Believability Notes

Chapter 1 Introduction

1.1 What is “believable”  ?

The meaning of “believable” is something that we consider to be true, or a person who we believe to be trustworthy. Believable can also be understood as “suspension of disbelief”. This can be defined as the ability to overcome the observer’s doubts that the subject presented is real or some form of truth. A common way to achieve this is to enable the observer to relate to the subject of the work on a personal level. In the artistic domain, examples of believable subjects can be a character in a play, the plot of a novel or an animated figure.

1.2 Suspension of Disbelief

Suspending disbelief has been the primary endeavour in character-based arts across all mediums, from sculptures and painting to theatre, over writing to radio and up to television and video games.

Throughout the evolution of media our ability to emulate reality in our creations, has become more refined. With this increasing degree of realism and fidelity, suspending disbelief in the viewer appears to become easier to achieve. Yet when we compare expressive media according to how much “work” is left to the observer’s imagination, we see that it has become more difficult. To bring across the “Gestalt” of a character (expressions, body language, choice of actions etc.) in a modern medium, requires the artist to pay attention to a much greater set of details and nuances, than was required in a less explicit, more abstract medium. If the artist does not cater to these details, the work will be less believable.

A medium like written text can “use” the reader’s imagination to fill in the details, while an inherently explicit medium like interactive animation is posed against closer scrutiny for lacking detail.

For example if a writer writes, “There is a room, it is dark”, the reader will imagine a dark room as he knows it from experience. On the other hand if a painter draws a black square and says “This is a dark room”, the observer is likely not to believe this, unless the painter considers and includes the details of the room: the dimension of the room, the perspective of the eye. The painter also has to put light into the dark room to make these properties visible.

–possibly describe the difference between believability and realism–

It could be said that Leonardo Da Vinci, who took around 5 years to create his masterpiece, the Mona Lisa, would have struggled even more to produce an animation of the same intrinsic quality– let alone an interactive animation. The medium of painting, with all its expressional limits allowed him to focus on the characteristic nuances that make it a masterpiece. A 10 second animation with 15 images a second, while retaining all that detail, would have taken a lifetime (~750 years, actually).

1.3 Details

Description of what those details are. Based mainly on thesis by Loyall and Disney and the Stanislavski.

While realism applies to the generalities, the physics of the world, believability rests in the nuances. Before I describe what these are, let me talk about a problem that occurs with increased realism, especially with human characters.

1.4 The Uncanny Valley Effect

For creators of believable human-like characters the Uncanny Valley concept has been a problematic issue. Originally the term was coined by psychologists Ernst Jentsch in 1906 (Jentsch 1997) and Sigmund Freud in 1919. The theory states that if a realistic human-like figure comes too close to looking like a real human being, an observer will suddenly switch from an empathetic, to a repulsed response. (White, McKay et al. 2007) state that this effect can be observed for static or moving images, figurines and robots and doesn’t just apply to the visual impression (looking like a human), but also to movement (moving like a human).

The movie “Final Fantasy: The Spirits Within” (Sakaguchi and Sakakibara 2001) is a good example. It featured characters that looked very realistic when static (Figure 1). The artists considered almost all the criteria for physical photo-realism, such as light reflections and refractions in the skin and eyes, texture, moisture and natural colours. Yet when seen in motion, the animated characters often elicit a feeling of discomfort, a feeling that somehow these characters look less like living breathing people and more like walking, talking corpses.

A way to avoid the Uncanny valley altogether is by avoiding realism. Non-realistic anthropomorphic characters, such as Disney’s Donald Duck do not run the risk of seeming too human-like, yet can be used to transport believable human traits – a method also used in Aesop’s Fables.

My work aims to show a new approach to creating interactive believable characters. My focus is not on creating human-like figures.

1.6 Key Related Research Projects

1.6.1 Oz Project and HAP Architecture by Joseph Bates and Bryan Loyall at CMU

I would not say that the agents created with HAP are autonomous. The agents have no ability to correct their behaviour and therefore fall under Searl’s Chinese room argument about weak AI. HAP creates an interactive narrative with additional, implied rules and dynamics that the author might add unintentionally while creating the agent’s rules. The agent is therefore not an interactive personality.

Jentsch, E. (1997). “On the psychology of the uncanny (1906).” Angelaki: Journal of Theoretical Humanities 2(1): 7-16.

Sakaguchi, H. and M. Sakakibara (2001). Final Fantasy: The Spirits Within. Japan.

White, G., L. McKay, et al. (2007). “{Motion and the uncanny valley}.” J. Vis. 7(9): 477-477.