The performance of current graphics engines makes it possible to incorporate subliminal cues within virtual environments (VEs), providing an additional way of communication, fully integrated with the exploration of a virtual scene. In order to advance the application of subliminal information in this area, it is necessary to explore in the psychological literature how techniques previously reported as rendering information subliminal can be successfully implemented in VEs. Previous literature has also described the effects of subliminal cues as quantitatively modest, which raises the issue of their inclusion in practical tasks. We used a 3D rendering engine (Unity3D) to implement a masking paradigm within the context of a realistic scene and a familiar (kitchen) environment. We report significant effects of subliminal cueing on the selection of objects in a virtual scene, demonstrating the feasibility of subliminal cueing in VEs. Furthermore, we show that multiple iterations of masked objects within a trial, as well as the speeding of selection choices, can substantially reinforce the impact of subliminal cues. This is consistent with previous findings suggesting that the effect of subliminal stimuli fades rapidly. We conclude by proposing, as part of further work, possible mechanisms for the inclusion of subliminal cueing in intelligent interfaces to maximize their effects.

The development of embodied conversational agents (ECA) as companions brings several challenges for both affective and conversational dialogue. These include challenges in generating appropriate affective responses, selecting the overall shape of the dialogue, providing prompt system response times, and handling interruptions. We present an implementation of such a companion showing the development of individual modules that attempt to address these challenges. Further, to resolve resulting conflicts, we present encompassing interaction strategies that attempt to balance the competing requirements along with dialogues from our working prototype to illustrate these interaction strategies in operation. Finally, we provide the results of an evaluation of the companion using an evaluation methodology created for conversational dialogue and including analysis using appropriateness annotation.

Causality is an important aspect of how we construct reality. Yet, while many psychological phenomena have been studied in their relation to virtual reality (VR), very little work has been dedicated specifically to causal perception, despite its potential relevance for user interaction and presence. In this paper, we describe the development of a virtual environment supporting experiments with causal perception. The system, inspired from psychological data, operates by intercepting events in the virtual world, so as to create artificial co-occurrences between events and their subsequent effects. After recognizing high-level events and formalizing them with a symbolic representation inspired from robotics planning, it modifies the events' effects using knowledge-based operators. The re-activation of the modified events creates co-occurrences inducing causal impressions in the user. We conducted experiments with fifty-three subjects who had to interact with virtual world objects and were presented with alternative consequences for their actions, generated by the system using various levels of plausibility. At the same time, these subjects had to answer ten items from the Presence Questionnaire corresponding mainly to control and realism factors: causal perception appears to have a positive impact on these items. The implications of this work are twofold: first, causal perception can provide an interesting experimental setting for some presence determinants, and second, the elicitation of causal impressions can become part of VR technologies to provide new forms of VR experiences.