Predicting video game players’ fun from physiological and behavioural data : one algorithm does not fit all

Finding a physiological signature of a player’s fun is a goal yet to be achieved in the field of adaptive gaming. The research presented in this paper tackles this issue by gathering physiological, behavioural and self-report data from over 200 participants who played off-the-shelf video games from the Assassin’s Creed series within a minimally invasive laboratory environment. By leveraging machine learning techniques the prediction of the player’s fun from its physiological and behavioural markers becomes a possibility. They provide clues as to which signals are the most relevant in establishing a physiological signature of the fun factor by providing an important score based on the predictive power of each signal. Identifying those markers and their impact will prove crucial in the development of adaptive video games. Adaptive games tailor their gameplay to the affective state of a player in order to deliver the optimal gaming experience. Indeed, an adaptive video game needs a continuous reading of the fun level to be able to respond to these changing fun levels in real time. While the predictive power of the presented classifier remains limited with a gain in the F1 score of 15% against random chance, it brings insight as to which physiological features might be the most informative for further analysis and discuss means by which low accuracy classification could still improve gaming experience

Systematic Analysis of Diguanylate Cyclases That Promote Biofilm Formation by Pseudomonas fluorescens Pf0-1 ▿ †

Cyclic di-GMP (c-di-GMP) is a broadly conserved, intracellular second-messenger molecule that regulates biofilm formation by many bacteria. The synthesis of c-di-GMP is catalyzed by diguanylate cyclases (DGCs) containing the GGDEF domain, while its degradation is achieved through the phosphodiesterase activities of EAL and HD-GYP domains. c-di-GMP controls biofilm formation by Pseudomonas fluorescens Pf0-1 by promoting the cell surface localization of a large adhesive protein, LapA. LapA localization is regulated posttranslationally by a c-di-GMP effector system consisting of LapD and LapG, which senses cytoplasmic c-di-GMP and modifies the LapA protein in the outer membrane. Despite the apparent requirement for c-di-GMP for biofilm formation by P. fluorescens Pf0-1, no DGCs from this strain have been characterized to date. In this study, we undertook a systematic mutagenesis of 30 predicted DGCs and found that mutations in just 4 cause reductions in biofilm formation by P. fluorescens Pf0-1 under the conditions tested. These DGCs were characterized genetically and biochemically to corroborate the hypothesis that they function to produce c-di-GMP in vivo. The effects of DGC gene mutations on phenotypes associated with biofilm formation were analyzed. One DGC preferentially affects LapA localization, another DGC mainly controls swimming motility, while a third DGC affects both LapA and motility. Our data support the conclusion that different c-di-GMP-regulated outputs can be specifically controlled by distinct DGCs

Life cycles, fitness decoupling and the evolution of multicellularity

Cooperation is central to the emergence ofmulticellular life; however, the means bywhich the earliest collectives (groups of cells) maintained integrity in the face of destructive cheating types is unclear. One idea posits cheats as a primitive germ line in a life cycle that facilitates collective reproduction. Here we describe an experiment in which simple cooperating lineages of bacteria were propagated under a selective regime that rewarded collective-level persistence. Collectives reproduced via life cycles that either embraced, or purged, cheating types. When embraced, the life cycle alternated between phenotypic states. Selection fostered inception of a developmental switch that underpinned the emergence of collectives whose fitness, during the course of evolution, became decoupled from the fitness of constituent cells. Such development and decoupling did not occur when groups reproduced via a cheat-purging regime. Our findings capture key events in the evolution of Darwinian individuality during the transition from single cells to multicellularity