Cohesion as a constraint on object persistence in infancy

A critical challenge for visual perception is to represent objects as the same persisting individuals over time and motion. Across several areas of cognitive science, researchers have identified cohesion as among the most important theoretical principles of object persistence: An object must maintain a single bounded contour over time. Drawing inspiration from recent work in adult visual cognition, the present study tested the power of cohesion as a constraint as it operates early in development. In particular, we tested whether the most minimal cohesion violation - a single object splitting into two - would destroy infants' ability to represent a quantity of objects over occlusion. In a forced-choice crawling paradigm, 10- and 12-month-old infants witnessed crackers being sequentially placed into containers, and typically crawled toward the container with the greater cracker quantity. When one of the crackers was visibly split in half, however, infants failed to represent the relative quantities, despite controls for the overall quantities and the motions involved. This result helps to characterize the fidelity and specificity of cohesion as a fundamental principle of object persistence, suggesting that even the simplest possible cohesion violation can dramatically impair infants' object representations and influence their overt behavior.     

Essential independence and likelihood-based ability estimation for polytomous items

A definition ofessential independence is proposed for sequences of polytomous items. For items satisfying the reasonable assumption that the expected amount of credit awarded increases with examinee ability, we develop a theory ofessential unidimensionality which closely parallels that of Stout. Essentially unidimensional item sequences can be shown to have a unique (up to change-of-scale) dominant underlying trait, which can be consistently estimated by a monotone transformation of the sum of the item scores. In more general polytomous-response latent trait models (with or without ordered responses), anM-estimator based upon maximum likelihood may be shown to be consistent for under essentially unidimensional violations of local independence and a variety of monotonicity/identifiability conditions. A rigorous proof of this fact is given, and the standard error of the estimator is explored. These results suggest that ability estimation methods that rely on the summation form of the log likelihood under local independence should generally be robust under essential independence, but standard errors may vary greatly from what is usually expected, depending on the degree of departure from local independence. An index of departure from local independence is also proposed.This work was supported in part by Office of Naval Research Grant N00014-87-K-0277 and National Science Foundation Grant NSF-DMS-88-02556. The author is grateful to William F. Stout for many helpful comments, and to an anonymous reviewer for raising the questions addressed in section 2. A preliminary version of section 6 appeared in the author's Ph.D. thesis.     

Aging Affects the Ability to Process the Optic Flow Stimulations: A Functional Near-Infrared Spectrometry Study

Abstract

Optic flow (OF) has been utilized to investigate the sensory integration of visual stimuli during postural control. It is little known how the OF speed affects the aging brain during the sensory integration process of postural control. This study was to examine the effect of OF speeds on the brain activation using functional near-infrared spectroscopy (fNIRS) and postural sway between younger and older adults. Eleven healthy younger adults (5M/6F, age 22?±?1-year-old) and ten healthy older adults (4M/6F, age 71?±?5-year-old) participated in this study. A virtual reality headset was used to provide the OF stimulus at different speeds. A forceplate was used to record the center-of-pressure to compute the amplitude of postural sway (peak-to-peak). Compared with younger adults, older adults showed significantly increased activation in the OF speed of 10?m/s and decreased activation in the OF speed of 20?m/s in the left dorsolateral prefrontal cortex. Older adults also showed decreased activation in the left temporoparietal region (VEST) in the OF speed of 20?m/s. A significant difference in peak-to-peak was found between groups. Our results indicated that age might be associated with the ability to process fast OF stimulation.     

Aggressive behavioral characteristics,hormones, and sexual orientation in men and women

Aggressive behavioral characteristics were assessed in groups of men and women by a self-report instrument, the Aggression Inventory, in which adult males reported more physical and verbal aggression than did females. Furthermore, males had higher scores on measures of impulsiveness and lack of frustration tolerance than did females, while women were more likely to avoid confrontation. In a second study, groups of male and female homosexuals and heterosexuals completed this Aggression Inventory after having blood samples taken to assay resting levels of testosterone (T) and estradiol (E). Groups of subjects within each gender were closely matched in terms of age, education, and vocational interests. Women were matched for the same time in their menstrual cycle (early follicular phase). Among men, homosexuals were indistinguishable from heterosexuals on all measures of aggression. Lesbians did not differ from heterosexual women on any aggression subscale except physical aggression, in which the homosexual women had lower scores. T and E were positively correlated with several indices of aggressive behavioral characteristics in men but were negatively correlated with those same measures in women.     

