Engineers, control theorists, and neuroscientists often view the delay imposed by finite signal propagation velocities as a problem that needs to be compensated for or avoided. In this article, we consider the alternative possibility that in some cases, signal delay can be used functionally, that is, as an essential component of a cognitive system. To investigate this idea, we evolve a minimal robot controller to solve a basic stimulus-distinction task. The controller is constrained so that the solution must utilize a delayed recurrent signal. Different from previous evolutionary robotics studies, our controller is modeled using delay differential equations, which (unlike the ordinary differential equations of conventional continuous-time recurrent neural networks) can accurately capture delays in signal propagation. We analyze the evolved controller and its interaction with its environment using classical dynamical systems techniques. The analysis shows what kinds of invariant sets underlie the various successful and unsuccessful performances of the robot, and what kinds of bifurcations produce these invariant sets. In the second phase of our analysis, we turn our attention to the parameter θ, which describes the amount of signal delay included in the model. We show how the delay destabilizes certain attractors that would exist if there were no delay and creates other stable attractors, resulting in an agent that performs well at the target task.

Pointing gestures -- particularly deictic references -- are ubiquitous in face-to-face communication. However, deictic pointing can be much more difficult in collaborative virtual environments (CVEs) than in everyday life -- early studies found that the 'fragmentation' caused by the environment greatly complicated object-based communication. In the fifteen years since these studies appeared, the technologies used in CVEs have improved substantially, and several techniques for improving pointing have been proposed or implemented. What these advances mean for the problems of fragmentation and deictic gesture, however, is not clear. To find out, we conducted a new observational study of deictic pointing in a CVE with several techniques that may reduce fragmentation: extra-wide and third-person views, precise control over an avatar's pointing arm, and visual enhancements such as object highlighting and laser pointing. Our study shows that although pointing has come a long way, problems of fragmentation still occur, and that visual and view enhancements can cause new problems for collaboration, even as they solve others. In addition, the visibility of a gesture's preparatory actions remained important to study participants, even when pointing was augmented. These results provide a richer understanding of the subtlety in avatar-based deictic communication, and of the ways that this critical communication mechanism can be better supported in CVEs.

We explore how expert First Person Shooter (FPS) players coordinate actions using a shared voice channel. Our findings emphasize the importance of the temporality and spatiality of these tactical verbal communications ("call-outs"). From here, we outline potential designs to mitigate problems in the production/interpretation of call-outs to better support coordination.

Collaborative Virtual Environments (CVEs) allow people to interact with each other in virtual worlds through computer-generated avatars. Avatars are much less expressive than real bodies, and one main limitation is their lack of support for non-verbal communication such as pointing gestures. Part of the problem is that these gestures must be created through an input device, but the user is already busy controlling the avatar's location, rotation, and view direction. Pointing gestures are only useful for collaborative communication if they can be controlled simultaneously with all other avatar actions. To determine whether there are input configurations that make pointing gestures feasible, we carried out a study that compared five different widely-available input devices in three non-verbal communication tasks. We found that users were able to successfully incorporate pointing gestures into tasks that already involved moving, turning, and looking, but that there were significant and substantial differences between devices. Two configurations performed best: a mode-switched version of standard mouse-and-keyboard control, and a direct-pointing scheme using a Wii remote. There were also minor effects of gender and video-game experience. Our study suggests that users will be able to successfully create free pointing gestures in CVEs, greatly improving the communicative richness of these environments.

Deictic reference -- pointing at things during conversation -- is ubiquitous in human communication, and should also be an important tool in distributed collaborative virtual environments (CVEs). Pointing gestures can be complex and subtle, however, and pointing is much more difficult in the virtual world. In order to improve the richness of interaction in CVEs, it is important to provide better support for pointing and deictic reference, and a first step in this support is to determine how well people can interpret the direction that another person is pointing. To investigate this question, we carried out two studies. The first identified several ways that people point towards distant targets, and established that not all pointing requires high accuracy. This suggested that natural CVE pointing could potentially be successful; but no knowledge is available about whether even moderate accuracy is possible in CVEs. Therefore, our second study looked more closely at how accurately people can produce and interpret the direction of pointing gestures in CVEs. We found that although people are more accurate in the real world, the differences are smaller than expected; our results show that deixis can be successful in CVEs for many pointing situations, and provide a foundation for more comprehensive support of deictic pointing.

Synchronous groupware depends on the assumption that people are fully connected to the others in the group, but there are many situations (network delay, network outage, or explicit departure) where users are disconnected for various periods. There is little research dealing with disconnection in synchronous groupware from a user and application perspective; as a result, most current groupware systems do not handle disconnection events well, and several user-level problems occur. To address this limitation, we developed the Disco framework, a model for handling several types of disconnection in synchronous groupware. The framework considers how disconnections are identified, what senders and receivers should do during an absence, and what should be done with accumulated data upon reconnection. We have implemented the framework in three applications that show the feasibility, generality, and functionality of our ideas. Our framework is the first to deal with a full range of disconnection issues for synchronous groupware, and shows how groupware can better support the realities of distributed collaboration.

Networked multiplayer games must support a much wider variety of interactions than single-player games because networked games involve communication and coordination between players. This means that designers must consider additional usability issues that relate to group play - but there are currently no usability engineering methods that are specifically oriented towards the needs of multiplayer games. To address this problem, we developed a new set of usability heuristics, called Networked Game Heuristics (NGH), which can be used in the design and evaluation of networked multiplayer games. The new heuristics were identified by analyzing problem reports from 382 reviews of networked PC games, covering six main genres. We aggregated problem reports into ten problem categories (covering issues from session management to cheating to training for novice players) and developed heuristics that describe how these usability problems can be avoided. We tested the new heuristics by having evaluators use them and an existing set to assess the usability of two networked games. Evaluators found more usability problems with NGH, and stated that the new heuristics were better for evaluating multiplayer game usability. Our research is the first to present networked game heuristics that are derived from real problem reports, and the first to evaluate the heuristics' effectiveness in a realistic usability test.

Most video games require constant interaction, so game designers must pay careful attention to usability issues. However, there are few formal methods for evaluating the usability of game interfaces. In this paper, we introduce a new set of heuristics that can be used to carry out usability inspections of video games. The heuristics were developed to help identify usability problems in both early and functional game prototypes. We developed the heuristics by analyzing PC game reviews from a popular gaming website, and the review set covered 108 different games and included 18 from each of 6 major game genres. We analyzed the reviews and identified twelve common classes of usability problems seen in games. We developed ten usability heuristics based on the problem categories, and they describe how common game usability problems can be avoided. A preliminary evaluation of the heuristics suggests that they help identify game-specific usability problems that can easily be overlooked otherwise.