Nonmetric individual differences multidimensional scaling: An alternating least squares method with optimal scaling features

A new procedure is discussed which fits either the weighted or simple Euclidian model to data that may (a) be defined at either the nominal, ordinal, interval or ratio levels of measurement; (b) have missing observations; (c) be symmetric or asymmetric; (d) be conditional or unconditional; (e) be replicated or unreplicated; and (f) be continuous or discrete. Various special cases of the procedure include the most commonly used individual differences multidimensional scaling models, the familiar nonmetric multidimensional scaling model, and several other previously undiscussed variants.The procedure optimizes the fit of the model directly to the data (not to scalar products determined from the data) by an alternating least squares procedure which is convergent, very quick, and relatively free from local minimum problems.The procedure is evaluated via both Monte Carlo and empirical data. It is found to be robust in the face of measurement error, capable of recovering the true underlying configuration in the Monte Carlo situation, and capable of obtaining structures equivalent to those obtained by other less general procedures in the empirical situation.This project was supported in part by Research Grant No. MH10006 and Research Grant No. MH26504, awarded by the National Institute of Mental Health, DHEW. We wish to thank Robert F. Baker, J. Douglas Carroll, Joseph Kruskal, and Amnon Rapoport for comments on an earlier draft of this paper. Portions of the research reported here were presented to the spring meeting of the Psychometric Society, 1975. ALSCAL, a program to perform the computations discussed in this paper, may be obtained from any of the authors.Jan de Leeuw is currently at Datatheorie, Central Rekeninstituut, Wassenaarseweg 80, Leiden, The Netherlands. Yoshio Takane can be reached at the Department of Psychology, University of Tokyo, Tokyo, Japan.     

Recognition time for information stored in long-term memory

Two experiments were performed to determine the effects of number of words in a target set (varying from 10 to 26) and the nature of distractor words on the latency of both positive and negative recognition responses. Before the test phase, S memorized a list of words and then was tested with a series of single words. To each presentation S made a positive or negative response to indicate whether or not the word was a member of the memorized target list. Response latency was observed to be an increasing function of memory list length. Negative response latency also was greater if distractor words were visually or semantically similar to specific target words. The results were analyzed in terms of a modified signal detection model. It is assumed that S makes a subjective judgment of the familiarity of a test item and on that basis decides either to respond immediately or to delay the response until a search of the memorized list can be executed. Several different models of the search process are considered and evaluated against latency measures and error data.     

Visual acuity improvement following fading and feedback training—II. Relationship to changes in refractive error

The present study evaluated the effects of behavioral training on visual acuity and refractive error in myopic adults. Twenty volunteers were matched on the basis of refractive error and one member of each matched pair was randomly assigned to either Fading and Feedback training or a no-treatment control condition. Visual acuity was measured with both recognition and resolution measures. Refractive error was measured subjectively using the LaserSpec optometer, and objectively by two retinoscopic examinations performed by an ophthalmologist with and without cycloplegia. The results indicated significant increases in recognition visual acuity, but not resolution visual acuity for trained subjects compared to the no-treatment controls. Trained subjects did not show improvement in refractive error on any measure, and refractive error changes were not correlated with changes in either measure of visual acuity. These data suggest that the visual acuity improvements typically found with behavioral training are not associated with changes in refractive error.     

Women's and men's willingness to self-disclose to therapists and friends: The moderating influence of instrumental,expressive, masculine,and feminine topics

The present study used the Masculine and Feminine Self-Disclosure Scale to investigate women's and men's willingness to self-disclose about the instrumental, expressive, masculine, and feminine aspects of themselves to four target persons: female and male therapists and friends. The data revealed that women's and men's willingness to self-disclose to therapists and friends was tempered by the gender of the target person and the particular “masculine” and “feminine” content of the disclosure topic. Men were more willing than women to discuss the global masculine aspects of themselves with a male friend. In contrast, women were more willing than men to discuss (1) their expressive behaviors with both female and male friends and (2) their global feminity with female and male therapists and friends. The discussion emphasizes gender role phenomena as an important dimension of women's and men's willingness to disclose personal information about their masculinity and femininity to therapists and friends.     

Retroactive and proactive interference effects in dual learning of blissymbolics and manual sign

Nonspeech systems can be either aided or unaided. Each system possesses its unique learning and memory characteristics. One instructional strategy designed to give learners the advantages of both systems is dual instruction in aided and unaided communication. One problem with this approach, however, might be that of retroactive and proactive interference in learning and memory. The current experiment investigated whether dual instruction in Blissymbolics and manual (ASL) sign would lead to retroactive and proactive interference. Lists of sign/symbol referents in the two systems were taught, to nonhandicapped adults in a controlled setting. No effects of retroactive or proactive interference were found. Additionally, a proactive facilitation effect was found for immediate retention. Results are discussed in terms of the nature of the task, the learning memory attributes of the nonspeech systems, and the effects of sign/symbol translucency.