Commentary on “Mediation analysis and categorical variables: The final frontier” by Dawn Iacobucci

The commentary discusses several topics in Dr. Iacobucci's article on mediation analysis with categorical variables including the lack of equivalency of mediated effect measures, ab, and c–c′, that are algebraically equivalent in ordinary least squares regression models. The commentary raises the issue of correlated mediation coefficients and presents formulas to include the correlation in the test of significance. References to new developments in causal mediation analysis for categorical variables are given and the importance of programs of research to establish a mediation theory is emphasized.     

Civilian Response Corps Force Review: The Application of Multi‐Criteria Decision Analysis to Prioritize Skills Required for Future Diplomatic Missions

Created by the State Department's Office of the Coordinator for Reconstruction and Stabilization, the Civilian Response Corps (CRC) contains a diverse pool of qualified and ready‐to‐deploy civilian professionals that support conflict prevention and response efforts in countries or regions that are at risk of, are currently in, or are transitioning from conflict or civil strife. As such, it is vital to optimize the CRC's skill groupings to maximize adaptability and responsiveness to highly uncertain and trying political conditions and crises across the globe. The nature of the CRC value proposition is such that determining which skill set compositions deliver the greatest benefit requires a multi‐faceted perspective that looks at a number of attributes and factors, both tangible and intangible. To meet these needs, an organizational decision‐making approach utilizing multi‐criteria decision analysis (MCDA) was applied to ensure that skill‐grouping allocations were determined in a logical and robust manner. The MCDA analysis allowed for a wide range of worldviews and perspectives, drawn from select members of academia and partner agencies of the CRC who provided their expert opinions on the expected demand for skill groupings commonly identified as most necessary in a civilian ‘surge’ capacity. These skills were assessed with reference to a values hierarchy of representative country scenarios, missions and sub‐missions identified by the Office of the Coordinator for Reconstruction and Stabilization. Of particular interest was the use of the MCDA method to prioritize CRC skill groupings and to help inform the Department of State's understanding of the ‘ideal’ proportion and types of civilian skills for inclusion in the CRC. Copyright © 2012 John Wiley & Sons, Ltd.     

The Role of Beliefs in the Relationship Between Health Problems and Posttraumatic Stress in Adolescent and Young Adult Cancer Survivors

In addition to the potential for ongoing health concerns, adolescent and young adult (AYA) childhood cancer survivors frequently report posttraumatic stress symptoms (PTSS). The current study examines whether beliefs about health moderate the relationship between the number of health problems and PTSS 2 months later in 140 survivors. Beliefs, as measured by scales of the Health Competence Beliefs Inventory (HCBI), negatively related to PTSS while health problems positively related to PTSS. Three scales of the HCBI-health perceptions, satisfaction with healthcare and cognitive competence—were significant moderators. The relationship between health problems and PTSS was stronger in the presence of less adaptive beliefs. These beliefs represent potentially malleable intervention targets for reducing PTSS in childhood cancer survivors.     

Adult mice maintained on a high-fat diet exhibit object location memory deficits and reduced hippocampal SIRT1 gene expression

Mounting evidence has established that diet-induced obesity (DIO) is associated with deficits in hippocampus-dependent memory. The bulk of research studies dealing with this topic have utilized rats fed a high-fat diet as an experimental model. To date, there has been a paucity of research studies that have established whether the memory deficits exhibited in DIO rats can be recapitulated in mice. Moreover, the majority of experiments that have evaluated memory performance in rodent models of DIO have utilized memory tests that are essentially aversive in nature (i.e., Morris water maze). The current study sought to fill an empirical void by determining if mice maintained on a high-fat diet exhibit deficits in two non-aversive memory paradigms: novel object recognition (NOR) and object location memory (OLM). Here we report that mice fed a high-fat diet over 23 weeks exhibit intact NOR, albeit a marked impairment in hippocampus-dependent OLM. We also determined the existence of corresponding aberrations in gene expression within the hippocampus of DIO mice. DIO mice exhibited significant reductions in both SIRT1 and PP1 mRNA within the hippocampus. Our data suggest that mice maintained on a high-fat diet present with impaired hippocampus-dependent spatial memory and a corresponding alteration in the expression of genes that have been implicated in memory consolidation.     

