Conditions Of Low Probability Research Articles

Spatial enhancement due to statistical learning tracks the estimated spatial probability.

It is well known that attentional selection is sensitive to the regularities presented in the display. In the current study we employed the additional singleton paradigm and systematically manipulated the probability that the target would be presented in one particular location within the display (probabilities of 30%, 40%, 50%, 60%, 70%, 80%, and 90%). The results showed the higher the target probability, the larger the performance benefit for high- relative to low-probability locations both when a distractor was present and when it was absent. We also showed that when the difference between high- and low-probability conditions was relatively small (30%) participants were not able to learn the contingencies. The distractor presented at a high-probability target location caused more interference than when presented at a low-probability target location. Overall, the results suggest that attentional biases are optimized to the regularities presented in the display tracking the experienced probabilities of the locations that were most likely to contain a target. We argue that this effect is not strategic in nature nor the result of repetition priming. Instead, we assume that through statistical learning the weights within the spatial priority map are adjusted optimally, generating the efficient selection priorities.

Distractor suppression leads to reduced flanker interference

Recent studies using the additional singleton paradigm have shown that regularities in distractor locations can cause biases in the spatial priority map, such that attentional capture by salient singletons is reduced for locations that are likely to contain distractors. It has been suggested that this type of suppression is proactive (i.e., occurring before display onset). The current study replicated the original findings using an online version of the task. To further assess the suppression of high-probability locations, we employed a congruence manipulation similar to the traditional flanker effect, where distractors could be either congruent or incongruent with the response to the target. Experiment 1 shows that through statistical learning distractor suppression reduces the interference from incongruent distractors, as participants made less errors in high-probability versus low-probability conditions. In Experiment 2, participants were forced to search for a specific target feature (the so-called feature-search mode), which is assumed to allow participants to ignore distractors in a top-down manner. Yet even when this “top-down” search mode was employed, there was still a congruence effect when the distractor singleton was presented at the low-probability but not at the high-probability location. The absence, but not reversal, of a congruence effect at the high-probability location also further indicates that this distractor suppression mechanism is proactive. The results indicate that regardless of the search mode used, there is suppression of the high-probability location indicating that this location competes less for attention within the spatial priority map than all other locations.

Strategic inhibition of distractors with visual working memory contents after involuntary attention capture

Previous research has suggested that visual working memory (VWM) contents had a guiding effect on selective attention, and once participants realized that the distractors shared the same information with VWM contents in the search task, they would strategically inhibit the potential distractors with VWM contents. However, previous behavioral studies could not reveal the way how distractors with VWM contents are inhibited strategically. By employing the eye-tracking technique and a dual-task paradigm, we manipulated the probability of memory items occurring as distractors to explore this issue. Consistent with previous behavioral studies, the results showed that the inhibitory effect occurred only in the high-probability condition, while the guiding effect emerged in the low-probability condition. More importantly, the eye-movement results indicated that in the high-probability condition, once few (even one) distractors with VWM contents were captured at first, all the remaining distractors with VWM contents would be rejected as a whole. However, in the low-probability condition, attention could be captured by the majority of distractors with VWM contents. These results suggested that the guiding effect of VWM contents on attention is involuntary in the early stage of visual search. After the completion of this involuntary stage, the guiding effect of task-irrelevant VWM contents on attention could be strategically controlled.

Effect of 3,4-diaminopyridine at the murine neuromuscular junction.

We investigated the effects of 3,4-diaminopyridine (3,4-DAP) and its acetylated metabolite, N-(4-amino-pyridin-3-yl) acetamide (3-Ac), at the mammalian neuromuscular junction. Quantal release of acetylcholine was studied in diaphragm muscles of mice, using in vitro intracellular microelectrode recordings. Under conditions of low probability of release, 3,4-DAP produced a 1,000% increase in quantal release, but 3-Ac had no effect. Under conditions of normal probability of release, the effect of 3,4-DAP was modest and limited by concurrent depletion of synaptic vesicles, especially with high concentrations of 3,4-DAP and high frequencies of nerve stimulation. These findings predict 3,4-DAP is most effective in conditions with low probability of quantal release, such as Lambert-Eaton myasthenic syndrome. A beneficial effect is also expected in disorders of neuromuscular transmission in which the effect of 3,4-DAP on quantal release is not limited by depletion of synaptic vesicles, such as postsynaptic congenital myasthenic syndromes. Muscle Nerve, 2016 Muscle Nerve 55: 223-231, 2017.

