ABSTRACT

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ABSTRACT
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TITLEBelievability and expectations

• BACKGROUND
• A believable experience is not necessarily the
  experience of something real or existent. A
  believable experience does not necessarily
  resemble to an experience with real or existent
  entities, at least not in the sense that
  believable entities simulate the physical aspect
  and behavior of real entities.
• Believability is a form of judgment associated to
  specific emotional reactions and the conditions
  that trigger believability are not necessarily
  coincident with reality or realism one
  significant condition seems to be represented by
  the respect of the users or audiences activated
  expectations.

• OBJECTIVES
• Identify the conditions that allow a believable
  experience with virtual or fictional entities
  even in absence of simulation of the
  phenomenological aspect and behavior of real
  entities.
• METHODS
• Investigate the role played by expectations in
  the judgment of believability, describe types of
  expectations especially in relationship to
  different types of knowledge and their
  differential impact on believability.

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• RESULTS
• Definition and types of expectations
• Expectations are mental states that range from
  beliefs based on symbolic knowledge to
  representations based on enactive forms of
  knowledge or connections and rules of perception
  produced by selection and repeated experience.
  When falsified by non-matching events,
  expectations give rise to surprise and revision
  (including anticipatory beliefs about future
  states of affairs) or at least to a sense of
  wrongness.
• Role of expectations in believability
• Experimental activity concerning the perception
  and interaction with both real and virtual worlds
  shows that the frustration of expectations and
  the violation of coherence play a negative role
  in adaptive and social behaviors and that the
  perceptual system actively works to maintain
  coherence. The awareness of violation of
  coherence and the frustration of expectations
  provoke a reaction of surprise and alerts the
  subject to the presence of some form of error,
  hence diminishing believability.

• Activated and de-activated of expectations
• Not all the expectations that users and audience
  hold are activated during a virtual or fictional
  experience. The activation and de-activation of
  expectations is a major instrument for enhancing
  believability. Certain expectations can be
  derived from other more general expectations or
  from expectations that are hold by the subject in
  virtue of the context of the cognitive activity
  and the intentions of the subject (volatile
  expectations). But also the expectations that are
  hold by the subject in a non-derived way need to
  be activated in order to produce cognitive
  effects. Epistemic and pragmatic goals on the
  side of the subject and the context of the
  cognitive activity are two components of the
  activation of expectations. Even the
  de-activation of expectations concerns
  expectations that have been previously activated.
  Different types of expectations present a
  different aptness to acquisition and modification
  through learning and training and a different
  profile of activation or de-activation.

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• CONCLUSIONS
• The acquisition of knowledge about the
  expectations that are hold by potential users of
  VR applications, their differential potential of
  activation/de-activation, the instruments for the
  production of new knowledge at different levels
  and for the activation and de-activation of the
  desired expectations is a necessary condition for
  the design of believable experiences in VR. In
  addition to psychological and theoretic research
  advancements in this direction can be produced by
  experimental activity directed to individuate the
  minimal conditions of believability by stretching
  the characteristics of believable experiences.

• Tests of believability should include both
  subjective reports based on self-awareness
  (judgment of believability) and behavioral
  measures concerning the emotional consequences of
  the violation of expectations.

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BACKGROUND

• Believability is a judgment. When we consider a
  certain experience as believable we do not
  necessarily consider the experience as being
  true, in the sense of being an experience with
  real, existing objects. Neither we consider that
  experience as being susceptible of becoming true
  of the real world, either in the future, as show
  by the fact that fictional characters as Alexis
  Karamazoff or Wil Coyote can be considered as
  believable.
• Un-believable has a different meaning than
  un-true because the judgment of
  un-believability implies impossibility and not
  only falsity something which is judged as
  un-believable is something that cant be as it
  appears (to perception or reasoning).
• Hence, the judgment of believability is a
  judgment of possibility or impossibility, at
  least within a certain context (such as the one
  represented in the virtual or fictional world).
• Possibility and impossibility are referred to the
  presence of a violation of coherence, both in the
  sense of the presence of a conflict between
  current experience and in the sense of the
  violation of past expectations. In daily life
  when someone exclaims I cant believe it! we
  guess that something unexpected has happened.
• In normal cases one does not notice that the real
  world is going on in a believable fashion the
  real world is trivially believable and it is only
  when expectations are unfulfilled that the
  problem of believability arises.
• It is especially in the framework of fictional
  virtual entities that the need for a
  characterization of the notion of believability
  arises. Readers and audience of works of fiction,
  users of VR worlds in fact are used to find a
  certain virtual or fictional experience as more
  or less believable and to judge the fictional or
  virtual world with its inhabitants in terms of
  believability.
• The judgment of believability is associated with
  a certain number of behavioral and emotional
  reactions.
• Negative believability is associated with
  surprise.
• Positive believability is associated with the
  possibility of putting in place a number of
  actions and emotions as if the experience were
  true (make believe game).

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• Two considerations follow
• Since no problem of existence in the real world
  is at stake, when we consider a certain
  experience as believable we just accept it as
  plausible or possible under certain conditions -
  such as the context of a certain virtual world -
  and as suitable for certain purposes - such as
  the purpose of playing a certain game of
  make-believe in which one can act or react as if
  the experience he is undertaking with the virtual
  world were true -.
• If the notion of reality has no role to play in
  the judgment that a certain experience is
  believable, then the adherence of the experience
  with the experienced reality cannot be a
  criterion for characterizing believability. The
  judgment of believability seems to be
  especially related to the existence of different
  kinds of expectations and to the fact of
  respecting or violating them.

