Reaction Time Response Research Articles

PATTERNS AND CONSISTENCY OF MUSCLE RECRUITMENT FOR A KARATE JAB

Adequate pattern and consistency of the muscle recruitment is essential to symbolize the destruction of the opponent with high movement velocities and precise targeting of the opponent's head and body during a karate jab. The purpose of this study was to evaluate the reaction time (RT), motor time (MT), and total response time (TRT), as well as their correlation during a karate jab, and to investigate the recruitment pattern and consistency of muscles during motor time. As many as 14 professional karate athletes (age: 23.67 ± 2.64 years; height: 174.57 ± 7.13 cm; and weight: 72.75 ± 10.65 kg) participated in the current study. Each subject was instructed to pose in combat stance first and then to use their left hand to jab at an instrumented kicking target as soon as they saw the start signal. Surface electromyograms (EMGs) were recorded from 16 muscles, namely the pronator teres, biceps brachii, triceps brachii, and deltoid of the left upper limb, right erector spinae, left rectus abdominis, and gluteus maximus, rectus femoris, biceps femoris, tibialis anterior, and medial gastrocnemius of the right and left lower limbs. Start and stop signals from the instrumented target were also recorded synchronously to obtain the TRT. Significant correlation between MT and TRT indicated that MT was a key determinant for the TRT of the jab. When performing a karate jab, the karate athletes initiated the movement with postural adjustments of the legs and trunk prior to the onset of the voluntary jab by the upper limb, and with a proximal-to-distal sequence of muscle activation in the left arm. Good consistencies of muscle recruitment of the trunk, left arm, and leg, and cocontraction of the left triceps and biceps brachii also indicated a well-controlled jab by the left arm. These results provide important information on the patterns and the consistencies of the muscle recruitment for coaching a karate jab, which should be helpful for a better understanding of the motor control strategies of a karate jab and for developing a suitable training protocol.

Effects of Menopausal Hot Flashes on Mental Workload

This study examined the differences in psychophysiological responses during mental task performance between women with (Group S) and without (Group A) menopausal hot flashes. Twelve women who reported experiencing daily moderate or severe menopausal hot flashes (Group S) and twelve women who reported having no hot flashes (Group A) participated in a mental arithmetic (Task) and a control (Non-task) experiment that occurred twice during 30 min. Although Group S experienced frequent hot flashes during mental arithmetic task, no significant differences between the two groups emerged for the percentage of correct responses and reaction time, and cardiovascular and thermoregulatory responses. However, the STAI state anxiety score was significantly higher in Group S than in Group A during both rest and mental tasks, and stress-related cortisol secretion showed a tendency to increase in Group S compared with Group A after task. The present study indicates that there were no significant differences in physiological responses and cognitive performance between women with and without menopausal hot flashes during mental arithmetic, but women with menopausal hot flashes might perceive higher psychological stress during rest and mental arithmetic tasks than asymptomatic women.

ICONE19-43207 Reaction-time response of a large commercial aircraft

ICONE19-43207 Reaction-time response of a large commercial aircraft

Modulation of headcut soil erosion in rills due to upstream sediment loads

Headcut erosion can severely accelerate soil loss in upland concentrated flows and lead to significant soil degradation in agricultural areas. Previous experimental work has demonstrated that actively migrating headcuts display systematic morphodynamic behavior and that impinging jet theory can provide an excellent analytic foundation for predicting these erosional phenomena. This research sought to examine systematically the effect of an upstream sediment load on the morphodynamics of actively migrating headcuts in upland concentrated flows. Using a specially designed experimental facility, actively migrating headcuts in packed soil beds were allowed to develop freely when subjected to concentrated, clear‐water flows similar to rills, crop furrows, and ephemeral gullies. After such headcut development and without altering the boundary conditions of the experiment, a sediment load composed of relatively coarser grained sand was introduced into the flow well upstream of the erosional feature. At relatively low upstream sediment loadings, the morphodynamics and sediment discharge of the actively migrating headcuts remained unchanged in time and space. As upstream sediment loadings increased, the size and migration rate of the headcuts decreased markedly, yet sediment discharge was not strongly affected as its sediment texture shifted from headcut‐controlled flux to sediment‐feed flux. The headcut erosion process was completely arrested when the upstream sediment feed rate exceeded a specific magnitude. Analytic arguments are used to explain the reaction time and morphodynamic response of an actively migrating headcut to this upstream sediment loading. This research shows that headcut erosion can be strongly modulated by an upstream sediment load, further complicating the prediction of soil erosion on upland areas dissected by sediment‐laden concentrated flows.

