The Influence of the BDNF Val66Met Polymorphism on Mechanisms of Semantic Priming: Analyses with Drift-Diffusion Models of Masked and Unmasked Priming

Automatic and strategic processes in semantic priming can be investigated with masked and unmasked priming tasks. Unmasked priming is thought to enable strategic processes due to the conscious processing of primes, while masked priming exclusively depends on automatic processes due to the invisibility of the prime. Besides task properties, interindividual differences may alter priming effects. In a recent study, masked and unmasked priming based on mean response time (RT) and error rate (ER) differed as a function of the BDNF Val66Met polymorphism (Sanwald et al., 2020). The BDNF Val66Met polymorphism is related to the integrity of several cognitive executive functions and might thus influence the magnitude of priming. In the present study, we reanalyzed this data with drift-diffusion models. Drift-diffusion models conjointly analyze single trial RT and ER data and serve as a framework to elucidate cognitive processes underlying priming. Masked and unmasked priming effects were observed for the drift rates ν, presumably reflecting semantic preactivation. Priming effects on nondecision time t0 were especially pronounced in unmasked priming, suggesting additional conscious processes to be involved in the t0 modulation. Priming effects on the decision thresholds a may reflect a speed-accuracy tradeoff. Considering the BDNF Val66Met polymorphism, we found lowered drift rates and decision thresholds for Met allele carriers, possibly reflecting a superficial processing style in Met allele carriers. The present study shows that differences in cognitive tasks between genetic groups can be elucidated using drift-diffusion modeling.     

Ethical decision-making models: a review of the literature

A comprehensive review of the literature on ethical decision-making models in counseling is presented, beginning in the fall of 1984 through the summer of 1998. (Materials "in press" were considered.) A general overview of the literature is provided. Theoretically or philosophically based, practice-based, and specialty-relevant approaches are surveyed. The literature is rich with publications describing decision-making models, although few models have been assessed empirically, and few models seem well grounded philosophically or theoretically.     

AIDS and pediatric HIV infection: the problem of the infected mother and her newborn

The number or pediatric AIDS cases in the US was around 2000 in 1990, and children under 13 accounted for about 2% of reported cases. Pediatric cases are increasing as the number of infected women increases. Such cases are concentrated in poor urban populations, aggravating the lack of resources of already overtaxed health services. Ethnic minorities are overrepresented among AIDS cases. In the US, 52% of AIDS cases in adult women are in blacks, 27% in non-Hispanic whites, and 20% in women of Hispanic origin. Among children under 13, 53% are in blacks, 25% in Hispanics, and 22% in whites. The majority of children with AIDS were 5 and were probably infected by vertical transmission. Over 80% were born to mothers with AIDS or at risk of HIV infection, 11% received transfusions of contaminated blood, and 5% received contaminated blood products. Through December 1989, 53% of white, 91% of black, and 85% of Hispanic children with AIDS were infected vertically by their mothers. In the US, over 1/2 of cases of vertical AIDS transmission are due to maternal IV drug abuse and 1/5 to mothers who have sexual relations with IV drug abusers. The rate of infection in children born to seropositive mothers has not been established. Estimates of rates of transmission range from 20% to 50%. The factors causing HIV transmission in 1/3 of infants and protecting the other 2/3 have not been identified. Transmission to the infant may occur during pregnancy or delivery or through breast feeding. There is no evidence that cesarean delivery can protect against infection. The risk of intrauterine infection is probably much greater than that of infection during delivery. Diagnosis of HIV infection in young infants is difficult. There are no physical characteristics distinguishing infected newborns, and laboratory diagnosis is unhelpful because maternal HIV antibodies cross the placental barrier to the fetus. There is as yet no vaccine or curative treatment for HIV infection. Prevention of pediatric HIV infection requires prevention of the infection and the disease in pregnant women. Primary prevention in women depends on their being adequately informed about risks and able to change risk behaviors. Secondary prevention is achieved through use of AZT, which slows the progression of the disease, and prevention or treatment of complications. There is no conclusive evidence as yet that pregnancy hastens the progression of maternal HIV infection. Seropositive mothers should avoid breast feeding if adequate substitute foods are available. The average age at appearance of symptoms in infected children is 8 months. Mortality is higher among children manifesting the disease in the 1st year, with a median survival of 38 months. Full information about HIV infection and voluntary and confidential screening should be available to all women contemplating pregnancy.     

The efficiency of holistic template matching in the recognition of unconstrained handwritten digits

Summary Psychological evidence suggests that simple visual patterns can be recognized by the use of internal representations as holistic templates, but the efficiency of holistic template matching in the recognition of real-life patterns, such as handwritten characters, has been doubted. To clarify this issue, we measured the efficiency of holistic template matching in machine recognition of totally unconstrained handwritten digits. Our learning and recognition algorithm was simple; no previous knowledge of handwritten digits was presupposed, and preprocessing was limited to Gaussian smoothing and normalization with respect to position, size, and orientation. For patterns presented in a known orientation, recognition rates were .69, .77, and .88, respectively, when about 5, 10, or 50 templates had been learned for each type of digit. For patterns presented in unknown orientations, recognition rates were slightly lower. High levels of reliability could be attained by the discounting of classifications based on weak evidence. Apparently, in high reliability recognition, holistic template matching can be used as a first operation by which recognition is achieved for most of the handwritten digits that are seen in real life.     

