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EN
Purpose. The aim of this case study is to define the involution of simple and complex reaction times in groups of adult men and women. Basic procedure. The tests were carried out during the years 2007-2008 among 128 men and 136 women aged between 21 and 80. Those examined were divided into three groups according to their calendar age. In order to define the meaning of differences of the analyzed reaction time between the results of the three age groups, the analysis of variance (ANOVA) method for independent attempts was used. Additionally, normalized differences between the groups as well as indices of sexual dimorphism were defined. Main findings. Among both men and women, gradual deterioration of reaction time performance with age can be observed. The scale of normalized differences shows that the most distinct differences are noticed between the first and the third group. They amount up to 1.3 of the standard deviation in men and up to 1.7 in women. Conclusions. The results derived from the following study confirm a long period of relative stabilization for all simple and complex reaction times among both genders. Significant involution of reaction times can be observed for all analyzed features only after the age of 55. Indices of sexual dimorphism indicate that men gain better results in all age groups. Indices of sexual dimorphism diminish with age.
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The aim of this study was to analyse the driver behaviour in simple and complex car-following situations under day- and night-time lighting conditions (four scenarios). Nearly 70 drivers participated in the tests, each taking several trials, during which they were exposed to randomly selected situations. The tests involved driving along a two-lane motorway with a vehicle in front and responding to its sudden braking. Different distances between the vehicles were simulated. The scenarios varied in complexity ranging from none to some vehicles around the subject vehicle. The study involved measuring different reaction times, i.e. the time to release the accelerator pedal, the time to apply the brake pedal and the time to start steering, to find out how the particular emergency manoeuvres contribute to the occurrence of collisions in the four scenarios. The results show that both the complexity of a road situation as well as the lighting conditions determine the type of emergency manoeuvre undertaken and the time of the driver reaction.
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Sport activities usually require a high efficiency of visual information processing. Therefore, it seems justified to determine the efficiency of visual sensorimotor processes in sports requiring a variety of perception competencies. The aim of this study was to assess the differentiation of sensorimotor processes in terms of simple and choice reaction time, and visual stimulus discrimination in various athletes and untrained persons. The study involved 119 men, of which 95 were athletes: football players (n = 24), volleyball players (n = 22), boxers (n = 26), and rowers (n = 23). The efficiency of sensorimotor processes was evaluated with the Vienna Test System (Schuhfried, Austria). The evaluations included simple reaction time (SRT), choice reaction time (CRT), and visual stimulus discrimination. Analysis of the results showed that volleyball and football players had shorter (p < 0.01) reaction times compared to non-athletes and representatives of the other sports. We found significant differences (p < 0.01) between athletes and non-athletes in visual stimulus discrimination. In addition, boxers showed fewer correct reactions than volleyball players, and shorter times of stimulus detection than in volleyball and soccer players.
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The purpose of this study was to investigate changes in reaction time of elite volleyball players during a game. Fourteen volleyball players participated in the study. Reaction time was measured using the Optojump system. In addition, blood lactate concentration was assessed to monitor physiological load during the game. All measurements were performed during a pre-game test and during sets 1, 2, 3 and 4. Reaction time during set 1 decreased significantly by 13,3 % compared with pre-game values, from 600 ms during the pre-game test to 520 ms during set 1 (p<0,05). Blood lactate concentration increased significantly during set 1, 2, 3 and 4 compared with pre-game conditions (p<0,05). Reaction time stays in the first phase of its changes pattern and elite volleyball players do not reach psychomotor fatigue threshold throughout the game.
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Visual and auditory simple reaction times for both right and left hands of young university male students were recorded with a simple reaction timer, before and after an exercise schedule without and with elevated temperatures in a climatic chamber. The results indicated a decrease in both visual and auditory reaction times after the exercise, but a marked increase in them was noticed when exercise was performed at elevated temperatures. The difference in reaction times in preferred and nonpreferred hands was negligible at rest, i.e., without any exercise and elevated temperature. However, the difference was significant when exercise was performed at elevated temperatures. Visual reaction time was longer than auditory reaction time in all conditions. The results suggest that in hot industries, increased temperature has a specific rather than general effect on cognitive processes, perception and attentiveness, leading to increased chances of human errors, fatal accidents and loss of productivity.
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Introduction.The aim of the study was to determine the age, level of achieving maximum results and growth of reaction time dynamics. Materials and methods. The study included 567 males of age between 7 and 22 years. Study materials included the results of simple reaction time and complex reaction time during progressive period. Conclusions. Progressive period of results' development lasts until the age of about 17-17.5, then stabilization of the analyzed results was observe. The most dynamic growth of all types of reaction time was observed in the analyzed 7 and 8-year-old boys.
