Variation In Individual Performance Research Articles

Metabolic Responses and Pacing Strategies during Successive Sprint Skiing Time Trials.

This study aimed to examine the metabolic responses and pacing strategies during the performance of successive sprint time trials (STTs) in cross-country skiing. Ten well-trained male cross-country skiers performed four self-paced 1300-m STTs on a treadmill, each separated by 45 min of recovery. The simulated sprint time trial (STT) course was divided into three flat (1°) sections (S1, S3, and S5) involving the double poling subtechnique interspersed with two uphill (7°) sections (S2 and S4) involving the diagonal stride subtechnique. Treadmill velocity and V˙O2 were monitored continuously, and gross efficiency was used to estimate the anaerobic energy supply. The individual trial-to-trial variability in STTs performance time was 1.3%, where variations in O2 deficit and V˙O2 explained 69% (P < 0.05) and 11% (P > 0.05) of the variation in performance. The first and the last STTs were equally fast (228 ± 10 s) and ~1.3% faster than the second and the third STTs (P < 0.05). These two fastest STTs were associated with a 14% greater O2 deficit (P < 0.05), whereas the average V˙O2 was similar during all four STTs (86% ± 3% of V˙O2max). Positive pacing was used throughout all STTs, with significantly less time spent on the first than second course half. In addition, metabolic rates were substantially higher (~30%) for uphill than for flat skiing, indicating that pacing was regulated to the terrain. The fastest STTs were characterized primarily by a greater anaerobic energy production, which also explained 69% of the individual variation in performance. Moreover, the skiers used positive pacing and a variable exercise intensity according to the course profile, yielding an irregular distribution of anaerobic energy production.

Effects of Transcranial Direct Current Stimulation over Left Dorsolateral pFC on the Attentional Blink Depend on Individual Baseline Performance.

Selection mechanisms that dynamically gate only relevant perceptual information for further processing and sustained representation in working memory are critical for goal-directed behavior. We examined whether this gating process can be modulated by anodal transcranial direct current stimulation (tDCS) over left dorsolateral pFC (DLPFC)--a region known to play a key role in working memory and conscious access. Specifically, we examined the effects of tDCS on the magnitude of the so-called "attentional blink" (AB), a deficit in identifying the second of two targets presented in rapid succession. Thirty-four participants performed a standard AB task before (baseline), during, and after 20 min of 1-mA anodal and cathodal tDCS in two separate sessions. On the basis of previous reports linking individual differences in AB magnitude to individual differences in DLPFC activity and on suggestions that effects of tDCS depend on baseline brain activity levels, we hypothesized that anodal tDCS over left DLPFC would modulate the magnitude of the AB as a function of individual baseline AB magnitude. Indeed, individual differences analyses revealed that anodal tDCS decreased the AB in participants with a large baseline AB but increased the AB in participants with a small baseline AB. This effect was only observed during (but not after) stimulation, was not found for cathodal tDCS, and could not be explained by regression to the mean. Notably, the effects of tDCS were not apparent at the group level, highlighting the importance of taking individual variability in performance into account when evaluating the effectiveness of tDCS. These findings support the idea that left DLPFC plays a critical role in the AB and in conscious access more generally. They are also in line with the notion that there is an optimal level of prefrontal activity for cognitive function, with both too little and too much activity hurting performance.

Repetition Suppression in the Left Inferior Frontal Gyrus Predicts Tone Learning Performance.

Do individuals differ in how efficiently they process non-native sounds? To what extent do these differences relate to individual variability in sound-learning aptitude? We addressed these questions by assessing the sound-learning abilities of Dutch native speakers as they were trained on non-native tone contrasts. We used fMRI repetition suppression to the non-native tones to measure participants' neuronal processing efficiency before and after training. Although all participants improved in tone identification with training, there was large individual variability in learning performance. A repetition suppression effect to tone was found in the bilateral inferior frontal gyri (IFGs) before training. No whole-brain effect was found after training; a region-of-interest analysis, however, showed that, after training, repetition suppression to tone in the left IFG correlated positively with learning. That is, individuals who were better in learning the non-native tones showed larger repetition suppression in this area. Crucially, this was true even before training. These findings add to existing evidence that the left IFG plays an important role in sound learning and indicate that individual differences in learning aptitude stem from differences in the neuronal efficiency with which non-native sounds are processed.