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OBJECTIVES

• Fictional and virtual worlds constitute a vast
  domain narrative, films, dramatic arts in
  general ad VR in its different declinations. A
  good characterization of the notion of
  believability should apply to all these
  situations, and to believability in the real
  world too.
• In order to respond to the requirement of
  generality, the characterization of the notion of
  believability should be minimalist provide the
  minimal necessary conditions for believability
  and eventually provide the rules for gaining more
  and more believability and for producing
  believability in different situations. In this
  way, general characteristics of instruments for
  testing believability and general factors for
  enhancing believability can be indicated that are
  valid for all kinds of situations.
• In the literature about dramatic arts, classic
  animation, and more recently computer animation
  for films and VR, interactive drama and VR in
  general, the issue of individuating the minimal
  conditions for believability is not directly
  addressed, and artists and designers normally
  provide a list of conditions that are considered
  as suitable for producing believable experiences
  and that are more or less related to the problem
  of realism and to the objective of designing or
  creating rich characters and agents.

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METHODS

• Characterize the notion of expectation
• Describe different forms of expectations in
  respect to
• The reaction of surprise
• Their behavioral and emotional reactions
• Their relationship with automatic/conscious
  mental states and processes
• Their relationship to different types of
  knowledge
• Describe the role of expectations upon
  believability through the description of the
• Effects of violation of expectations upon
  adaptive behavior
• Effects of the violation of expectations upon
  epistemic judgments
• Describe the ways in which expectations can be
  acquired, derived, activated and de-activated
• Indicate the conditions for testing believability
  in terms of expectations and for enhancing
  believability by the suitable activation/de-activa
  tion of expectations

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DISCUSSIONExpectations and surprise

• Expectations/Surprise
• Expectations explain the reaction of surprise
  toward certain events and surprise constitutes a
  crucial element in the characterization and in
  the individuation of expectations, even when they
  are not linguistically expressed.
• When an event produces that has never been
  experienced before two reactions can be observed
  in people they are surprised by the event or
  they just accept the event and integrate the
  informational contents it represents. If someone
  is surprised, it means he was holding some
  expectation concerning that event that do not
  match with the event as it has produced.
  Expectations are hence necessary in order to
  justify the reaction of surprise and surprise can
  be characterized as being the reaction to the
  frustration of an expectation (Davidson, 2004).
• The possibility of being surprised can hence
  function as a test (surprise test) for the
  capacity of entertaining expectations, or more
  generally beliefs
• Someone puts his hand in his pocket and finds a
  coin. If he his surprised in finding the coin,
  then he comes to believe that his previous belief
  about his pockets and coins was false. Hence, he
  is aware that there is an objective reality which
  is independent from (previous) beliefs (Davidson,
  1982.
• Since surprise is a telling betrayal of the
  subjects having expected something else.
  (Dennett, 2001, p. 982), the reaction of surprise
  can be used in order to shed light on the
  expectations of the subject.

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• Expectations Active, Passive and Volatile
• Let us have a look at some examples of surprise
  in relationship to unfulfilled expectations
• (1) I want to wear my brown shoes I have a
  belief of my brown shoes being in the white shoe
  box or I expect to find them there. But they are
  not in the white box, hence I am surprised.
• (2) They are there but they have no strings. I am
  surprised.
• (3) I believe that my brown shoes have strings,
  hence I expect to find strings if I check my
  belief against reality or if I go to take my
  brown shoes.
• (4) Ive been surprised in not finding strings to
  my shoes of course, I expected to find them
  there.
• (5) Ive been surprised in not finding strings to
  my brown shoes it must be that I expected to
  find them there, even if I cant remember to have
  ever entertained such an expectation
• The examples (2), (4) and (5) show that one is
  not always aware of entertaining a certain
  expectation and that the expectations one can
  gain access to through the reaction of surprise
  can present different levels of awareness
• in case (4) the subject re-gains awareness on a
  belief he did entertain in case (5) the subject
  apparently was not aware of holding such a belief
  before the non-matching event was produced.
• Case (5) can receive two interpretations.
• In the first interpretation, case (5) can be
  associated with the removed psychological
  states described in psychoanalysis the subject
  entertains a certain belief or intention which is
  removed far from his conscious states this
  belief or intention shows itself in the subjects
  behaviors and the subject can be forced to admit
  its existence, for instance in virtue of the
  interpretation of certain behaviors.
• In cognitive psychology terms, one can consider
  the existence of two types of expectations
  passive and active, with corresponding forms of
  surprise.
• Active beliefs and expectations are expectations
  that are generically under the focus of attention
  and passive expectations are potentially
  derivable beliefs and expectations that are not
  actually under the focus of attention.

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• This distinction gives rise to a corresponding
  distinction between two types of surprise Ortony
  Partridge, 1987
• Surprise which results from the input proposition
  conflicting with an active, already derived
  expectation
• Surprise which results from the input proposition
  conflicting with a passive and practically
  deducible expectation
• An analogous distinction is operated by Lorini,
  2005
• Mismatch-based Surprise generated by the
  mismatch between active predictions and the
  explained raw sensor data (function of
  Unexpectedness). The mismatch is based on the
  existence of three conditions sensory data which
  must be interpreted, a theory based on general
  conceptual knowledge or general knowledge
  concerning a certain domain (in any case, general
  knowledge), a set of active expectations composed
  of beliefs and expectations of different degrees
  of certainty (expectations are active in the
  sense that they are under the focus of attention
  of the subject, in contrast with potentially
  derivable beliefs that are not actually under the
  focus of attention). The set of expectations and
  the theory are consistent. On the basis of the
  theory, the raw data are interpreted (inferential
  approach to perception) and compared with the set
  of expectations a certain mismatch and relative
  surprise can arise. The degree of the mismatch is
  calculated by taking into account the degree of
  certainty of the set of expectations that are
  referred to the explanation provided for the raw
  data and also the degree of certainty of
  expectations concerning the correlation of
  couples of elements of the theory (degree of
  dependence between the perceived features, after
  interpretation). This second quantity is not
  considered into other theories for calculating
  surprise, in which surprise is function of the
  unexpectedness of perceived single features only
  (see Macedo Cardoso, 2001). The degree of the
  mismatch has also an effect on the explanatory
  value of the hypothesis or explanation of the raw
  data, when the mismatch is great, the explanation
  is revised for a better one.
• Passive Prediction-based Surprise generated by a
  later mismatch between the explained raw sensor
  data and a set of expectations that is derived
  from the set of active expectations and the
  theory. It can give rise to a further mismatch.

