Validity and reliability of a ruler drop test to measure dual-task reaction time, choice reaction time and discrimination reaction time.

BACKGROUND: The aim of this study was to determine the absolute and relative reliability of the Ruler Drop Test (RDT) for assessing dual-task, choice, and discrimination reaction time. In addition, the construct validity of the RDT is examined in comparison to the Deary-Liewald reaction time (DLRT). METHODS: Tests were administered by the same evaluator, one week apart. Intraclass Correlation Coefficient (ICC3.1) was used to measure relative reliability, and the standard error of measurement (SEM) and minimal detectable change (MDC95) were used to measure absolute reliability. Spearman correlation test was used to measure construct validity. RESULTS: The results showed that the relative reliability was good for the choice ruler drop (ICC = 0.81), moderate for the dual-task ruler drop test (ICC = 0.70) and discrimination ruler drop test (ICC = 0.72), and good for simple ruler drop test. However, the simple ruler drop test had poor reliability (ICC = 0.57). The RDT shows construct validity compared to the DLRT. CONCLUSION: We conclude that the RDT is a suitable instrument for measuring dual-task, choice and discrimination reaction time. Future studies should explore the reliability of these measures in other populations.

Utilization of peripheral nerve feedback at a preconscious level.

Introduction: Sensorimotor integration is important, if not required, when using our hands. The integration of the tactile and motor systems is disrupted in individuals with upper limb amputations because their connection to their fingertips is lost. Direct cortical stimulation allows for modality and location matched perceptions; however, studies show that the time to process and act upon direct cortical feedback significantly exceeds the time to do the same with naturally produced tactile feedback. Direct cortical stimulation does not engage multiple parallel structures in the brain stem meant to integrate tactile feedback with signals from the motor system at a sub-perceptual or pre-perceptual level before the somatosensory cortex is involved. While reasonable to assume, it is not known if the artificially generated signals will engage the same peripheral tactile pathways to the pre-perceptual and perceptual structures as natural tactile sensation. Our hypothesis is that pre-perceptual structures will process the electrically generated neural activity as it would naturally generated neural activity. Methods: In this study, stimulation of the median nerve in multiple subjects' residual limbs produced modal, and location matched sensory perceptions in their hands. We found the time to process different stimuli using simple reaction time tests in three different formats. Results: We showed the minimum time to process peripheral nerve stimulation and initiate a motor plan is similar to naturally generated tactile feedback and is processed upwards of 50 - 175 ms faster than visual feedback alone. We also found the effect of stimulation intensity on the rate of feedback processing follows the same trend of natural sensory feedback, Piéron's law indicating that the unimodal processing of PNS is similar to natural touch. Finally, we found that tactile feedback given to a pre-perceptual level is again used in the motor plan. Discussion: Taken together, we conclude that peripheral nerve stimulation engages the pre-perceptual pathways of the brain, and hence demonstrate advantages of peripheral restoration of sensory inputs.

Effect of transcranial static magnetic stimulation over unilateral or bilateral motor association cortex on performance of simple and choice reaction time tasks.

Background: Transcranial static magnetic stimulation (tSMS) is a non-invasive brain stimulation technique that place a strong neodymium magnet on scalp to reduce cortical excitability. We have recently developed a new tSMS device with three magnets placed close to each other (triple tSMS) and confirmed that this new device can produce a stronger and broader static magnetic field than the conventional single tSMS. The aim of the present study was to investigate the effect of the conventional single tSMS as well as triple tSMS over the unilateral or bilateral motor association cortex (MAC) on simple and choice reaction time (SRT and CRT) task performance. Methods: There were two experiments: one involved the conventional tSMS, and the other involved the triple tSMS. In both experiments, right-handed healthy participants received each of the following stimulations for 20 min on different days: tSMS over the unilateral (left) MAC, tSMS over the bilateral MAC, and sham stimulation. The center of the stimulation device was set at the premotor cortex. The participants performed SRT and CRT tasks before, immediately after, and 15 min after the stimulation (Pre, Post 0, and Post 15). We evaluated RT, standard deviation (SD) of RT, and accuracy (error rate). Simulation was also performed to determine the spatial distribution of magnetic field induced by tSMS over the bilateral MAC. Results: The spatial distribution of induced magnetic field was centered around the PMd for both tSMS systems, and the magnetic field reached multiple regions of the MAC as well as the sensorimotor cortices for triple tSMS. SD of CRT was significantly larger at Post 0 as compared to Pre when triple tSMS was applied to the bilateral MAC. No significant findings were noted for the other conditions or variables. Discussion: We found that single tSMS over the unilateral or bilateral MAC did not affect performance of RT tasks, whereas triple tSMS over the bilateral MAC but not over the unilateral MAC increased variability of CRT. Our finding suggests that RT task performance can be modulated using triple tSMS.