Efficient Estimation of the Probability of Small-Disturbance Instability of Large Uncertain Power Systems

This paper proposes a methodology to efficiently estimate the probability of small-disturbance rotor angle instability of uncertain power systems. Traditional Monte Carlo (MC) approaches are computationally intensive and inefficient, particularly when used to study low probability conditions which result in small disturbance instabilities and develop into serious outage events high impact. The proposed methodology uses importance sampling to focus on conditions which contain the high information content required to make relevant decisions about low probability events. Latin hypercube sampling (LHS) is used to efficiently bound the search space and identify operating conditions leading to a marginally stable or unstable system response. The proposed approach is demonstrated on a model of a multi-area transmission network with a significant capacity of intermittent generation connected through a multi-terminal voltage source converter-based high voltage direct current (VSC-HVDC) grid. It is demonstrated that the methodology yields accurate results with just a small fraction of the sample points required using a conventional numerical MC approach.

Effect of social influence on effort-allocation for monetary rewards.

Though decades of research have shown that people are highly influenced by peers, few studies have directly assessed how the value of social conformity is weighed against other types of costs and benefits. Using an effort-based decision-making paradigm with a novel social influence manipulation, we measured how social influence affected individuals’ decisions to allocate effort for monetary rewards during trials with either high or low probability of receiving a reward. We found that information about the effort-allocation of peers modulated participant choices, specifically during conditions of low probability of obtaining a reward. This suggests that peer influence affects effort-based choices to obtain rewards especially under conditions of risk. This study provides evidence that people value social conformity in addition to other costs and benefits when allocating effort, and suggests that neuroeconomic studies that assess trade-offs between effort and reward should consider social environment as a factor that can influence decision-making.

Receptor-specific modulation of risk-based decision making by nucleus accumbens dopamine.

The nucleus accumbens (NAc) serves as an integral node within cortico-limbic circuitry that regulates various forms of cost-benefit decision making. The dopamine (DA) system has also been implicated in enabling organisms to overcome a variety of costs to obtain more valuable rewards. However, it remains unclear how DA activity within the NAc may regulate decision making involving reward uncertainty. This study investigated the contribution of different DA receptor subtypes in the NAc to risk-based decision making, assessed with a probabilistic discounting task. In well-trained rats, D1 receptor blockade with SCH 23,390 decreased preference for larger, uncertain rewards, which was associated with enhanced negative-feedback sensitivity (ie, an increased tendency to select a smaller/certain option after an unrewarded risky choice). Treatment with a D1 agonist (SKF 81,297) optimized decision making, increasing choice of the risky option when reward probability was high, and decreasing preference under low probability conditions. In stark contrast, neither blockade of NAc D2 receptors with eticlopride, nor stimulation of these receptors with quinpirole or bromocriptine influenced risky choice. In comparison, infusion of the D3-preferring agonist PD 128,907 decreased reward sensitivity and risky choice. Collectively, these results show that mesoaccumbens DA refines risk-reward decision biases via dissociable mechanisms recruiting D1 and D3, but not D2 receptors. D1 receptor activity mitigates the effect of reward omissions on subsequent choices to promote selection of reward options that may have greater long-term utility, whereas excessive D3 receptor activity blunts the impact that larger/uncertain rewards have in promoting riskier choices.

Implicit attentional orienting in a target detection task with central cues

Studies using Posner's spatial cueing paradigm have demonstrated that participants can allocate their attention to specific target locations based on the predictiveness of preceding cues. Four experiments were conducted to investigate attentional orienting processes operating in a high probability condition (cues 75% predictive) as compared to a low probability condition (cues 50% predictive) using various types of centrally-presented cues. Spatially-informative cues (arrows and circles with gaps) resulted in cueing effects (CEs) for both probability conditions, with significantly larger CEs in the high probability conditions than the low probability conditions. Participants in the high probability conditions reported little or no awareness of cue-target probabilities after task completion. Our results provide support for an implicit learning account of the proportion valid effect under experimental conditions involving spatially-informative central cues and relatively short stimulus onset asynchronies (SOAs).

Usage of statistical cues for word boundary in reading Chinese sentences

The present study examined the use of statistical cues for word boundaries during Chinese reading. Participants were instructed to read sentences for comprehension with their eye movements being recorded. A two-character target word was embedded in each sentence. The contrast between the probabilities of the ending character (C2) of the target word (C12) being used as word beginning and ending in all words containing it was manipulated. In addition, by using the boundary paradigm, parafoveal overlapping ambiguity in the string C123 was manipulated with three types of preview of the character C3, which was a single-character word in the identical condition. During preview, the combination of C23′ was a legal word in the ambiguous condition and was not a word in the control condition. Significant probability and preview effects were observed. In the low-probability condition, inconsistency in the frequent within-word position (word beginning) and the present position (word ending) lengthened gaze durations and increased refixation rate on the target word. Although benefits from the identical previews were apparent, effects of overlapping ambiguity were negligible. The results suggest that the probability of within-word positions had an influence during character-to-word assignment, which was mainly verified during foveal processing. Thus, the overlapping ambiguity between parafoveal words did not interfere with reading. Further investigation is necessary to examine whether current computational models of eye movement control should incorporate statistical cues for word boundaries together with other linguistic factors in their word processing system to account for Chinese reading.