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• In the second interpretation, the subject is
  right in not remembering himself entertaining the
  belief that his brown shoes have strings, because
  he did not. He did entertain the general belief
  that shoes have strings and the local belief that
  there are brown shoes in the white box, but not
  the local belief or expectation that the brown
  shoes have strings.
• The concept of Volatile expectations (Casati
  Pasquinelli, Forthcoming) must be introduced
• There is no need for individuals to hold all the
  expectations like (5) all the time, and in
  particular to hold all the beliefs that
  correspond to all of these expectations all the
  time. Common people minds would be a little bit
  overloaded.
• It is just possible that people hold some general
  beliefs, such as some general beliefs about the
  ontology of our world (the entities that furnish
  our world and the laws that describe their
  behavior), with no belief, for instance, about
  the entities that do not furnish our world.
• In special occasions expectations that are
  related to general beliefs are frustrated, as it
  happens when a gremlin appears.
• The expectation that gremlins do not exist is
  hence a volatile expectation, generated by a
  certain context and related to some general
  belief about the entities that furnish our world,
  with no corresponding specific belief.
• Volatile expectations can also be derived from
  local beliefs and expectations, not only from
  general beliefs and relative expectations.
• The difference between the concept of volatile
  expectations and the concept of passive or
  derived expectations consists in the fact that
  volatile expectations are generated only when
  precise conditions are given these conditions
  can be related to the context of the experience
  and/or to the goals of the subject. The
  conditions that operate the generation of
  volatile expectations are relevant for the
  content of the generated expectations. Hence, the
  content of volatile expectations depends both on
  the beliefs that are hold by the subject and on
  the conditions of their generation. On the
  contrary the content of passive expectations
  seems to depend only on the expectations and
  beliefs that are hold by the subject in an active
  way.
• Volatile expectations are not expectations that
  are hold by that subject and that are not under
  the focus of attention they are not hold by the
  subject up to the moment in which they are
  unfulfilled by some event.
• Only the reaction of surprise alerts the
  individual about the fact that the sudden
  appearance of a gremlin is an unexpected event to
  him, and only at that point the individual can
  express the belief expectation that gremlins do
  not exist, or at least that they do not appear
  out of the blue.

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• Non-volatile expectations are expectations that
  are hold by the subject and that do not need
  special conditions in order to be generated in a
  particular occasion.
• Nevertheless, even if they do not need to be
  generated, non-volatile expectations might need
  to be activated.
• In fact, not all the expectations and beliefs
  that are hold by a subject are relevant at any
  moment and in any condition. This fact might
  explain the analogies and differences between the
  emotional and behavioral reactions that are
  evoked by a certain event in the real world and
  the same event in a fictional world (the
  so-called paradox of fiction).
• Independently of the fact of being derived or
  direct, non-volatile expectations could hence be
  considered as passive or active depending on if
  they are relevant or activated in a certain
  situation or if the are not relevant and passive
  in that situation.
• Two hypothesis can be advanced
• Hypothesis of activation. Activation of
  expectations might be coincident with focusing
  the attention on them but not necessarily with
  the fact of the content of the expectations
  becoming aware or being symbolically expressed.
  As for volatile expectations, certain factors
  such as the context of the experience or the
  goals of the subject might in fact select some
  expectations between all the expectations that
  are hold by the subject, and only the selected
  expectations would be active and would be
  relevant (have effects) on the emotional and
  behavioral reactions of the subject.
• Hypothesis of de-activation. All the expectations
  that are hold by the subject in a non-derived way
  are active, and special conditions of context and
  goals de-activate the expectations that are not
  relevant for the situation.
• The necessity of activation and de-activation and
  the conditions that produce the activation or
  de-activation of expectations will be
  investigated later in this document.
• Following the two hypotheses we hence have the
  following types of expectations
• Hypothesis of activation volatile expectations
  that are not hold by the subject but are
  generated by context/goals, non-volatile passive
  expectations that are hold by the subject but are
  not relevant for the current context/goals and
  are hence not activated, non-volatile active
  expectations that are relevant for the current
  context/goals and that are in fact under the
  focus of attention in virtue of the activating
  effect of the context/goals condition.
• Hypothesis of de-activation volatile
  expectations that are not hold by the subject but
  are generated by context/goals, non-volatile
  expectations that are hold by the subject and are
  thus all active even if they are not relevant for
  the current context/goal unless the context/goal
  condition de-activates them.