"Homogeneity" and Constitutional Democracy: Coping with Identity Conflicts through Group Rights

In this article I explore some ancient issues of political theory in the light of some contemporary social and cultural issues. After developing a check list of the virtues and vulnerabilities of constitutional democracy (Section I), I go on to discuss some types and symptoms of difference, conflict, fragmentation and heterogeneity (Section II). I then proceed to a critical review of a particular set of strategies and institutional solutions—political group rights—that are often thought promising devices for strengthening the virtues and overcoming the vulnerabilities of the constitutional democratic form of regime (Section III).
Much of the contemporary philosophical and political discussion of these issues is enchanted by the post-modern spirit of "multiculturalism,""diversity" and "identity." It tends to neglect issues of citizenship and social justice. It also tends to fixate on North American examples, neglecting some of the less benign West European and, in particular, Central East European varieties of identity politics. The discussion here, while mostly raising questions rather than claiming to provide definitive answers, nevertheless tries to overcome some of these biases.     

Taste reactivity and consumption measures in the assessment of overshadowing: Modulation of aversive,but not ingestive,reactivity

Three dependent measures—a taste reactivity test, a two-bottle preference test, and a one-bottle extinction test—were used to investigate the conditioning effects of pairing a taste/taste compound with LiCl-induced illness in rats. Avoidance of saccharin consumption in the one-bottle test was attenuated if saccharin and denatonium were paired during illness training (overshadowing). Also, saccharin was found to be more palatable if paired with denatonium during training as reflected by aversive (but not ingestive) taste reactivity measures. It is argued that overshadowing was reflected mainly by a modulation of aversive taste reactivity behavior with little influence on ingestive taste reactivity. The results are discussed in terms of current palatability issues, and it is suggested that applying taste reactivity tests to phenomena associated with taste avoidance learning (e.g., overshadowing or potentiation) may further our understanding of the mechanisms that guide such learning.     

Color segregation and selective attention in a nonsearch task

Relations between selective attention and perceptual segregation by color were investigated in binary-choice reaction time experiments based on the non search paradigm of Eriksen and Eriksen (1974). In focused attention conditions (Experiment 1), noise letters flanking a central target letter caused less interference when they differed from the target in color, although color carried no information as to whether or not a letter was the target. When blocking of trials favored a strategy of dividing attention between target and noise letters (Experiment 2), no benefit accrued from difference between target color and noise color. The results supported an attentional interpretation of the effect of color demonstrated in Experiment 1, implying that perceptual segregation by color improved the efficiency of focusing attention on the target.     

Visual selection of features and objects: Is location special? A reinterpretation of Nissen’s (1985) findings

Nissen (1985) compared selection by location with selection by color or shape in partial-report experiments. Her analysis of response contingencies when a target was defined in terms of one attribute (location, color, or shape), and when the task was to report the two remaining attributes, suggested a special role for selection by location: It appeared that cross-referencing between color and shape was mediated by location. An alternative interpretation is developed here: The findings are explained by a theory of attention (Bundesen, 1990), in which selection by location is treated on a par with selection by color or shape.     

Quantification and analysis of saccadic and smooth pursuit eye movements and fixations to detect oculomotor deficits

Assessment of deficits in oculomotor function may be useful to detect visuomotor impairments due to a closed head injury. Systematic analysis schemes are needed to reliably quantify oculomotor deficits associated with oculomotor impairment via brain trauma. We propose a systematic, automated analysis scheme using various eye-tracking tasks to assess oculomotor function in a cohort of adolescents with acute concussion symptoms and aged-matched healthy controls. From these data we have evidence that these methods reliably detect oculomotor deficits in the concussed group, including reduced spatial accuracy and diminished tracking performance during visually guided prosaccade and self-paced saccade tasks. The accuracy and tracking deficits are consistent with prior studies on oculomotor function, while introducing novel discriminatory measures relative to fixation assessments – methodologically, a less complicated measure of performance – and thus represent a reliable and simple scheme of detection and analysis of oculomotor deficits associated with brain injury.     

Out with the old? The role of selective attention in retaining targets in partial report

In the partial-report task, subjects are asked to report only a portion of the items presented. Selective attention chooses which objects to represent in short-term memory (STM) on the basis of their relevance. Because STM is limited in capacity, one must sometimes choose which objects are removed from memory in light of new relevant information. We tested the hypothesis that the choices among newly presented information and old information in STM involve the same process—that both are acts of selective attention. We tested this hypothesis using a two-display partial-report procedure. In this procedure, subjects had to select and retain relevant letters (targets) from two sequentially presented displays. If selection in perception and retention in STM are the same process, then irrelevant letters (distractors) in the second display, which demanded attention because of their similarity to the targets, should have decreased target report from the first display. This effect was not obtained in any of four experiments. Thus, choosing objects to keep in STM is not the same process as choosing new objects to bring into STM.