Influential observations in principal factor analysis

We propose a method for detecting influential observations in iterative principal factor analysis. For this purpose we derive the influence functionsI(x; LL ^T ) andI(x; ) for the common variance matrixT =LL ^T and the unique variance matrix , respectively, in the common factor decomposition =LL ^T + . A numerical example is given for illustration.The authors are grateful to Tomoyuki Tarumi and Atsuhiro Hayashi for their kind permission to use their software Seto/B for drawing Figures 1 and 2 and to anonymous reviewers for comments on the paper.     

Female physical attractiveness in Britain and Malaysia: a cross-cultural study

Two purported cues to perceived female physical attractiveness are body mass index (BMI) and body shape as measured by the waist-to-hip ratio (WHR). This study examined the relative contribution of both cues in several culturally socio-economically distinct populations. Six hundred and eighty-two participants from Britain and Malaysia were asked to rate a set of images of real women with known BMI and WHR. The results showed that BMI is the primary determinant of female physical attractiveness, whereas WHR failed to emerge as a significant predictor. The results also showed that there were significant differences in preferences for physical attractiveness along a gradient of socio-economic development, with urban participants preferring images of women with significantly lower BMIs than their rural counterparts. The findings are discussed in terms of evolutionary psychological explanations of mate selection, and sociocultural theory, which emphasises the learning of preferences for body sizes in social and cultural contexts.     

Living with Contradictions: The Taken-for-Granted in Israeli Political Discourse

Two apparently contradictory ideas are closely linked in Israeli political discourse: Israel is powerful and independent and Israel is vulnerable and dependent. This study used content analysis and focus groups, as well as existing survey data analyzed by others, to explore how this paradox has been reflected in newspapers and conversations during six different time periods from 1948 to 1996. The goal was not to explain the paradox but to examine its consequences for Israeli perceptions of U.S. policy in the Middle East—and, in the process, to explore Israeli self-images. The nature of U.S. strategic interests was originally treated as problematic and in need of political discussion, but in the past 25 years these interests have become taken for granted. Surprisingly, even after the end of the Cold War, a critical discourse moment in which a reexamination of U.S. interests in the Middle East would seem inevitable, the U.S. role remains taken for granted and largely unexamined. The strong/vulnerable paradox explains this absence of discussion: Examining U.S. interests too closely upsets the delicate balance that keeps the sense of vulnerability in check.     

The Protestant Reformation and Catholic Publishing: A Framework for Contemporary Understanding

Drawing from the perspective of an interdisciplinary exploration of the sociocultural impact of the printing press and its effects on Catholic thinkers, educators, and worship practices, the author of this article explores the educational mission of Catholic publishing during the Reformation and how it has evolved in modern times. First, the author discusses the communication dynamics of the Reformation and specifically the impact of the printing press. Second, the author explores the historical reasons for why the Roman Church perceived the need for uniformity in worship. Third, the author focuses on how the Roman Church built upon this framework of uniformity to define and shape the issues that were being discussed when expanding their outreach to the public during this period. Fourth, the author shows how Catholic worship and education evolved within an interpretation that is relevant to the educational mission of Catholic publishers today.     

Influence of Destabilization on the Temporal Characteristics of “Volitional” Stepping

Previous work suggests that there may be fundamental differences between compensatory stepping responses evoked by postural perturbation and visually cued “volitional” stepping (e.g., gait initiation). In contrast to visual cueing, postural destabilization evokes an array of sensory inputs that are intrinsically linked to the mobilization of rapid compensatory responses. The hypothesis examined in this study was that this fundamental difference would lead to distinct changes in the temporal characteristics of the stepping response. Six healthy young adults were instructed to step quickly in response to either visual cueing or anterioposterior platform motion. Both forward and backward stepping responses were characterized, using measures of vertical ground reaction force. A stereotypical temporal patterning of the stepping response occurred in both stimulus conditions and both directions of stepping, and anticipatory postural adjustments were evident in all trials. However, postural destabilization led to a more rapid initiation and execution of the temporal pattern, in comparison with visually cued responses. The most pronounced effect was seen in the duration of the response, which was reduced by a factor of two, with approximately proportional foreshortening of both the preparatory and swing phases. The results suggest that sensory information conveying a state of instability has a distinct influence on the characteristics of a subsequent stepping reaction. The persistence of the anticipatory postural adjustments suggests that the failure to see this element of the response in previous studies may reflect fundamental differences between volitional and unplanned compensatory stepping.     

Oscillations in Motor Priming: Positive Rebound Follows the Inhibitory Phase in the Masked Prime Paradigm

From among the diverse meanings of stability, the one the author adopts here is that the effects of a perturbation are opposed, and therefore small effects remain small. Except in linear systems, however, instability need not lead to unbounded motion and may actually be desirable when maneuverability is important. Moreover, properties of nerves, muscles, and tendons present serious challenges to stabilization. A review of observations from the motor control literature reveals that responses to perturbations in many common situations assist rather than resist the perturbation and are therefore presumably destabilizing. The observations encompass situations of position maintenance as well as impending or ongoing movement. The author proposes that the motor control system responds to a sudden perturbation by a pattern of muscle activity that mimics an accustomed voluntary movement, oblivious of stability considerations. What prevents runaway motion in the face of short-term instability appears to be voluntary intervention.     