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• Expectations Future
• (1) overtly expresses an expectation as a belief
  about a future state of affairs. In (2) no belief
  about future states of affairs is overtly
  expressed. Once the reaction of surprise has been
  produced it is possible to evince that the
  subject did entertain the belief that the brown
  shoes have strings or that shoes have strings as
  in (4) and (5).
• A belief becomes an expectation once the belief
  is considered in the perspective of future states
  of affair, as in (3). This is in accord with
  (Castelfranchi, Castelfranchi Lorini, 2003) who
  characterize expectations as part of a class of
  mental states that consist in more or less
  certain anticipatory representations about future
  states of affairs this class includes
  expectations, hypotheses and forecasts or
  predictions.
• Hypotheses consist in the belief that the future
  state p is possible
• Forecasts in the belief that the future state p
  is probable (that is, in the belief that the
  chance threshold for p has been exceeded)
• Predictions in the belief that the future state p
  is quite certain (probability esteemed next to
  100)
• Expectations are predictions or forecasts
  associated to a motivational component (a goal,
  drive, motive, concern).
• As shown in (3) goals can be represented by
  epistemic intentions (verify ones own belief) or
  by pragmatic intentions (act on some object which
  is believed to present certain characteristics).
• But in (4) and (5) the existence of an
  expectation and the content of the belief that
  constitutes the expectation are evinced only
  après-coup, because the subject becomes aware of
  entertaining that certain belief only after the
  non-matching state of affairs has produced.
• In (4) the non-matching event allows the subject
  to recover an expectation that he did know to
  entertain in (5) the subject is informed about
  the fact that surprise is a telling betrayal of
  expectations, hence he is forced to admit that he
  did entertain a certain expectation, even if he
  was not aware of that.
• Expectations are hence beliefs that can be
  expressed in the form of anticipations, at least
  après-coup - after that a certain state of affair
  has provoked a reaction of surprise and hence
  alerted the subject to the fact that he must have
  entertained a certain expectation.

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• Expectations Goals
• Goals activate expectations Castelfranchi
  Lorini, 2003.
• And also, expectations are different from other
  purely anticipatory states because they matter
  for the subject, the subject is involved, has
  motivations concerning his predictions that
  induce him to make predictions Castelfranchi, .
  
• Since goals can be realized or discarded, not any
  goal implies (activates) expectations, but only
  active non-realized goals do.
• Expectations activate Epistemic Control (a
  sub-category of epistemic actions, that is,
  actions directed to gain knowledge about the
  world) active perception, monitoring, testing,
  matching activities. Epistemic control includes
  goal-directed, rule-based actions
  (proto-intentions, anticipatory classifiers) ad
  intentional actions with explicit representations
  of the expected state.
• Goal-directed systems are different from reactive
  systems because the formers present purposive
  behaviors activated by a mismatch between the
  current state of the world (perception) and the
  state of the world represented as a goal
  (explicit representation).

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• On the basis of the accord between belief and
  goal, expectations can be described as being
  negative or positive (Castelfranchi,
  Castelfranchi Lorini, 2003).
• Negative expectations have goal opposite to the
  prediction positive expectation have the
  conformable goal of the expectation.
• A positive expectation is always present in order
  to satisfy a need to confirm ones own capacity
  of prediction or predictability as a major
  meta-goal of the cognitive system. Epistemic
  agents are in fact in any case frustrated and
  disoriented by surprise, by non-concordant events
  because they represent failures of their capacity
  to predict, hence to control (Miceli, 2002).
• There are hence four possible scenarios negative
  expectations (prediction that p, goal that
  not-p), positive expectations (prediction that p,
  goal that p), ambivalent expectations (belief
  that p, goal that not-p and goal that p), neutral
  expectations (belief that p, goal that p and not
  goal that not-p).
• But negative expectations are always ambivalent
  in virtue of the presence of the positive
  expectations that confirms the subjects capacity
  of prediction.
• Castelfranchi describes two major types of
  expectation in relationship to the active or
  passive character of the experience.
• Expectations are active if the goal implies
  action on the side of the subject.
• Expectations are passive if the realization of
  the goal does not depend on him, but he just
  executes matching procedures for controlling if
  the goal has been realized (by others, by
  nature).
• Goals in fact include also epistemic intentions
  that are not necessarily related to actions and
  other desires that are not realized by the action
  of the subject who entertains the expectation
  hence expectations are broader than goal-directed
  actions, for instance the desire that ones own
  predictions are confirmed. This goal is related
  to the importance for the subject of representing
  himself as a successful predictor and on the
  importance of mechanisms of control.
• Once quantitative parameters are added (both on
  the side of beliefs, that can present different
  degrees of certainty or strength, and on the side
  of goals, that can present a greater or lesser
  value or subjective importance for the subject),
  other anticipatory states can be characterized
  (Castelfranchi, Castelfranchi Lorini, 2003)
• Hopes can be characterized as positive
  expectations with different levels of certainty
  (hopes or hope-casts) and fears as negative
  expectations with any degree of certainty (from
  fears to fear-casts) and value.

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• The question arises if fictional and virtual
  worlds can present expectations in the sense of
  anticipatory states with goals or only
  predictions.
• The question is relevant because the effects of
  validation and invalidation are different for
  expectations and for predictions an expectation
  that reveals wrong is a frustration or goal
  failure for the goal that p and an invalidation,
  falsification, prediction-failure for the belief
  that p.
• In relationship to the positive or negative
  expectation and the nature of the validating or
  invalidating event (and consequent belief), in
  fact there will be the following forms of
  invalidation
• No surprise but achievement when a positive
  expectation is validated
• Frustration with negative surprise or
  disappointment when a positive expectation (hope
  or hope-cast) is invalidated
• Positive surprise or relief when a negative
  expectation (fear or fear-cast) is invalidated
• Frustration with no surprise when a negative
  expectation is validated.
• The degree of disappointment and relief are in
  relation with both the strength of the belief and
  the value of the goal.
• Frustration or goal-failure is the falsification
  of a goal and belief-failure is the falsification
  of a belief.
• The strength of the effects of invalidating
  beliefs can be measured because it is function of
  the strength of the belief (expressed in terms of
  the degree of certainty) and of the strength of
  the goal (expressed in terms of the subjective
  value of the goal).
• The surprise component is in relation to the
  failure of the prediction (hence its strength is
  in relation to the degree of certainty of the
  prediction) and the disappointment/relief
  component is in relation to the frustration of
  the goal (hence its strength is in relation to
  the value of the goal). (See Lorini, 2005).
• For this reason, surprise is activated even in
  case of failure of a prediction in a negative
  expectation, when no frustration is evoked.