Self-report and laboratory measures of impulsivity in patients with schizophrenia or schizoaffective disorder and healthy controls

This study examined self-reported impulsivity and aggression and performance on the stop-signal task in patients with schizophrenia or schizoaffective disorder and healthy volunteers. Compared to controls, patients had higher scores on interview and questionnaire measures of impulsivity and aggression and showed increased stop-signal reaction time and greater response variability. These findings are consistent with a specific impairment in response inhibition in schizophrenia.

Individual Differences in Subconscious Motor Control Predicted by GABA Concentration in SMA

Subliminal visual stimuli affect motor planning, but the size of such effects differs greatly between individuals. Here, we investigated whether such variation may be related to neurochemical differences between people. Cortical responsiveness is expected to be lower under the influence of more of the main inhibitory neurotransmitter, GABA. Thus, we hypothesized that, if an individual has more GABA in the supplementary motor area (SMA)--a region previously associated with automatic motor control--this would result in smaller subliminal effects. We measured the reversed masked prime--or negative compatibility--effect, and found that it correlated strongly with GABA concentration, measured with magnetic resonance spectroscopy. This occurred specifically in the SMA region, and not in other regions from which spectroscopy measurements were taken. We replicated these results in an independent cohort: more GABA in the SMA region is reliably associated with smaller effect size. These findings suggest that, across individuals, the responsiveness of subconscious motor mechanisms is related to GABA concentration in the SMA.

The Effect of Warning Design and Personalization on User Compliance in Computer Security Dialogs

To combat the rise in internet-based crime, computer security warnings must be optimized to improve user compliance. Past research has shown various methods for improving warning efficiency but little research has examined the effectiveness of these methods on computer-based warnings. At present, a subset of the data from a proposed factorial design has been collected from seventy participants who encountered one of two computerized warnings: a control warning similar to these that are currently in use or an experimental warning that contained a number of physical and content improvements. The techniques used to improve the design of the experimental warning included color, borders, symbols, improved message clarity, the addition of a warning source and warning personalization. Compliance rates and reaction time responses were collected for each of the two warnings. Preliminary results indicated that the warning improvement increased compliance, though not at a statistically significant level. Potential directions for computer security software design, user training, and future research are discussed.

Effect of body hydration status on the psycho-physiological profile of college level women basketball players (18–22 years)

The effect of body hydration status was assessed on the psycho-physiological profile of college level women basketball players (18–22 years). Thirty basketball players and 30 training in a fitness centre,...

Sensori-motor integration during stance: Time adaptation of control mechanisms on adding or removing vision

Sudden addition or removal of visual information can be particularly critical to balance control. The promptness of adaptation of stance control mechanisms is quantified by the latency at which body oscillation and postural muscle activity vary after a shift in visual condition. In the present study, volunteers stood on a force platform with feet parallel or in tandem. Shifts in visual condition were produced by electronic spectacles. Ground reaction force (center of foot pressure, CoP) and EMG of leg postural muscles were acquired, and latency of CoP and EMG changes estimated by t-tests on the averaged traces. Time-to-reach steady-state was estimated by means of an exponential model. On allowing or occluding vision, decrements and increments in CoP position and oscillation occurred within about 2 s. These were preceded by changes in muscle activity, regardless of visual-shift direction, foot position or front or rear leg in tandem. These time intervals were longer than simple reaction-time responses. The time course of recovery to steady-state was about 3 s, shorter for oscillation than position. The capacity of modifying balance control at very short intervals both during quiet standing and under more critical balance conditions speaks in favor of a necessary coupling between vision, postural reference, and postural muscle activity, and of the swiftness of this sensory reweighing process.

Impaired anticipatory event-related potentials in schizophrenia

Deficits in anticipation are implicated across a variety of cognitive and emotional processes in schizophrenia. Although diminished anticipatory event-related potentials (ERPs) have been detected during tasks requiring motor response preparation in schizophrenia, no prior ERP study has examined non-motor-related anticipatory processes or used motivationally engaging stimuli. Thirty-four schizophrenia outpatients and 36 healthy controls completed a cued, reaction-time contingent picture viewing task to assess two types of anticipatory ERPs, one involving motor response preparation (Contingent Negative Variation [CNV]) and one not involving motor preparation (Stimulus Preceding Negativity [SPN]). The ERP paradigm included emotional and non-emotional pictures, and participants also completed trait anhedonia questionnaires. Patients and controls demonstrated similar patterns of reaction time and self-reported emotional responses to the pictures. However, patients demonstrated generally lower CNV and SPN across pleasant, neutral, and unpleasant picture conditions. Patients also reported lower anticipatory pleasure than controls on a trait questionnaire. Schizophrenia patients demonstrate diminished motor- and non-motor-related anticipatory processing, which may have wide-ranging adverse functional consequences.

