Reaction Time Cost Research Articles

Subthalamic Nucleus Stimulation Impairs Sequence Processing in Patients with Parkinson's Disease.

Maintaining and manipulating sequences online is essential for language and memory. In Parkinson's disease (PD), poor performance in sequencing tasks has been associated with basal ganglia dysfunction, especially subthalamic hyperactivity. This study is aimed to investigate the impact of high-frequency subthalamic nucleus (STN) deep brain stimulation (DBS) on sequence processing in PD. Twenty-nine patients with PD (17 women) completed a 'before/after' sentence task and a digit ordering task with STN DBS ON and OFF. In the sentence task, patients read a sequence of events expressed in the actual order of occurrence ('after' sentences) or reversed order ('before' sentences) for comprehension. In the digit task, patients recalled a sequence of ordered digits (ordered trials) or reordered and recalled random digits in ascending order (random trials). Volumes of tissue activated (VTAs) were estimated for the motor and associative STN. Patients were slower with STN DBS ON versus OFF in both tasks, although their motor symptoms were significantly improved under DBS. In the sentence task, patients showed higher ordering-related reaction time costs ('before' > 'after') with DBS ON versus OFF. Moreover, patients with larger left associative VTAs, smaller total motor VTAs, and more daily exposure to dopaminergic drugs tended to show larger reaction time cost increases under DBS. In the digit ordering task, patients with too large or too small right associative VTAs tended to show larger reaction time cost increases under DBS. Stimulating the STN, especially its associative part, might impair sequence processing in language and memory.

Regulating mirroring of emotions: A social-specific mechanism?

There is evidence that humans mirror others’ emotional responses: brain responses to observed and experienced emotion overlap, and reaction time costs of observing others’ pain suggest that others’ emotional states interfere with our own. Such emotional mirroring requires regulation to prevent personal distress. However, currently it is unclear whether this “empathic interference effect” is uniquely social, arising only from the observation of human actors, or also from the observation of non-biological objects in “painful” states. Moreover, the degree to which this interference relates to individual differences in self-reported levels of empathy is yet to be revealed. We introduce a modified pain observation task, measuring empathic interference effects induced by observation of painful states applied to both biological and non-biological stimuli. An initial validation study (N = 50) confirmed that painful states applied to biological stimuli were rated explicitly as more painful than non-painful states applied to biological stimuli, and also than both painful and non-painful states applied to non-biological stimuli. Subsequently, across two independent discovery (N = 83) and replication (N = 80) samples, the task elicited slowing of response times during the observation of painful states when compared to non-painful states, but the magnitude of this effect did not differ between biological and non-biological stimuli. Little evidence was found for reliable relationships between empathic interference and self-reported empathy. Caution should therefore be taken in using the current task to pursue an individual differences approach to empathic interference, but the task shows promise for investigating the specificity of the mechanism involved in regulating emotional mirroring.

Prediction of size, precursor ratio and monodispersity of silica nanospheres though adaptive neuro- fuzzy inference system

Highly monodisperse nanostructures are becoming the centre of focus in the field of material science towards the application of sensors, photocatalysis, gas sensing, antibacterial activity, drug delivery and energy applications. Monodisperse resembles uniform nanostructures towards better device performances and applications. In order to minimize the reaction time and characterization costs, an attempt has been made for development of a prediction model for the synthesis of monodisperse silica nanospheres using Adaptive Neuro-Fuzzy Inference System (ANFIS) software. Experimental parameters of the Stober method such as precursor's ratio (ethanol, water and ammonia), Tetraethyl Orthosilicate (TEOS) and sphere size were predicted in the model. The results from the prediction model were used for carrying out experimentation on thin films using vertical deposition technique. The prepared substrates were characterized by FE-SEM & XRD analysis. Obtained Experimental results shows that nanosphere with a size range of 200- 250 nm will form monodisperse layer. XRD analysis confirms the amorphous nature of SiO2 film. ANFIS has predicted best suitable size of silica nanospheres and optimized precursor's ratios for attaining highly monodisperse structure. The optimized parameters predicted from the ANFIS network matches well with the experimental results.