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Volleyball is a dynamic game which requires a high level of visual skills. The first aim of this study was to investigate the several aspects of reaction times (RT) to visual stimuli in volleyball players (12) compared to non-athletic subjects (12). By using the tests included in the Vienna Test System (Schuhfried, Austria), simple reaction time (SRT), choice reaction time (CRT) and peripheral reaction time (PRT) were examined. The second aim of this study was to assess the neurophysiological basis of early visual sensory processing in both examined groups. We measured two sets of pattern-reversal visual evoked potentials (VEPs) during monocular central field stimulation (Reti Scan, Roland Consult, Germany). The latencies of waves N75, P100 and N135 were determined. We observed significantly shorter (p<0.05) total reaction time to stimuli appearing in the central and peripheral field of vision in the volleyball players compared to non-athletes. With regard to SRT and CRT the main differences between the groups appeared in pre-motor reaction times. Volleyball players had shorter VEPs P100 wave latencies (p<0.05) than the non-athlete group. The results indicate faster signal transmission in visual pathways in athletes than in non-athletes. This fact can be attributed to the effect of rapid visual-activity-demanding sports on the central nervous system.
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The paper presents the results of the behaviour of drivers in emergency/risk situations caused by a pedestrian entering the driving lane from the right. They were carried out on Kielce Track in Miedziana Góra. 100 drivers were tested in various age groups at different value risk times behind 0,5s - 3,0 s. The drivers have the opportunity to perform variant defensive manoeuvres: braking, bypassing or braking with bypassing. The researchers used a specially designed, safe model-up a pedestrian, moving on the path of a car from behind the curtains limiting the visibility of the model. The paper presents and analyses the results of measurements of the reaction times of drivers in a risk time function (mental reaction time, psychomotor reaction time while "braking", motor reaction time when braking psychomotor reaction time). The presented results of drivers reaction time confirm the thesis about the influence the risk time on reaction time. Drivers' reaction times confirm the thesis on the influence of the risk time on reaction times, both when turning and braking and also indicate a trend to shorten reaction times in difficult situations. The research method allowed for the capture of many of these disturbances though the fact of such a capture itself does not mean the possibility of their unambiguous interpretation.
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Content available remote Listeners' reaction time response to speech-in-noise material
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The paper addresses the problem of choosing speech material for the experiments concerning measurements of the composed reaction time (CRT). A comparison was done of mean reaction times measured for a group of subjects exposed to Polish vowels /a, e, i, o, u, y/ and to non-words recorded on a dummy head against traffic noise (European Standard EN 1793-3) generated from an open window. The results of this experiment, analyzed for various signal-to-noise ratios and different reverberation conditions, indicate that the mean reaction time was greater for non-words (when the subjects were exposed to more complex signals) rather then for vowels. However, differences in the relative growth of the reaction time values with decrease of signal to noise-source output difference level (SNS) were relatively small.
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We assessed the effect of physical effort with increasing intensity on the visuomotor processing in physically active young men (n=22). Subjects performed three 10-minute effort-tests with increasing intensity on a cycloergometer. Each participant was assigned individual workload values below the lactate threshold (40% VO2max), at the lactate threshold (60% VO2max) and above the lactate threshold (80% VO2max). Special Ability Signal Test included in the Vienna Test System (Schuhfried, Austria) was used to examine visuomotor processing. The numbers of correct reactions and the median reaction time as a measure of the speed of the detection process were analyzed. Four Signal test recordings were taken: pre-exercise and immediately after the three subsequent effort tests. The numbers of correct reactions increased after the first effort (40% VO2max) in comparison to the pre-exercise state and then significantly decreased after the third effort test (80% VO2max). In contrast, no significant changes in time of signal detection were observed. Physical effort with high intensity might disturb the visuomotor processing in accordance to the accuracy of the visuospatial differentiation of the relevant signal within irrelevant signals.
EN
The driver’s reaction time is one of the most important parameters for the road pre-accident analysis. There are known the results of tests, in which the value of this parameter was determined in expected and unexpected road situations. But in some cases, this time may be longer e.g. in situations in which the driver’s attention may be distracted by keeping observations other than the area, in front of the car’s surroundings. There are many manoeuvres, when the driver is obliged to observe many areas at the same time. Thus, his attention must be turned away from the main area – in front of the vehicle. The paper presents the results of tests involving the measurement of the driver’s attention time focused on observing the surrounding other than the car’s path. During the test, the driver’s attention was focus on observing the side and back mirror, car radio and at the mobile phone. Certain values can be potentially considered as extending the typical driver’s reaction time. The results of the presented tests have practical applications and can be used in the process of issuing opinions on traffic accidents.