Counterfactual antecedent falsity and the epistemic sensitivity of counterfactuals

Why do utterances of counterfactual conditionals typically, but not universally, convey the message that their antecedents are false? I demonstrate that two common theoretical commitments–commitment to the existence of scalar implicature and of informative presupposition—can be supplemented with an independently motivated theory of the presuppositions of competing conditional alternatives to jointly predict this information when and only when it appears. The view works best if indicative and counterfactual conditionals have a closely related semantics, so I conclude by undermining two familiar arguments for a nonunified semantics of indicative and counterfactual conditionals.     

Self-esteem, performance feedback, and cardiovascular stress reactivity

This study sought to establish the impact of performance-related feedback on cardiovascular responses to stressors, and whether this impact is influenced by individual differences in self-esteem. A total of 66 college women were categorized as either high or low in self-esteem on the basis of their scores in a standardized psychometric test. They then took part in a laboratory experiment, in which they were assigned to one of three performance-feedback manipulations. Following the provision of feedback on an initial laboratory task (picture-matching), they undertook a second task (mental arithmetic). Cardiovascular functioning was monitored throughout. Provision of negative feedback to the initial task exerted an adverse impact on cardiovascular responses, suggestive of unhappiness with performance. Provision of positive feedback to the initial task exerted an impact on cardiovascular functioning during the second task, suggestive of task engagement. Importantly, low self-esteem exacerbated the adverse impact of negative feedback. The impact of feedback and the buffering role of self-esteem may have important consequences for cardiovascular health. Further, discrepancies in the findings of previous feedback research may be accounted for by dispositional individual differences.     

Assessing self-critical perfectionism in clinical depression

Several facets of perfectionism have been strongly associated with depression and anxiety. Dunkley and Blankstein (2000) combined these maladaptive traits with self-criticism to create a general construct labeled self-critical perfectionism. In this study, we employed confirmatory factor analysis to evaluate a model for assessing self-critical perfectionism in a clinically depressed sample using scales from 3 instruments. Participants were 356 depressed adult outpatients who completed 2 multidimensional measures of perfectionism and a measure of self-criticism. A confirmatory factor model that separated a self-critical perfectionism construct from a more adaptive, achievement-striving component of perfectionism was supported. A composite scale assessing self-critical perfectionism demonstrated much larger correlations with distress measures compared to a composite scale assessing achievement striving and also showed evidence of discriminant validity. In this study, we provided further support for the valid assessment of self-critical perfectionism and extended evidence for its assessment to a clinically depressed sample.     

Effects of a Fluency-Building Program on the Reading Performance of Low-Achieving Second and Third Grade Students

This study evaluated the effects of a fluency-based reading program with 15 second and third grade students and 15 matched controls. Gains in oral reading fluency on untrained CBM probes were evaluated using a matched-pairs group-comparison design, whereas immediate and two-day retention gains in oral reading fluency on trained passages were evaluated using an adapted changing criterion design. Increases in WRCM due to training and number of trainings to criterion were also evaluated as a function of pre-training fluency levels. Results showed statistically significant gains on dependent measures for the treatment group, mean increases of two to three grade levels in passages mastered, and an optimal pre-training fluency range of 41-60 WRCM. Implications for fluency-based reading programs are discussed.     

The Clash of Medical Civilizations: Experiencing “Primary Care” in a Neoliberal Culture

An anthropologist describes how he found himself at the vortex of a “clash of medical civilizations:” neoliberalism and the international primary health care movement. His involvement in a $6 million social change initiative in medical education became a basis to unlock the hidden tensions, contradictions and movements within the “primary care” phenomenon. The essay is structured on five ethnographic stories, situated on a continuum from “natural” species-level primary care to “unnatural” neoliberal primary care. Food is an element of all tales. Taking the long view of history/prehistory permits us to better recognize ideological distortions in order to more capably transform medicine.