The surprising role of stimulus modality in the dual-task introspective blind spot: a memory account

Being able to accumulate accurate information about one’s own performance is important in everyday contexts, and arguably particularly so in complex multitasking contexts. Thus, the observation of a glaring gap in participants’ introspection regarding their own reaction time costs in a concurrent dual-task context is deserving of closer examination. This so-called introspective blind spot has been explained by a ‘consciousness bottleneck’ which states that while attention is occupied by one task, participants cannot consciously perceive another stimulus presented in that time. In the current study, a series of introspective Psychological Refractory Period (PRP) experiments were conducted to identify the determinants of an introspective blind spot; to our surprise, in half of the experiments participants appeared to be aware of their dual-task costs. A single trial analysis highlighted the sensory modality of the two stimuli within the trial as an important predictor of introspective accuracy, along with temporal gaps in the trial. The current findings call into question the claim that attention is required for conscious awareness. We propose a memory-based account of introspective processes in this context, whereby introspective accuracy is determined by the memory systems involved in encoding and rehearsing memory traces. This model of the conditions required to build up accurate representations of our performance may have far-reaching consequences for monitoring and introspection across a range of tasks.

Paired cognitive flexibility task with symptom factors improves detection of sports-related concussion in high school and collegiate athletes

Determining the sensitivity and specificity of short neurocognitive assessments to objectively detect concussion will help clinicians more confidently integrate such tools in clinical management decisions. This study quantified the sensitivity and specificity of a computerized cognitive flexibility task isolating shifts of visuospatial attention in combination with clinical symptoms acutely (< 72 h) following concussion. A total of 100 athletes (53 concussed; 47 non-injured control; 42% female) completed computerized neurocognitive testing and clinical symptom reports (Sport Concussion Assessment Tool 3rd edition: SCAT3). Separate discriminant function analyses were performed for individual, combination, and stepwise inclusion of neurocognitive and clinical symptomology assessments. Findings revealed the combination of neurocognitive outcomes (i.e., mean reaction time, response accuracy, and response accuracy cost) with clinical symptom factor scores exhibited the greatest sensitivity (95.7%) and specificity (88.7%) as well as the highest positive predictive value (95.9%) and negative predictive value (88%) relative to other approaches. Further, a stepwise approach predicting concussion status using the discriminant functions improved detection of concussion (98.2% sensitivity, 95.7% specificity, 96.4% positive predictive value, and 97.8% negative predictive value) when clinical symptom factors failed to indicate the presence of a concussion. Incorporating a cognitive flexibility task involving shifts of visuospatial attention combined with clinical symptom factor scores may improve clinical decision-making as this approach exceeds the sensitivity and specificity of widely popular neurocognitive test batteries and takes less than 10 min to administer.

Low glycemic CHO ingestion minimizes cognitive function decline during a simulated soccer match

Often cognitive function is affected adversely during prolonged, high intensity exercise. We assessed whether hydrothermally modified corn starch (HMS) ingestion minimizes cognitive decline with soccer play. 11 men (177.7 ± 6.8 cm, 77.3 ± 7.9 kg, 22 ± 3 y, 12.8 ± 4.9% body fat, [Formula: see text]O2max = 57.1 ± 3.9 ml•kg BM−1•min−1; mean ± SD) completed 60 min simulated soccer matches with HMS (8% CHO; 0.7 g•kg BM−1•h−1; 2.8 kcal·kg BM−1•h−1) vs isoenergetic dextrose (DEX) consumed 30 min prior to the match and at half time. Compared to DEX, blood glucose was lower (p &lt; 0.001) with HMS at 15 (5.3 ± 0.6 vs 7.7 ± 1.4 mmol•L−1) and 30 min post ingestion (5.6 ± 0.6 vs 8.3 ± 1.0 mmol•L−1), and greater (p = 0.004) after 15 min of play (5.8 ± 0.5 vs 5.1 ± 0.6 mmol•L−1). With HMS, perceived exertion ratings were reduced throughout the match (p = 0.025 at 15 min). Flanker test incongruent trial reaction time (p = 0.040) and conflict cost (p = 0.019) were both better with HMS. These data suggest that HMS ingestion minimizes cognitive decline during soccer play. More study is warranted to elucidate fully the cognition benefits of HMS ingestion for sport performance.

