the algorithms discussed here as well as those of Lawley and Maxwell. We are particularly indebted to Michael Browne for convincing us of the significance of this work and for helping to guide its development and to Harry H. Harman who many years ago pointed out the need for standard errors of estimate.     

Physiological learning theory

Attention or concentration requires control of activity in those excess neurons that are not necessary for the present task. The control is probably not a massive inhibitory suppression but may be a recruiting process, a function of complex perceptual and associative learning that begins with early experience. Inhibition, however, may still be of crucial importance as a sharpener of associative mechanisms, and the child with minimal brain damage may have suffered a selective loss of inhibitory neurons.Paper prepared for reading at the Ciba Medical Horizons conference on MBD (minimal brain dysfunction), Omaha, Nebraska, April 2, 1976.     

Individual differences in perceived similarity and preference for visual art: A multidimensional scaling analysis

Previous studies have shown that individuals may attend to different dimensions in making an overall judgment of similarity between complex stimuli. The present study investigated the nature of differences in the perceived similarity of reproductions of paintings by the use of multidimensional scaling techniques. Using the INDSCAL model, a group of art-trained students are shown to differ significantly from a group of nonart students in terms of their differential weighing of a set of common dimensions. The same subjects’ preferences are examined in relation to these differences by use of the PREFMAP hierarchy of models. While the simplest (vector) model was found to be appropriate for almost all subjects, large differences in vector direction and average subject ideal-point location are found. Implications for future studies of responses to art are discussed.     

Acquisition, extinction and reacquisition of a conditioned response in the cockroach: The effects of orotic acid

Cockroaches can be trained to keep their metathoracic leg out of a saline solution. Isolated metathoracic ganglia learnt faster than headless animals, which in turn learnt faster than intact animals. Extinction took longer in the isolated ganglion than in the other two preparations. Extinction times increased with increasing dose of orotic acid, a precursor of RNA. Orotic acid did not systematically affect the times for acquisition and reacquisition of the learnt response.     

Some puzzling results on the Poggendorff illusion

Results obtained by Weintraub and Krantz on the Poggendorff illusion were critically evaluated. It was also shown that the assimilation theory of the Poggendorff illusion adequately predicted the form of the function that results from rotating one of the oblique arms.     

Seeing and hearing and space and space and time

A previous experiment had shown spatial location to be judged in terms of the framework provided by the modality in which stimuli were presented. In the present study, digits were either auditorally or visually presented, and in either form the three digits appeared successivly to the left, in the center, and to the right of the S. The digit which occurred temporally in the middle of the sequence was never central from the spatial viewpoint. The S was asked to indicate which digit was the middle one. Ss were blind, deaf, or normal. The deaf and two control groups saw visual displays, and the blind and their controls heard auditory displays. The former groups predominantly chose the spatially middle digit and the latter groups the temporally middle. It was concluded that modality of presentation was the trigger which switched in the coding dimension of time or space.