TY - THES A1 - Ehrlenspiel, Felix T1 - Choking under pressure : attention and motor control in performance situations T1 - Versagen unter Druck : Aufmerksamkeit und Bewegungskontrolle in Leistungssituationen N2 - When top sports performers fail or “choke” under pressure, everyone asks: why? Research has identified a number of conditions (e.g. an audience) that elicit choking and that moderate (e.g. trait-anxiety) pressure – performance relation. Furthermore, mediating processes have been investigated. For example, explicit monitoring theories link performance failure under psychological stress to an increase in attention paid to a skill and its step-by-step execution (Beilock & Carr, 2001). Many studies have provided support for these ideas. However, so far only overt performance measures have been investigated which do not allow more thorough analyses of processes or performance strategies. But also a theoretical framework has been missing, that could (a) explain the effects of explicit monitoring on skill execution and that (b) makes predictions as to what is being monitored during execution. Consequently in this study, the nodalpoint hypothesis of motor control (Hossner & Ehrlenspiel, 2006) was taken to predict movement changes on three levels of analysis at certain “nodalpoints” within the movement sequence. Performance in two different laboratory tasks was assessed with respect to overt performance (the observable result, for example accuracy in the target), covert performance (description of movement execution, for example the acceleration of body segements) and task exploitation (the utilization of task properties such as covariation). A fake competition (see Beilock & Carr, 2002) was used to invoke pressure. In study 1 a ball bouncing task in a virtual-reality set-up was chosen. Previous studies (de Rugy, Wei, Müller, & Sternad, 2003) have shown that learners are usually able to “passively” exploit the dynamical stability of the system. According to explicit monitoring theories, choking should be expected either if the task itself evokes an “active control” (Experiment 1) or if learners are provided with explicit instructions (Experiment 2). In both experiments, participants first went through a practice phase on day 1. On day 2, following the Baseline Test participants were divided into a High-Stress or No-Stress Group for the final Performance Test. The High-Stress Group entered a fake competition. Overt performance was measured by the Absolute Error (AE) of ball amplitudes from target height; covert performance was measured by Period Modulation between successive hits and task exploitation was measured by Acceleration (AC) at ball-racket impact and Covariation (COV) of impact parameters. To evoke active control in Exp. 1 (N=20), perturbations to the ball flight were introduced. In Exp. 2 (N=39) half of the participants received explicit skill-focused instructions during learning. For overt performance, results generally show an interaction between Stress Group and Test, with better performance (i. e. lower AE) for the High-Stress group in the final Performance Test. This effect is also independent of the Instructions that participants had received during learning (Exp. 2). Similar effects were found for COV but not for AC. In study 2 a visuomotor tracking task in which participants had to pursuit a target cross that was moving on an invisible curve. This curve consisted of 3 segments of 6 turning points sequentially ordered around the x-axis. Participants learned two short movement sequences which were then concatenated to form a single sequence. It was expected that under pressure, this sequence should “fall apart” at the point of concatenation. Overt Performance was assessed by the Root Mean Square Error between target and pursuit cross as well as the Absolute Error at the turning points, covert performance was measured by the Latency from target to pursuit turning and task exploitation was measured by the temporal covariation between successive intervals between turning points. Experiment 3 (intraindividual variation) as well as Experiment 4 (interindividual variation) show performance enhancement in the pressure situation on the overt level with matching results on covert and task exploitation level. Thus, contrary to previous studies, no choking under pressure was found in any of the experiments. This may be interpreted as a failure in the experimental manipulation. But certainly also important characteristics of the task are highlighted. Choking should occur in tasks where performers do not have the time to use action or thought control strategies, that are more relevant to their “self” and that are discrete in nature. N2 - Wenn Top-Athleten im Wettkampf versagen fragt sich jeder: warum? Die Forschung hat dazu einerseits Bedingungen identifiziert (z.B. die Anwesenheit von Publikum), die „Versagen“ auslösen und die Beziehung Druck- Leistung moderieren. Zudem wurden vermittelnde Prozesse gefunden wie zum Beispiel die bewusste Aufmerksamkeitsfokussierung („explicit monitoring“) auf die Ausführung der Bewegung (Beilock & Carr, 2001). Obwohl es gerade für diese Vorstellungen einige Befunde gibt, wurde bislang fast ausschließlich das Bewegungsresultat („overt performance“) untersucht, nicht aber Variablen, die Aussagen über