An integrated population model for a long‐lived ungulate: more efficient data use with Bayesian methods

We develop an integrated population model for Svalbard reindeer Rangifer tarandus platyrhynchus, and demonstrate how this type of model can be used to extract more information from the data and separate different sources of variability in population estimates. Our model combines individual mark–recapture data with population counts and harvesting data within a Bayesian model framework, and accounts for observation error, environmental and demographic stochasticity, and age structure. From this model we obtain annual estimates of age‐specific population size, survival and fecundity. The model provides estimates of age structure at a finer scale than that found in the census data, and enables us to estimate survival for the period before calves are first caught and marked, i.e. before they enter the individual mark–recapture data. The modeling framework provides an improved approach to studying age‐structured populations that are imperfectly censused and where the demography of only a sample of individuals is known. We use data from independent censuses of the same population to evaluate population estimates obtained from the model, and show that it is successful at correcting for different types of observation error. Based on our model results, we suggest that allocating resources to the collection of supplementary mark–recapture data could improve the reliability of population projections more than making regular population censuses as exhaustive as possible. Our work demonstrates how integrated Bayesian population modeling can be used to increase the amount of information extracted from collections of data, identifying and disentangling sources of variation in individual performance and population size. This represents an important step towards increasing the predictive ability of population growth models for long‐lived species experiencing changes in environmental conditions and harvesting regimes.

Multiple brain networks underpinning word learning from fluent speech revealed by independent component analysis

Although neuroimaging studies using standard subtraction-based analysis from functional magnetic resonance imaging (fMRI) have suggested that frontal and temporal regions are involved in word learning from fluent speech, the possible contribution of different brain networks during this type of learning is still largely unknown. Indeed, univariate fMRI analyses cannot identify the full extent of distributed networks that are engaged by a complex task such as word learning. Here we used Independent Component Analysis (ICA) to characterize the different brain networks subserving word learning from an artificial language speech stream. Results were replicated in a second cohort of participants with a different linguistic background. Four spatially independent networks were associated with the task in both cohorts: (i) a dorsal Auditory-Premotor network; (ii) a dorsal Sensory-Motor network; (iii) a dorsal Fronto-Parietal network; and (iv) a ventral Fronto-Temporal network. The level of engagement of these networks varied through the learning period with only the dorsal Auditory-Premotor network being engaged across all blocks. In addition, the connectivity strength of this network in the second block of the learning phase correlated with the individual variability in word learning performance. These findings suggest that: (i) word learning relies on segregated connectivity patterns involving dorsal and ventral networks; and (ii) specifically, the dorsal auditory-premotor network connectivity strength is directly correlated with word learning performance.

Evaluation of healthy EEG responses for spelling through listener-assisted scanning.

We investigated whether listener-assisted scanning, an alternative communication method for persons with severe motor and visual impairments but preserved cognitive skills, could be used for spelling with EEG. To that end spoken letters were presented sequentially, and the participants made selections by performing motor execution/imagery or a cognitive task. The motor task was a brisk dorsiflexion of both feet, and the cognitive task was related to working memory and perception of human voice. The motor imagery task yielded the most promising results with respect to letter selection accuracy, albeit with a large variation in individual performance. The cognitive task yielded significant ( p = 0.05) albeit moderate results. Closer inspection of grand average ERPs for the cognitive task revealed task-related modulation of a late negative component, which is novel in the auditory BCI literature. Guidelines for further development are presented.