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• As a first consideration, the distinction
  between expectations and predictions is not
  always clear.
• (6) A certain experience in the visual sensory
  modality activates the anticipation of a
  corresponding experience in the touch sense
  modality, only on the basis of connections based
  on statistical co-activation.
• (7) a subject intends to catch a ball (goal of
  catching a ball) and evaluates the shape of the
  ball in order to catch it properly with his
  hands. On the basis of the visual information the
  subject pre-shapes his hand in relationship to
  the shape and dimension of the ball.
• The behavior in (7) seems to be a purely
  anticipatory one, because no goal is directly
  associated with it. Nevertheless, the behavior
  described in case (7) is common to goal-directed
  and reactive systems reactive systems react to a
  ball with sensorimotor matching and actions plans
  even if no explicit (in the sense of symbolic)
  goal of catching a ball can be ascertained. It
  all depends if we associate the general goal to
  the different predictions that follow.
• (8) a subject intends to dance and is a skilled
  dancer. The subject puts in action a number of
  movements that are based on automatic action
  plans and sensorimotor matchings. No specific
  goal is related to the single matchings and
  plans. The dance behavior is hence composed of
  general goals and hence of goal-directed
  behaviors, but also of purely reactive behaviors
  activated by the context (state of muscles,
  sensory feedbacks).
• If only automatic, reactive actions activated by
  the context are present, the behavior in (8) is
  not a dance (as the so-called dance of bees is
  not a dance but a reactive behavior in presence
  of certain conditions) it is the presence of
  goals, hence of symbolic representations, that
  makes (8) be a case of dance. Nevertheless, it is
  not clear which of the behaviors put in place in
  the case (8) are pure predictions and which ones
  are expectations.
• Hence the distinction between expectations and
  predictions becomes less clear.

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• Additionally, according to (Castelfranchi,
  Giardini, Lorini, Tummolini, 2003) beliefs have a
  tendency to become expectations.
• Simple beliefs about future actions and events
  tend to become full expectations (with goals) in
  reason of the component of prediction and
  self-efficacy which is implicated in anticipatory
  states cognitive agents make predictions in
  order to avoid anxiety and stress, act in order
  to find their predictions validated by facts and
  feel distress in case of invalidation. Hence,
  when a cognitive agent predicts a certain event,
  he has a tendency to act as if he wanted the
  prediction to be confirmed, even if it is a
  negative prediction.
• An invalidated hope-cast is felt not as a simple
  distress but as an ill-treatment. People have a
  tendency to add a normative component to their
  strong predictions. Since the belief that p is
  well grounded and the agents wants it to happen,
  p turns to be something that is bound to happen.
• Miceli, 2002 considers the need for
  predictability as a meta-goal it is not
  represented (at the conscious or unconscious
  level) but has a function on the regulation of
  mind processes.
• In analogy with the concern for predictability
  that would be present in any anticipatory state,
  we could consider that a general concern for
  coherence constitutes another regulatory goal or
  meta-goal.
• As we will see in fact, when a violation of
  expectation or violation of coherence is detected
  by the system, the system reacts with a tentative
  to eliminate the inconsistency and re-establish
  coherence.
• Miceli, 2002 considers regulatory principles as
  the re-establishment of coherence and the need
  for prediction as meta-goals because they do not
  need to be present in the mind as representations
  on the basis of which the mind reasons and plans
  (for instance when calculating costs and
  benefits) , but as functions or procedures that
  are implemented, for instance when a
  contradiction is detected.
• It is important to maintain the functional
  meta-goal level distinct from the goal-level
  even if meta-goals can become goals when assumed
  as representations they do not need to be
  represented.
• The need for coherence is testified by the
  existence of procedures for eliminating
  contradiction when it is detected, because
  contradiction produces unpleasant cognitive
  states (Festinger, 1957 Carlsmith Aronson,
  1963 Cooper Fazio, 1984 Fazio Cooper, 1983)
  and by manifestations of the principle of minimal
  change in belief revision ( Gardenfors, 1992
  Harman, 1986).
• Thus, if the content of the experience is not
  coherent, the subject experiences both prediction
  failure (invalidation of the belief or in general
  of the anticipation) and frustration or
  disappointment in reason of the invalidation of
  the coherence procedure. Frustration will be more
  or less strong in connection with the strength of
  coherence procedure. We can in fact imagine that
  the need forcoherence is stronger when action is
  involved because violations of coherence block
  action than when the organism is just a
  spectator. The spectator can be more disappointed
  when he holds prevision with a high degree of
  certainty about the enjoyment he will obtain from
  the spectacle or when the fact of enjoying the
  spectacle has a great value for him.

20

• (9) The user of a VR world can act in the virtual
  environment and hence have goals that concern his
  actions and their result, for instance the goal
  of surviving during a pilot test and the belief
  that the executed action is efficient for the
  goal. The results of the user actions are the
  object of active expectations, because they
  involve beliefs and goals.
• (10) In the case of passive media, the spectator
  of a movie can make certain predictions or
  forecasts concerning the story which is
  represented (what will happen to the hero, for
  instance) if the spectator is involved he can
  also have a preference for certain events to
  happen (the hero is saved in a difficult
  situation). The preference constitutes a form of
  goal, and we are hence in presence of an
  expectation, passive expectation in this case.
• When the expectations in (9) and (10) are
  unfulfilled the users and spectators are
  surprised in virtue of the invalidation of
  expectations and also disappointed, at different
  degrees according to the respective degree of
  certainty of the belief and value of the goal.
• These emotions concern the contents of the story
  or more in general the events that take place in
  the virtual and fictional worlds.
• We can hence conclude that users and spectators
  hold expectations (with goals) when the events
  that happen in the frame-work of the virtual or
  fictional world are concerned (contents of the
  fictional or virtual world).
• The case of passive medias (such as cinema,
  radio) is different from the case of interactive
  media, where the subject can actively operate on
  the fictional or distant world (VR systems but
  also telephone). In the case of the interaction
  with a virtual environment, the user can have the
  goal of chasing a gremlin or catching a virtual
  ball, which is not the case for the spectator of
  a movie, even of a SF movie featuring gremlins or
  of a movies featuring baseball.
• Only experiences with interactive media can
  present active expectations, because only in this
  case action on the side of the subject is
  allowed.