Neural mechanisms for the effect of prior knowledge on audiovisual integration

Converging evidence indicates that prior knowledge plays an important role in multisensory integration. However, the neural mechanisms underlying the processes with which prior knowledge is integrated with current sensory information remains unknown. In this study, we measured event-related potentials (ERPs) while manipulating prior knowledge using a novel visual letter recognition task in which auditory information was always presented simultaneously. The color of the letters was assigned to a particular probability of being associated with audiovisual congruency (e.g., green = high probability (HP) and blue = low probability (LP)). Results demonstrate that this prior began affecting reaction times to the congruent audiovisual stimuli at about the 900th trial. Consequently, the ERP data was analyzed in two phases: the “early phase” (<trial 600) and the “late phase” (>trial 900). The effects of prior knowledge were revealed through difference waveforms generated by subtracting the ERPs for the congruent audiovisual stimuli in the LP condition from those in the HP condition. A frontal-central probability effect (90–120 ms) was observed in the early phase. A right parietal-occipital probability effect (40–96 ms) and a frontal-central probability effect (170–200 ms) were observed in the late phase. The results suggest that during the initial acquisition of the knowledge about the probability of congruency, the brain assigned more attention to audiovisual stimuli for the LP condition. Following the acquisition of this prior knowledge, it was then used during early stages of visual processing and modulated the activity of multisensory cortical areas.

A Roundtable Discussion … Increased Focus on Human Factors Drives Device Safety Improvements

<i>A Roundtable Discussion</i> … Increased Focus on Human Factors Drives Device Safety Improvements

Processing emotional facial expressions influences performance on a Go/NoGo task in pediatric anxiety and depression

This study investigated whether processing emotionally salient information such as emotional facial expressions influences the performance on a cognitive control task in pediatric anxiety and depression. The sample included 68 participants between 8 and 16 years of age selected into three diagnostic groups: Anxiety Disorder (ANX, n = 23), Major Depressive Disorder (MDD, n = 19), and Low-Risk Normal Control (LRNC, n = 26). Participants completed an Emotional Go/NoGo task in which participants must either respond to (Go trials) or not respond to (NoGo trials) specific facial expressions (angry, fearful, sad, happy, neutral). In order to manipulate the level of cognitive control needed to perform the task, the probability of occurrence of the Go trials was varied across 3 probability conditions (low, moderate, high). Analyses showed that the MDD group had significantly faster reaction times to sad face Go trials embedded in neutral face NoGo trials in the moderate probability condition and that the ANX group had significantly slower reaction times to neutral face Go trials embedded in angry face NoGo trials in the low probability condition. These data demonstrate that processing emotional facial expressions influences the performance on a cognitive control task in children and adolescents diagnosed with an anxiety disorder and major depression.

The pre-movement component of motor cortical local field potentials reflects the level of expectancy

Cortical local field potentials (LFPs) are modulated in parallel with single neuron discharge, but the information they carry is often unclear. Multi-electrode recordings of both LFPs and single neuron activities were made in motor cortex as monkeys performed a delayed pointing task in which the probability of the moment of signal occurrence, and thus movement execution, was manipulated. A large positive LFP component (P1) appeared immediately preceding movement onset only under conditions of low probability, that is, when a response signal was weakly expected. The amplitude of P1 was much smaller when probability of signal occurrence was high, or when the same movement was self-paced. Although P1 has been described as being linked to the descending motor signal, we found that it was more closely associated with the processing of movement-related information than with the ultimate motor command. Its timing did not bear a fixed relationship with movement onset and its frequency of occurrence in each monkey varied in parallel with each animal's overall performance and the percentage of context-related “pre-processing” neurons encountered.

Getting ready for the bad times: self‐esteem and anticipatory coping

AbstractWhen we cannot alter the characteristics of an aversive event, we are still able to prepare ourselves for what is to come. In other words, we can engage in ‘anticipatory coping.’ Known self‐esteem differences in self‐regulation led to the prediction that low self‐esteem (LSE) individuals would evidence different anticipatory coping patterns than high self‐esteem (HSE) people. HSE and LSE participants were faced with either a low or high probability of engaging in a painful task. They were told about, and given the opportunity to engage in, a preparatory strategy aimed at minimizing discomfort during the painful task. Those participants in the low probability condition prepared for the painful task less than did those participants in the high probability condition. As hypothesized, the effect of probability condition was more pronounced for HSE, compared to LSE, participants. Also, in the low probability condition, there was a trend towards LSE participants preparing more than HSE participants. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Interactive effects of difficulty and instrumentality of avoidant behavior on cardiovascular reactivity.

