1. From Interaction to Trajectories
Steve Benford
Mixed Reality Laboratory
University of Nottingham

2. Desert Rain (1997)

3. Uncle Roy All Around You (2003)

4. Fairground: Thrill Laboratory (2006)

5. Day of the Figurines (2006)

6. Trajectories
All four experiences combine interactivity with live performance
They also exhibit complex and extended spatial and temporal structures
They are unified by the approach of creating a coherent journey through the experience
Building on recent studies of interactive exhibits, these journeys can be described in terms of trajectories

7. Trajectories through hybrid space
Mixed Reality Continuum (Milgram and Kishino)
Virtual Reality
(Everyday) Reality
Augmented Reality
Augmented Virtuality
immersion
ubiquity
Our experiences combine multiple points on the continuum to form complex hybrid space through which participants move

8. Trajectories through hybrid time
Time as perceived by the participant
Perceived time
The timing of interactions as perceived by the participant
Interaction time
The times at which a participant chooses or is able to interact
Schedule time
The times at which the narration is made available
Plot time
The temporal structure of the narration of the story
Story time
The temporal structure of the underlying story world
Time as conceived by the author

9. Trajectories through roles
Participants
Street players
Online players
each role follows its own trajectory and there are trajectories between roles
Performers
Actors
Orchestrators
Spectators
Audience
Bystanders

10. Trajectories through interfaces
Interfaces are designed and also arranged to establish a trajectory of interaction

11. Transitions and Traversals
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

12. Transitions and Traversals
beginnings
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

13. Transitions and Traversals
Role and interface transitions
beginnings
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

14. Transitions and Traversals
Role and interface transitions
Temporal episodes
beginnings
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

15. Transitions and Traversals
Role and interface transitions
Temporal episodes
Physical-virtual traversals
beginnings
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

16. Transitions and Traversals
Role and interface transitions
Temporal episodes
Physical-virtual traversals
beginnings
Access to physical resources
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

17. Transitions and Traversals
Role and interface transitions
Temporal episodes
Seams
Physical-virtual traversals
beginnings
Access to physical resources
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

18. Transitions and Traversals
Role and interface transitions
endings
Temporal episodes
Seams
Physical-virtual traversals
beginnings
Access to physical resources
Trajectories have to negotiate various transitions and traversals during which continuity may be at risk

19. Negotiating Trajectories
Canonical trajectory
Participant trajectory
Canonical and participant trajectories represent an author’s ideal journey and a participant’s actual journey respectively

20. Negotiating Trajectories
Canonical trajectory
Interactivity drives divergence
Participant trajectory
Canonical and participant trajectories represent an author’s ideal journey and a participant’s actual journey respectively

21. Negotiating Trajectories
Orchestration drives
convergence
Canonical trajectory
Participant trajectory
Canonical and participant trajectories represent an author’s ideal journey and a participant’s actual journey respectively

22. Interleaving Trajectories
Participant ‘red’
Participant ‘blue
Multiple trajectories can represent different participants or different applications

23. Interleaving Trajectories
Mutual awareness and encounters when trajectories come together
Participant ‘red’
Participant ‘blue
Multiple trajectories can represent different participants or different applications

24. Interleaving Trajectories
Participant ‘red’
Participant ‘blue
Steer trajectories apart to avoid contention or to minimise distractions and interruptions
Multiple trajectories can represent different participants or different applications

25. Interleaving Trajectories
Participant ‘red’
Pacing involves keeping trajectories together
Participant ‘blue
Multiple trajectories can represent different participants or different applications

26. Summary of Trajectories
A trajectory describes a journey through an extended user experience emphasising continuity and coherence
Trajectories pass through hybrid structures of space, time, roles and ecologies of interfaces
Trajectories have to cross key transitions including beginnings, endings, role and interface transitions, physical-virtual transitions, temporal episodes, physical resources and seams
Canonical trajectories and participant trajectories represent author and participant control and diverge and converge due to interactivity and orchestration
Interleaved trajectories describe collaborative and/or multi-tasking situations and address encounters, awareness, separation, pacing and prioritisation

27. Putting Trajectories to Work
Providing sensitising concepts for empirical studies
A vehicle for compiling craft knowledge
Identifying requirements for new technologies
Towards a dramaturgy of interactive user experience

28. ‘Serious’ experiences?
Cultural experiences may provoke reflection and debate
Addressing challenging themes
Using ambiguity to provoke interpretation
Wider applications of trajectories
Designing complete VR experiences
Supporting learning

29. Further Information www.mrl.nott.ac.uk www.blasthoery.co.uk
Papers and videos available at:
Benford, Giannachi, Koleva & Rodden, ‘From Interaction to Trajectories: Designing Coherent Journeys Through User Experiences’, ACM CHI 2009
Benford &Giannachi, ‘Temporal Trajectories in Shared Interactive Narratives’, ACM CHI 2008
Benford et al, ‘The Frame of the Game’, ACM CHI 2006
Reeves, Benford, O’Malley and Fraser, ‘Designing the Spectator Interface, ACM CHI 2005
Gaver, Beaver & Benford, ‘The Role of Ambiguity in Interfac Design’, ACM CHI 2003