Changes in global and regional modularity associated with increasing working memory load

Using graph theory measures common to complex network analyses of neuroimaging data, the objective of this study was to explore the effects of increasing working memory processing load on functional brain network topology in a cohort of young adults. Measures of modularity in complex brain networks quantify how well a network is organized into densely interconnected communities. We investigated changes in both the large-scale modular organization of the functional brain network as a whole and regional changes in modular organization as demands on working memory increased from n = 1 to n = 2 on the standard n-back task. We further investigated the relationship between modular properties across working memory load conditions and behavioral performance. Our results showed that regional modular organization within the default mode and working memory circuits significantly changed from 1-back to 2-back task conditions. However, the regional modular organization was not associated with behavioral performance. Global measures of modular organization did not change with working memory load but were associated with individual variability in behavioral performance. These findings indicate that regional and global network properties are modulated by different aspects of working memory under increasing load conditions. These findings highlight the importance of assessing multiple features of functional brain network topology at both global and regional scales rather than focusing on a single network property.

Understanding high and low patient experience scores in primary care: analysis of patients’ survey data for general practices and individual doctors

Objectives To determine the extent to which practice level scores mask variation in individual performance between doctors within a practice.Design Analysis of postal survey of patients’ experience of face-to-face consultations...

Individual variability in visual discrimination and reversal learning performance in common marmosets

Detailed information about the characteristics of learning behavior in marmosets is useful for future marmoset research. We trained 42 marmosets in visual discrimination and reversal learning. All marmosets could learn visual discrimination, and all but one could complete reversal learning, though some marmosets failed to touch the visual stimuli and were screened out. In 87% of measurements, the final percentage of correct responses was over 95%. We quantified performance with two measures: onset trial and dynamic interval. Onset trial represents the number of trials that elapsed before the marmoset started to learn. Dynamic interval represents the number of trials from the start before reaching the final percentage of correct responses. Both measures decreased drastically as a result of the formation of discrimination learning sets. In reversal learning, both measures worsened, but the effect on onset trial was far greater. The effects of age and sex were not significant as far as we used adolescent or young adult marmosets. Unexpectedly, experimental circumstance (in the colony or isolator) had only a subtle effect on performance. However, we found that marmosets from different families exhibited different learning process characteristics, suggesting some family effect on learning.

Prospective study of the association between exercise‐induced pulmonary haemorrhage and long‐term performance inThoroughbred racehorses

Exercise-induced pulmonary haemorrhage (EIPH) is associated with impaired short-term race performance but consequences to long-term race performance of Thoroughbred racehorses are unknown. Knowledge of effects of EIPH on performance over a prolonged time would inform the need for management and treatment of this disorder. To determine the relationship between EIPH detected on a single occasion and long-term athletic performance in Thoroughbred racehorses. Prospective, longitudinal, observational epidemiological study conducted from 2003 to 2012. Seven hundred and forty-four Thoroughbred racehorses underwent a single tracheobronchoscopic examination to determine presence and severity of EIPH in 2003. Following retirement of all the horses from racing, career after examination and lifetime performance data (including career duration, earnings, starts, wins and placings) were abstracted from a commercial database. The association between presence and severity of EIPH and individual performance variables were analysed using survival analysis, linear regression and negative binomial regression. No association was detected between the presence of any EIPH (grade ≥1) and all measures of long-term performance examined except that horses with EIPH (grade ≥2) had fewer earnings after endoscopic examination than did horses with mild EIPH or no EIPH (grades ≤1). Multiple associations were detected between the most severe form of EIPH (grade 4) and measures of long-term performance suggesting that the severity of EIPH commonly associated with epistaxis adversely affects either the horse's opportunity to race or physiologic capacity to race. We conclude that there is no association between EIPH grades 0, 1, 2 and 3 and long-term racing performance of Thoroughbred racehorses. These results are based on a single endoscopic evaluation of EIPH grade made during a horse's career. Further studies are required to determine the reasons for an association of severe (grade 4) EIPH with impaired long-term race performance.