21

• Surprise Believability
• The problem arises of the relationship between
  surprise and believability.
• The examples in (9) and (10) show that
  invalidated expectations are tolerated at the
  level of the story, at least a certain number of
  invalidations and invalidations of a certain
  kind. The user or spectator accept the situation
  and change their beliefs, as in the case of the
  surprise test.
• What makes an experience of mismatch that causes
  surprise be un-believable?
• The judgment of un-believability can be applied
  to single experiences or to long course
  experiences, such as a film or an entire
  experience with a virtual world.

22

• We can advance several hypothesis, that are not
  mutually exclusive
• Believability is related to the degree of
  surprise or to the degree of violation of the
  expectation, in two senses
• distance between the expectation and the
  invalidating belief
• (11) I expected it would snow, and it rains
• (12) I expected it would snow and its 40
  degrees.
• In (12) the distance between expectation and
  invalidating belief is greater than in (11). It
  can be hypothesized that the greater the distance
  the greater the surprise. It is not clear if
  great distance alone can give rise to an
  experience which appears wrong.
• Degree of certainty of the invalidated
  expectation the invalidation of beliefs with
  high degree of certainty (predictions) is more
  suitable to produce un-believability. The degree
  of certainty can, on its side, depend on
  different conditions
• Active expectations and passive expectations. For
  instance,
• (13) the expectations concerning what a movies
  hero will do next cannot have a high level of
  certainty, because the spectator knows that it is
  up to the writer and director to decide about the
  contents of the story.
• The type of knowledge to which the expectation is
  related the type of belief or type of knowledge
  involved can be relevant because different types
  of belief might present different levels of
  certainty.

23

• Believability of a certain experience with long
  duration is related to the quantity of surprising
  effects or of violations of coherence the
  presence of a certain number of violations of
  coherence could be tolerated, also in reason of
  their degree of surprise, but an excessive amount
  of violations of coherence would make the global
  experience un-believable
• Believability of a certain experience is related
  to the quality of the surprise, hence to the
  invalidation of the goal and not only, as in 1.
  and 2. to the invalidation of belief relief
  would be more tolerated than disappointment.
• Believability depends on the existence of a
  certain threshold of subjective tolerance to the
  invalidation of expectations, which could be
  related to
• The emotional state of the subject
• The cognitive state of the subject, in
  particular will to believe vs. will to
  ascertain, hence to the presence of general goals
  concerning the global experience

24

• Believability depends on the type of expectation,
  in three senses
• The type of knowledge to which the expectation is
  related the type of belief or type of knowledge
  involved can be relevant because different types
  of belief might be more or less easy to revise.
• This issue will be discussed later in this
  document where the different types of knowledge
  expectations are related to will be analyzed.

25

• The type of content of the expectation the
  invalidation of expectations such as in (9) ad
  (10) that concern the contents of the world seems
  to be more tolerated than the invalidation of
  expectations that concern the way of presentation
  of the contents of the fictional or virtual world
• - (13) Spectators and users of VR
  environments make predictions or have
  expectations concerning the complexity and
  accuracy in the representation of the motor
  behavior of a represented character because of
  the level of complexity and accuracy of the
  representation of the physical aspect of the same
  character. An example of this kind of expectation
  or prediction and of the disrupting effects of
  its invalidation are described by Garau et al.
  (2003) in an experiment featuring a discrepancy
  between levels of realism for the representation
  of the physical aspect and the representation of
  motor behavior.
• Four conditions are tested in the first one
  realistic physical aspect is associated with a
  less-realistic behaviour, in the second one
  realistic physical aspect is associated with
  realistic behaviour, in the third one
  non-realistic physical aspect is associated with
  realistic behaviour and finally non-realistic
  physical aspect is associated with non-realistic
  behaviour. The non-realistic physical aspect is
  represented by a sort of sticky human and the
  behaviour is the avatars expressiveness
  represented by gaze in the realistic option gaze
  is associated with the speaking and listening
  turns during the communication between the avatar
  and the human (inferred gaze), in the
  less-realistic option random gaze is used. Four
  effects are measured through a questionnaire
  face-to-face effectiveness, sense of co-presence,
  involvement and partner evaluation. The results
  indicate the following impact of behavioral
  realism with different levels of visual realism
  for the lower realism avatar, the more realistic
  inferred gaze behaviour reduces face-to-face
  effectiveness, sense of co-presence and partner
  evaluation, but has no effect on involvement for
  the higher realism avatar the more realistic
  inferred gaze behaviour increases face-to-face
  effectiveness, sense of co-presence and partner
  evaluation. It hence seems that for lower
  realistic avatars, the realistic behaviour has a
  consistently negative effect. The opposite is
  true for more realistic avatars. In other words,
  it seems that low fidelity in one domain,
  physical aspect or motor behaviour, demands the
  same level of low fidelity in the other domains
  and that consistency between the visual aspect
  and the motor behaviour is necessary in order to
  produce effective communication and co-presence
  in the case of the interaction of human beings
  with artificial human-like entities.
• It is proposed that realism in one domain
  (physical aspect or motor behaviour) raises in
  the audience or users a certain number of
  expectations concerning the other domains for
  instance a realistic representation of the motor
  behaviour of an entity raises certain
  expectations about the aspect of the entity. The
  effect of the violation of these expectations is
  more powerful than the effect of the motor
  behaviour. The relation between the audience or
  users and the artificial entity is disrupted.