die Bewegungsausführung zulassen. Zudem fehlt ein theoretischer Rahmen, der Vorhersagen zulässt darüber, (a) welche Veränderungen der Bewegungsausführung unter Druck zu erwarten sind und (b) welchen Stellen der Bewegung bewusst fokussiert werden. Darum wurde für diese Studie die „Knotenpunkthypothese motorischer Kontrolle“ (Hossner & Ehrlenspiel, 2006) herangezogen um auf drei Analyse-Ebenen zu ermöglichen Vorhersagen an Knotenpunkten der Bewegung zu treffen. Leistung wurde entsprechend auf einer overt-Ebene (beobachtbare Bewegungsresultat, z.B. Treffgenauigkeit), einer covert-Ebene (z.B. raum-zeitliche Verlaufe von Gelenkwinkeln) und einer task-exploitation-Ebene (z.B. die Covariation von Ausführungsparametern) untersucht. Für die Manipulation einer „Druck-Bedingung“ wurde ein Pseudowettkampf (nach Beilock & Carr, 2002) verwendet. Für die Experimente 1 und 2 wurde eine semi-virtueller „ball bouncing“-Aufgabe verwendet, für die sich gezeigt hat (de Rugy, Wei, Müller, & Sternad, 2003), dass Lernende tatsächlich in der Lage sind, die dynamische Stabilität der Aufgabe zunehmend auszunutzen. Angenommen wurde, dass Versagen unter Druck erscheinen sollte, wenn die Aufgabe entweder eine „aktive Kontrolle“ verlangt (Experiment 1) oder aber die Lernenden explizite Instruktionen während der Lernphase erhalten. Allerdings zeigen die Ergebnisse beider Experimente nur Leistungsverbesserungen unter Druck-Bedingungen auf overt-Ebene, die mit entsprechenden Verbesserungen auf covefrt- und task-exploitation-Ebene einhergehen. Für die Experimente 3 und 4 wurde eine visuomotorische Tracking-Aufgabe verwendet in der die Probanden zunächst zwei kleinere Bewegungssequenzen erlernten, bevor diese zu einer großen Sequenz verbunden wurde. Unter Druck sollte diese Gesamtsequenz „auseinander brechen“. Jedoch zeigt sich auch hier in beiden Experimenten eine Resultatsverbesserung unter Druck (gegenüber Kontrollbedingungen bzw. –gruppen) auf overt wie auf covert-Ebene. Im Gegensatz zu vielen vorangehenden Studien zeigte sich kein „Choking under Pressure“. Sicherlich stellt sich zunächst die Frage nach der Validität der Druckmanipulation, die aber zumindest für die beiden ersten Experimente gesichert scheint. Relevanter scheint demnach eine Inspektion der Aufgabe. Hier dürfte es sein, dass diskrete Aufgaben, die einen Einsatz von Handlungskontroll-Strategien nicht erlauben und die von größerer „Selbst“-Relevanz sind, eher unter Druck beeinträchtigt werden. KW - Aufmerksamkeit KW - Bewegungssteuerung KW - Leistungsdruck KW - Bewegungsanalyse KW - Knotenpunkte KW - attention KW - motor control KW - pressure KW - movement analysis KW - nodalpoints Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12377 ER - TY - GEN A1 - Mondal, Suvendu Sekhar A1 - Dey, Subarna A1 - Baburin, Igor A. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Seifert, Gotthard A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Syntheses of two imidazolate-4-amide-5-imidate linker-based hexagonal metal–organic frameworks with flexible ethoxy substituent N2 - A rare example of in situ linker generation with the formation of soft porous Zn- and Co-MOFs (IFP-9 and -10, respectively) is reported. The flexible ethoxy groups of IFP-9 and -10 protrude into the 1D hexagonal channels. The gas-sorption behavior of both materials for H2, CO2 and CH4 showed wide hysteretic isotherms, typical for MOFs having a flexible substituent which can give rise to a gate effect. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 234 KW - adsorption KW - behavior KW - carbon-dioxide KW - crystals KW - gases KW - ligand KW - pressure KW - selectivity KW - temperature KW - zinc Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-94360 SP - 9394 EP - 9399 ER - TY - JOUR A1 - Grabow, Lena A1 - Young, James D. A1 - Alcock, Lynsey R. A1 - Quigley, Patrick J. A1 - Byrne, Jeannette M. A1 - Granacher, Urs A1 - Skarabot, Jakob A1 - Behm, David George T1 - Higher Quadriceps Roller Massage Forces Do Not Amplify Range-of-Motion Increases nor Impair Strength and Jump Performance JF - Journal of strength and conditioning research : the research journal of the NSCA N2 - Grabow, L, Young, JD, Alcock, LR, Quigley, PJ, Byrne, JM, Granacher, U, Škarabot, J, and Behm, DG. Higher quadriceps roller massage forces do not amplify range-of-motion increases nor impair strength and jump performance. J Strength Cond Res 32(11): 3059–3069, 2018—Roller massage (RM) has been reported to increase range of motion (ROM) without subsequent performance decrements. However, the effects of different rolling forces have not been examined. The purpose of this study was to compare the effects of sham (RMsham), moderate (RMmod), and high (RMhigh) RM forces, calculated relative to the individuals' pain perception, on ROM, strength, and jump parameters. Sixteen healthy individuals (27 ± 4 years) participated in this study. The intervention involved three 60-second quadriceps RM bouts with RMlow (3.9/10 ± 0.64 rating of perceived pain [RPP]), RMmod (6.2/10 ± 0.64 RPP), and RMhigh (8.2/10 ± 0.44 RPP) pain conditions, respectively. A within-subject design was used to assess dependent variables (active and passive knee flexion ROM, single-leg drop jump [DJ] height, DJ contact time, DJ performance index, maximum voluntary isometric contraction [MVIC] force, and