Timing is affected by demands in memory search but not by task switching.

Recent studies suggest that timing and tasks involving executive control processes might require the same attentional resources. This should lead to interference when timing and executive tasks are executed concurrently. This study examined the interference between timing and task switching, an executive function. In 4 experiments, memory search and digit classification were performed successively in 4 conditions: search-search (search followed by search), search-digit, digit-search, and digit-digit. In a control reaction time (RT) condition, participants provided RT responses in each of the 2 tasks. In a time production condition, an RT response was provided to the first stimulus, but the response to the second stimulus, S2, was given only when participants judged that a previously presented target duration had elapsed. When responding to S2 required a switch, RTs to S2 were longer, but produced intervals were unaffected. These results show that memory search affects concurrent timing, but not task switching. Task switching seems therefore to be 1 executive function that does not interfer with timing.

Individual differences in face recognition memory: Comparison among habitual short, average, and long sleepers

Research indicates that habitual short sleepers show more rapid accumulation of slow-wave sleep at the beginning of the night. Enhancement in performance on declarative memory tasks has been associated with early NonREM sleep, consisting of the highest percentage of slow-wave sleep. Twenty-four subjects (eight short sleepers ≤7 h, nine average >7 but <9 h, seven long ≥9 h) were tested. Subjects were presented with unfamiliar face stimuli and asked to memorize them for a subsequent test. Following sleep, the subjects were presented with the 40 “old/studied” items intermixed with 40 new and asked to indicate the previously presented stimuli. Event-related potentials (ERPs) were analyzed to verify the existence of the “Old/New” effect, i.e. amplitude difference [in ERPs] between the old and new stimuli. ANOVA on the scores revealed a significant interaction between the stimuli and group. Post-hoc test on the studied items revealed more accurate responses in the short sleepers compared to the average and long sleepers. Strikingly, the long sleepers failed to show significant retention of the old/studied items, with their recognition of old faces not different from chance. Reaction time (RT) responses were faster for the old vs. the new items. Pearson correlation revealed a significant negative correlation between accuracy and sleep duration in the short sleepers. However, long and average sleepers showed a positive correlation between the two variables. ANOVA performed on the ERPs revealed main effects of stimuli and site, and no interactions involving the group factor. In conclusion, our data show that individual differences in recognition memory performance may be associated with differences in habitual sleep duration.

Age-Related Changes in Attentional Capacity and the Ability to Multi-Task as a Predictor for Falls in Adults Aged 75 Years and Older

[Purpose] Examine the age-related deterioration of attentional capacity and predictive validity of multi-tasking performances for falls in adults aged 75 and older. [Methods] This study involved 45 elderly individuals and 15 healthy and young volunteers. Reaction times to a visual stimulus were measured under three different conditions: 1) stepping in place (dual-tasking condition with dynamic balance demands); 2) counting backwards during quiet standing (dual-tasking condition with cognitive demands); and 3) counting backwards while stepping in place (triple-tasking condition). The participating elderly individuals reported subsequent falls after a 5-month follow-up period. [Results] Elderly adults demonstrated significantly longer reaction time responses in all task conditions in comparison to young adults. There were statistically significant differences in reaction times between fallers and non-fallers during dual-tasking conditions, but not during triple-tasking conditions. The slower reaction times during dual-tasking conditions with dynamic balance demands were significantly related to the occurrence of subsequent falls, whereas there was only a weak association in model-adjusted physical performance tests. [Conclusions] Attentional capacity in multi-tasking conditions decreases with aging. Slow reaction time response during dual-tasking conditions with dynamic balance demands may be a predictor of falls in adults aged 75 and older.

The Influence of Short-term Strength Training on Health-related Quality of Life and Executive Cognitive Function

Strength training has been reported as a potentially useful exercise to improve psychological aspects in the elderly, but its effects remain controversial. This study investigated the effectiveness of strength training conducted twice a week for 12 weeks for improving health-related quality of life (HRQOL) and executive cognitive function. The study was a single-blind randomized controlled trial with assessments before and after intervention. HRQOL and executive function were assessed using the SF-36 Health Status Survey and a computerized neuro-cognitive assessment using task-switch reaction time trials, respectively. Subjects comprised 119 participants > or =65 years old, randomized to either strength training (n=65) or health education classes (controls, n=54). The strength training program was designed to strengthen the large muscle groups most important for functional activities and to improve balance. The effects of the intervention on the eight dimensions of the SF-36 in the control and training groups were analyzed. Only the mental health scale of the SF-36 was significantly improved for the training group compared with controls after 12 weeks. Task-switch reaction time and correct response rate remained unchanged. Short-term strength training might have modest positive effects on HRQOL, although this training period may not be sufficient to affect executive function in relatively healthy older people.

