Differences In Initial Performance Research Articles

Higher surface folding of the human premotor cortex is associated with better long-term learning capability

The capacity to learn enabled the human species to adapt to various challenging environmental conditions and pass important achievements on to the next generation. A growing body of research suggests links between neocortical folding properties and numerous aspects of human behavior, but their impact on enhanced human learning capacity remains unexplored. Here we leverage three training cohorts to demonstrate that higher levels of premotor cortical folding reliably predict individual long-term learning gains in a challenging new motor task, above and beyond initial performance differences. Individual folding-related predisposition to motor learning was found to be independent of cortical thickness and intracortical microstructure, but dependent on larger cortical surface area in premotor regions. We further show that learning-relevant features of cortical folding occurred in close spatial proximity to practice-induced structural brain plasticity. Our results suggest a link between neocortical surface folding and human behavioral adaptability.

Metal-supported solid oxide fuel cells operating with reformed natural gas and sulfur

The performance, long-term durability, and thermal cycling tolerance of metal supported solid oxide fuel cells (MS-SOFCs) operating with natural gas reformate fuels is assessed. Symmetric MS-SOFCs with composite SDC-Ni anode catalysts and PrO x cathode catalysts are operated with simulated natural gas steam-reformate and partial-oxidation-reformate fuels with 1 ppm and 5 ppm of sulfur. Cells are operated for 1000 h with initial degradation rates similar to humidified H 2 , and initial performance differences attributed to the lower H 2 concentration in reformate fuels. Additionally, cells tolerate many aggressive thermal cycles with sulfur present, with minimal impact on performance. Post mortem analysis suggests that Ni particle coarsening and Cr deposition are sources of degradation, while carbon and sulfur deposition are not observed. Overall, MS-SOFCs operate successfully with reformed natural gas. • MS-SOFCs are operated for 1000 h with natural gas reformates. • Cells tolerate sulfur levels exceeding typical natural gas pipeline levels. • Cells show high reliance toward aggressive thermal cycling.

Acquisition of Mathematical and Linguistic Skills in Children With Learning Difficulties.

Comorbid learning difficulties in linguistic and mathematical skills often emerge in primary school age. The cause of coinciding of both learning difficulties during children’s development spanning pre- and primary-school age is not yet well understood. To address this research gap, we used data from the German National Educational Panel Study (NEPS; n = 301) of four groups of children which were categorized according to their skill levels in pre-school age: children with learning difficulties isolated in linguistic skills (LD), children with learning difficulties isolated in mathematical skills (MD), children with learning difficulties combined in linguistic and mathematical skills (MD/LD), and children with typical development in both skills (TA). Computing univariate and repeated measures ANCOVAs we compared the mathematical and linguistic development of the four groups of children (LD, MD, LD/MD, and TA) spanning age four to ten. Results reveal a partial catch-up in linguistic skills (lexical, grammatical) for children with LD. In contrast, children with MD did not overcome their mathematical competence gap in comparison with TA and LD. Moreover, children with MD showed a decrease in grammatical skills during transition in primary school. Further, children with MD/LD displayed the weakest performance in linguistic and mathematical skills during pre- and primary-school age in general. However, after controlling for working memory, initial performance differences between the groups decreased in favor of MD/LD. The relation between linguistic skills and mathematical skills in persisting learning difficulties as well as the specific role of working memory are discussed.

Initial performance modulates the effects of cathodal transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex on inhibitory control

Transcranial direct current stimulation (tDCS) has received considerable attention as a new option to facilitate cognitive ability or rehabilitation in healthy populations or in individuals with neuropsychiatric disorders. However, the tDCS effect varies widely, possibly because individual differences in initial performance have frequently been ignored in previous research. Here, we aimed to examine the influence of initial performance on inhibitory control after tDCS. Fifty-six participants were randomly divided into three groups: anodal, cathodal and sham stimulation. The go/no-go task, stop-signal task and Stroop task were performed to measure inhibitory control before and immediately after tDCS. tDCS was applied to the F4 site (international 10–20 system), corresponding to the right dorsolateral prefrontal cortex (rDLPFC), for 20 min with an intensity of 1.5 mA. Neither anodal nor cathodal stimulation had significant effects on the performance of these three tasks at the group level in comparison with sham stimulation. However, the analyses at the individual level only showed a negative relationship between baseline performance and the magnitude of change in go/no-go task performance following cathodal tDCS, indicating the dependence of the change amount on initial performance, with greater gains (or losses) observed in individuals with poorer (or better) initial performance. Together, the initial performance modulates the proactive inhibitory effect of cathodal tDCS of the rDLPFC. Additionally, the rDLPFC plays a crucial role in proactive inhibition.