Evaluation of Reaction Time during the One-Leg Balance Activity in Young Soccer Players: A Pilot Study.

This study's aim was two-fold: (i) to test the intra-session reliability of the one-leg balance activity test; and (ii) to assess the influence of age on reaction time (RT) and the differences between dominant and non-dominant feet. Fifty young soccer players with an average age of 12.4 ± 1.8 years were divided into two groups: younger soccer players (n = 26; 11.6 ± 0.9 years) and older soccer players (n = 24; 14.2 ± 0.8 years). Each group then completed four trials (two with each leg) of the one-leg balance activity (OLBA) to evaluate RT under a single-leg stance. Mean RT and the number of hits were calculated, and the best trial was also selected. T-tests and Pearson correlations were performed for statistical analysis. Values for RT were lower, and the number of hits was higher while standing on the non-dominant foot (p = 0.01). MANOVA revealed that the "Dominant Leg" factor did not affect the multivariate composite (Pillai Trace = 0.05; F(4, 43) = 0.565; p = 0.689; Partial ETA Squared = 0.050; Observed Power = 0.174). The "Age" factor did not present an effect on the multivariate composite (Pillai Trace = 0.104; F(4, 43) = 1.243; p = 0.307; Partial ETA Squared = 0.104; Observed Power = 0.355). The results of the present investigation demonstrate that RT may be lower while standing on the non-dominant foot.

Measurement of Simple Reaction Time of the Cyclist in the Laboratory and Natural Environment Condition.

The most commonly used reaction time tests within the athlete community require appropriate testing conditions and equipment, most frequently laboratory ones, which are not suitable for testing athletes in their natural environment and do not fully represent athletes' natural capabilities and the influence of the surrounding environment. Therefore, this study's goal is to compare the simple reaction times (SRTs) of cyclists during tests in laboratory conditions and in natural cycling surroundings. The young cyclists (55 participants) took part in the study. The SRT was measured in a quiet laboratory room with the use of the special device. During riding and standing with a bike outdoors, the necessary signal was captured and transmitted by a folic tactile sensor (FTS) and an extra intermediary circuit (both invented by our team member) connected to a muscle activity measurement system (Noraxon DTS Desktop, Scottsdale, AZ, USA). The results showed that external conditions significantly affect the SRT, with it being the longest when riding and the shortest if measured in an isolated laboratory room, but without an effect of gender. Typically, men have a shorter reaction time, but our result supports other observations, where people with an active lifestyle show no sex differentiation in SRT. The proposed FTS with an intermediary circuit allowed us to measure SRT with the use of non-dedicated equipment and avoid buying a new one for a single specific use.

Validation of cognitive and neuromuscular latencies using an iPad-based tool to quantify simple reaction times in asymptomatic subjects.