Supplemental Material for Temporal Frequency Modulates Reaction Time Responses to First-Order and Second-Order Motion

Supplemental Material for Temporal Frequency Modulates Reaction Time Responses to First-Order and Second-Order Motion

Temporal frequency modulates reaction time responses to first-order and second-order motion.

This study investigated the effect of temporal frequency and modulation depth on reaction times for discriminating the direction of first-order (luminance-defined) and second-order (contrast-defined) motion, equated for visibility using equal multiples of direction-discrimination threshold. Results showed that reaction times were heavily influenced by temporal frequency, especially in the case of second-order motion. At 1 Hz, reaction times were faster for first-order compared with second-order motion. As temporal frequency increased, reaction times for first-order motion decreased slightly, but those for second-order motion decreased more rapidly. At 8 Hz, reaction times for second-order motion were, in many cases, faster than those for first-order motion. Reaction times decreased as stimulus modulation depth increased at approximately the same rate for both motion types. The findings demonstrate that behavioral response latencies to first-order and second-order motion are dependent on specific stimulus parameters and may, in some cases, be shorter in response to second-order compared with first-order motion.

Working memory, response inhibition, and within-subject variability in children with attention-deficit/hyperactivity disorder or reading disorder

This study compared children with ADHD (n = 19), reading disorder (RD; n = 17), ADHD+RD (n = 21), and control children (n = 19) on linguistic and executive function measures. We found no evidence of response inhibition problems in ADHD or RD when a baseline measure of functioning was taken into account. General working memory problems were only found in children with RD or ADHD+RD. Both children with ADHD and RD showed a highly inaccurate (more commission errors) and variable (higher within-subject standard deviation of reaction time) response style. The comorbid group made most errors, suggesting that different factors underlie the high error rate in both disorders.

Why cognitive performance in ADHD may not reveal true potential: Findings from a large population-based sample

Focusing on symptoms of attention deficit hyperactivity disorder (ADHD) in a sample obtained from the general population, we aimed to investigate the effects of incentives and event rate on reaction time (RT) performance and response inhibition. We assessed 1156 children, at a mean age of 8 years, on their performance on an inhibition task and a RT task under different experimental conditions that manipulated event rate and incentives. Children with high ADHD (ADHD-H) symptoms showed cognitive performance deficits only under some of the experimental conditions compared to a control group. The fast-incentive condition of the RT task succeeded in normalizing the RT variability, as well as the slow overall speed, in the ADHD-H group. Analyses of ADHD symptom scores as a quantitative trait in the total sample were overall consistent with these findings. The findings suggest that at least some cognitive performance deficits in children with high ADHD symptoms do not reflect stable cognitive deficits. The degree to which cognitive impairments in ADHD can be modulated by energetic or motivational factors has important implications for clinical and educational interventions.

Effects of acute nicotine on event-related potential and performance indices of auditory distraction in nonsmokers

Although nicotine has been purported to enhance attentional processes, this has been evidenced mostly in tasks of sustained attention, and its effects on selective attention and attentional control under conditions of distraction are less convincing. This study investigated the effects of nicotine on distractibility in 21 (11 males) nonsmokers with event-related potentials (ERPs) and behavioral performance measures extracted from an auditory discrimination task requiring a choice reaction time response to short- and long-duration tones, with and without imbedded deviants. Administered in a randomized, double-blind, placebo-controlled crossover design, nicotine gum (6 mg) failed to counter deviant-elicited behavioral distraction characterized by longer reaction times and increased response errors. Of the deviant-elicited ERP components, nicotine did not alter the P3a-indexed attentional switching to the deviant, but in females, it tended to diminish the automatic processing of the deviant as shown by a smaller mismatch negativity component, and it attenuated attentional reorienting following deviant-elicited distraction, as reflected by a reduced reorienting negativity ERP component. Results are discussed in relation to attentional models of nicotine and with respect to future research directions.

The Effect of Feedback Schedule Manipulation on Speech Priming Patterns and Reaction Time

Speech priming tasks are frequently used to delineate stages in the speech process such as lexical retrieval and motor programming. These tasks, often measured in reaction time (RT), require fast and accurate responses, reflecting maximized participant performance, to result in robust priming effects. Encouraging speed and accuracy in responding can take many forms, including verbal instructions and feedback, and often involves visually displayed RT feedback. However, it is uncertain how manipulation of the schedule of this RT feedback influences speech RT speed and, ultimately, the priming effect. This experiment examined the effect of visually presented RT feedback schedules on priming patterns in 20 older healthy adults. Results suggested that feedback schedule manipulation had a differential effect on reaction time, depending on the interstimulus interval between the prime and the target, but no effect on response priming patterns.