The initial visual performance modulates the effects of anodal transcranial direct current stimulation over the primary visual cortex on the contrast sensitivity function

Transcranial direct current stimulation (tDCS) has great potential to modulate cortical excitability and further facilitate visual function or rehabilitation. However, tDCS modulation effects are largely variable, possibly because of the individual differences in initial performance. The present study investigated the influence of the initial performance on contrast sensitivity function (CSF) following tDCS. Fifty healthy participants were randomly assigned to three groups: anodal, cathodal and sham stimulation. The CSF was measured through a grating detection task before and immediately after tDCS. Active and reference electrodes were applied to the primary occipital cortex (Oz) and the middle of the head (Cz) for 20 min with an intensity of 1.5 mA, respectively. Compared with sham stimulation, anodal or cathodal stimulation had no effect on the area under the log CSF (AULCSF) or contrast sensitivity (CS) of various spatial frequencies at the group level. However, a negative relationship was found between initial performance and the AULCSF change (or CS change at a spatial of frequency 8 c/°) after the application of anodal tDCS, indicating that the degree of change was dependent on initial performance, with greater gains observed for those with poorer initial performance. Initial performance modulated the effect of anodal tDCS over the Oz on the CSF, indicating that the Oz plays a crucial role in visual function. These results contribute to a deep understanding of the mechanisms of tDCS and to the design of more precise and efficient personalized simulation approaches based on individual differences.

Multi-Technique Characterization of Gas Diffusion Fuel Cell Electrodes

The development of large-scale manufacturing capabilities for the most critical component in polymer electrolyte membrane fuel cells (PEMFC), the membrane electrode assembly (MEA) is essential for the commercialization of this technology. Most commonly, the catalyst is combined with a solvent to make an ink, which is then deposited onto the polymer membrane, producing a catalyst coated membrane (CCM). Gas diffusion electrodes (GDEs), in which the catalyst layer (CL) is deposited directly on the gas diffusion media (GDM) are easier to manufacture in a roll-to-roll (R2R) fashion. Additionally, some of the issues associated with polymer electrolyte membrane swelling that are observed during CCM fabrication are eliminated with R2R GDEs. While significant work has been done to study the differences in initial performance for CCM based MEAs further studies are needed on electrodes made with scalable routes.This work focuses on comparing several spectroscopic characterization methods that were applied to a set of GDEs to better understand the bulk and local ionomer distribution and its correlation to initial performance metrics. The GDEs were made with a state-of-the-art Pt catalyst supported on high surface area carbon, a 0.9 ionomer to carbon ratio, and a 1-propanol and water ink solvent mixture. The GDEs in this study were fabricated by an ultrasonic spraying system, as well as, by slot die and gravure roll-to-roll coating methods. Various ink solvent ratios were used, and in the case of the sprayed electrodes the incorporation of additional ionomer on the GDE surface was explored. The F/Pt ratio of all the GDEs was measured by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) probing the difference in the ionomer amount at different depth (around 10 vs 100 nm). Additionally, scanning transmission electron microscopy (STEM-EDS) analysis of the electrode cross-sections was performed at low magnifications to measure F/Pt ratio within the entire thickness of the electrode as well as at a higher magnification to probe the local F/Pt ratio inside of the catalyst layer (CL). The F/Pt from the three techniques was then correlated with the initial performance metrics of potential at 1 A/cm2 and at 1.5 A/cm2, as well as, CL resistance, and electrochemically active surface area (ECSA). It was found that values extracted from both SEM-EDS and XPS show similar correlations that track with the initial performance values. The R2R slot die GDE with a high water ink content showed the highest F/Pt at the surface of the electrode and demonstrated the best performance. A certain range of ionomer content present at the electrode surface was shown to induce a more favorable Cl/membrane interface improving the fuel cell performance. This work highlights the importance of assessing the composition and structure of fuel cell electrodes at different surface depths and builds towards identifying key metrics that correlate to performance that can be derived quickly to explore a larger space of processing and fabrication parameters.

Visual motion perception improvements following direct current stimulation over V5 are dependent on initial performance.

