Retrieving relevant factors with exploratory SEM and principal-covariate regression: A comparison

Behavioral researchers often linearly regress a criterion on multiple predictors, aiming to gain insight into the relations between the criterion and predictors. Obtaining this insight from the ordinary least squares (OLS) regression solution may be troublesome, because OLS regression weights show only the effect of a predictor on top of the effects of other predictors. Moreover, when the number of predictors grows larger, it becomes likely that the predictors will be highly collinear, which makes the regression weights’ estimates unstable (i.e., the “bouncing beta” problem). Among other procedures, dimension-reduction-based methods have been proposed for dealing with these problems. These methods yield insight into the data by reducing the predictors to a smaller number of summarizing variables and regressing the criterion on these summarizing variables. Two promising methods are principal-covariate regression (PCovR) and exploratory structural equation modeling (ESEM). Both simultaneously optimize reduction and prediction, but they are based on different frameworks. The resulting solutions have not yet been compared; it is thus unclear what the strengths and weaknesses are of both methods. In this article, we focus on the extents to which PCovR and ESEM are able to extract the factors that truly underlie the predictor scores and can predict a single criterion. The results of two simulation studies showed that for a typical behavioral dataset, ESEM (using the BIC for model selection) in this regard is successful more often than PCovR. Yet, in 93% of the datasets PCovR performed equally well, and in the case of 48 predictors, 100 observations, and large differences in the strengths of the factors, PCovR even outperformed ESEM.     

Post-conflict slowing: cognitive adaptation after conflict processing

The aftereffects of error and conflict (i.e., stimulus or response incongruency) have been extensively studied in the cognitive control literature. Each has been characterized by its own behavioral signature on the following trial. Conflict leads to a reduced congruency effect (Gratton effect), whereas an error leads to increased response time (post-error slowing). The reason for this dissociation has remained unclear. Here, we show that post-conflict slowing is not typically observed because it is masked by the processing of the irrelevant stimulus dimension. We demonstrate that post-conflict slowing does occur when tested in pure trials where helpful or detrimental impacts from irrelevant stimulus dimensions are removed (i.e., univalent stimuli).     

The Concept Shifting Test: adult normative data

The Concept Shifting Test (CST) is a newly developed Trail Making Type test that measures concept shifting and executive functioning. The purpose of the present study was to determine whether CST performance was affected by age, gender, educational level, or handedness and to establish the normal range of test performance. The CST was administered to a large sample (N = 1,794) of cognitively intact adults (age range 24 to 81 years). The results showed that CST performance was superior in women, decreased with age, and increased with level of education. Handedness did not affect CST performance. Normative data that are corrected for the influences of these demographical variables were established with a regression-based normative approach.     

Top-down and bottom-up sequential modulations of congruency effects

Several studies have demonstrated reduced congruency effects after incongruent trials. The conflict monitoring hypothesis (Botvinick, Braver, Barch, Carter, & Cohen, 2001) assumes that this sequential modulation is based on top-down cognitive control and suggests that more control is engaged after the detection of conflict. An alternative account is based on repetition effects of stimulus and response features and can be considered bottom up. This study investigates both modulatory sources. In a Stroop task with two response-stimulus intervals (RSIs), we demonstrate that top-down modulation does not occur with a very short RSI, suggesting that it takes some time before the system can be reconfigured. Bottom-up modulation is observed for both RSIs. This finding demonstrates that two different sources simultaneously reduce congruency effects after incongruent trials.     

Stimulus conflict predicts conflict adaptation in a numerical flanker task

Conflict monitoring theory states that response conflict triggers conflict adaptation, resulting in reduced congruency effects after response-incongruent trials (Botvinick, Braver, Barch, Carter, & Cohen, 2001). Verbruggen, Notebaert, Liefooghe, and Vandierendonck (2006) observed conflict adaptation after stimulus-incongruent trials without any response conflict. In this study, we further explore the hypothesis that stimulus conflict is an important trigger for conflict adaptation. We propose a measure for stimulus conflict that adequately explains the data of Verbruggen et al. and new data from a numerical flanker task. We conclude that stimulus conflict and response conflict have dissociable effects on behavior Whereas response conflict is a good predictor of response times, stimulus conflict is a better predictor of the adaptation effect.     

Stimulus- and response-conflict-induced cognitive control in the flanker task

Recently, several studies have been conducted to investigate the top-down adjustments made after incongruent trials during conflict tasks. In the present study, we investigated conflict monitoring with different types of conflict. In a modified version of the flanker task, a distinction was made between stimulus—stimulus conflict and stimulus—response conflict. Six colors were mapped to three responses in order to exclude all sequences in which a relevant or an irrelevant stimulus- or response-related feature was repeated from trialn−1 to trialn. An analysis of the effect of the congruency of the previous trial demonstrated that conflict adaptation was present. The stimulus congruency effect was reduced after both a stimulus-incongruent trial and a response-incongruent trial. The response congruency effect did not vary as a function of previous congruency. These findings are discussed in relation to the distinction between conflict detection and conflict regulation.     