Time required to determine performance variables and production efficiency of lactating dairy cows

Thirty-five lactating dairy cows throughout weeks of lactation (WOL) 16 to 30 were used to determine optimal time needed for reliable measurement of performance variables, and to classify the cows into high-, medium-, and low-efficiency groups. Individual performance variables [body weight (BW), dry matter intake (DMI), and milk production] were measured daily with a computerized monitoring system. Body condition was visually scored weekly and used to calculate retained or depleted body energy as a result of fat content change (REF). Milk composition was analyzed weekly. Body weight, DMI, and total recovered energy (RE), which represents energy in milk production plus REF, were summarized weekly. Efficiency was calculated as RE/DMI and as residual feed intake (RFI; i.e., the difference between actual and expected DMI), which was calculated from multiple linear regression of DMI dependence on BW0.75 and RE. Unexpectedly, it was found that BW did not affect DMI and RE/DMI. Changes and relative changes in phenotypic coefficient of variation and correlations among data from shortened tests ranging from 1wk (WOL 16) to a sequence of 15-wk tests were used to determine optimal test period durations for 5 traits: BW, DMI, RE, RE/DMI, and RFI. Traits were fitted into a mixed model with repeated measures. For each week, the traits were summarized as a sequence of cumulative data, starting from WOL 16 and cumulated over periods that increased in 1-wk steps up to WOL 16 to 29. Weekly cumulations were compared with those for entire test period (WOL 16 to 30). Consistency of each cow’s efficiency classification as high, medium, or low was tested by the total-agreement procedure; the kappa index P-value was used. Throughout WOL 16 to 30, the effects of increasing test period duration on between-animal coefficient of variation differed with respect to the various performance variables and RE/DMI: it tended to change with respect to BW, did not change with respect to DMI, and decreased with respect to RE and RE/DMI. In conclusion, compared with a 15-wk study, a 2-wk study can classify RFI and RE/DMI to 3 efficiency levels, with an individual correlation coefficient of 0.6. When the study was carried out over 3wk or more, the lowest significant index of the classification was P<0.004, the lowest individual correlation coefficient was 0.65, and its lowest significance was P<0.01. The current study indicated that the insignificant effect of the BW of dairy lactating cows on their DMI should be validated in more studies.

Affective and cognitive mechanisms of risky decision making

The ability to make advantageous decisions under circumstances in which there is a risk of adverse consequences is an important component of adaptive behavior; however, extremes in risk taking (either high or low) can be maladaptive and are characteristic of a number of neuropsychiatric disorders. To better understand the contributions of various affective and cognitive factors to risky decision making, cohorts of male Long-Evans rats were trained in a “Risky Decision making Task” (RDT), in which they made discrete trial choices between a small, “safe” food reward and a large, “risky” food reward accompanied by varying probabilities of footshock. Experiment 1 evaluated the relative contributions of the affective stimuli (i.e., punishment vs. reward) to RDT performance by parametrically varying the magnitudes of the footshock and large reward. Varying the shock magnitude had a significant impact on choice of the large, “risky” reward, such that greater magnitudes were associated with reduced choice of the large reward. In contrast, varying the large, “risky” reward magnitude had minimal influence on reward choice. Experiment 2 compared individual variability in RDT performance with performance in an attentional set shifting task (assessing cognitive flexibility), a delayed response task (assessing working memory), and a delay discounting task (assessing impulsive choice). Rats characterized as risk averse in the RDT made more perseverative errors on the set shifting task than did their risk taking counterparts, whereas RDT performance was not related to working memory abilities or impulsive choice. In addition, rats that showed greater delay discounting (greater impulsive choice) showed corresponding poorer performance in the working memory task. Together, these results suggest that reward-related decision making under risk of punishment is more strongly influenced by the punishment than by the reward, and that risky and impulsive decision making are associated with distinct components of executive function.