Mass Perturbation of a Body Segment: 2. Effects on Interlimb Coordination

The shifts in relative phase that are observed when rhythmically coordinated limbs are submitted to asymmetric mass perturbations have typically been attributed to the induced eigenfrequency difference ($DL$oM) between the limbs. Modeling the moving limbs as forced linear oscillators, however, reveals that asymmetric mass perturbations may induce a difference not only in eigenfrequency (i.e., $DL$oM $$ 0) but also in the covarying low-frequency control gains (i.e., $DLk $$ 0). Because the inverse of the lowfrequency control gain (k) reflects the level of muscular torque (input) required for a particular displacement from equilibrium (output), asymmetric mass perturbations may result in an imbalance in the muscular torques required for task performance (related to $DLk $$ 0). Thus, it is possible that the effects attributed to $DL$oM were in fact mediated by $DLk. In 2 experiments, the authors manipulated $DLk and $DL$oM separately by applying mass perturbations to the lower legs of 9 participants. The relative phasing between the legs was not affected by $DLk, but manipulation of $DL$oM (while $DLk remained approximately 0) induced systematic relative phase shifts that were more pronounced for antiphase than for in-phase coordination. That indication that the coordination dynamics is indeed influenced by an imbalance in eigenfrequency is discussed vis-à-vis the question of how such a merely peripheral property may affect the underlying coordination process.     

Age-Related Changes in Distance From Center of Mass to Center of Pressure During One-Leg Standing

ABSTRACT. The purpose of this study was to clarify the age-related effects of distances from the center of pressure (COP) to the center of mass (COM) (COP-COM distances) during one-leg standing (OLS) task. Healthy old and young adults (n = 11 each) participated in this study. The authors divided the task into 3 phases (accelerated, decelerated, and steady) based on the relationship between COM and COP. COP-COM distances in the older group were significantly reduced during the accelerated phase, then significantly increased during the decelerated and steady phases. Furthermore, distances during these phases correlated inversely with OLS time. The authors conclude that OLS time is shortened by the larger braking response to COM shifts just after leg-lifting, and the production of larger inertial forces to maintain COM position during the OLS in older individuals.     

Age and Cognitive Stress Influences Motor Skill Acquisition,Consolidation, and Dual-Task Effect in Humans

This study examined motor skill learning using a weight-bearing and cognitive-motor dual-task that incorporated unexpected perturbations and measurements of cognitive function. Forty young and 24 older adults performed a single-limb weight bearing task with novel speed, resistance, and cognitive dual task conditions to assess motor skill acquisition, retention and transfer. Subjects performed a cognitive dual task: summing letters in one color/orientation (simple) or two colors/orientations (complex). Increased cognitive load diminished the rate of skill acquisition, decreased transfer to new conditions, and increased error rate during an unexpected perturbation; however, young adults had a dual-task benefit from cognitive load. Executive function predicted 80% of the variability in dual-task performance. Although initial learning of a weight-bearing cognitive-motor dual-task was poor, longer term goals of improved dual-task effect and retention emerged.     

The Relationships Among Sensory Processing Styles,Personality Traits,and Body Mass Index: A Pilot Study

The purpose of the authors in this study is to explore the possible relationships among sensory processing styles, possible sensory processing disorders, personality traits, and body mass index. There is research on the relationship between obesity as defined by body mass index and temperament, and sensory processing and temperament; however, no information could be found on the relationship between body mass index and sensory processing styles, or the role that temperament and personality styles may play in these relationships. The 50 female participants were recruited from the University of New England community. The sample included women between the ages of 19 and 59 years, and of various weights. None of the participants had a history of thyroid problems, diabetes, or any physical disabilities that would limit daily physical activity. None had been diagnosed with sensory processing disorder. All participants filled out two self-reports and a demographic questionnaire. The Adult/Adolescent Sensory Profile (Brown &; Dunn, 2002 Brown , C. E. , &; Dunn , W. ( 2002 ). Adult/Adolescent Sensory Profile . San Antonio , TX : The Psychological Corporation . [Google Scholar]) determines a person's sensory processing style and possible sensory processing disorder, and the Basic Personality Inventory (Jackson, 1996 Jackson , D. N. ( 1996 ). Basic Personality Inventory Manual , (2nd ed.) . Port Huron , MI : Sigma Assessment  [Google Scholar]) focuses on everyday behaviors to describe temperament and “adult behavioral syndromes” (p. 5). Through this study the authors show only tentative relationships between body mass index and sensory processing styles and personality traits. The data could be interpreted to support both discriminant and convergent validity between the Adult/Adolescent Sensory Profile and the Basic Personality Inventory. There were, however, significant correlations between aspects of sensory processing and aspects of personality that appeared to strengthen the idea that differences in sensory processing result in predictable types of behavior, indicating that sensory processing disorders are a separate diagnostic category.