A note on partitioned determinants

A formula for the determinant of a partitioned matrix, possibly with singular submatrices, is derived and applied to some psychometric and numerical problems.     

Generalized eigenvalue problems with positive semi-definite matrices

In a recent paper in this journal McDonald, Torii, and Nishisato show that generalized eigenvalue problems in which both matrices are singular can sometimes be solved by reducing them to similar problems of smaller order. In this paper a more extensive analysis of such problems is used to sharpen and clarify the results of McDonald, Torii, and Nishisato. Possible extensions are also indicated. The relevant mathematical literature is reviewed briefly.     

Associative facilitation of word recognition as measured from a neutral prime

It is shown that lexical decision times to strong associates with an associative strength of approximately 40% are facilitated relative to targets following a neutral prime, “blank,” whereas very weak associates with an associative strength of less then 3% are neither facilitated nor inhibited. It is also shown that relative to the “blank” baseline time, a row of crosses inhibits processing of the following target. The latter finding has implications for earlier studies that have used crosses as a neutral prime. In these studies, facilitation effects have been overestimated and inhibition effects have been underestimated. Neely 1976 has proposed a predict-and-match strategy according to which subjects are assumed to predict one or more targets from the prime and to match the actual target onto the predicted targets. A part of this theory is not supported by the present data. The results are discussed in terms of the two-process theory of expectancy (Posner & Snyder, 1975). They are also considered in the light of a recent theory by Becker (1980). As an alternative interpretation of part of the reported data, a coherence assumption by the subjects about all reading materials is introduced.     

Perceived depth vs. structural relevance in the object-superiority effect

When subjects must identify a barely visible line in a briefly flashed display, their accuracy depends on the configuration of the context in which the target line appears. Weisstein and Harris (1974) found that accuracy is highest when the target is part of a pattern that resembles a unified, three-dimensional object, and lowest in a flat-looking pattern composed of disconnected lines; they labeled this phenomenon the object-superiority effect. In the three experiments reported here, identification accuracy was found to correlate highly and significantly (r =.78) with the judged depth of the patterns. Judged structural relevance of the target line to the pattern (McClelland & Miller, 1979) was uncorrelated with accuracy (r=?.28). Even when the target line appeared as an isolated fragment within the context pattern, a pattern perceived as three-dimensional yielded higher identification accuracy than one perceived as flat.     

Evidence that a factor besides progesterone, prolactin, or plasma-estradiol-binding protein inhibits estrogen-induced sexual receptivity in pregnant rats.

Daily administration of estradiol benzoate stimulated significantly less lordotic behavior in rats during the second half of pregnancy than in ovariectomized females that received subcutaneous progesterone implants, pituitary grafts that raised plasma prolactin, or both treatments combined. Following an initial facilitation of receptivity, females with progesterone implants showed only moderate reductions in lordosis quotients over 3 test days. The capacity of plasma from pregnant rats to bind estradiol was found to increase significantly during the second half of pregnancy. However, daily administration to pregnant rats of a synthetic estrogen, R 2858, which is not bound by plasma protein, was no more effective than estradiol benzoate in stimulating receptive behavior. Administration of estradiol benzoate also stimulated significantly lower levels of sexual behavior in pregnant females than in females in which pseudopregnancy had been prolonged by previous hysterectomy or induction of uterine decidualization. These findings suggest that some endocrine factor other than progesterone, prolactin, or estradiol-binding protein is primarily responsible for the potent suppression of behavioral responsiveness to estrogen which occurs in pregnant rats. It is suggested that 5 alpha-reduced androgens may cause these behavioral effects.     

Facial and vocal cues of deception and honesty

Facial expressions and vocal cues (filtered speech) of honest and deceptive messages were examined in posed and spontaneous situations. The question of interest was the degree to which nonverbal cues transmit information about deception. Results indicated that (a) for both the facial and vocal channels, posing (as compared to spontaneous behavior) produced a higher level of communication accuracy; (b) facial expressions of deceptive (as compared to honest) messages were rated as less pleasant, while vocal expressions of deception were rated as less honest, less assertive, and less dominant, particularly in the posed condition; (c) the sender's ability to convey honesty was negatively correlated with his/her ability to convey deception, suggesting the existence of a demeanor bias—individual senders tend to appear and sound consistently honest (or dishonest) regardless of whether they deliver an honest or a deceptive message; (d) in the posing condition, the sender's abilities to convey honesty/deception via facial and vocal cues were positively and significantly correlated, whereas in the spontaneous condition they were not; and (e) senders whose full (unfiltered) speech indicated more involvement with their responses were judged as more honest from both their vocal (filtered speech) and facial cues, in both the honest and deceptive conditions.     

Demonstration of an aftereffect occurring in the tactile-kinesthetic domain

Summary The aim of this work is the demonstration of a tactile-kinesthetic aftereffect. A sequence of stimuli was offered to adult subjects whose task was to compare two weights presented simultaneously to both hands by means of a Piéron gravimeter. In Experiment 1 the inspection stimuli consisted of two successive presentations of unequal weights for a period of 2 × 10 s. The test stimuli consisted of two equal weights rapidly following an inspection stimulus. Control stimuli consisting of two equal weights not preceded by an inspection stimulus were interspersed in the sequence. The results obtained confirm the existence of a contrast effect after presentation of an inspection stimulus. In Experiment 2 the inspection stimuli consisted of a single presentation of two unequal weights for a period of 20 s. The results confirm those of the first experiment and provide data enabling the contrast effect obtained to be interpreted as a Köhler-type aftereffect. In order to avoid confusion with the kinesthetic-figural aftereffect, we propose to call the effect demonstrated here the Gravimetric Aftereffect.     

TEACHING COIN EQUIVALENCE TO THE MENTALLY RETARDED1

A program was designed to teach coin equivalence to mentally retarded adolescents. Coin equivalence was defined as choosing several different combinations of coins to equal specified target values. A pretest-posttest matched-groups design was employed with an experimental group receiving the monetary training, and a no-training control group. A multiple baseline across coin-counting responses was also incorporated in the experimental group. Training was divided into six stages, each teaching one specific method of combining coins to equal 10 target values from 5¢ through 50¢. A three-component response chain was used, requiring (a) naming, (b) selecting and counting, and (c) depositing target monetary values into a coin machine. Experimental subjects improved significantly in coin equivalence performance and maintained their skill on follow up tests; control subjects did not.     

Correctness of Kruskal's algorithms for monotone regression with ties

Kruskal has proposed two modifications of monotone regression that can be applied if there are ties in nonmetric scaling data. In this note we prove Kruskal's conjecture that his algorithms give the optimal least squares solution of these modified monotone regression problems. We also propose another (third) approach for dealing with ties.Comments by Dr. J. B. Kruskal have been most helpful.     

What do you do after you say hello? Observing,coding, and analyzing parent-infant interactions

Procedures for observing, coding, and analyzing parent-infant interactions are described. Sample data are presented to illustrate the outcome of these procedures and the manner in which developmental issues can be addressed using the hardware and software systems described.