Transcranial direct current stimulation (tDCS) can improve visual perception. However, the effect of tDCS on visual perception is largely variable, possibly due to individual differences in initial performance. The goal of the present study was to evaluate the dependency of visual motion perception improvements on initial performance. Twenty-eight observers were randomly divided into two groups. Anodal tDCS and sham stimulation were separately applied to V5 (1.5mA, 20min), while observers performed a coherent motion direction identification task. The results showed that compared to sham stimulation, anodal tDCS induced a significant improvement in motion perception that lasted at least 20min. In addition, the degree of improvement was dependent on initial performance, with a greater improvement magnitude observed for those with poorer initial performance. These results may have implications for understanding the nature of the stimulation rule and for the use of a customised stimulation protocol to enhance tDCS efficiency in practical applications.

157 Impact of weaning strategy on heifer performance and reproductive development

Abstract Weaning is recognized as one of the most stressful times of a beef calf’s post-natal life. The objective of this study was to determine if weaning strategy impacts heifer development and reproduction. At 7 months of age, 96 predominantly Angus heifers at 2 locations were assigned to 1 of 3 weaning treatments: abrupt relocation of the calf on d0 (Abrupt, n = 32), fenceline contact starting on d0 prior to relocation of the calf on d7 (Fence, n = 33), and abrupt relocation of the calf on d84 (Late, n = 31). Calf weights, hip heights, and body condition scores (BCS) were collected to evaluate post-weaning performance. Reproductive tract scores (RTS; 0–5 scale, 5=most mature) were assigned every 54 days from d56 to d218. Heifers were synchronized using a 7-day CO-Synch + CIDR® protocol and artificially inseminated (AI) on d246. Data were analyzed using PROC MIXED of SAS with repeated measures. Statistical significance was determined at P ≤ 0.05. Late heifers were heavier at d28 and d56 than Abrupt and Fence (P < 0.05), but BW was similar across treatments starting at d84. Average daily gain (ADG) was greater for Late than Abrupt (0.39 and -0.03 kg/day respectively; P < 0.01) and tended to be greater than Fence (0.16 kg/day; P = 0.07) to d28; however, Late had lower ADG than Abrupt and Fence from d28-84 (0.66, 0.83, and 0.81 kg/day respectively; P < 0.05). No treatment differences were observed in BCS or hip height. Late tended to have greater RTS than Abrupt and Fence (2.54, 2.20, and 2.16 respectively; P ≤ 0.10) on d56, but there was no difference on or after d164. Fence tended to have greater AI conception rates than Abrupt and Late (66%, 44%, and 42% respectively; P ≤ 0.08). This data indicates there were initial performance differences based on weaning strategy, but this had minimal impact on heifer development.

Early Numeracy Trajectories: Baseline Performance Levels and Growth Rates in Young Children by Disability Status

Data indicate that children with disabilities typically display lower levels of proficiency in mathematics than their nondisabled peers, with this difference remaining stable over time. Although literature exists regarding school-age children, few studies have examined early numeracy skills of preschoolers and child characteristics associated with performance and growth over time. Thus, the purpose of this study is to examine the performance and growth over time of preschool-age children who have a disability and those without a disability to determine whether patterns of performance are evident at this age and how patterns may differ between the two groups. Results from a sample of children enrolled in inclusive preschool classrooms ( N = 205) indicated differences in initial performance as well as growth over time across measures of oral counting, quantity discrimination, and one-to-one counting; fewer differences were noted for numeral recognition. Results are discussed in the context of early identification and intervention.

Testing Sleep Consolidation in Skill Learning: A Field Study Using an Online Game.

Using an observational sample of players of a simple online game (n>1.2million), we are able to trace the development of skill in that game. Information on playing time, and player location, allows us to estimate time of day during which practice took place. We compare those whose breaks in practice probably contained a night's sleep and those whose breaks in practice probably did not contain a night's sleep. Our analysis confirms experimental evidence showing a benefit of spacing for skill learning, but it fails to find any additional benefit of sleeping during a break from practice. We discuss reasons why the well-established phenomenon of sleep consolidation might not manifest in an observational study of skill development. We put the spacing effect into the context of the other known influences on skill learning: improvement with practice, and individual differences in initial performance. Analysis of performance data from games allows experimental results to be demonstrated outside of the lab and for experimental phenomenon to be put in the context of the performance of the whole task.

