Dept. of Computer Science

Questionnaires are vital in games user research (GUR) to assess player experience (PX). However, having too many questions in surveys prevents wider uptake among GUR professionals because of games' rapid production cycles. To address this issue, we present the miniPXI---an eleven-item measure of the popular Player Experience Inventory (PXI)---providing single items for each of its eleven constructs. To develop the scale and examine its reliability and validity, we present three studies, conducted with 15 experts and 628 digital game players across continents. In the first survey study (n=366, 15 experts), single items were selected. In a second survey study (n=232), we explored reliability and validity of the single-item scale. Participants completed both full and single-item (SI) variants in three days. In the last study (n=30), we established the validity and sensitivity via an experimental evaluation of two games. The results are nuanced; SI reliability estimates for PXI cons...

In this paper, we present PXI Bench, an online tool to provide actionable insight into the player experience, designed by and for games user researchers. Based on the Player Experience Inventory (PXI), it provides detailed information about the baseline theoretical model and supports a layman analysis of PXI questionnaire data. Moreover, it provides an interactive feature to explore benchmark PXI data of existing game evaluations. This helps a GUR expert to explore and compare their own game data to data from a relevant genre or specific game.

Short questionnaires, using only a few items for measuring user experience related constructs, have been used in a variety of domains. In the field of games, the miniPXI is such a validated short version of the player experience inventory (PXI), containing 11 single items to measure 11 different PX-related constructs. Previous validations of the miniPXI were carried out in an experimental setting with existing, fully finished games. In this study, we conduct a preliminary investigation of the potential of miniPXI to evaluate prototypes during game development. We explore differences in PX across two iterations of nine games prototypes, based on input from 16 participants. Findings suggest that the miniPXI is capable of detecting differences between the two prototype versions. In addition, at the level of individual games, the miniPXI is effective at identifying differences in nearly all PX dimensions. However, we also find limited use for the single enjoyment item, and suggest that including alternative measures such as the Net Promotor Score may be more useful. Overall, this work suggests that the miniPXI has the potential to evaluate different iterations of game prototypes, starting from the earliest stages of game development. CCS CONCEPTS • Human-centered computing → User studies.

The input of free-form text is frequently utilized in surveys for gamerelated research. While this provides flexibility, it also presents the challenge of dirty data, which includes spelling errors, missing series titles, and unofficial yet popular abbreviations inputted by the user. The manual resolution of these anomalies is impractical and resource-intensive. To address this issue, a fuzzing string machinebased game mapping system was designed and evaluated using 1,096 game titles input by users. GMap-R, a real-time autocomplete game title system to aid runtime user entry, was also created and evaluated using 150 game titles provided by 30 participants, each of whom listed their five favorite games twice. With GMap-R, the correct mapping percentage increased to 98.67%. These preliminary evaluations indicate that the proposed strategy can significantly enhance the cleansing and input of game titles' free-form text. In turn, this helps to conserve resources when obtaining unsupervised data through online studies. CCS CONCEPTS • Information systems → Recommender systems.

Utilizing a validated scale to assess player experience (PX) in video games can yield important findings. Nevertheless, insufficient quantitative data analysis expertise among games user research (GUR) self-taught practitioners, poses obstacles to effectively analyzing and interpreting the data obtained from various measurement scales. Hence, in this paper, we present a guided interface based web platform to support data analysis of the Player Experience Inventory (PXI), following a user-centered design (UCD) process, incorporating insights from Games User Research (GUR) specialists. The interface, extending a current platform for PXI data evaluation, aspires to enable data analysis with a high degree of flexibility, offering explanatory support for both, inexperienced and experienced analysts. The findings from user testing sessions indicated that the platform was perceived as user-friendly. However, findings also suggest that more accessible explanations of the statistical approaches are needed to aid in understanding data analysis and interpretation of outcomes. CCS CONCEPTS • Human-centered computing → HCI design and evaluation methods; • Information systems → Web interfaces.

