Proactive Control of Emotional Distraction: An ERP Investigation

<p>According to the Dual Mechanisms of Control (DMC) framework (Braver, 2012) distraction can be controlled either proactively (i.e., before the onset of a distractor) or reactively (i.e., after the onset of a distractor). Research clearly indicates that, when distractors are emotionally neutral, proactive mechanisms are more effective at controlling distraction than reactive mechanisms. However, whether proactive control mechanisms can control irrelevant emotional distractions as effectively as neutral distraction is not known. In the current thesis I examined cognitive control over emotional distraction. In Experiment 1, I tested whether proactive mechanisms can control emotional distraction as effectively as neutral distraction. Participants completed a distraction task. On each trial, they determined whether a centrally presented target letter (embedded amongst a circle of ‘o’s) was an ‘X’ or an ‘N’, while ignoring peripheral distractors (negative, neutral, or positive images). Distractors were presented on either a low proportion (25%) or a high proportion (75%) of trials, to evoke reactive and proactive cognitive control strategies, respectively. Emotional images (both positive and negative) produced more distraction than neutral images in the low distractor frequency (i.e., reactive control) condition. Critically, emotional distraction was almost abolished in the high distractor frequency condition; emotional images were only slightly more distracting than neutral images, suggesting that proactive mechanisms can control emotional distraction almost as effectively as neutral distraction. In Experiment 2, I replicated and extended Experiment 1. ERPs were recorded while participants completed the distraction task. An early index (the early posterior negativity; EPN) and a late index (the late positive potential; LPP) of emotional processing were examined to investigate the mechanisms by which proactive control minimises emotional distraction. The behavioural results of Experiment 2 replicated Experiment 1, providing further support for the hypothesis that proactive mechanisms can control emotional distractions as effectively as neutral distractions. While proactive control was found to eliminate early emotional processing of positive distractors, it paradoxically did not attenuate late emotional processing of positive distractors. On the other hand, proactive control eliminated late emotional processing of negative distractors. However, the early index of emotional processing was not a reliable index of negative distractor processing under either reactive or proactive conditions. Taken together, my findings show that proactive mechanisms can effectively control emotional distraction, but do not clearly establish the mechanisms by which this occurs.</p>

EEG evidence for the effective proactive control of emotional distraction

<p>Recent behavioural studies using an emotional flanker task have found that task-irrelevent emotional images are more distracting than neutral images under infrequent, but not frequent, distractor conditions.It has been proposed the effective control of distraction in the high distractor frequency condition may be due to a shift to a proactive control strategy, whereby a potential distraction is anticipated and minimised in advance. However, although it is well established that proactive control is effective at reducingneutral distraction, it is not yet clear whether emotional distraction can be effectively proactively controlled. In this thesis, I used EEG to measure pre-stimulus indices of proactive control in order to determine whether proactive control is responsible for the effective control of emotional and neutral distraction in the high distractor frequency condition, as well asto examine whether proactive control differs according whether a neutral or emotional distraction is anticipated.In addition to replicating the previous behavioural findings, posterior EEG alpha was found to be tonically suppressed in the high compared to low distractor frequency condition, strongly supporting the hypothesis that proactive control was engaged in the high distractor frequency condition. By contrast, there was no difference in phasic alpha suppression (i.e., the drop in alpha in response to fixation onset) between conditions, indicating that the more effective control of distraction in the high frequency distractor conditions was due to a sustained proactive control strategy, rather than greater trial-by-trial preparation to attend to the target. In addition, no alpha lateralisation was found, indicating the mechanisms by which distraction was proactively controlled did not include the preparatory suppression of expected distractor locations. Finally, tonic alpha did not differ according to the expected distractor valence, but phasic alpha suppression was more pronounced when negative, compared to neutral or positive, distractors were expected, independent of distractor frequency condition. This suggests proactive control was also used to some extent in the low distractor frequency condition, but more importantly also provides initial evidence that the proactive control of negative distraction may be unique. Taken together, my findings provide compelling evidence that emotional distraction can be effectively proactively controlled. Future research is needed to determine the mechanisms by which this occurs, and whether the proactive control of emotional distraction is particularly effortful.</p>