Investigating whether fractional anisotropy is associated with reduced reaction time cost on an attentional control task

AbstractBackgroundPrevious research has shown that with age and disease, the integrity of white matter (WM) structures can decline. One such measure of WM integrity is fractional anisotropy (FA), where lower values are often associated with disrupted WM. Similarly, previous work has highlighted that attentional control also declines with age and disease. It was therefore of interest to investigate whether FA was associated with cognitive ability in an aging population. To assess this, we derived a measure of attentional control performance from the Consonant‐Vowel, Odd‐Even (CVOE) task.Method246 participants aged 42‐87 years (M = 69, SD = 8.5), who were enrolled in studies at the Knight ADRC, were included in this analysis. Participants were classified as cognitively normal (CDR = 0, n = 185), or cognitively impaired (CDR &gt; 0, n = 61). All participants completed an MRI, and the CVOE task. Tract‐Based Spatial Statistics (TBSS) were run on FA maps calculated for the participants. We used reaction time (RT) cost, the burden caused by the most difficult aspects of this task, as our behavioral measure of interest. This measure was calculated as the difference between RTs on congruent vs incongruently ordered trials.ResultUsing TBSS, we found that the relationships between FA and RT‐cost were significantly different for each group (Figure 1). More specifically, we found no relationship between RT‐cost and FA in our cognitively normal individuals (r = 0.14, p = 0.052; Figure 2). In contrast, we do observe a significant negative relationship between RT‐cost and FA in our cognitively impaired individuals (r = ‐0.64, p &lt; 0.01; Figure 3).ConclusionOverall, we found a strong relationship between WM integrity and cognitive performance, as measured by the CVOE task. That is, as integrity becomes more compromised, participants become slower at switching between trial types within the CVOE task. Importantly, this relationship is only observed for individuals who are cognitively impaired. Taken together, our results add to a body of literature that report a relationship between WM integrity and cognitive performance, but hint that further development of more sensitive cognitive tasks may be needed to fully understand this relationship.

Delayed picture naming in the first and second language

AbstractSecond language (L2) speakers produce speech more slowly than first language (L1) speakers. This may be due to a delay in lexical retrieval, but it is also possible that the delay is situated at later stages. This study used delayed picture naming to test whether late production stages (leading up to articulation) are slower in L2 than in L1. Dutch–English unbalanced bilinguals performed a regular and a delayed picture naming task in English and Dutch. Monolingual English controls performed these tasks in English. Speakers were slower when naming pictures in L2 during regular picture naming but not in delayed naming. Reaction time costs of using L2 did not vary with phonological complexity, but there was a larger L2 cost in accuracy with more complex words. We conclude that the very last stages prior to articulation are not significantly slower when bilinguals name pictures in their L2.

Cutaneous Adverse Drug Reactions (CADRs) at a Quaternary Care Hospital in South India: Focus on Reaction Time and Treatment Cost

Cutaneous Adverse Drug Reactions (CADRs) at a Quaternary Care Hospital in South India: Focus on Reaction Time and Treatment Cost

Cross-sensory inhibition or unisensory facilitation: A potential neural architecture of modality switch effects

In a simple reaction time task in which auditory and visual stimuli are presented in random sequence alone (A or V) or together (AV), there is a so-called reaction time (RT) cost on trials in which sensory modality switches (A→V) compared to when it repeats (A→A). This is always true for unisensory trials, whereas RTs to AV stimuli preceded by unisensory stimuli are statistically comparable with the Repeat condition (AV→AV). Neural facilitation for Repeat trials or neural inhibition for Switch trials could both account for these effects. Here we used a neural network model (Multisensory Integration with Crossed Inhibitory Dynamics (MICID) model) to test the ability of these two distinct mechanisms, inhibition and facilitation, to produce the specific patterns of behavior that we see experimentally, modeling switch and repeat trials as well as the influence of the interval between the present and the previous trial. The model results are consistent with an inhibitory account in which there is competition between the different sensory modalities, instead of a facilitation account in which the preceding stimulus sensitizes the neural system to its particular sensory modality. Moreover, the model shows that multisensory integration can explain the results in case of multisensory stimuli, where the preceding stimulus has little effect. This is due to faster dynamics for multisensory facilitation compared to cross-sensory inhibition. These findings link the cognitive framework delineated by the empirical results to a plausible neural implementation.