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Extraction times for selected metal cations (Mg2+, Al3+, Zn2+, Cd2+, Cu2+, Ni2+, Co2+, Mn2+, Fe2+ and Fe3+) have been measured using cation-exchanging extractants - Versatic 10 (neodecanoic acid), DEHPA (bis(2-ethylhexyl)phosphoric acid) and Cyanex 272 (bis(2,4,4-trimetylpentyl)phosphinic acid). Data was collected directly by measuring and recording pH of the two phase reaction mixture with maintaining continuity of the aqueous phase. Similarly, the stripping rate of selected cations (Mg2+, Al3+, Zn2+, Cu2+, Ni2+, Co2+) in a sulphuric acid solution was measured. Viscosities of organic phases, saturated with cations, were measured before their stripping. Additionally, the extraction dependence of Mg2+, Al3+, Fe2+ and Fe3+ on pH was measured using Versatic 10 at various concentrations (7.5, 15 and 30 %).
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The current paper examines the role of intonation in the perception of foreign-accented speech. In order to assess how difficult it is to mentally process native, non-native and modified speech melodies, four conditions were analyzed and compared: native English, native English with Czech melody, Czech English with native melody and Czech English. The method of reaction times measurement in a word monitoring task was employed, in which 108 Czech listeners heard English sentences in the explored conditions and pressed a button when hearing a target word. Speech melody turned out to have a relatively weak but discernible impact on perceptual processing. Interestingly, Czech English proved to be more difficult to process than native English, although the listeners were Czech. The implementation of English F0 contours on Czech English speech slightly alleviated the cognitive load, however, the second hybrid, native English with Czech melody, pointed to the opposite direction. The causes of this discrepancy were investigated, particularly higher degrees of collocability in certain expressions.
EN
Introduction. The purpose of this investigation was to examine the structure of coordination motor abilities (CMA) in male basketball players at different levels of competition. Material and methods. The study included 183 male basketball players from 10 Polish sports clubs. The examined groups consisted of seniors (n=42) aged 24.5 (± 3.3), juniors (n=37) aged 16.8 (± 0.6), cadets (n=54) aged 14.5 (± 0.1) and children (n=50) aged 13.4 (± 0.2). A battery of motor tests was administered to assess the following CMA: kinesthetic differentiation of movements, spatio-temporal orientation, reaction time, movement coupling, sense of balance, sense of rhythm and adjustment of movements. The structure of CMA under investigation was determined based on the results of Hotelling's principal component analysis in Tucker's modification, completed with Kaiser's Varimax rotation [1, 2]. Results. The CMA structure of basketball players was composed of three or four factors. Most often these included rhythm, movement differentiation, movement coupling and adjustment of movements. Less frequently the structure consisted of spatio-temporal orientation, balance and reaction time. An in-depth analysis of the CMA structure revealed that factors ranged from heterogeneous (children and cadets) to homogeneous ones (juniors and seniors). The distribution of identified factors in the common variance was the smallest in children and cadets (58.9% and 62.9%, respectively) and the biggest in juniors and seniors (69.3% and 68.48%, respectively).
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In athletic sprint disciplines, the segments of start and start acceleration occupy an important place that significantly generates the final outcome of the race. The question is to what extent the start time of the reaction (latent time) has a contribution to achieving the results of sprint disciplines. The aim of the current research was to determine the influence and connection between the reaction time and the result performance of running in the disciplines of 100 m, 200 m, 400 m finalists of ten world championships. The results of a total of 456 finalists (231 men) and 225 (women) competitors who competed in the final races of the championships (from Edmonton, 2001 to Doha, 2019) were analyzed. The evaluation of the start reaction time and sprint results was based on reports officially published by the International Association of Athletics Federation (IAAF). Central and dispersion parameters were calculated for all variables. The relationship between reaction time and sprint results was calculated using the Pearson correlation coefficient, and simple regression analysis determined the direct influence of reaction time on the result success and calculated the relevant coefficients for the level of statistical significance p < 0.05. Based on the obtained results, a positive but low correlation was recorded between the mean values of the 100 m sprint results and the reaction time in men (r = 0.230p < 0.044), which was also confirmed by regression analysis. In other correlations and values of regression coefficients, no significant numerical values of the influence of reaction time on the result success were recorded in both categories of finalists.
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Time-related changes in the speeded performance of complex cognitive tasks are considered to arise from the combined effects of practice and mental fatigue. Here we explored the differential contributions of practice and fatigue to performance changes in a self-paced speeded mental addition and comparison task of about 50 min duration, administered twice within one week's time. Performance measures included average response speed, accuracy, and response speed variability. The results revealed differential effects of prolonged work on different performance indices: Practice effects, being more pronounced in the first session, were reflected in an improvement of average response speed, whereas mental fatigue, occurring in both sessions, was reflected in an increase of response speed variability. This demonstrates that effects of mental fatigue on average speed of performance may be masked by practice effects but still be detectable in the variability of performance. Therefore, besides experimental factors such as the length and complexity of tasks, indices of response speed variability should be taken into consideration when interpreting different aspects of performance in self-paced speed tests.