College-aged subjects performed 35 trials of an easy or difficult digit-recognition task. Half were told that a good performance would ensure a high chance of avoiding a blast of noise, and half were told that a good performance would ensure a low chance of avoiding the noise. Results indicated that heart rate and systolic blood pressure reactivity were higher in the difficult condition than in the easy condition only when the probability of avoiding the noise (given success) was high. When the probability of avoiding the noise (given success) was low, heart rate and systolic responsivity were low regardless of task difficulty. It also was found that (1) performance quality was poorer overall among difficult subjects than among easy subjects, and (2) that the difference in performance quality between the easy and difficult groups was somewhat (not significantly) greater in the low-probability conditions than in the high-probability conditions. Major findings are considered in terms of Obrist's reasoning regarding the psychophysiological consequences of active coping and a motivational model by Brehm, which specifies conditions under which individuals will be more and less task engaged.

Coalition Formation in the Competition for Power Precedence

The present study was intended to investigate the characteristics of coalition formation processes in the competition for power precedence, focusing on the phase where motivation to defend status was dominant. Subjects, 90 male undergraduates, were divided into 30 groups of three persons each and were assigned to each rank order of power such as TOP, MIDDLE, and BOTTOM. Then they were confronted with the task to form two person coalition to obtain new resources for promoting their power ranks. Although TOP always preferred BOTTOM as a coalition partner and BOTTOM preferred TOP any time, MIDDLE changed his preferable partner depending on the probability that he could recover in the future if he lose his rank. While high probability motivated MIDDLE strongly to promote his rank and to select BOTTOM as his coalition partner, low probability motivated MIDDLE intensely to defend his status and to make large concessions to TOP to let TOP select him. Consequently, coalitions consisting of TOP and BOTTOM were formed more frequently on high probability condition, but coalitions consisting of TOP and MIDDLE more frequently on low probability condition.

Stress and strain considerations in the design of mechanical components in nuclear power plants

The design of mechanical components in nuclear power plants must consider a series of loading conditions according to legal requirements. The quality of the design must be demonstrated to the authorized expert predominantly with the help of analyses. The basic approach for analyzing mechanical components is discussed, with emphasis on stress and strain limitation, using piping systems other than primary as an example. The KWU concept includes strain limitation for all postulated loading conditions of low probability, beyond stress limitation required for all operational loading conditions. This makes it possible to take a more balanced view of operational and accident loads, to take advantage of ductile material behavior, and to further improve upon piping systems and their supports with respect to operational conditions. Current design methods, including their effect on the required hardware configuration, and the role of strain limitation in the case of accident loads are described.

Determinants of reduction in intended effort as a strategy for coping with anticipated failure

The present study investigated the use of reduction in intended effort as a strategy for protecting self-esteem from the threat of anticipated failure. It was hypothesized that people reduce the amount of effort they intend to exert when they expect a low probability of success on a highly ego-relevant task. Female subjects anticipated taking an easy (high probability of success) or difficult (low probability of success) test that was either high or low in ego relevance. Subjects' levels of intended effort and other task-relevant cognitions were assessed. It was found that subjects in the low-probability condition intended to exert less effort on the highly ego-relevant test than did subjects in the high-probability condition; probability of success had no effect on intended effort level on the low ego-relevance test. Subjects also reported that it was a worse day for a test in the low-probability condition than in the high-probability condition. The relevance of these findings to the egotism explanation of learned helplessness effects and general theories of motivation was discussed.

The late positive component (P3) in auditory evoked potentials: effects of probabilities and numbers of stimulus presentation (author's transl)

Scalp evoked potentials to tone pips were recorded for nine subjects while performing a visual tracking task. The pips, which differed in intensity (40 & 60 dB), were presented as either frequent on infrequent stimuli. These stimuli were randomly presented under three stimulus conditions which were determined in terms of probability (0.10 or 0.40) and number of infrequent stimuli (24 or 96) in one run. It was shown that the amplitude of the P3 wave (around 340 ms latency) in response to the infrequent stimuli was larger for the low probability condition than for the high probability condition, while no effect on the P3 amplitude was found for the numbers of the stimuli.

The effects of probability of test success, test importance, and risk of detection on the incidence of cheating

This study attempts to investigate the incidence of test cheating under various situational conditions. Twenty four fifth and sixth grades (611 pupils) were randomly assigned to treatment conditions formed by all possible combinations of the three variables being studied: high or low probability of test success, high or low risk of detection, and high or low test importance. The highest incidence of cheating occurred in groups under the combination of conditions of low probability of test success, low risk of detection, and high test importance. The results were discussed in terms of the extent of risk (of being caught cheating) vs. the extent of the “payoff” (i.e. avoiding failure) as they each affect test cheating.