26

• The type of experience during which expectations
  are expressed. Certain experiences might alert to
  the possibility of implausibility and put in
  place implausibility tests, and also generate a
  special type of surprise, of the kind described
  by Lorini, 2005, as Implausibility-based
  surprise
• Lorini, 2005 affirms that even if surprise is
  always generated by expectations failure, three
  types of surprise can be distinguished
  mismatch-based, passive prediction-based and
  implausibility-based surprise
• Implausibility-based Surprise generated by a
  test about the plausibility of the explained raw
  sensor data in relation with my active belief
  system (function of Incredulity). Implausibility
  or incredulity is not generated from a mismatch,
  but is generated by some form of simulation the
  agent assumes a certain explanation of the raw
  data to be a possible explanation and before
  assuming it the distance between the explanation
  and the expectations and knowledge is measured.

27

• Implausibility tests could be put in place in
  special situations, such as experiences with
  representations, when the agent is somehow
  alerted to the possibility that what he perceives
  does not correspond to reality, or special
  perceptual conditions such as the presence of
  disturbances that create uncertainty (mist) or
  even special conditions of the perceiver that
  make him unsure about his senses (drug).
• In case of representations, such as it is the
  case for fictional and virtual worlds, one is not
  disposed to revise his own previous beliefs just
  because they conflict with the contents of the
  representation. If a conflict exists, the
  contents of the representation are considered as
  un-believable and the expectations are
  maintained.
• Nevertheless, a conflict precedes the reaction of
  surprise and the judgment of un-believability of
  the current experience.
• On the contrary, when experience with the real
  world is at stake and a conflict is ascertained
  with previous beliefs, perception is normally
  more trusted than knowledge (at least in daily
  conditions, and not in the frame-work of
  scientific research, where even observational
  proposition are interpreted in the light of the
  theory).
• We can say that perception is evidence against
  which beliefs are normally revised, unless
  certain conditions occur that alert the perceiver
  that the perceptual experience cannot be trusted
  more than expectations and knowledge.

28

• The different attitude toward perception of the
  real world and perception of representations
  could explain the fact that believability is much
  more a problem in virtual and fictional
  experiences than in in reality. In the experience
  with the real world, one does not start with
  thinking let see if this is plausible or not,
  let us control if what I perceive is plausible.
• It is not only a matter of certainty of the
  expectations, but of a different attitude to the
  revision of beliefs when perception of the real
  world or perception of fictional and virtual
  world are concerned.
• Hence, the fact of being aware of the presence of
  a representation would activate a plausibility
  test (or considerations about the plausibility of
  the experience) and would explain the fact that
  in case of conflict with expectations or other
  type of conflict, surprise gives rise to
  un-believability rather than to belief revision.
• The cited situations would give rise to a special
  form of surprise, especially related to
  un-believability, which is implausibility-based
  surprise.
• It can be hypothesized that normal mismatch-based
  surprise can give rise to implausibility-based
  surprise even in normal perceptual conditions
  for instance in the case of a great number of
  conflicts or of conflict of great strength, the
  perceiver could begin to put into doubt the
  perceptual evidence, start some simulation
  procedures and be startled with implausibility
  based surprise.

29

• Belief revision
• In any case the problem of un-believability and
  surprise seems to be related to the problem of
  belief revision following the experience of a
  conflict.
• When an expectation conflicts with another or
  with an invalidating belief and surprise arises
  three possible consequences are
• The invalidating belief is accepted as true, and
  the belief which is contained in the expectation
  is revised. It is the case of (9) and (10) and of
  the surprise test.
• The invalidating belief is not accepted, but the
  belief contained in the expectation is
  maintained. This case resembles to other cases of
  assimilation to expectations. We will see that
  assimilation as a way for solving the conflict
  between two inconsistent contents is quite a
  common solution for the perceptual and cognitive
  systems.
• The assimilation can be unconscious, when the
  subject does not notice the conflict
• or the subject is aware of the presence of a
  discrepancy and of the value of the discrepant
  elements and chooses to rely on his past beliefs
  more than on current evidence. Hence the
  invalidating belief is rejected as inconsistent
  with a belief which is not revised, hence as
  false. The fact that the subject is aware of
  refuting the perceptual evidence creates a
  special condition because, in the mean time, the
  subject knows that perception is normally
  reliable and he is hence faced with a special
  kind of surprise, of the type of
  implausibility-based surprise. This case hence
  concerns perception
• In the case of cognitive evidence (reasoning)
  rather than perceptual evidence, the subject does
  not experience the same kind of implausibility.

30

• Finally, the subject cannot say which of the
  conflicting expectations is true or false, he
  only knows that something must be wrong.
• The invalidating belief cannot be accepted but it
  is not possible to operate assimilation or to
  find other solutions, and the conflict remains
  unsolved.
• Or there is no necessity of choosing between one
  of the conflicting expectations, but the simple
  fact of a conflict makes the experience appear
  un-believable because the subject is alerted to
  the presence of an error. This situation might be
  common for special violations of expectations
  that will be described later as synchronic and
  not diachronic violations of expectations, and
  for expectations, as in (13) that do not concern
  the content of the experience but its way of
  presentation, hence structural elements that can
  pass unnoticed at the level of symbolic beliefs
  but operate at the automatic, sub-personal level.
  
• Also in this case, the awareness that something
  must be wrong (the sense of wrongness and
  impossibility) creates the conditions for a
  special kind of surprise based on implausibility.
  