CONTEXT: Simple reaction times (SRTs), measured in milliseconds (msec), are equal to the sum of subject-dependent latencies that occur during cognitive processing and neuromuscular responses to a preprogrammed stimulus presented to a subject. SRTs have the advantage of being a relatively pure, neurologically driven motor/sensory task that provides a clinician with a generalized assessment of functional deficits. SRTs are easily obtained, and studies have reported that the average number of finger-taps during a 10-s interval can be utilized to distinguish between patients with mild traumatic brain injury (TBI) and healthy controls. OBJECTIVES: A stimulus/response SRT protocol, utilizing an iPad-based tool, was utilized to see if differentiation and quantification of individual components of cognitive latency (CL) and neuromuscular latency (NL) from a subject's total SRT could be accomplished. The study hypothesis was that cognitive latencies, related to a specific cognitive challenge, would remain constant even as latencies due to neuromuscular challenges changed. METHODS: Two categories of SRT tests were utilized. The first was a simple finger tapping test (FTT), without any cognitive involvement, that was designed to quantify pure NL. The second test was a choice test (CT) that was characterized by the addition of a cognitive task to the FTT. The objective of the FTT was for the subject to simply tap a single target positioned on the iPad screen as fast as possible over an interval of 10 s. Measurement of the SRT began when a target was displayed and ended when the target was tapped. Two levels of challenge for the FTT and CT tests were presented to the subjects: a small random displacement (SD) of the target of up to 6 mm, and a large random displacement (LD) of the target of up to 24 mm. It was expected that the magnitude of the SRT (FTT) would be directly related to the magnitude of the displacement of the target due to kinematic response characteristics of the hand and arm. RESULTS: To validate the study hypothesis, CL for both small and large displacements was calculated by subtracting the respective NL from the total SRT. Utilizing a repeated measures t-test analysis utilizing SPSS, a significant difference between CL (SD) and CL (LD) at p=0.696 was not observed. CONCLUSIONS: Differentiation and quantification of individual components of CL and NL from a subject's total SRT was accomplished. An Apple iPad Pro was selected as a platform for our study because: (1) it is readily available, affordable, and programmable; (2) it meets a requirement for portability; and (3) it allows the modification/addition of test parameters to meet future needs. The ability to quantify the extent of cognitive and neuromuscular dysfunction in the TBI patient is an essential component of developing an effective treatment plan.

Impact of work exposure on cognitive performance in Faroese deep-sea fishers: a field study.

BACKGROUND: This study examines the impact of work-related exposure on the cognitive performance of Faroese deep-sea fishers. Faroese fishing crews work long hours in demanding and noisy environments amidst highly uncertain and challenging weather conditions. These factors, together with compromised patterns of rest and sleep, are known to increase fatigue. Our aim was to study if changes could be measured in fishers' cognitive performance at the end of the trip when compared with the baseline measure at the beginning. MATERIALS AND METHODS: Data was collected over 15 months (May 2017 to July 2018) from 157 fishers on 18 fishing trips which involved 202 investigative days on board. Questionnaires and six computerised cognitive tests: Simple Reaction Time, Numeric Working Memory, Corsi Blocks, Rapid Visual Information Processing, Digit Vigilance, and Card Sorting Test were used for data collection at the beginning and end of the trip. Differences between the outcomes on the two test points were analysed with one-way ANOVA comparing the performances at the beginning and end of the voyage, and two-way ANOVA to examine the interactive effect of chronotype and test occasions on the outcomes. Mixed models were used to test for the effects of predictor variables. RESULTS: Significant declines in cognitive performance were observed from the beginning to the end of the trip, with decreases in visuospatial memory and reaction times, and increases in cognitive lapses. Furthermore, slowing in response times was observed in the second half of the Digit Vigilance test when comparing the halves. CONCLUSIONS: Declines in performance were observed from the start to the end of the trip. Furthermore, fishers performed significantly worse in the second half of some parted tests, and evening types seem less influenced by irregular work hours. These findings call for improving the safety of the vessels and their crew.

Association of military-specific reaction time performance with physical fitness and visual skills.

Background: The aim of the present study was to explore whether military-specific reaction time (RT) test performance is affected by individuals' physical and visual skills. Method: In a single testing session, the military-specific Simple and Go, No-Go RT, aerobic power (20-m Multistage Shuttle Run test), maximal upper- and lower-body mechanical capacities (bench press and squat against different loads), and visual skills (multiple object tracking and dynamic visual acuity) of 30 young men (15 active-duty military personnel and 15 sport science students) were evaluated. Results: The main findings revealed that the Simple RT and Go, No-Go RT presented (1) with aerobic power non-significant small correlations in military personnel (r = -0.39 and -0.35, respectively) and non-significant negligible correlations in sport science students (r = -0.10 and 0.06, respectively), (2) inconsistent and generally non-significant correlations with the maximal mechanical capacities of the upper- and lower-body muscles (r range = -0.10, 0.67 and -0.27, 0.48, respectively), (3) non-significant correlations with visual skills (r magnitude ≥ 0.58) with the only exception of the Go, No-Go RT that was significantly correlated to all visual variables in the group of students (i.e., students who achieved better results during visual tests had shorter RT; r magnitude ≥ 0.58), and (4) none of the physical and visual variables significantly predicted the Simple RT or Go, No-Go RT. Conclusion: Altogether, these results indicate that military-specific RT performance is generally independent of physical and visual skills in both military personnel and active university students.