force produced in the first 200 milliseconds [F200] of the knee extensors and flexors). A 2-way repeated measures analysis of variance showed a main effect of testing time in active (p < 0.001, d = 2.54) and passive (p < 0.001, d = 3.22) ROM. Independent of the RM forces, active and passive ROM increased by 7.0% (p = 0.03, d = 2.25) and 15.4% (p < 0.001, d = 3.73) from premeasure to postmeasure, respectively. Drop jump and MVIC parameters were unaffected from pretest to posttest (p > 0.05, d = 0.33–0.84). Roller massage can be efficiently used to increase ROM without substantial pain and without subsequent performance impairments. KW - self-massage therapy KW - neuromuscular rolling KW - pressure KW - self-myofascial release Y1 - 2018 U6 - https://doi.org/10.1519/JSC.0000000000001906 SN - 1064-8011 SN - 1533-4287 VL - 32 IS - 11 SP - 3059 EP - 3069 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - JOUR A1 - Villatoro Leal, José Andrés A1 - Zühlke, Martin A1 - Riebe, Daniel A1 - Beitz, Toralf A1 - Weber, Marcus A1 - Löhmannsröben, Hans-Gerd T1 - Sub-ambient pressure IR-MALDI ion mobility spectrometer for the determination of low and high field mobilities JF - Analytical and bioanalytical chemistry : a merger of Fresenius' journal of analytical chemistry, Analusis and Quimica analitica N2 - A new ion mobility (IM) spectrometer, enabling mobility measurements in the pressure range between 5 and 500 mbar and in the reduced field strength range E/N of 5-90 Td, was developed and characterized. Reduced mobility (K-0) values were studied under low E/N (constant value) as well as high E/N (deviation from low field K-0) for a series of molecular ions in nitrogen. Infrared matrix-assisted laser desorption ionization (IR-MALDI) was used in two configurations: a source working at atmospheric pressure (AP) and, for the first time, an IR-MALDI source working with a liquid (aqueous) matrix at sub-ambient/reduced pressure (RP). The influence of RP on IR-MALDI was examined and new insights into the dispersion process were gained. This enabled the optimization of the IM spectrometer for best analytical performance. While ion desolvation is less efficient at RP, the transport of ions is more efficient, leading to intensity enhancement and an increased number of oligomer ions. When deciding between AP and RP IR-MALDI, a trade-off between intensity and resolving power has to be considered. Here, the low field mobility of peptide ions was first measured and compared with reference values from ESI-IM spectrometry (at AP) as well as collision cross sections obtained from molecular dynamics simulations. The second application was the determination of the reduced mobility of various substituted ammonium ions as a function of E/N in nitrogen. The mobility is constant up to a threshold at high E/N. Beyond this threshold, mobility increases were observed. This behavior can be explained by the loss of hydrated water molecules. KW - ion mobility spectrometry KW - IR-MALDI KW - high field mobility KW - dub-ambient KW - pressure KW - peptides Y1 - 2020 U6 - https://doi.org/10.1007/s00216-020-02735-0 SN - 1618-2642 SN - 1618-2650 VL - 412 IS - 22 SP - 5247 EP - 5260 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Wachs, Sebastian A1 - Wettstein, Alexander A1 - Bilz, Ludwig A1 - Gamez-Guadix, Manuel T1 - Motivos del discurso de odio en la adolescencia y su relación con las normas sociales BT - Adolescents' motivations to perpetrate hate speech and links with social norms JF - Comunicar : revista científica de comunicación y educación N2 - Hate speech has become a widespread phenomenon, however, it remains largely unclear why adolescents engage in it and which factors are associated with their motivations for perpetrating hate speech. To this end, we developed the multidimensional "Motivations for Hate Speech Perpetration Scale" (MHATE) and evaluated the psychometric properties. We also explored the associations between social norms and adolescents' motivations for hate speech perpetration. The sample consisted of 346 adolescents from Switzerland (54.6% boys; Mage=14; SD=0.96) who reported engagement in hate speech as perpetrators. The analyses revealed good psychometric properties for the MHATE, including good internal consistency. The most frequently endorsed subscale was revenge, followed by ideology, group conformity, status enhancement, exhilaration, and power. The results also showed that descriptive norms and peer pressure were related to a wide range of different motivations for perpetrating hate speech. Injunctive norms, however, were only associated with power. In conclusion, findings indicate that hate speech fulfills various functions. We argue that knowing the specific motivations that underlie hate speech could help us derive individually tailored prevention strategies (e.g., anger management, promoting an inclusive classroom climate). Furthermore, we suggest that practitioners working in the field of hate speech prevention give special attention to social norms surrounding adolescents. KW - Hate speech KW - cyberhate KW - motives KW - social norms KW - injunctive norms KW - peer KW - pressure Y1 - 2022 U6 - https://doi.org/10.3916/C71-2022-01 SN - 1134-3478 SN - 1988-3293 VL - 30 IS - 71 SP - 9 EP - 20 PB - Grupo Comunicar CY - Huelva ER -