Motor Learning: An Analysis of 100 Trials of a Ski Slalom Game in Children with and without Developmental Coordination Disorder

ObjectiveAlthough Developmental Coordination Disorder (DCD) is often characterized as a skill acquisition deficit disorder, few studies have addressed the process of motor learning. This study examined learning of a novel motor task; the Wii Fit ski slalom game. The main objectives were to determine: 1) whether learning occurs over 100 trial runs of the game, 2) if the learning curve is different between children with and without DCD, 3) if learning is different in an easier or harder version of the task, 4) if learning transfers to other balance tasks.Method17 children with DCD (6–10 years) and a matched control group of 17 typically developing (TD) children engaged in 20 minutes of gaming, twice a week for five weeks. Each training session comprised of alternating trial runs, with five runs at an easy level and five runs at a difficult level. Wii scores, which combine speed and accuracy per run, were recorded. Standardized balance tasks were used to measure transfer.ResultsSignificant differences in initial performance were found between groups on the Wii score and balance tasks. Both groups improved their Wii score over the five weeks. Improvement in the easy and in the hard task did not differ between groups. Retention in the time between training sessions was not different between TD and DCD groups either. The DCD group improved significantly on all balance tasks.ConclusionsThe findings in this study give a fairly coherent picture of the learning process over a medium time scale (5 weeks) in children novice to active computer games; they learn, retain and there is evidence of transfer to other balance tasks. The rate of motor learning is similar for those with and without DCD. Our results raise a number of questions about motor learning that need to be addressed in future research.

The effects of acoustic variability on absolute pitch categorization: Evidence of contextual tuning.

Absolute pitch (AP) is defined as the ability to label a musical note without the aid of a reference note. Despite the large amounts of acoustic variability encountered in music, AP listeners generally experience perceptual constancy for different exemplars within note categories (e.g., recognizing that a C played on a tuba belongs to the same category as a C played on a piccolo). The present studies investigate whether AP possessors are sensitive to context variability along acoustic dimensions that are not inherently linked to the typical definition of a note category. In a speeded target recognition task, AP participants heard a sequence of notes and pressed a button whenever they heard a designated target note. Within a trial the sequence of notes was either blocked according to note-irrelevant variation or contained a mix of different instruments (Experiment 1), amplitude levels (Experiment 2), or octaves (Experiment 3). Compared to the blocked trials, participants were significantly slower to respond in the mixed-instrument and mixed-octave trials, but not the mixed-amplitude trials. Importantly, this performance difference could not be solely attributed to initial performance differences between instruments, amplitudes, or octaves. These results suggest that AP note identification is contextually sensitive.

Rapid adaptation to time-compressed speech in young and older adults.

The ability of human listeners to comprehend rapid speech improves quickly with experience, a process known as adaptation. Whether inefficient adaptation to rapid speech partially accounts for the marked difficulties of older listeners with rapid speech is not clear. Two conditions of adaptation to time-compressed speech were used. A baseline condition intended to test the hypothesis that adaptation is different in older and younger listeners, and an interference condition in which sentences compressed to two different rates were interleaved. Identification accuracy was compared between two time points (before and after adaptation) and between older and younger listeners. The effects of adaptation did not differ between younger and older listeners in either adaptation condition. It seems that once initial performance differences are taken into account, rapid adaptation to time-compressed speech is as effective and as immune to interference by competing speech rates in younger and older adults.

Learning fast accurate movements requires intact frontostriatal circuits

The basal ganglia are known to play a crucial role in movement execution, but their importance for motor skill learning remains unclear. Obstacles to our understanding include the lack of a universally accepted definition of motor skill learning (definition confound), and difficulties in distinguishing learning deficits from execution impairments (performance confound). We studied how healthy subjects and subjects with a basal ganglia disorder learn fast accurate reaching movements. We addressed the definition and performance confounds by: (1) focusing on an operationally defined core element of motor skill learning (speed-accuracy learning), and (2) using normal variation in initial performance to separate movement execution impairment from motor learning abnormalities. We measured motor skill learning as performance improvement in a reaching task with a speed-accuracy trade-off. We compared the performance of subjects with Huntington's disease (HD), a neurodegenerative basal ganglia disorder, to that of premanifest carriers of the HD mutation and of control subjects. The initial movements of HD subjects were less skilled (slower and/or less accurate) than those of control subjects. To factor out these differences in initial execution, we modeled the relationship between learning and baseline performance in control subjects. Subjects with HD exhibited a clear learning impairment that was not explained by differences in initial performance. These results support a role for the basal ganglia in both movement execution and motor skill learning.