Reaction Times among Batik Workers: The Influence of Gender and Occupational Lead Exposure.

(1) Background: Neglected occupational health and safety aspects in batik industries cause their workers to have an increased risk of lead exposure. The effect of occupational lead exposure on neurocognitive performance is inconclusive. Therefore, we conducted an observational study to examine the difference in simple reaction time between lead-exposed batik workers and non-exposed referents. (2) Methods: This cross-sectional study was conducted in seven batik enterprises in Lendah District, Indonesia, excluding workers with medical conditions impairing reaction time. Simple reaction time tests were conducted using an online tool. Two-way model ANCOVAs examined interactions between gender and job types on the mean differences in reaction time. (3) Results: After controlling for age and body mass index, we observed longer reaction times among lead-exposed batik workers than non-exposed referents with an adjusted mean difference of 0.19 (95% CI: 0.016-0.368) seconds. A more prominent detrimental effect of lead exposure on reaction time among female workers than among male workers was observed. (4) Conclusions: Our results suggest that occupational lead exposure could contribute to longer reaction time, notably among female workers. Thus, occupational health and safety precautions are vital to protect batik workers and preserve their important contributions to cultural heritage.

Reactive Task Performance Under Varying Loads in Division I Collegiate Soccer Athletes.

This study was conducted to identify whether team-wide or positional differences exist in simple or choice reactivity of collegiate soccer athletes when completed under various loads. Much research exists surrounding the assessment of reaction time in the general population, but given variations in training, little insight exists surrounding how unique and elite populations may differ based upon performance demands and task translatability to training. Reactive performance was assessed using the Dynavision D2 in 24 female soccer players (19.73 ± 1.05 years old) from a team within a power five conference of the National Collegiate Athletic Association. Evaluated loads included two conditions of simple reactivity (no additional load and with a concurrent lower body motor task) and three conditions of choice reactivity (no additional load, with a concurrent lower body motor task, and prolonged durations). Paired t-tests and ANOVAs were used to identify differences in task performance based upon load and positional group. No significant load-based or positional differences existed in measured simple reaction times. Performances in choice reaction tasks across the team were found to be slower when completed across extended durations (p < 0.0001) and faster when completed concurrent with an added balance task (p = 0.0108), as compared to performance under normal conditions. By assessment of positional differences, goalkeepers tended to be slower than other positions in reactivity during choice tasks, despite no differences existing in simple task performance. Given the unique population utilized herein, measured reactivity in different tasks suggests a strong relation to the training demands of soccer, as well as those of goalkeepers as compared to field positions. Findings suggest that sport and positional demands may be substantial contributors to population- and individual-based reactivity performance.

Frequency-Specific Effects of Galvanic Vestibular Stimulation on Response-Time Performance in Parkinson's Disease.

