Implicit Contextual Integrity in Online Social Networks

Many real incidents demonstrate that users of Online Social Networks need mechanisms that help them manage their interactions by increasing the awareness of the different contexts that coexist in Online Social Networks and preventing them from exchanging inappropriate information in those contexts or disseminating sensitive information from some contexts to others. Contextual integrity is a privacy theory that conceptualises the appropriateness of information sharing based on the contexts in which this information is to be shared. Computational models of Contextual Integrity assume the existence of well-defined contexts, in which individuals enact pre-defined roles and information sharing is governed by an explicit set of norms. However, contexts in Online Social Networks are known to be implicit, unknown a priori and ever changing; users relationships are constantly evolving; and the information sharing norms are implicit. This makes current Contextual Integrity models not suitable for Online Social Networks. In this paper, we propose the first computational model of \emph{Implicit} Contextual Integrity, presenting an information model for Implicit Contextual Integrity as well as a so-called Information Assistant Agent that uses the information model to learn implicit contexts, relationships and the information sharing norms in order to help users avoid inappropriate information exchanges and undesired information disseminations. Through an experimental evaluation, we validate the properties of the model proposed. In particular, Information Assistant Agents are shown to: (i) infer the information sharing norms even if a small proportion of the users follow the norms and in presence of malicious users; (ii) help reduce the exchange of inappropriate information and the dissemination of sensitive information with only a partial view of the system and the information received and sent by their users; and (iii) minimise the burden to the users in terms of raising unnecessary alerts

Exploring the influence of practice design on the development of tennis players

This thesis examined the efficacy of contemporary tennis practice for maximizing skill learning and transfer to competition performance. Theory suggests that experimental and practice tasks should be designed to promote emergent behaviours that are functional and adaptable to changing situations that occur during competition. Current evaluations of practice design in multiple sports, however, suggest that coaches do the opposite, prioritising tasks that promote mechanical consistency over adaptability. Practice in many sports may therefore be sub-optimal. To address this concern, Representative Learning Design (RLD) has been proposed as a framework for assessing the extent to which a task is representative of a situation of interest (e.g., an athletes competition environment). The terminology within the RLD framework, however, requires simplification for application by coaches in applied settings. Moreover, despite suggestions of its importance, no empirical work has assessed the longitudinal benefits of practicing in tasks more representative of competition contexts. This thesis combined the experiential and theoretical knowledge of experts in skill acquisition and tennis with concepts from RLD to design the Representative Practice Assessment Tool (RPAT). Application of the RPAT confirmed that tennis coaches prioritised tasks low in representativeness. This is a concern given it was also found that athlete behaviours observed in matchplay are best simulated in tasks that more closely represent matchplay contexts. Most importantly, this thesis provides empirical evidence which suggests that increasing the representativeness of a task does not simply imply enhanced skill learning, rather changes to task representativeness promotes different learning outcomes/adaptations that remain specific to how practice was conducted. To summarise, this thesis extended current knowledge of designing practice tasks for enhanced skill learning and transfer. Practitioners and coaches are recommended to individualise the representativeness of tasks to the specific needs of their athlete in a manner which facilities the emergence of functional behaviours that are transferable to competition

Quantifying Contextual Interference and Its Effect on Skill Transfer in Skilled Youth Tennis Players

The contextual interference effect is a well-established motor learning phenomenon. Most of the contextual interference effect literature has addressed simple skills, while less is known about the role of contextual interference in complex sport skill practice, particularly with respect to skilled performers. The purpose of this study was to assess contextual interference when practicing the tennis serve. Study 1 evaluated tennis serve practice of nine skilled youth tennis players using a novel statistical metric developed specifically to measure between-skill and within-skill variability as sources of contextual interference. This metric highlighted that skilled tennis players typically engaged in serve practice that featured low contextual interference. In Study 2, 16 skilled youth tennis players participated in 10 practice sessions that aimed to improve serving “down the T.” Participants were stratified into a low contextual interference practice group (Low CI) and a moderate contextual interference practice group (Moderate CI). Pre- and post-tests were conducted 1 week before and 1 week after the practice period. Testing involved a skill test, which assessed serving performance in a closed setting, and a transfer test, which assessed serving performance in a match-play setting. No significant contextual interference differences were observed with respect to practice performance. However, analysis of pre- and post-test serve performance revealed significant Group × Time interactions. The Moderate CI group showed no change in serving performance (service displacement from the T) from pre- to post-test in the skill test, but did display improvements in the transfer test. Conversely, the Low CI group improved serving performance (service displacement from the T) in the skill test but not the transfer test. Results suggest that the typical contextual interference effect is less clear when practicing a complex motor skill, at least with the tennis serve skill evaluated here. We encourage researchers and applied sport scientists to use our statistical metric to measure contextual interference

Equity of physical characteristics between adolescent males and females participating in single- or mixed-sex sport

Krause, LM, Naughton, GA, Benson, AC, and Tibbert, S. Equity of physical characteristics between adolescent males and females participating in single- or mixed-sex sport. J Strength Cond Res 32(5): 1415-1421, 2018-Policies on single- or mixed-sex junior sports participation continue to be challenged publically and legally. Often challenges relate to perceptions of size and performance variability between adolescent males and females, yet the evidence base behind these challenges lacks recent review and rigor. Physical performance was compared between males and females from 2 groups of younger (=13 years, n = 108, 43% females, 57% males) adolescents. Using a cross-sectional design, adolescents were tested for speed, strength, power, and endurance. No sex differences were found for most of the physical test results in the =13 years, males scored better than females in all physical tests, without exception (p > 0.05). Further explorations comparing how many females in the same age grouping shared test results equal to or greater than the top third of males were fewer in the older than younger age group. Equality of participation in mixed-sex sport becomes more difficult to guarantee for older adolescents when results from generic sport-related physical test performances are considered

The effects of familiarity and social hierarchy on group membership decisions in a social fish

Members of animal groups face a trade-off between the benefits of remaining with a familiar group and the potential benefits of dispersing into a new group. Here, we examined the group membership decisions of Neolamprologus pulcher, a group-living cichlid. We found that subordinate helpers showed a preference for joining familiar groups, but when choosing between two unfamiliar groups, helpers did not preferentially join groups that maximized their social rank. Rather, helpers preferred groups containing larger, more dominant individuals, despite receiving significantly more aggression within these groups, possibly owing to increased protection from predation in such groups. These results suggest a complex decision process in N. pulcher when choosing among groups, dependent not only on familiarity but also on the social and life-history consequences of joining new groups

Understanding mismatches in body size, speed and power among adolescent rugby union players

Objectives: With adolescent sport increasingly challenged by mismatches in size, new strategies are important to maximize participation. The objectives were to (1) improve the understanding of mismatches in physical size, speed and power in adolescent rugby union players, (2) explore associations between size and performance with demographic, playing-history, and injury profiles, and (3) explore the applicability of existing criteria for age/body mass-based dispensation (playing-down) strategies