It’s About Time: The Illusions of Time Perception and Travel in Immersive Virtual Reality

Abstract

Changing the passage of time is a concept that has captured the imagination of many philosophers and writers throughout history, but we have no evidence of anyone being capable of altering it at a macroscopic level. But what if it were possible? This question formed the basis of our research, and in this thesis we describe a series of experiments carried out to address this. In this thesis we report three main experiments. The first considered whether the perception of elapsed time can be influenced by the tempo of music. We placed participants in an immersive virtual reality environment where they heard in the background two versions of a musical piece, varying only in tempo, for 7.5 minutes in two separate sessions. Volunteers retrospectively estimated the length of each session. The results show that participants’ estimates were not correlated with background music tempo. In the second experiment we considered whether previous findings that body size and age influence the perception of space might also influence the perception of time. In this experiment we immersed participants in a virtual reality scenario in which they performed a task for 200 seconds while embodied in one of three avatars that depicted three different age groups. Volunteers underwent two trials where the only change was the avatar they embodied, and compared the length of the sessions. The results suggested that time perception was not affected by body shape, but the task performance was. In the third experiment we addressed the notion of time travel itself, and considered whether virtual reality can be used to give people the illusion of having travelled back through time. We immersed participants in virtual reality where they experienced a series of events that unknowingly led to a violent incident. Immediately after they were either transported in time to the beginning of the developments or they simply restarted the session, depending on the condition. We found that participants felt as if they had travelled back in time whenever subjective levels of other three illusions were high. We also describe an application of the technology that was developed for the time travel to a psychological counselling situation, where people could maintain a conversation with an embodied version of themselves. We set the background of this thesis in reviewing the major themes of virtual reality research, including the concepts of presence and its constituent elements of ‘place illusion’ and ‘plausibility’ – the sense of being in the place depicted by the virtual environment, and the illusion that events are real. Of particular importance in our work is the concept of ‘body ownership’ – the feeling that a co-located virtual body seen from first person perspective is the participant’s real body, and we present a critical review of the relevant literature showing how this thesis relates to past work and is a further contribution. Finally, in order to carry out the scientific work reported in this thesis we have made technical advances in virtual reality, including the development of a software platform that integrates compatibility for several different devices. The conclusion of the thesis is that more research is necessary in the field of time perception and time travel in immersive virtual reality. We have seen that body shape can affect cognitive task performance, and further studies should expand the knowledge by analysing more variables. Additionally, a novel kind of illusion is presented in this thesis. Its potential and limits should be explored in future experiments, possibly with completely different applications. Indeed, the technology involved was applied in a study, reported in this thesis, concerned with personal counselling. Overall, this thesis contains several different angles on the illusions of time perception and time travel. We present a thorough review of the literature involving the perception of time and the illusions of presence, body ownership and agency, as well as the technical background. Furthermore, the description of three studies that take a novel approach to time perception and time travel is included. Finally, we discuss our results and outline a future work direction.

En esta tesis reportamos tres experimentos principales. En el primero examinamos si la percepción del tiempo puede ser influenciada por la música de fondo. Pusimos a participantes en un entorno virtual inmersivo donde oyeron dos versiones de una misma pieza musical de fondo, con la única variación del tempo, durante 7,5 minutos en dos sesiones distintas. Los voluntarios estimaron retrospectivamente la duración de cada sesión. Los resultados indican que las estimaciones no estaban correlacionadas con el tempo de la música. En el segundo experimento analizamos si los resultados de estudios anteriores, que encontraron que la edad y la forma corporal afectan a la percepción espacial, se pueden aplicar también en la percepción del tiempo. En este experimento pusimos a voluntarios en un escenario de realidad virtual en donde realizaron una tarea durante 200 segundos, mientras su cuerpo era substituido en realidad virtual por avatares que representaban a tres grupos distintos de edad. Los participantes experimentaron dos sesiones donde el único cambio era el avatar, y compararon la duración de las sesiones. Los resultados sugieren que la percepción del tiempo no fue alterada por la forma del cuerpo, pero el rendimiento sí. En el tercer experimento evaluamos la noción de viajar en el tiempo propiamente, y examinamos si la realidad virtual puede ser usada para dar la ilusión de viajar atrás en el tiempo. Pusimos a varios participantes en un escenario virtual donde experimentaron una serie de eventos que, sin saberlo, llevaban a un incidente violento. Inmediatamente después eran transportados en el tiempo hasta el inicio de los eventos, o simplemente se reiniciaba la sesión, dependiendo de la condición. Encontramos que los voluntarios tuvieron la ilusión de haber viajado atrás en el tiempo siempre y cuando los niveles subjetivos de otras tres ilusiones fueran altos. La conclusión de esta tesis es que más investigación es necesaria en el dominio de la percepción del tiempo y en el de los viajes virtuales en el tiempo. Hemos visto que la forma del cuerpo puede afectar el rendimiento en una tarea, pero estudios futuros deberían expandir el conocimiento analizando más variables. Además, se presenta en esta tesis una nueva ilusión. Sus límites y su potencial deberían ser explorados en experimentos futuros, posiblemente en aplicaciones completamente distintas.