• Both 2.2 and 3. are cases of un-believability in
  the sense of implausibility, characterized by a
  special type of surprise connected to
  impossibility or implausibility.

31

• When a virtual or fictional world or agent or
  object presents a certain level of violation of
  coherence and expectations the users or
  spectators react with a special form of surprise
  (in the sense of alert to error) which does not
  give rise to belief revision but to a judgment of
  implausibility which concerns the current
  experience the actual experience is rejected.
• The rejected experience is not simply considered
  as false it cant be true because, if it were
  true, it would create a conflict, a violation of
  coherence, with other experiences or with
  expectations that cannot be dismissed (because
  they are too strong, too important for the
  subject, etc.) or with expectations for which the
  current experience does not give sufficient
  reasons for revising (because the current
  experience is known to be fictional or virtual,
  because the subject cannot trust his senses,
  etc.).
• It can be suggested that coherence is a
  regulatory principle for the cognitive system and
  that violations of coherence are perceived as
  impossible conditions. This issue will be
  discussed later in detail when the consequences
  of violations of coherence for the cognitive
  system will be analized.
• The rejected experience is hence un-believable
  because if it were true a conflict or violation
  of coherence would arise, an impossible situation
  which is unacceptable for the cognitive system.
• The fact of considering what would happen if the
  experience were true is a form of simulation and
  suggests the existence of plausibility-implausibil
  ity tests that are practiced in particular
  conditions.
• When the test gives a negative result (a result
  that indicates that conflict will ensue), a
  judgment of un-believability is expressed which
  means if it were true, conflict would ensue, but
  this is impossible, hence the experience is
  un-believable.
• When the test gives a positive result (a result
  that indicates that conflict will not ensue), a
  judgment of believability is expressed, which
  means if it were true, no conflict would ensue,
  hence it is possible, at least within the present
  context.
• In the case of virtual and fictional experience a
  mismatch can be at the origin of the necessity of
  practicing a simulation test of plausibility. A
  simulation test can be motivated by particular
  conditions of uncertainty, but also by the
  perception of a mismatch with expectations or
  between current experiences. In this latter case,
  surprise based on mismatch could precede the
  judgment of believability or un-believability.

32
DISCUSSIONExpectations and knowledge

• The different hypotheses expressed in the first
  part concerning the relationship between surprise
  and believability evidence the importance of
  knowing which types of knowledge are involved in
  the formation of expectations and which are their
  different characteristics in terms of degree of
  certainty, susceptibility to revision, type of
  experience and type of conflicts to which they
  give rise.
• The different types of knowledge that give rise
  to expectations that play a role in the
  believability of experiences with virtual and
  fictional worlds should hence be classified and
  the different characteristics of each type of
  expectation should be analyzed.

33

• Knowledge expectations are related to different
  types of knowledge, only the case of symbolic
  knowledge gives rise to beliefs, hence to
  expectations based on beliefs.
• According to Dennett, Surprise is only possible
  when it upsets belief. But there are examples of
  non-linguistic expectations. (Dennett, 2001, p.
  98)
• (1) and (3) are examples of linguistically
  expressed expectations in (4) and (5) the
  expectation is linguistically expressed only
  after that a state of affairs has produced which
  does not fulfill some of the subjects belief. We
  can say that in cases (4) and (5) a belief is
  entertained (or at least it can be derived from
  entertained beliefs) even if it is not
  linguistically expressed (at least not before the
  surprising event).
• But there are also other possibilities in which
  expectations are not linguistically expressed,
  and even cases in which expectations do not
  necessarily have a belief for content. Dennett is
  right in the sense that the outcome of the
  upsetting of this type of expectations is not a
  full reaction of surprise, but a reaction which
  share many analogies with surprise and which
  consists in a sense of wrongness and bizarreness.
  

34

• Expectations in (1), (3), (4), (5) are all based
  on beliefs, that can be linguistically or not
  linguistically expressed but that have all a
  symbolic nature.
• They are based upon a form of knowledge which
  contents are organized and represented in a
  symbolic form symbolic knowledge, the kind of
  abstract knowledge which is proper for cognitive
  functions as language and mathematics Bruner,
  1966 Bruner, 1968.
• Two types of symbolic knowledge can be described
  that are relevant for distinguishing between
  types of expectations
• Scientific knowledge
• Commonsense knowledge

35

• Scientific knowledge
• Scientific knowledge is a special form of
  symbolic knowledge which is true of the world and
  justified.
• A recently appeared discussion about the
  believability of the planets and worlds depicted
  by the Star Wars saga, conducted by two
  scientists specialized in astrophysics and
  extraterrestrial life Lovgren, 2005, suggests
  the specific role that expectations might play in
  the characterization of the notion of
  believability. The interviewed scientists, B.
  Betts (a planetary scientist at the Planetary
  Society in Pasadena, California) and S. Shostak
  (a senior astronomer at theSETI - Search for
  Extraterrestrial Intelligence Institute in
  Mountain View, California), affirm having trouble
  buying some planets of the galaxy far, far away
  because they are beyond our current expectations
  or measurements. Following their discussion we
  evince that their judgment on the believability
  of the planets and worlds depicted in Star Wars
  depends on the expectations based on what
  scientific knowledge tells about planets and
  worlds a credible world is a world that could
  exist without violating the expectations that
  scientists have. It is a possible world
  relatively to scientific knowledge, even if it is
  not necessarily an existing world, or a world
  that will ever exist. Science fiction is not
  scientific discovery, it can just be
  scientifically plausible.
• The knowledge of the two scientists that judge of
  the believability of the Star Wars worlds is
  specialized and scientific (astrophysics,
  astrobiology). So are the expectations they hold
  and against which they judge the believability of
  their experience.
• Also VR experiences can involve scientific
  knowledge, as it can be the case for training and
  simulation for medical a