Differential effects of mind-wandering and visual distraction on age-related changes in neuro-electric brain activity and variability

Optimal performance in many tasks requires minimizing the impact of both visual distractors in the environment and distracting internal thoughts (i.e., mind-wandering). Prior research has indicated that older adults are disproportionately affected by the presence of visual distractors compared to young adults, but are not excessively affected by distracting thoughts. Yet an explanation for these dissociable effects remains elusive. In the current study, we assessed age-related differences in event-related potentials and neural variability associated with internal distraction and visual distractors in a go/no-go task. Compared to young adults, older adults showed an increased visual distraction cost in mean reaction time (RT) and RT variability but a reduction in internal distraction frequency and a reduced internal distraction cost on go accuracy and RT variability. Visual distraction and internal distraction were associated with opposite patterns of behavioral and neural effects. Behaviorally, across age groups, internal distraction was associated with more no-go errors whereas visual distraction was associated with reduced no-go errors. Across groups, internal distraction was associated with decreased P3 amplitude, whereas visual distraction was associated with increased P3 amplitude. In addition, internal distraction was associated with an increase in neural variability (more so in young versus older adults), while visual distraction was associated with a reduction in variability in young adults only. We suggest that the opposing effects of the two distractor types on behavioral and neural measures occur because visual distraction is associated with increased attentional resources devoted to the task to overcome visual interference whereas internal distraction is associated with decreased attentional resources devoted to the task. Moreover, older adults exhibited reduced flexibility of neural variability as a function of both distractor types, which may correspond to a diminished ability to up-regulate attention in the face of visual distraction and a diminished shift in attention away from the task during internal distraction.

Fabrication of carboxyl nitrile butadiene rubber composites with high dielectric constant and thermal conductivity using Al2O3@PCPA@GO hybrids

Owing to excellent adhesion and easy process, dopamine has been widely used as an intermediate for adjusting the molecular structure of nanoparticles. However, the high cost of dopamine largely impedes its large-scale applications. Herein, alumina@poly(catechol-polyamine)@graphene oxide (denoted as Al2O3@PCPA@GO) multilayer core-shell hybrids were prepared via poly(catechol-polyamine) (PCPA) modification. The as-prepared hybrids were added into the carboxyl nitrile butadiene rubber (XNBR) latex to produce composites with high thermal conductivity because of the strong interaction between polar groups in Al2O3@PCPA@GO core-shell hybrids and CN groups in XNBR matrix. Finally, the maximum thermal conductivity (0.48 W/mK) was obtained with 30 vol% Al2O3@PCPA@GO/XNBR composite, which was about three times of pure XNBR matrix (0.16 W/mK). Moreover, 30 vol% Al2O3@PCPA@GO composite showed a high dielectric constant (16.84 at 100 Hz) and low dielectric loss tangent (0.45 at 100 Hz). Besides, the 30 vol% Al2O3@PCPA@GO/XNBR composite displayed a high tensile strength of 11.86 MPa, which is an advantage for practical applications. The developed method has a shorter reaction time and lower cost compared with poly(dopamine) coating, suggesting potential applications as thermally conductive materials for electronic equipment.

Limited interactions between space- and feature-based attention in visually sparse displays.

Top-down visual attention selectively filters sensory input so relevant information receives preferential processing. Feature-based attention (FBA) enhances the representation of relevant low-level features, whereas space-based attention (SBA) enhances information at relevant location(s). The present study investigates whether the unique influences of SBA and FBA combine to facilitate behavior in a perceptually demanding discrimination task. We first demonstrated that, independently, both color and location pre-cues could effectively direct attention to facilitate perceptual decision making of a target. We then examined the combined effects of SBA and FBA in the same design by deploying a predictive color arrow pre-cue. Only SBA effects were observed in performance accuracy and reaction time. However, we detected a reaction time cost when a valid spatial cue was paired with a feature cue. A computational perceptual decision-making model largely provided converging evidence that contributions from FBA were restricted to facilitating the speed with which the relevant item was identified. Our results suggest that both selection mechanisms can be used in isolation to resolve a perceptually challenging target in a sparse display, but with little additive perceptual benefit when cued simultaneously. We conclude that there is at least some higher order interdependence between space-based and feature-based selection during decision making under specific conditions.