Spontaneous neuronal activity predicts intersubject variations in executive control of attention

Executive control of attention regulates our thoughts, emotion and behavior. Individual differences in executive control are associated with task-related differences in brain activity. But it is unknown whether attentional differences depend on endogenous (resting state) brain activity and to what extent regional fluctuations and functional connectivity contribute to individual variations in executive control processing. Here, we explored the potential contribution of intrinsic brain activity to executive control by using resting-state functional magnetic resonance imaging (fMRI). Using the amplitude of low-frequency fluctuations (ALFF) as an index of spontaneous brain activity, we found that ALFF in the right precuneus (PCUN) and the medial part of left superior frontal gyrus (msFC) was significantly correlated with the efficiency of executive control processing. Crucially, the strengths of functional connectivity between the right PCUN/left msFC and distributed brain regions, including the left fusiform gyrus, right inferior frontal gyrus, left superior frontal gyrus and right precentral gyrus, were correlated with individual differences in executive performance. Together, the ALFF and functional connectivity accounted for 67% of the variability in behavioral performance. Moreover, the strength of functional connectivity between specific regions could predict more individual variability in executive control performance than regionally specific fluctuations. In conclusion, our findings suggest that spontaneous brain activity may reflect or underpin executive control of attention. It will provide new insights into the origins of inter-individual variability in human executive control processing.

Is Performance Variability Necessary? A Qualitative Study on Cognitive Resilience in Forestry Work

In forestry work, conditions exist and develop that are complex, unpredictable, and highly consequential and therefore cannot be handled entirely by following static work procedures. Cognitive adjustments are necessary. The objective of this research was to determine whether performance (cognitive) variability is actually necessary to safely fell trees in the coastal region of British Columbia, Canada. In this paper two perspectives were contrasted: the traditional view of safety and the resilience perspective. A collection of empirical evidence established that while safe work procedures provide a good foundation, it is individual performance variability shaped by experience and ‘‘know-how’’ that guides the application of technical skills in such a complex, dynamic, high-risk environment.

The production of relative clauses by Italian cochlear-implanted and hearing children

This study investigates the elicited production of subject (SRs) and object relatives (ORs) in Italian by 13 cochlear-implanted (CI) children (age: 7;9–10;8) to determine whether and to what extent they differ from three groups of 13 normal hearing (NH) children matched on morphosyntactic abilities (age: 5;0–7;9), chronological age (age: 7;5–10;3), and auditory age (e.g. duration of CI use (age: 4;11–9;4)) respectively.Results showed that for CI children, SRs are more accurate than ORs. The same asymmetry is observed in all NH groups, although NH children's percentages of target responses are higher for both sentence typologies.The syntactic difficulty with ORs led CI and NH groups to adopt a considerable number of answering strategies: among them, production of passive relatives, causative constructions, and wh- elements replacing the complementizer che (‘that’).Individual performance variability within the CI group is observed. Some CI children showed good competence in Italian and age-peer performance by producing passive relatives, which are largely attested in older children's production. For other CI children, however, the tendency to produce sentences attested in young children's production is evidence of the linguistic delay associated to hearing impairment. In this case, the performance of these CI children was comparable to that of younger NH children.

Gestural Workspaces for Computer Interaction

While the hardware challenges facing integration of hand-gestural controls into mainstream computer interfaces appear to be shrinking, design challenges related to the physical and mental burden required of gesture interfaces remain. This study aims to determine the effect of the gestural workspace configuration (vertical, horizontal, and jointspace) and affordance of arm support on speed, accuracy, and performance when performing pointing tasks on a computer. Seventeen participants played a computer card game (Solitaire) and then completed Fitts’ serial clicking tasks to evaluate performance in five gestural workspace configurations implemented using a Microsoft Kinect®. Gestural input configurations were also compared to a traditional mouse input. A traditional mouse performed better than gestural controls in all aspects of performance. Among gestural workspaces, the vertical configuration performed significantly better in throughput and accuracy outcomes. Limitations of the gestural tracking system and large variation in individual performance may hinder establishment of generalized design recommendations at this point; however, gestural workspace configurations with direct mapping to onscreen movements and the presence of supporting surfaces appear to increase user performance and reduce perceived difficulty.