EEG evidence for the effective proactive control of emotional distraction

<p>Recent behavioural studies using an emotional flanker task have found that task-irrelevent emotional images are more distracting than neutral images under infrequent, but not frequent, distractor conditions.It has been proposed the effective control of distraction in the high distractor frequency condition may be due to a shift to a proactive control strategy, whereby a potential distraction is anticipated and minimised in advance. However, although it is well established that proactive control is effective at reducingneutral distraction, it is not yet clear whether emotional distraction can be effectively proactively controlled. In this thesis, I used EEG to measure pre-stimulus indices of proactive control in order to determine whether proactive control is responsible for the effective control of emotional and neutral distraction in the high distractor frequency condition, as well asto examine whether proactive control differs according whether a neutral or emotional distraction is anticipated.In addition to replicating the previous behavioural findings, posterior EEG alpha was found to be tonically suppressed in the high compared to low distractor frequency condition, strongly supporting the hypothesis that proactive control was engaged in the high distractor frequency condition. By contrast, there was no difference in phasic alpha suppression (i.e., the drop in alpha in response to fixation onset) between conditions, indicating that the more effective control of distraction in the high frequency distractor conditions was due to a sustained proactive control strategy, rather than greater trial-by-trial preparation to attend to the target. In addition, no alpha lateralisation was found, indicating the mechanisms by which distraction was proactively controlled did not include the preparatory suppression of expected distractor locations. Finally, tonic alpha did not differ according to the expected distractor valence, but phasic alpha suppression was more pronounced when negative, compared to neutral or positive, distractors were expected, independent of distractor frequency condition. This suggests proactive control was also used to some extent in the low distractor frequency condition, but more importantly also provides initial evidence that the proactive control of negative distraction may be unique. Taken together, my findings provide compelling evidence that emotional distraction can be effectively proactively controlled. Future research is needed to determine the mechanisms by which this occurs, and whether the proactive control of emotional distraction is particularly effortful.</p>

Proactive Control of Emotional Distraction: An ERP Investigation

<p>According to the Dual Mechanisms of Control (DMC) framework (Braver, 2012) distraction can be controlled either proactively (i.e., before the onset of a distractor) or reactively (i.e., after the onset of a distractor). Research clearly indicates that, when distractors are emotionally neutral, proactive mechanisms are more effective at controlling distraction than reactive mechanisms. However, whether proactive control mechanisms can control irrelevant emotional distractions as effectively as neutral distraction is not known. In the current thesis I examined cognitive control over emotional distraction. In Experiment 1, I tested whether proactive mechanisms can control emotional distraction as effectively as neutral distraction. Participants completed a distraction task. On each trial, they determined whether a centrally presented target letter (embedded amongst a circle of ‘o’s) was an ‘X’ or an ‘N’, while ignoring peripheral distractors (negative, neutral, or positive images). Distractors were presented on either a low proportion (25%) or a high proportion (75%) of trials, to evoke reactive and proactive cognitive control strategies, respectively. Emotional images (both positive and negative) produced more distraction than neutral images in the low distractor frequency (i.e., reactive control) condition. Critically, emotional distraction was almost abolished in the high distractor frequency condition; emotional images were only slightly more distracting than neutral images, suggesting that proactive mechanisms can control emotional distraction almost as effectively as neutral distraction. In Experiment 2, I replicated and extended Experiment 1. ERPs were recorded while participants completed the distraction task. An early index (the early posterior negativity; EPN) and a late index (the late positive potential; LPP) of emotional processing were examined to investigate the mechanisms by which proactive control minimises emotional distraction. The behavioural results of Experiment 2 replicated Experiment 1, providing further support for the hypothesis that proactive mechanisms can control emotional distractions as effectively as neutral distractions. While proactive control was found to eliminate early emotional processing of positive distractors, it paradoxically did not attenuate late emotional processing of positive distractors. On the other hand, proactive control eliminated late emotional processing of negative distractors. However, the early index of emotional processing was not a reliable index of negative distractor processing under either reactive or proactive conditions. Taken together, my findings show that proactive mechanisms can effectively control emotional distraction, but do not clearly establish the mechanisms by which this occurs.</p>

Wear Mechanism of Nomex/PTFE Fiber Reinforced Composites

This paper is aimed at the problems of abnormal tribological damage and fluctuation of tribological performance in the self-lubricating composite serving in heavy load spherical plain bearing in aerospace field. The Nomex/PTFE fiber reinforced composite was used to carry out a reciprocating block on ring tribological test, investigating the tribological performance of the material and its wear evolution. Results show that the influence of oscillating frequency on material wear is obviously higher than that of load under high load condition (more than 90 MPa or 180 kN). Under a certain load and frequency condition, friction temperature is a key factor to affect wear behavior of the material. Friction heat plays a dominant role in the process of worn out failure of the material. Too high friction temperature greatly weakens the friction and wear performance, resulting in material failure in a short time. Thermal fatigue is the main tribological damage mode of the material under the high load and high frequency condition, with local worn out occurred. This finding was also verified by SEM analysis of the worn surface and wear debris.