Study of the transesterification of waste cooking oil for the production of biodiesel in a microreactor pilot: The effect of acetone as the co-solvent

The development and use of new technologies for the amplification of the biodiesel production process in the transesterification reaction, which improves the mixing between the two phases, has led to the development and use of new reactors, including micro-reactors. Hence, the present study aimed at investigating the performance of a semi-industrial microreactor in the production of biodiesel from waste cooking oil (WCO) with methanol. The process was carried out through transesterification using acetone as the co-solvent at the presence of limescale (kettle limescale deposit) under different conditions. To optimize the reaction conditions, the main parameters affecting the purity of produced biodiesel, including residence time, reaction temperature, methanol to oil volume ratio, and acetone concentration (oil-based) were studied via response surface methodology (RSM). The best performance in biodiesel production was observed at a residence time of 12.5 min, reaction temperature of 60 °C, methanol to oil volume ratio of 2.15:5, and acetone concentration (pure oil-based) of 13.95 wt%, which resulted in a biodiesel purity of 97.16%. According to the results, the utilization of kettle limescale deposits as the catalyst and acetone as the co-solvent can help to reduce reaction time and production cost.

Examining the effectiveness of language-switching practice for reducing cross-language competition in L2 grammatical processing

AbstractThis study examined the extent to which language-switching practice enhanced L2 learners’ L2 grammatical processing by improving language selection abilities. Thirty-six English-speaking learners of French completed the same language-switching practice of L1 and L2 sentences, but received different types of pre-practice explicit information (EI) designed to address L2 learning difficulties resulting from crosslinguistic influence: one group (n = 17) received EI about English–French differences for viewpoint aspect, and a second group (n = 19) received EI about viewpoint aspect in French only. This design investigated the extent to which pre-practice linguistic knowledge moderated the effectiveness of the language-switching practice. Longitudinal analyses showed that increasing amounts of practice improved language selection abilities (increased accuracy, reduced reaction time costs), but only for learners who received EI about L1-L2 differences. These findings that language-switching was moderated by type of pre-practice EI have important implications for theories of L2 learning and instruction.

Evaluating the causal contribution of fronto-parietal cortices to the control of the bottom-up and top-down visual attention using fMRI-guided TMS

Previous studies demonstrate that frontal and parietal cortices are involved in bottom-up and top-down attentional processes. However, their respective contribution to these processes remains controversial. The purpose of the current study was to compare the causal contribution of frontal and parietal cortices to the control of bottom-up and top-down visual attention using functional magnetic resonance imaging (fMRI) and repetitive transcranial magnetic stimulation (rTMS). Subjects performed visual search for targets that were easy (pop-out) or difficult (non-pop-out) to distinguish from distractors. Three sites of interest were used, based on the individual fMRI activation during the performance of a search task: the right dorsolateral prefrontal cortex (rDLPFC), the right frontal eye field (rFEF) and the right superior parietal lobule (rSPL). Online rTMS stimulation, with the search onset, showed that relative to rTMS over the vertex, rTMS over the rDLPFC, the rFEF and the rSPL increased the search reaction time (RTs) in the non-pop-out condition. In comparison, no TMS effect was found in the pop-out condition. In addition, the search RT cost caused by the non-pop-out condition was larger after the rDLPFC-TMS compared to the vertex-TMS. The findings suggest that the frontal and parietal cortical regions are both involved in attentional processing during top-down visual search, and that the rDLPFC is causally related to the executive control of cognitive load increases between the pop-out and the non-pop-out search.

Incidental Categorization of Vibrotactile Stimuli.