Distinct manifestations of executive dysfunction in aged rats

Different components of executive function such as working memory, attention, and cognitive flexibility can be dissociated behaviorally and mechanistically; however, the within-subject influences of normal aging on different aspects of executive function remain ill-defined. To better define these relationships, young adult and aged male F344 rats were cross-characterized on an attentional set-shifting task that assesses cognitive flexibility and a delayed response task that assesses working memory. Across tasks, aged rats were impaired relative to young; however, there was significant variability in individual performance within the aged cohort. Notably, performance on the set-shifting task and performance at long delays on the delayed response task were inversely related among aged rats. Additional experiments showed no relationship between aged rats' performance on the set-shifting task and performance on a hippocampal-dependent spatial reference memory task. These data indicate that normal aging can produce distinct manifestations of executive dysfunction, and support the need to better understand the unique mechanisms contributing to different forms of prefrontal cortical-supported executive decline across the lifespan.

Are golf-shots distinguished by power control? Or it is just individual differences?

The purpose of this study was to compare individual shots by different players in terms of control of power as a biomechanical aspect. This study expected that there might be similarity in power of golf shots irrespective of individual players. For the study, 5 different powers of golf shots (70%, 80%, 90%, Max and round style) were measured by 10 Vicon cameras, 2 AMTI force plates and the Flightscope analysis system (Kudu). Biomechanical indicators for the measurement were 10 indicators that were measured in 5 events during golf-swing such as address, top of backswing, middle of downswing, left foot GRF peak and impact. The Self-Organising Map, which is an artificial intelligence technique, was used to compare how each individual is able to be distinguished from others. The Self-Organising Map was designed and applied to the data analysis with a batch learning algorithm in order to update weight vectors between nodes in the Self-Organising Map. As a result, golf shots were distinguished by each individual player, but not by power of shots in terms of biomechanical factors. Consequently, this study was found variability of individual performance (with lower handicap golf players).

Changes in Task-Related Functional Connectivity across Multiple Spatial Scales Are Related to Reading Performance

Reading requires the interaction of a distributed set of cortical areas whose distinct patterns give rise to a wide range of individual skill. However, the nature of these neural interactions and their relation to reading performance are still poorly understood. Functional connectivity analyses of fMRI data can be used to characterize the nature of interactivity of distributed brain networks, yet most previous studies have focused on connectivity during task-free (i.e., “resting state”) conditions. Here, we report new methods for assessing task-related functional connectivity using data-driven graph theoretical methods and describe how large-scale patterns of connectivity relate to individual variability in reading performance among children. We found that connectivity patterns of subjects performing a reading task could be decomposed hierarchically into multiple sub-networks, and we observed stronger long-range interaction between sub-networks in subjects with higher task accuracy. Additionally, we found a network of hub regions known to be critical to reading that displays increased short-range synchronization in higher accuracy subjects. These individual differences in task-related functional connectivity reveal that increased interaction between distant regions, coupled with selective local integration within key regions, is associated with better reading performance. Importantly, we show that task-related neuroimaging data contains far more information than usually extracted via standard univariate analyses – information that can meaningfully relate neural connectivity patterns to cognition and task.

Examining the Correspondence between Self-Regulated Learning and Academic Achievement: A Case Study Analysis

Four high school students received 11 weeks of a self-regulated learning (SRL) intervention, called the Self-Regulation Empowerment Program (SREP), to improve their classroom-based biology exam scores, SRL, and motivated behaviors. This mixed model case study examined the correspondence between shifts in students’ strategic, regulated behaviors with their performance on classroom-based biology tests. The authors used traditional SRL assessment tools in a pretest-posttest fashion (e.g., self-report questionnaires, teaching rating scales) and gathered SRL data during the intervention using field note observations and contextualized structured interviews. This multidimensional assessment approach was used to establish convergence among the assessment tools and to facilitate interpretation of trends in students’ biology test performance relative to their SRL processes. Key themes in this study included the following: (a) the close correspondence between changes in students SRL, biology exam performance, and SREP attendance; (b) individual variability in student performance, SRL behaviors, and beliefs in response to SREP; and (c) the importance of using a multi-dimensional assessment approach in SRL intervention research. Furthermore, this study provided additional support for the potential effectiveness of SREP in academic contexts.