1. Personality and Believability
Panel at the 2nd Workshop on Intelligent Virtual Agents (Virtual Agents 99)
The Centre for Virtual Environments
University of Salford, Salford, United Kingdom
13th September 1999

2. Believability tradeoffs: BALANCE
What is elicited from user vs. system capabilities
Can go wrong both ways!
System raises too high/complex/… expectations in users
Systems places to high demands on users in terms of competence/ duration of interaction/...
Slide 2,

3. Believability tradeoffs: EXPRESSIVITY
Action expression problem (Phoebe Sengers)
Convey a summary of the “story” behind a given situation, provide clues about ongoing task
E.g.: local expressive behaviour by itself is insufficient for discrimination of current emotional state! (cf. action tendencies, Nico Frijda)
Slide 3,

4. Believability tradeoffs: BELIEVABILITY vs. FIDELITY
Impact of prior knowledge, “folk theories”, prejudices,… on subjective assessment of system performance
Emphasis on believability allows better exploitation of available resources
Emphasis on fidelity (usually) results in higher robustness and better consistency (see next slides)
Slide 4,

5. Believability tradeoffs: ROBUSTNESS
“Brittle depth” vs. “Robust shallowness”
Depth (may be) required for “interestingness”
Lessons from knowledge-based systems design
Semantic vs. Architectonic Space (Nancy Kaplan)
Capitalize on ambiguities/under-determination
Leave space for multiple interpretation by users
Symmetric requirements for system:
Ability to make multiple/different interpretations/appraisals
Meta-reasoning
Slide 5,

6. Believability tradeoffs: CONSISTENCY
Consistent behaviour over time entails predictability and facilitates recognition of “personality traits”
E.g.: consistency of problem solving and action selection across different situations (difficult!?)
May be achieved via an “inverse mapping” of dimensions of consistency to system lifeworld/ architecture
“Big 3” (5) traits, action tendencies…
Slide 6,

7. Believability tradeoffs: PERSISTENCE
Persisting consequences of choices, actions, events
“No undo”
Slide 7,

8. SOCIA(L A)BILITIY Basic requirement for interactivity How?
integration of system+user into a “bigger whole”: interactive system
How?
E.g. via social psychology models, such as:
Power&Status (T. Kemper)
Emotional Competence (C. Saarni)
Seizure/relinquishment* of control at different levels
Acceptance of broad classes of inputs (recognition of affordances)
*(difficult/unusual for system designers)
Slide 8,