Past research has demonstrated incidental learning of task-irrelevant visual and auditory stimuli. Motivated by the possibility of similar evidence in the tactile domain and potential applications in tactile speech communication systems, we investigated incidental categorization of vibrotactile stimuli through a visuomotor task of shape identification. Two experiments were conducted where participants were exposed to position-based or movement-based vibrotactile stimuli prior to performing a speeded response to one of two targets. The two experiments differed only in the particular sets of such stimuli employed. Unbeknownst to the participants, the vibrotactile stimuli and visual targets were initially correlated perfectly to facilitate the incidental learning of their associations, briefly uncorrelated to check the cost in reaction time, and correlated again to re-establish the initial association. Finally, participants were asked to predict visual targets from novel position-based and movement-based stimuli. The results from both experiments provided evidence of incidental categorization of vibrotactile stimuli. The percent-correct scores and sensitivity indices for the overt categorization of novel stimuli from both experiments were well above chance, indicating generalization of learning. And while both experiments showed an increase in reaction time when the association between vibrotactile stimuli and visual targets was disrupted, this reaction time cost was significant only for the stimuli used in the second experiment. Our finding of incidental categorization in the tactile domain has important implications for the effective acquisition of speech in tactile speech communication systems.

Processing time not modality dominates shift costs in the modality-shifting effect

Shifting attention between visual and auditory targets is associated with reaction time costs, known as the modality-shifting effect. The type of modality shifted from, e.g., auditory or visual is suggested to have an effect on the degree of cost. Studies report greater costs shifting from visual stimuli, yet notably used visual stimuli that are also identified slower than the auditory. It is not clear whether the cost is specific to modality effects, or with identification speed independent of modality. Here, to interpret whether the effects are due to modality or identification time, switch costs are instead compared with auditory stimuli that are identified slower than the visual (inverse of tested previously). A second condition used the same auditory stimuli at a low intensity, allowing comparison of semantically identical stimuli that are even slower to process. The current findings contradicted suggestions of a general difficulty in shifting from visual stimuli (as previously reported), and instead suggest that cost is reduced when targets are preceded by a more rapidly processed stimulus. ‘Modality-Shifting’ as it is often termed induces shifting costs, but the costs are not because of a change of modality per se, but because of a change in identification speed, where the degree of cost is dependent on the processing time of the surrounding stimuli.

Cognitive Flexibility Improves Memory for Delayed Intentions.

The ability to delay the execution of a goal until the appropriate time, prospective memory (PM), can be supported by the following two different cognitive control strategies: proactive control involving working memory maintenance of the goal and active monitoring of the environment; or reactive control relying on timely retrieval of goal information from episodic memory. Certain situations tend to favor each strategy, but the manner in which individuals adjust their strategy in response to changes in the environment is unknown. Across two experiments, human participants performed a delayed-recognition PM task embedded in an ongoing visual search task that fluctuated in difficulty. A control strategy was identified from moment to moment using reaction time costs and fMRI measures of goal maintenance. We found that people fluidly modified control strategies in accordance with changes in task demands (e.g., shifting toward proactive control when task difficulty decreased). This cognitive flexibility proved adaptive as it was associated with improved PM performance.

Degree of Language Experience Modulates Visual Attention to Visible Speech and Iconic Gestures During Clear and Degraded Speech Comprehension.

Visual information conveyed by iconic hand gestures and visible speech can enhance speech comprehension under adverse listening conditions for both native and non‐native listeners. However, how a listener allocates visual attention to these articulators during speech comprehension is unknown. We used eye‐tracking to investigate whether and how native and highly proficient non‐native listeners of Dutch allocated overt eye gaze to visible speech and gestures during clear and degraded speech comprehension. Participants watched video clips of an actress uttering a clear or degraded (6‐band noise‐vocoded) action verb while performing a gesture or not, and were asked to indicate the word they heard in a cued‐recall task. Gestural enhancement was the largest (i.e., a relative reduction in reaction time cost) when speech was degraded for all listeners, but it was stronger for native listeners. Both native and non‐native listeners mostly gazed at the face during comprehension, but non‐native listeners gazed more often at gestures than native listeners. However, only native but not non‐native listeners' gaze allocation to gestures predicted gestural benefit during degraded speech comprehension. We conclude that non‐native listeners might gaze at gesture more as it might be more challenging for non‐native listeners to resolve the degraded auditory cues and couple those cues to phonological information that is conveyed by visible speech. This diminished phonological knowledge might hinder the use of semantic information that is conveyed by gestures for non‐native compared to native listeners. Our results demonstrate that the degree of language experience impacts overt visual attention to visual articulators, resulting in different visual benefits for native versus non‐native listeners.