Background: Galvanic vestibular stimulation (GVS) is being increasingly explored as a non-invasive brain stimulation technique to treat symptoms in Parkinson's disease (PD). To date, behavioral GVS effects in PD have been explored with only two stimulus types, direct current and random noise (RN). The interaction between GVS effects and anti-parkinsonian medication is unknown. In the present study, we designed multisine (ms) stimuli and investigated the effects of ms and RN GVS on motor response time. In comparison to the RN stimulus, the ms stimuli contained sinusoidal components only at a set of desired frequencies and the phases were optimized to improve participants' comfort. We hypothesized GVS motor effects were a function of stimulation frequency, and specifically, that band-limited ms-GVS would result in better motor performance than conventionally used broadband RN-GVS. Materials and Methods: Eighteen PD patients (PDMOFF/PDMON: off-/on-levodopa medication) and 20 healthy controls (HC) performed a simple reaction time task while receiving sub-threshold GVS. Each participant underwent nine stimulation conditions: off-stimulation, RN (4-200 Hz), ms-θ (4-8 Hz), ms-α (8-13 Hz), ms-ß (13-30 Hz), ms-γ (30-50 Hz), ms-h1 (50-100 Hz), ms-h2 (100-150 Hz), and ms-h3 (150-200 Hz). Results: The ms-γ resulted in shorter response time (RPT) in both PDMOFF and HC groups compared with the RN. In addition, the RPT of the PDMOFF group decreased during the ms-ß while the RPT of the HC group decreased during the ms-α, ms-h1, ms-h2, and ms-h3. There was considerable inter-subject variability in the optimum stimulus type, although the frequency range tended to fall within 8-100 Hz. Levodopa medication significantly reduced the baseline RPT of the PD patients. In contrast to the off-medication state, GVS did not significantly change RPT of the PD patients in the on-medication state. Conclusions: Using band-limited ms-GVS, we demonstrated that the GVS frequency for the best RPT varied considerably across participants and was >30 Hz for half of the PDMOFF patients. Moreover, dopaminergic medication was found to influence GVS effects in PD patients. Our results indicate the common "one-size-fits-all" RN approach is suboptimal for PD, and therefore personalized stimuli aiming to address this variability is warranted to improve GVS effects.

Is simple reaction time or choice reaction time an indicator of all-cause mortality or CVD mortality?

OBJECTIVES: Simple reaction time (SRT) and choice reaction time (CRT) have been shown to be good indicators for quantitatively assessing the level of human cognitive impairment, but these parameters have also been linked to the risk of human death. This study aimed to quantitatively assess the independent predictive value of SRT or CRT for all-cause mortality or cardiovascular disease (CVD) mortality by conducting a meta-analysis of prospective studies. STUDY DESIGN: The study design of this study is a prospective cohort study. METHODS: We conducted a meta-analysis by combining hazard ratios (HRs) and 95% confidence intervals (95% CIs) of SRT or CRT with all-cause mortality or CVD mortality in healthy community residents aged 18 and over. Heterogeneity was evaluated by using Q statistics and Cochrane's I2 statistics. RESULTS: A total of seven prospective studies that examined all-cause mortality and CVD mortality were included. The pooled HR of all-cause mortality in SRT was 1.099 (1.065-1.134, I2 = 11.9%), and an increased risk of CVD mortality was associated with lower SRT (HR = 1.186, 95% CI = 1.137-1.236; I2 = 52.4%). Similarly, the pooled HR of all-cause mortality in CRT was 1.140 (95% CI = 1.085-1.197, I2 = 33.7%). However, lower CRT was not statistically associated with an increased risk of CVD mortality. CONCLUSION: SRT may be a predictor of all-cause-mortality and CVD mortality, and CRT is significantly associated with an increased risk of all-cause mortality.

Characteristics of Cognitive Abilities among Youths Practicing Football.

The aim of the study was to assess selected cognitive abilities depending on age, anthropometric parametres, physical fitness and technical skills in the group of young players training football. The study covered a group of 258 young players practicing football (age: 12.1± 2.03), who were divided into 5 age categories (8-9 years old, 10-11 years old, 12-13 years old, 14-15 years old, 16-17 years old). Selected cognitive abilities include: simple reaction time (SIRT), complex reaction time (CHORT), hand-eye coordination (HECOR) and spatial orientation (SPANT). Studies were performed using Test2Drive computer tests. In addition, the level of physical fitness was measured using: The standing long jump, 30 m sprint, 20 m shuttle run test (without and with the ball) and slalom (without and with the ball). The analysis showed a statistically significant relationship between age and cognitive abilities. There was also a statistically significant correlation between fitness tests and reaction time in individual cognitive tests. There were no statistically significant relationships between technical skills and cognitive abilities. The study confirms that age and physical fitness affect the level of cognitive abilities.

Foods, nutrient intakes and Mediterranean dietary pattern in midlife are not associated with reaction times: a longitudinal analysis of the UK Women's Cohort Study.

