Minimum rank and minimum trace of covariance matrices

This paper considers some mathematical aspects of minimum trace factor analysis (MTFA). The uniqueness of an optimal point of MTFA is proved and necessary and sufficient conditions for a point x to be optimal are established. Finally, some results about the connection between MTFA and the classical minimum rank factor analysis will be presented.     

The fertility related behavior of Mexican American adolescents

Data from a clinic sample of pregnant adolescents are analyzed for differences in fertility related variables between Mexican American and non Mexican. The independent variables are birthplace, ethnicity, and exposure to United States culture of Mexican and non Mexican adolescents. The dependent variables are talking about sex, pregnancy, birth control, hearing about birth control, and use of birth control. The data support the hypothesis that in the process of acculturation the fertility related behavior of immigrant Mexican adolescent females is affected by the indigenous United States Mexican culture rather than by United States Anglo culture. Implications for delivery of services are discussed. The delivery of fertility related services should take into account the cultural preferences of Mexican women, and should not involve coercion from legal or medical authorities. While liberation of Mexican American women, and accompanying changes in childbearing patterns may be desirable, these efforts should originate within the Mexican American community. Data is presented in tables on selected sample and subsample characteristics and compares fertility behaviors across ethnic groups, including Anglo, Black, US non-Mexican, and US Mexican.     

Validity of Social Behavior Assessment in discriminating emotionally disabled from nonhandicapped students

Discriminant analyses and stepwise multiple regression techniques were applied to teacher ratings of 184 kindergarten through eighth-grade students using Stephen's Social Behavior Assessment (SBA) inventory and were used to predict group membership as emotionalyy disabled (ED) or non-ED. The results suggested that the SBA was highly effective in correctly discriminating ED from non-ED students. The linear discriminant function derived from the 30 SBA subcategories correctly classified 83% of the subjects, yielding a highly significant separation of groups of ED and non-ED children. While the results of the discriminant analyses have not yet been cross-validated, these findings support the discriminant validity of the SBA for ED versus non-ED classification and suggest that the SBA is potentially a useful instrument for school psychologists as one source of information in a multifactored assessment regarding the identification of children as ED.     

Death anxiety, dissent, and competence

A total of 64 male undergraduates were administered a multistage interview which was structured to assess (a) their level of overtly expressed death anxiety, (b) covert (GSR) arousal to death stimuli (c) self-perceived competence, and (d) agreement with or dissent from life threatening national policies. The analyses that followed were concerned with examining the relationships among these variables. In previous studies of this kind it had been typically found that (1) self-perceived competence and magnitude of expressed death concern are inversely related and (2) overt expressions of death concern and covert physiological arousal to death cues are inversely related. Psychodynamic formulations centering on the ego-defensive nature of inhibited expressions of death anxiety have been cited to explain these past data. The current investigation proposed that the magnitude of expressed death concern would bear an inverse relationship to both felt competence and covert death arousal only when the level of overt concern was not contingent upon the individual's attitudes concerning the imminence of real life threatening circumstances in the environment. The rationale behind these predictions inheres in the notion that the neurotic components of strongly expressed death anxiety derive from its lack of anchoring in "real" external threats. Conversely, the expression of low death fear can only be regarded as "defensive" when real threats are perceived and acknowledged. The obtained results strongly support this rationale and the discussion centers on the impact of social conditions on psychodynamic processes.     

The effects of delayed auditory feedback on the overt behaviors of stutterers

This study investigated the differential effect of delayed auditory feedback (DAF) upon general (e.g., repetitions) and specific (e.g., repetitions of initial, medial, and final syllables) overt types of dysfluent behaviors. Ten moderate to severe stutterers performed an oral reading task under both NDAF and DAF (200 msec). DAF resulted in a significant increase in the total number of dysfluencies but had a differential effect upon certain general and specific behaviors. Blocks decreased significantly, prolongations increased significantly, and repetitions and interjections did not change significantly in frequency of occurence. To a limited extent, DAF had a differential effect on specific behaviors. All specific prolongation behaviors increased significantly while only one specific block behavior (ddelays in starting words) decreased. The authors discuss these results in terms of the vocal changes that occurred under DAF and speculate as to their importance in establishing fluency. DAF is viewed as promoting prolongations and prolongations are viewed as inhibiting excessive stoppages of the breathstream, thus promoting fluency (e.g., delays in starting words).     

The hydra-headed Mueller-Lyer effect: A theoretical puzzle

Three experiments were conducted to examine the effects of multiple fins on the magnitude of the Mueller-Lyer illusion. All studies showed that the multiple form of the elongation illusion was greater than the average of the components and that the multiple form of the shrinkage illusion was smaller than either of the components. The pattern of results failed to support either simple addition models or more complex averaging theories of illusions. A cross-attribute summation hypothesis and a filled space hypothesis were proposed as possible explanations for the results.