Utilizing a validated scale to assess player experience (PX) in video games can yield important findings. Nevertheless, insufficient quantitative data analysis expertise among games user research (GUR) self-taught practitioners, poses obstacles to effectively analyzing and interpreting the data obtained from various measurement scales. Hence, in this paper, we present a guided interface based web platform to support data analysis of the Player Experience Inventory (PXI), following a user-centered design (UCD) process, incorporating insights from Games User Research (GUR) specialists. The interface, extending a current platform for PXI data evaluation, aspires to enable data analysis with a high degree of flexibility, offering explanatory support for both, inexperienced and experienced analysts. The findings from user testing sessions indicated that the platform was perceived as user-friendly. However, findings also suggest that more accessible explanations of the statistical approaches are needed to aid in understanding data analysis and interpretation of outcomes. CCS CONCEPTS • Human-centered computing → HCI design and evaluation methods; • Information systems → Web interfaces.

This paper is concerned with addressing how plant tissue mechanics is related to the micromechanics of cells. To this end, we propose a mesh-free particle method to simulate the mechanics of both individual plant cells (parenchyma) and cell aggregates in response to external stresses. The model considers two important features in the plant cell: (1) the cell protoplasm, the interior liquid phase inducing hydrodynamic phenomena, and (2) the cell wall material, a viscoelastic solid material that contains the protoplasm. In this particle framework, the cell fluid is modeled by smoothed particle hydrodynamics (SPH), a mesh-free method typically used to address problems with gas and fluid dynamics. In the solid phase (cell wall) on the other hand, the particles are connected by pairwise interactions holding them together and preventing the fluid to penetrate the cell wall. The cell wall hydraulic conductivity (permeability) is built in as well through the SPH formulation. Although this model is also meant to be able to deal with dynamic and even violent situations (leading to cell wall rupture or cell-cell debonding), we have concentrated on quasi-static conditions. The results of single-cell compression simulations show that the conclusions found by analytical models and experiments can be reproduced at least qualitatively. Relaxation tests revealed that plant cells have short relaxation times (1 micros-10 micros) compared to mammalian cells. Simulations performed on cell aggregates indicated an influence of the cellular organization to the tissue response, as was also observed in experiments done on tissues with a similar structure.

We discuss the numerical computation of homoclinic and heteroclinic orbits in delay differential equations. Such connecting orbits are approximated using projection boundary conditions, which involve the stable and unstable manifolds of a steady state solution. The stable manifold of a steady state solution of a delay differential equation (DDE) is infinite-dimensional, a problem which we circumvent by reformulating the end conditions using a special bilinear form. The resulting boundary value problem is solved using a collocation method. We demonstrate results, showing homoclinic orbits in a model for neural activity and travelling wave solutions to the delayed Hodgkin–Huxley equation. Our numerical tests indicate convergence behaviour that corresponds to known theoretical results for ODEs and periodic boundary value problems for DDEs.

An important class of problems exhibits macroscopically smooth behaviour in space and time, while only a microscopic evolution law is known, which describes effects on fine space and time scales. A simulation of the full microscopic problem in the whole space-time domain can therefore be prohibitively expensive. In the absence of a simplified model, we can approximate the macroscopic behaviour by performing appropriately initialized simulations of the available microscopic model in a number of small spatial domains (“boxes”) over a relatively short time interval. Here, we show how to obtain such a scheme, called “patch dynamics,” by combining the gap-tooth scheme with projective integration. The gap-tooth scheme approximates the evolution of an unavailable (in closed form) macroscopic equation in a macroscopic domain using simulations of the available microscopic model in a number of small boxes. The projective integration scheme accelerates the simulation of a problem with multiple time scales by taking a number of small steps, followed by a large extrapolation step. We illustrate this approach for a reaction-diffusion homogenization problem, and comment on the accuracy and efficiency of the method.

In traditional physicochemical modeling, one derives evolution equations at the (macroscopic, coarse) scale of interest; these are used to perform a variety of tasks (simulation, bifurcation analysis, optimization) using an arsenal of analytical and numerical techniques. For many complex systems, however, although one observes evolution at a macroscopic scale of interest, accurate models are only given at a more detailed (fine-scale, microscopic) level of description (e.g., lattice Boltzmann, kinetic Monte Carlo, molecular dynamics). Here, we review a framework for computer-aided multiscale analysis, which enables macroscopic computational tasks (over extended spatiotemporal scales) using only appropriately initialized microscopic simulation on short time and length scales. The methodology bypasses the derivation of macroscopic evolution equations when these equations conceptually exist but are not available in closed form-hence the term equation-free. We selectively discuss basic algorithms and underlying principles and illustrate the approach through representative applications. We also discuss potential difficulties and outline areas for future research.