Openness to Experience as a Predictor of Job Performance Trajectories

The present study used a longitudinal design to examine the relationship between openness to experience and 4‐year job performance trajectories for a sample of 129 newly employed professionals. For the typical person, performance increases decelerated over time, plateaued at 2.93 years, and then started to decline thereafter. Openness was not significantly related to initial performance differences or the initial linear rate of growth in performance; however, the performance of individuals high on openness decelerated at a slower rate and started to decline at a later point in time than that of individuals low on openness. We discuss the implications of our findings for theories of job performance and for the use of openness measures in selection contexts.

Use of auditory learning to manage listening problems in children

This paper reviews recent studies that have used adaptive auditory training to address communication problems experienced by some children in their everyday life. It considers the auditory contribution to developmental listening and language problems and the underlying principles of auditory learning that may drive further refinement of auditory learning applications. Following strong claims that language and listening skills in children could be improved by auditory learning, researchers have debated what aspect of training contributed to the improvement and even whether the claimed improvements reflect primarily a retest effect on the skill measures. Key to understanding this research have been more circumscribed studies of the transfer of learning and the use of multiple control groups to examine auditory and non-auditory contributions to the learning. Significant auditory learning can occur during relatively brief periods of training. As children mature, their ability to train improves, but the relation between the duration of training, amount of learning and benefit remains unclear. Individual differences in initial performance and amount of subsequent learning advocate tailoring training to individual learners. The mechanisms of learning remain obscure, especially in children, but it appears that the development of cognitive skills is of at least equal importance to the refinement of sensory processing. Promotion of retention and transfer of learning are major goals for further research.

Age Differences on a Paired-Associates Task: How Does Practice Type and Order Affect Training?

The purpose of this research was to determine if manipulating the order and type of practice would affect the outcome of training for both young and older adults. We examined age differences in performance on a paired-associates task in which type and order of practice were manipulated. Two versions of a noun-pair associates task were used; in the consistent mapping (CM) version the noun-pairs did not change from trial to trial; in the varied mapping version (VM) the noun-pairs changed from trial to trial. The CM task allowed the subjects to learn the noun-pairs whereas the VM task required that subjects always refer to a key in order to perform the task. Two groups of subjects were trained and the order in which they received the CM and VM versions was manipulated between groups. There were group differences in initial performance on the CM task for both young and older adults. The data indicate that having performed the task at all provided some benefit in terms of reaction time. The subjects were able to acquire the skill of performing the task in the first version they performed and this skill acquisition aided their subsequent performance. In addition, the benefits of prior practice were longer-lasting for older adults relative to young adults.

Stabilometer Performance of Educable Mentally Retarded Children under Differential Feedback Conditions

Abstract Twelve trials on a stabilometer task were administered to 100 educable mentally retarded children whose IQs ranged from 55 to 80 and whose mean age was 12.6 years. Four groups were trained under different supplementary auditory or visual feedback conditions while a fifth group was trained under control conditions. Using the mean time-in-balance (TIB) as the criterion measure, there were no initial performance differences among groups. Significant TIB performance differences among groups were demonstrated during the supplementary feedback training sessions; the visual/in-balance group demonstrated performance superiority. Final performance measures, obtained after withdrawal from the feedback conditions, were compared among groups; the visual/in-balance group maintained performance superiority over all other study groups. Comparisons within groups, from initial to final performance, indicated that only the control group failed to demonstrate significant performance gains and, therefore, did not ac...

Novelty and familiarity as redundant cues in retardate discrimination learning

Forty retarded children, a Low Mental Age (MA) Group (mean MA 3-3 yrs.) and a High MA Group (mean MA 5–7 yrs.) were trained on 120 different two-choice visual discrimination problems. For all subjects, half of these problems were standard four-trial problems (Standard Condition). The remaining 60 problems were variants of the Moss-Harlow Design, the first trial differing from the initial two-choice trial of the Standard Condition in having only a single stimulus present, either the positive stimulus (Positive Condition) or the negative stimulus (Negative Condition), in both cases followed by three trials with both stimuli present. Each subject received either Positive Condition Problems or Negative Condition Problems, but not both. An analysis of Trial 2 performance revealed that although no interproblem changes in the Standard Condition occurred, there were large initial performance differences and large interproblem changes in the Positive and Negative Conditions which varied with MA. Initial performance differences were interpreted as a differential preference for novel and familiar stimuli in the two MA Groups. Changes in interproblem performance were consistent with the hypothesis that these MA dependent novelty-familiarity preferences could be influenced by novelty-familiarity redundancy training. These interpretations were supported by predictions from theory.