Associations between dietary factors and general cognition in the elderly have been documented; however, little is known about reaction time ability in relation to midlife diet. The present study aimed to investigate associations between reaction time and midlife dietary factors, specifically foods, nutrients and Mediterranean diet (MeDi) pattern. The UK Women's Cohort Study collected dietary information from middle-aged women (52 (sd 9·4) years old) using a validated 217-item FFQ in 1995-1998. In 2010-2011, a sub-group of 664 participants completed online reaction time ability tests including simple reaction time (SRT) and choice reaction time; 503 participants were eligible for analysis. Participants were grouped into fast and slow groups by their median reaction time. The intake of particular foods, nutrients, adherence to the MeDi and cooking methods (roasting/baking, frying and barbecuing/grilling) were explored in relation to reaction times. We did not find any significant associations between reaction times and investigated foods, nutrients or adherence to the MeDi in adjusted models. However, consumers of roasted/baked fish and fried vegetables were associated with slower SRT (adjusted OR 1·46, 95 % CI 1·00, 2·13, P = 0·049; and adjusted OR 1·64, 95 % CI 1·12, 2·39, P = 0·010, respectively) compared with non-consumers of that particularly cooked food. Overall, our findings show no significant associations between midlife diet and reaction time ability 10-15 years later.

A Study to Assess and Correlate Serum Lipid Profile with Reaction Time in Healthy Individuals.

Dyslipidaemia, metabolic syndrome, diabetes mellitus and arterial hypertension contribute to the risk of cognitive disorder and dementia. However very few and conflicting results are available with respect to the impact of lipoprotein ratios on cognitive functions in healthy individuals. Therefore, this study was aimed to investigate the association of lipid profile and its ratios with reaction time in young healthy individuals. 89 individuals (54 male and 35 female) with mean age of 31.20 ± 3.19 years were selected for this observational study conducted at AIIMS Rishikesh and written consent was obtained. TC, TG, HDL were measured by semi auto analyzer following the manufacturers' instruction and LDL was calculated by Friedewald formula. Reaction time (simple and choice reaction time) was assessed using a software package, Deary-Liewald reaction time task. Association of various parameters was calculated by pearson's correlation coefficient using SPSS version 23.0. Reaction time showed significant negative association with BMI (r = - 0.323, p = 0.002) in total study participants as well as with TG (r = - 0.440, p = 0.008) and TG/HDL (r = - 0.402, p = 0.025) in female individuals. From this study, it could be concluded that TG/HDL ratio, the superlative predictor of concomitant presence of cardiovascular disease, insulin resistance and metabolic syndrome may be considered as a biomarker for assessment of cognitive function in young healthy female individuals.

Programming of action timing cannot be completed until immediately prior to initiation of the response to be controlled.

We consider, in depth, findings from across 6 decades regarding generating a motor response in a simple reaction-time (i.e., delayed response) paradigm. The early results robustly show a response complexity effect whereby the more response elements, the longer the simple reaction time (RT). This effect is puzzling because it indicates that preparation of some aspect of a response cannot be completed prior to the simple RT interval even though a precue had identified the response in advance. Results obtained during the past 10 years indicate that this finding reflects a restriction in advance preparation of the code that controls timing of the onsets for elements making up the response. This code cannot be prepared prior to the simple RT interval even though the parameters to be achieved by the response can be established earlier so that the difficulty of their selection does not influence RT. The general principle that emerges from these studies is that the abstract goal for a response can be determined in advance, but programming of action timing cannot be completed until immediately prior to initiation of the response to be controlled. We suggest that this restriction may arise because limitations in working memory prevent temporary storage of the timing code even though the abstract response goal can be stored until needed. Regardless of its origin, the limitation regarding preparation of response timing represents a fundamental feature in control of motor action.

The effects of aging and driving experience on reaction times of professional drivers.

BACKGROUND: Professional drivers are part of the active working population, so there is a need for continuous improvement of operating efficiency and safety in driving. Reaction time is a very important driver's trait. OBJECTIVE: The aim of this study was to examine the effects of age and driving experience on reaction times of professional drivers. METHODS: This study assesses part of driving efficiency of professional drivers by measuring simple reaction time and complex reaction time which are important to driving safety. Reaction times of 278 male professional drivers were tested using a hardware-software system for determining the speed of response to psychomotor simple and complex audio-visual stimuli. RESULTS: Our results showed a positive correlation between ageing and slowing of reaction times. This suggests that the natural ageing process clearly slows down reaction times. CONCLUSIONS: The response times of professional drivers are more dependent on age than on driving experience.