Overlapping neural substrates between intentional and incidental down-regulation of negative emotions

Emotion regulation can be achieved in various ways, but few studies have evaluated the extent to which the neurocognitive substrates of these distinct operations overlap. In the study reported here, functional magnetic resonance imaging (fMRI) was used to measure activity in the amygdala and prefrontal cortex of 10 participants who completed two independent tasks of emotion regulation-reappraisal, measuring intentional emotion regulation, and affect labeling, measuring incidental emotion regulation-with the objective of identifying potential overlap in the neural substrates underlying each task. Analyses focused on a priori regions of interest in the amygdala and inferior frontal gyrus (IFG). For both tasks, fMRI showed decreased amygdala activation during emotion regulation compared with emotion conditions. During reappraisal, this decrease in amygdala activation was accompanied by a proportional decrease in emotional intensity ratings; during affect labeling, the decrease in amygdala activation correlated with self-reported aggression. Importantly, across participants, the magnitude of decrease in amygdala activation during reappraisal correlated with the magnitude of decrease during affect labeling, even though the tasks were administered on separate days, and values indexing amygdala activation during each task were extracted independently of one another. In addition, IFG-amygdala connectivity, assessed via psychophysiological interaction analysis, overlapped between tasks in two regions within the right IFG. The results suggest that the two tasks recruit overlapping regions of prefrontal cortex, resulting in similar reductions in amygdala activation, regardless of the strategy employed. Intentional and incidental forms of emotion regulation, despite their phenomenological differences, may therefore converge on a common neurocognitive pathway.     

A COMPARISON OF THE EFFECTS OF BRIEF RULES, A TIMER, AND PREFERRED TOYS ON SELF-CONTROL

Some children make impulsive choices (i.e., choose a small but immediate reinforcer over a large but delayed reinforcer). Previous research has shown that delay fading, providing an alternative activity during the delay, teaching participants to repeat a rule during the delay, combining delay fading with an alternative activity, and combining delay fading with a countdown timer are effective for increasing self‐control (i.e., choosing the large but delayed reinforcer over the small but immediate reinforcer). The purpose of the current study was to compare the effects of various interventions in the absence of delay fading (i.e., providing brief rules, providing a countdown timer during the delay, or providing preferred toys during the delay) on self‐control. Results suggested that providing brief rules or a countdown timer during the delay was ineffective for enhancing self‐control. However, providing preferred toys during the delay effectively enhanced self‐control.     

When local processing increases the appeal of healthy options

People often encounter self-control challenges in complex everyday environments in which objects that promote a given goal (e.g., to eat healthily) are mixed together with objects that obstruct that goal. For example, healthy and unhealthy food choices are often mixed together in restaurant menus. Because local processing facilitates attention to low-level details, we expect that it may play an important role in these complex situations. In the present studies, we test the hypothesis that local processing supports self-control when goal items and temptations are contextually paired. As predicted, our findings revealed that local processing (relative to global processing) increased evaluations of healthy items when those items were presented together with unhealthy items. As hypothesized, this effect of local processing only occurred when healthy and unhealthy foods were presented as complementary – not competing – options, suggesting that local processing may increase evaluations of healthy options by decreasing the extent to which individuals accept environmental cues that healthy and unhealthy foods belong together. These findings support recent research demonstrating that despite strong evidence of the advantages of global processing for self-control, local processing may also support self-control efforts in some important everyday situations.     

Religious Involvement Measurement Model in a National Sample of African Americans

This study examined the factor structure of a brief measure of religious involvement developed previously in research with African American women. Telephone interview methods were used with a national sample of both African American women and men (N = 2,370). Confirmatory factor analyses supported the distinction between religious beliefs and religious behaviors factors and indicated that the factor loadings were equivalent for women and men. Women reported higher levels of religious involvement than men. These results support the validity of this relatively brief instrument for assessing these two dimensions of religious involvement for both African American women and men.     

Locus of Control Beliefs Mediate the Relationship Between Religious Functioning and Psychological Health

Theistic and spiritually based beliefs and behaviors have been demonstrated to consistently predict physical and mental health, although the psychological processes underlying these relationships are unclear. This study investigated associative relationships and pathways of mediation between religious functioning, locus of control (LOC) and health. The sample consisted of 122 Christians (79 women, 43 men) who were predominately Catholic, ranging in age from 18 to 80 (M = 45.47, SD = 15.0). Participants were recruited from churches in the Western suburbs of Melbourne, Australia, and completed a questionnaire package measuring (1) psychological and physical health, (2) the religious variables of awareness of God, instability and impression management, and (3) God, internal and external LOC domains. Results indicated that awareness of God and internal LOC were associated with better health, whereas external LOC and instability were associated with poorer health. God LOC and impression management were not significantly associated with health. Sobel tests were used to analyse mediation hypotheses. Internal LOC was found to mediate the relationship between awareness of God and better psychological health, and external LOC was found to mediate the relationship between instability and poorer psychological health. These findings are of considerable clinical significance.