Neural substrates of successful working memory and long-term memory formation in a relational spatial memory task

Working memory (WM) tasks may involve brain activation actually implicated in long-term memory (LTM). In order to disentangle these two memory systems, we employed a combined WM/LTM task, using a spatial relational (object-location) memory paradigm and analyzed which brain areas were associated with successful performance for either task using fMRI. Critically, we corrected for the performance on the respective memory task when analyzing subsequent memory effects. The WM task consisted of a delayed-match-to-sample task assessed in an MRI scanner. Each trial consisted of an indoor or outdoor scene in which the exact configuration of four objects had to be remembered. After a short delay (7–13 s), the scene was presented from a different angle and spatial recognition for two objects was tested. After scanning, participants received an unexpected subsequent recognition memory (LTM) task, where the two previously unprobed objects were tested. Brain activity during encoding, delay phase and probe phase was analyzed based on WM and LTM performance. Results showed that successful WM performance, when corrected for LTM performance, was associated with greater activation in the inferior frontal gyrus and left fusiform gyrus during the early stage of the maintenance phase. A correct decision during the WM probe was accompanied by greater activation in a wide network, including bilateral hippocampus, right superior parietal gyrus and bilateral insula. No voxels exhibited supra-threshold activity during the encoding phase, and we did not find any differential activity for correct versus incorrect trials in the WM task when comparing LTM correct versus LTM incorrect trials.     

Tactile perception of thermal diffusivity

The thermal diffusivity of an object is a parameter that controls the rate at which heat is extracted from the hand when it touches that object. It is an important feature for distinguishing materials by means of touch. In order to quantitatively describe the ability of human observers to discriminate between materials on the basis of heat extraction rate, we conducted an experiment in which this heat extraction was performed in a controlled way. In different conditions, subjects were repeatedly asked to select from two stimuli the one that cooled faster. The discrimination threshold was around 43% of the extraction rate. A rate that was twice as slow also yielded twice the absolute threshold. When we halved the temperature difference between the beginning and end of the stimulus, the threshold did not change as much. In separate experiments, we investigated the different cues that were available in the stimulus: initial cooling rate and end temperature. Both cues were used for discrimination, but cooling rate seemed to be the most important.     

Christian and Political Conservatism Predict Opposition to Sexual and Gender Minority Rights through Support for Christian Hegemony

Although significant strides have been made for sexual and gender minority (SGM) rights in the United States, there continues to be opposition to SGM rights from many conservative Christians and political conservatives. In this study, we investigate this opposition by examining support for Christian hegemony (i.e., the idea that Christianity should be the norm and Christians should be in power in the United States) and unawareness of Christian privilege (i.e., unearned advantages for Christians) as religiopolitical variables that help to explain the association between Christian and political conservatism and opposition to a host of SGM rights (same-sex marriage, same-sex adoption, nondiscrimination policies in jobs and housing for SGMs, and bills regarding transgender public bathroom use). Based on structural equation modeling analysis with heterosexual cisgender Christian (n = 688) and Areligious (n = 327) students, we demonstrate that support for Christian hegemony and unawareness of Christian privilege help to explain the association between Christian and political conservatism and opposition to SGM rights. These findings advance our understanding of a new type of religious-based variable focused on religious power and privilege to help understand conservative religious and political opposition to SGM rights. Limitations, implications, and directions for future research also are discussed.     

Salient material properties and haptic volume perception: The influences of surface texture, thermal conductivity, and compliance

We investigated the influences of surface texture, thermal conductivity, and compliance on the haptic perception of the volume of small cubes. It was hypothesized that an object containing highly salient material properties would be perceived as larger in volume than the same object without these properties. Blindfolded subjects were asked to explore pairs of cubes differing in their material properties and to select the one with the larger volume. The results showed that, counterintuitively, a smooth cube was perceived as being significantly larger than a rough cube of the same physical volume, with average biases of about 19 %. Furthermore, cubes with a higher thermal conductivity were perceived as significantly larger than cubes with a lower thermal conductivity (average bias of about 7 %). In addition, the magnitude of the bias in this condition was not changed by increasing or decreasing the temperature of the test objects, suggesting that the effect of thermal conductivity could not be attributed directly to the heat flow. Finally, a hard cube was perceived as significantly larger than a soft cube of equal physical volume, with an average bias of about 25 %. These results reveal that the studied material properties have significant and consistent influences on the haptic perception of volume. The observed biases provide an indication of the levels at which the processing of haptic information on volume and material properties occurs.     