Between- and within-person contributions of simple reaction time to executive function skills in early childhood.

This study tested whether the bivariate association between simple reaction time (SRT) and executive function (EF) performance that has been observed in early childhood represented a between- and/or within-person association. Up to three repeated assessments (i.e., fall, winter, and spring assessments from September to May) were available for 282 preschool-aged children (Mage = 4.2 years; 54% female) who participated in the Kids Activity and Learning Study. A series of three-level hierarchical linear models (repeated measures nested in child; child nested in classroom) was used to disaggregate the observed variation in EF and SRT into between-classroom, between-person, and within-person components. EF composite scores were regressed on two indicators of SRT, which reflected between- and within-child sources of variation, along with demographic covariates (child age, gender, and parental education). Both between-person (b = -21.2, p < 0.001) and within-person (b = -13.2, p < 0.001) sources of SRT variation were uniquely related to EF performance. These results are discussed with respect to interest in using SRT as a proxy for foundational cognitive processes that contribute to EF task performance in early childhood, including the appropriateness of using SRT to refine EF task scores.

Program of Seven 45-min Dry Immersion Sessions Improves Choice Reaction Time in Parkinson's Disease.

The study hypothesis held that in subjects with Parkinson's disease (PD), the reaction time (RT) tests of the higher cognition demand would have more readily improved under the program of analog microgravity (µG) modeled with "dry" immersion (DI). To test this hypothesis, 10 subjects with PD have passed through a program of seven DI sessions (each 45 min long) within 25-30 days, with overall µG dose 5 1/4 h. Five patients were enrolled as controls, without DI (noDI group). Simple RT (SRT), disjunctive RT (DRT), and choice RT (CRT) were assessed in four study points: before the DI program (preDI), 1 day after the DI program (postDI), 2 weeks after the DI program (DI2w), and 2 months after the DI program (DI2m). The motor time (MT) was assessed with the tapping test (TT). Additionally, signal detection time (SDT) and central processing time (CPT) were extracted from the data. Before the program of DI, the RT tests are in accordance with their cognition load: SRT (284 ± 37 ms), DRT (338 ± 38 ms), and CRT (540 ± 156 ms). In accordance with the hypothesis, CRT and DRT have improved under DI by, respectively, 20 and 8% at the study point "DI2w," whereas SRT, SDT, and MT did not change (<5% in the preDI point, p > 0.05). Thus, the program of DI provoked RT improvement specifically in the cognitively loaded tasks, in a "dose of cognition-reaction" manner. The accuracy of reaction has changed in none of the RT tests. The neurophysiologic, hormonal/neuroendocrine, behavioral, neural plasticity, and acclimation mechanisms may have contributed to such a result.

Comparison of reaction time between beginners and experienced fencers during quasi-realistic fencing situations.

This study aimed (I) to investigate the impact of the number of stimulus-responses alternatives on reaction time (RT) under quasi-realistic fencing situations, and (II) to elucidate whether the regression slope based on the RT and the number of stimulus-responses alternatives could distinguish between beginners and experienced fencers. Ten beginners (7 men) and 10 experienced (6 men) fencers participated in the study. A video-based method was used to present four typical fencing movement techniques (i.e. "stimulus") after which the participants had to perform an offensive (high or low attack) or defensive (high or low defence) action (i.e. "response"). The simple-RT (specific stimulus known in advance), 2Choice-RT (only defensive or offensive stimuli), and 4Choice-RT (all possible stimuli) were evaluated. The increase in the number of stimulus-responses alternatives was associated with higher RT (4Choice-RT > 2Choice-RT > Simple-RT; p < 0.05). Beginners always presented higher RT compared to fencers (range: 25.5-34.8%; p < 0.05) and also showed a steeper slope of the relationship between RT and the number of stimulus-responses alternatives (range: 35.2-55.2%; p < 0.05). These results suggest that the capability to quickly respond to specific fencing stimuli increases with training experience, being the differences accentuated with increasing number of stimulus-responses alternatives.