Breeding behaviour of colour-aberrant Adélie penguins (Pygoscelis adeliae) at Cape Crozier, Ross Island, Antarctica

Plumage colour variation occurs widely among bird species and is often associated with individual fitness. More specifically, colouration can affect thermoregulatory ability, mate selection and conspicuousness during foraging. Colour aberrations can be caused by genetic mutations, dietary imbalances, environmental conditions or disease and are rare. Plumage variations have previously been noted in Adélie penguins, although without any follow-up to measure implications for behaviour or fitness. To assess how this low-frequency condition affects breeding in Adélie penguins, we monitored the breeding of several colour-aberrant Adélie penguins during the 2019–2020 nesting season at the large Cape Crozier, Ross Island colony (> 300,000 pairs). In total, we found 12 individuals with unusual plumage for a frequency of 1:50,000 breeding penguins. There were seven dark brown Adélie penguins, three progressive greying Adélie penguins, one dilute Adélie penguin and one brown Adélie penguin, of which five were female, three male and four of unknown sex. Six colour aberrants initiated breeding with a normal-coloured mate, and five raised at least one chick to crèche. The likelihood of breeding and breeding success of colour aberrants were similar to those of normal-coloured Adélie penguins, suggesting that colour aberrations do not negatively affect breeding.

A New Cycle-Slip Repair Method for Dual-Frequency BDS Against the Disturbances of Severe Ionospheric Variations and Pseudoranges with Large Errors

Many Beidou navigation satellite system (BDS) receivers or boards provide dual-frequency measurements to conduct precise positioning and navigation for low-power consumption. Cycle-slip processing is a primary work to guarantee consistent, precise positioning with the phase data. However, the cycle-slip processing of BDS dual-frequency phases still follows with those of existing GPS methods. For single-satellite data, cycle-slip detection (CSD) with the geometry-free phase (GF) is disturbed by severe ionospheric delay variations, while CSD or cycle-slip repair (CSR) with the Melbourne–Wubbena combination (MW) must face the risk of the tremendous disturbance from large pseudorange errors. To overcome the above limitations, a new cycle-slip repair method for BDS dual-frequency phases (BDCSR) is proposed: (1) An optimal model to minimize the variance of the cycle-slip calculation was established to the dual-frequency BDS, after correcting the ionospheric variation with a reasonable and feasible way. (2) Under the BDS dual-frequency condition, a discrimination function was built to exclude the adverse disturbance from the pseudorange errors on the CSR, according to the rankings of the absolute epoch-difference GFs calculated by the searched cycle-slip candidates after correcting the ionospheric variation. Subsequently, many compared CSR tests were implemented in conditions of low and medium elevations during strong geomagnetic storms. Comparisons from the results of different methods show that: (1) The variations of ionospheric delays are intolerable in the cycle-slip calculation during the geomagnetic storm, and the tremendous influence from the ionospheric variation should be corrected before calculating the cycle-slip combination with the BDS dual-frequency data. (2) Under the condition of real dual-frequency BDS data during the geomagnetic storm, the actual success rate of the conventional dual-frequency CSR (CDCSR) by employing the optimized combinations, but absenting from the discrimination function, is lower than that of BDCSR by about 2%; The actual success rate of the CSD with MW (MWCSD), is lower than that of BDCSR by about 2%. (3) After adding gross errors of 0.7 m to all real epoch-difference pseudoranges epoch-by-epoch, results of CDCSR and MWCSD showed many errors. However, BDCSR achieved a higher actual success rate than those of CDCSR and MWCSD, about 43% and 16%, respectively, and better performance of refraining the disturbance of large pseudorange error on the cycle-slip determination was achieved in the BDCSR methodology.

Manufacture and Properties of Metasequoia-Based Three-Layer Parquet Flooring

Metasequoia-based three-layer parquet flooring (MPF) was prepared under the following conditions: hot-pressing temperature of 95°C, hot-pressing time of 7 minutes, hot-pressing pressure of 9 kg·cm−2, and addition of 200 g·m−2 urea-formaldehyde resin adhesive. The results showed that the moisture content, density, formaldehyde emission, static bending strength, and elastic modulus of the three kinds of parquet flooring were not much different than poplar-based multilayer parquet flooring (PPF) or fir-based three-layer parquet flooring (FPF) on the market. The thermal conductivity of the MPF was 0.195 W·m−1·K−1, which was the lowest among the three kinds of parquet flooring. The sound absorption coefficient of MPF under 11 frequency conditions in the range of 0.2 to 2 kHz was higher than that of PPF and FPF under the same frequency condition. The research results provide a reference value for the efficient use of low-quality M. glyptostroboides wood.

Electrical response of organic molecule supported preformed and in-situ formed antimony sulfide nanoparticles under frequency condition

A complexation route mediated synthesis of orthorhombic antimony sulfide nanoparticles is described in this report where uniformly distributed particles within the size range of 2-12 nm are stabilized within the...