EEG theta phase coupling during executive control of visual working memory investigated in individuals with schizophrenia and in healthy controls

In healthy humans, it has been shown that executive functions are associated with increased frontal-midline EEG theta activity and theta phase coupling between frontal and posterior brain regions. In individuals with schizophrenia, central executive functions are supposed to be heavily impaired. Given that theta phase coupling is causally involved in central executive functions, one would expect that patients with an executive function deficit should display abnormal EEG theta synchronization. We therefore investigated executive functioning in 21 healthy controls and 21 individuals with schizophrenia while they performed a visuospatial delayed match to sample task. The task required either high executive demands (manipulation of content in working memory [WM]) or low executive demands (retention of WM content). In addition, WM load (one vs. three items) was varied. Results indicated higher frontal theta activity for manipulation processes than for retention processes in patients with schizophrenia, as compared with healthy controls, independently of WM load. Furthermore, individuals with schizophrenia revealed a reduction in theta phase coupling during early stages of the delay period for retention, as well as for manipulation processes at high-WM loads. Deviations in theta phase coupling in individuals with schizophrenia were mainly characterized by aberrant fronto-posterior connections, but also by attenuated posterior connections during manipulation of high-WM load. To conclude, fronto-parietal theta coupling seems to be substantially involved in executive control, whereas frontal theta activity seems to reflect general task demands, such as deployment of attentional resources during WM.     

The combined influence of hardiness and cohesion on mental health in a military peacekeeping mission: A prospective study

A large number of studies have shown that hardiness and cohesion are associated with mental health in a military context. However, most of them are presented without controlling for baseline mental health symptoms, which is their most significant source of error. The present study investigates the combined effect of hardiness and cohesion in a prospective design, controlling for baseline levels of symptoms among Norwegian personnel serving in a peacekeeping operation in Kosovo. Multivariate regression analyses were performed in which self‐reported mental health complaints were regressed on our explanatory variables. Our findings suggest that both cohesion and hardiness contributed to increased stress resiliency, as measured by a lower level of reported mental health complaints. Our baseline measure of mental health accounted for a larger proportion of the variance than our other predictors. A significant interaction between cohesion and hardiness suggested a combined effect, over and above the individual contributions of the predictors. For individuals who scored high on hardiness, cohesion levels did not influence levels of mental health complaints. Individuals who scored low on hardiness, on the other hand, reported lower levels of mental health complaints when cohesion levels were high.     

The effect of hardiness on PTSD symptoms: A prospective mediational approach

Psychological hardiness has been associated with lower PTSD in military personnel, but the processes of action remain unclear. This study uses a prospective design to examine whether hardiness has an indirect effect on PTSD symptoms through avoidance coping. Our sample included 163 Norwegian military personnel who served in international operations between 2009 and 2010. Regression analyses were performed to estimate the coefficients in a simple mediation model, with baseline PTSD symptoms, combat exposure, and deprivation of basic needs entered as control variables. The results showed that the effect of hardiness on PTSD symptoms worked through reducing the use of avoidance coping. It was concluded that an avoidant-focused coping style acts as a vulnerability factor for PTSD symptoms, whereas hardiness acts as a resilience factor against symptoms development.     

Psychological Hardiness Predicts Success in a Norwegian Armed Forces Border Patrol Selection Course

The present study investigates the effects of psychological hardiness and successful completion of a rigorous 250‐km ski march over 9 days in Arctic winter conditions. This ski march is the final portion of a selection program for border rangers in the Norwegian Armed Forces. Study participants were N = 178 soldiers with a mean age of 19.9 years (range 18–23). Hierarchical regression results showed that successful completion of the ski march was predicted by total hardiness scores, after controlling for nutrition factors, physical fitness and sensation seeking. A second hierarchical regression found that the commitment facet of hardiness was the most significant predictor of ski march success, again controlling for nutrition, physical fitness and sensation seeking. Analyses of daily participant surveys showed that the high commitment group reported the highest levels of positive daily coping, and also evaluated their performance more positively. This group also showed increasingly positive self‐evaluations as the exercise went on. Together, these results indicate that hardiness commitment is a key factor influencing performance in a rigorous and stressful endurance task requiring sustained effort, perhaps by enhancing active coping skills and self‐efficacy beliefs.