The Stroop color-word test: influence of age, sex, and education; and normative data for a large sample across the adult age range

The Stroop Color-Word Test was administered to 1,856 cognitively screened, healthy Dutch speaking participants aged 24 to 81 years. The effects of age, gender, and education on Stroop test performance were investigated to adequately stratify the normative data. The results showed that especially the speed-dependent Stroop scores (time to complete a subtest), rather than the accuracy measures (the errors made per Stroop sub-task), were profoundly affected by the demographic variables. In addition to the main effects of the demographic variables, an Age Low Level of Education interaction was found for the Error III and the Stroop Interference scores. This suggests that executive function, as measured by the Stroop test, declines with age and that the decline is more pronounced in people with a low level of education. This is consistent with the reserve hypothesis of brain aging (i.e., that education generates reserve capacity against the damaging effects of aging on brain functions). Normative Stroop data were established using both a regression-based and traditional approach, and the appropriateness of both methods for generating normative data is discussed.     

Measuring health-related stigma--a literature review

Stigma related to chronic health conditions such as HIV/AIDS, leprosy, tuberculosis, mental illness and epilepsy is a global phenomenon with a severe impact on individuals and their families, and on the effectiveness of public health programmes. To compare stigma measurement in different disciplines, a literature review was conducted. References were obtained through a search of literature databases and through examining relevant bibliographies. Sixty-three papers were selected that addressed the issue of measurement of stigma or related constructs and that contained a sample of the instrument or items used. Five unpublished studies were also included in the review. The aspects of health-related stigma used for assessment can be grouped in five categories. First, the experience of actual discrimination and/or participation restrictions on the part of the person affected; second, attitudes towards the people affected; third, perceived or felt stigma; fourth, self or internalized stigma; and fifth, discriminatory and stigmatizing practices in (health) services, legislation, media and educational materials. Within each of these areas, different research methods have been used, including questionnaires, qualitative methods, indicators and scales. The characteristics of the instruments considered most promising are described and compared. The purpose of stigma assessment is to increase our understanding of stigma and its determinants and dynamics, to determine its extent or severity in a given setting or target group and to monitor changes in stigma over time. The conclusions from this review are that (a) the consequences of stigma are remarkably similar in different health conditions, cultures and public health programmes; (b) many instruments have been developed to assess the intensity and qualities of stigma, but often these have been condition-specific; and (c) development of generic instruments to assess health-related stigma may be possible. To achieve this aim, existing instruments should be further validated, developed or adapted for generic use, where possible.     

Personality, identity styles, and religiosity: an integrative study among late adolescents in Flanders (Belgium)

The relationship between the two main dimensions of the religiosity domain (Exclusion vs. Inclusion of Transcendence and Literal vs. Symbolic) and both the Five-Factor Model of personality and Berzonsky's (1990) identity styles was investigated in a Flemish sample of late adolescents (N = 335). The results show that, whereas Exclusion vs. Inclusion is unrelated to any of the personality dimensions, Literal vs. Symbolic was strongly related to Openness to Experience and moderately to Agreeableness. Further, it was shown that Exclusion vs. Inclusion was positively related to the normative identity style, and that Literal vs. Symbolic correlated positively with the informational identity style and negatively with the diffuse/avoidant identity style. As expected, the relation between Openness to Experience and Literal vs. Symbolic was fully mediated by the informational identity style. Once Openness to Experience was taken into account, Agreeableness was no longer an important determinant of Literal vs. Symbolic.     

Unconscious primes activate motor codes through semantics

Today, it is generally accepted that unconscious stimuli can activate a response code, which leads to a response congruency effect (RCE) on a subsequent target. However, it is not yet clear whether this is due to the semantic processing of the primes or to the formation of direct stimulus-response (S-R) associations bypassing the semantic system. Recently, it was shown that even novel primes, for which no direct S-R links exist, can also evoke an RCE that is in line with the activation of response codes through semantics. In these experiments, the authors examined 3 alternatives for this RCE from novel primes and report a novel effect in unconscious priming. First, the authors show that this effect is not limited to a small set of numerical stimuli but also extends to letter stimuli (Experiments 1-3). Second, the authors show that the RCE is not a side effect of the prime-target distance effect, as has been reported before (Experiments 1-2). Third, the authors found that, for RCE to occur, overlap at the motor level but not at the semantic level was crucial (Experiments 2-3). Finally, in addition, the results showed a category match priming effect independent of RCE. This last result is evidence that novel unconscious primes activate their semantic category prior to the target and might be considered a good marker for semantic processing.