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PbZr0.52Ti0.48O3 nanocrystals were synthesized by a hydrothermal method. The effect of NaOH concentration, reaction temperature and time on nucleation and growth of PbZr0.52Ti0.48O3 nanocrystals was investigated. As the 0.05 mol/L PbZr0.52Ti0.48O3 precursors were heated at 200 °C for 21 h with NaOH concentration of 0.5 mol/L, the tetragonal PbZr0.52Ti0.48O3 nanocrystals were formed, and the grain size was more than 20 nm. With increasing the NaOH concentration from 0.5 to 1.5 mol/L, the grain size of PbZr0.52Ti0.48O3 nanocrystals decreased. When the precursors were heated at different temperatures (140 °C to 200 °C) for 21 h with 1.0 mol/L NaOH, single-phase PbZr0.52Ti0.48O3 nanocrystals were obtained at 160 °C to 200 °C. With increasing the reaction temperature from 160 °C to 200 °C, the grains size of PbZr0.52Ti0.48O3 nanocrystals increased from 5 nm to 9 nm. When the precursors were heated at 160 °C in different reaction times from 6 h to 21 h, the evolution from amorphous to crystalline PbZr0.52Ti0.48O3 nanocrystals in correlation with the reaction time was observed. Single crystalline PbZr0.52Ti0.48O3 nanocrystals with narrow size distribution (from 5 nm to 9 nm) were synthesized by controlling the NaOH concentration, reaction temperature and time. The obtained results can find potential application in preparing PbZr0.52Ti0.48O3 thin films on flexible substrates.
EN
The aim of this paper was to investigate whether it is possible to evaluate the relationship between different phases of sprint start objectively. The participants of the research were the top level of elite National Sprint Team (8 female, 9 male). The run times were as follows: 10.39 ±0.12 s for men and 11.63 ±0.20 s for women. The data that were taken into account during the research in order to examine typical kinetic parameters of the sprint start were: reaction time, delay between simple reaction time and reaction time (IAAF), time to front peak force, time to rear peak force, delay between end of front force and gun signal and total start time. The analysis of the study identifies the major kinematic parameters of the phases of the sprint start and block acceleration that influence the results of sprint running. The following correlation analyses were conducted, a linear regression for the typical kinetic parameters of the sprint start, initial speed on 100 metre race. Finally, a simple coaching related model for the development of sprinting is presented which is consistent with scientific evidence recommendations for coaches to make changes in training.
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Content available remote Latency of Neighborhood Based Recommender Systems
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Latency of user-based and item-based recommenders is evaluated. The two algorithms can deliver high quality predictions in dynamically changing environments. However, their response time depends not only on the size, but also on the structure of underlying datasets. This constitutes a major drawback when compared to two other competitive approaches i.e. content-based and modelbased systems. Therefore, we believe that there exists a need for comprehensive evaluation of the latency of the two algorithms. During a typical worst case scenario analysis of collaborative filtering algorithms two assumption are made. The first assumption says that data are stored in dense collections. The second assumption states that large amount of computations can be performed in advance during the training phase. As a result it is advised to deploy user-based system when the number of users is relatively small. Item-based algorithms are believed to have better technical properties when the number of items is small. We consider a situation in which the two assumptions are not necessarily met. We show that even though the latency of the two methods depends heavily on the proportion of users to items, this factor does not differentiate the two methods. We evaluate the algorithms with several real-life datasets. We augment the analysis with both graph-theoretical and experimental techniques.
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Purpose. The purpose of this study was to evaluate the effects of short-term perturbation-based balance training and a detraining period on postural control in older adults. Methods. A group of healthy older women were recruited and divided into two groups: an exercise group (EG, n = 21, age = 67.0 ± 2.0 y) that performed balance-based exercises three times a week over a sixweek period and a control group (CG, n = 20, age = 67.9 ± 3.1 y). Center-of-pressure displacement (CoP) and electromyographic data (EMG onset, time-to-peak and amplitude) were assessed during forward and backward perturbations for six leg muscles. All variables were analyzed before the training program began, at its end, and after a six-week period of detraining. A mixed ANOVA model was used to analyze the within- and between-subject results. Results. A decrease in backward CoP displacement, EMG onset and time-to-peak of the ankle muscles, especially the tibialis anterior (TA) and gastrocnemius (MG), was observed. Improvement in muscle EMG amplitude for the ankle muscles (TA, MG and Soleus - SO) at the early phase (0-200 ms) of the perturbation test, with the SO also showing an increase in amplitude at the intermediate phase (201-400 ms). After the detraining period, only the TA muscle maintained an improvement in reaction time. Conclusions. Perturbation-based balance training improved neuromuscular responses such as muscle reaction time and ankle muscle activation and consequently aided the body’s ability to maintain correct center of pressure, although after a period of detraining this gain was not maintained for most of the assessed variables.
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