3/6/2016
Realism
The typical goal of mediated interfaces that seek to be believable is realism, which could
be intended as means of representing an entity by reproducing the sensory stimulation
generated by that entity. However many believable representations are not realistic (cf.
Tamagotchi), not all realistic representations are believable, and all too realistic
experiences in general incur the risk of fooling the user, thereby raising behavioural and
ethical issues.
It is the opinion of Hochberg that film-makers have the advantage of pointing
their cameras at real world’s events an so many of the constraints upon object
construction, appearance and behavior that our visual (or other) perceptual
systems might make use of are implicitly recorded in the resulting film, despite
the optical interventions of the medium. Computer graphics and VR designers
have not such constraints: scenes can portray anything, behaving in any fashion
with different levels of veridicality, detail, etc.
To this difficulty one should add the possibility for the user to interact with the
virtual environment, of creating modifications and be affected by his own actions.
Is this an advantage for believability or an additional difficulty?
The freedom from constraints which characterizes VR constitutes the ideal
condition for studying the minimal conditions for believability and the relative role
of realism.
Realism and the Uncanny Valley
Realism and the Tamagotchi
Realism and the Uncanny Valley
The uncanny valley and VR
An overview of positions and a proposal of some lines of inquiry
1. Introduction
The Uncanny Valley is a mathematical model introduced by Mori (1970)
and employed to describe the particular trend of a reaction indicated as “sense of
familiarity” human beings seems to experience when faced to more and more
realistic (human-like) robotic artefacts. Mori observes that the sense of familiarity
increases in association to human-likeness up to a certain point and then comes
to a valley. This valley of negative familiarity is a valley of strangeness and
uncanny. At the end of the valley there is another, higher peak of positive
familiarity associated with perfectly human-like artefacts and real humans. The
model leads to a pragmatic indication for designers of robots and prostheses that
consists in the advice of avoiding to approach too much to the first peak of the
Valley: whether the conditions of the second peak of perfect realism -both at the
level of the physical aspect and of the motor behaviour- cannot be achieved, the
quest for realism runs the risk of falling into the valley of the uncanny; designers
are hence invited to turn toward less realistic, non-human-like artefacts toward
which human beings will be more inclined to develop a sense of familiarity.
The following idea is implicated by the model: that a quest for realism runs
the risk of being counterproductive, at least when certain conditions are not
accomplished, and in particular in the case of human-life or life-like artificial
entities This idea has a certain appeal and seems to find anecdotal confirmation
especially in the domain of computer animation (both for what concerns
animation films and VR).
A. Jones, Final Fantasy animation director, for instance, notices that trying
to produce a complete replication of a human being can produce eerie
sensations while the characters become grotesque, as if puppeteering a corpse
(Hiltzik, 2001). Similarly, it seems that the Dream Works team involved in Shrek
movie had to pull back a little on the realistic look of Princess Fiona because the
effect was getting unpleasant.
Famous film critic, R. Ebert, adopts the idea of an uncanny valley 1 in
reviewing the animals of the animated movies “The wild” and “Final Fantasy”
(Ebert, 2006). Ebert finds that The wild’s animals’ physical aspect (fur, hairs,
feathers) and behaviour (lip-synching) is too good (as Ebert says, lip-synching in
I will the following convention : the notation “Uncanny Valley” makes reference to Mori’s model with
all its components, the notation “uncanny valley” makes reference to the general idea implicated by the
model.
1
animation usually ranges from bad to perfunctory to fairly good and that fairly
good is as good as it should be): such a precision in realism provokes the effects
described for the Uncanny Valley: creepy feeling and the feeling that something
is wrong. Ebert seems to attribute the experience associated to the uncanny
valley to the fact that excessive realism destroys the cartoon illusion: according
to Ebert in fact the style of an animated film is based on the distortion of reality
and it should never become too real. The choice to give a cartoonist aspect to
characters that are very refined in movement would hence explain, according to
J. Canemaker (2004), the success of Pixar’s “The Incredibles”, while excessive
realism and the fall into the uncanny valley would explain the rejection of “Final
Fantasy”, in which computer animation is used to create real characters.
Two indications are suggested in the domain of animation films in order to
avoid the fall into the uncanny valley: respect the cartoonist nature of animation
by avoiding too much realism in the reproduction of life-like characters
(simulations of existing animals or simulations of human beings) but also create
new characters that do not simulate real entities and hence can be as realistic as
one wants them to be. The example proposed by Ebert is the character of
Gollum in The Lord of the Rings (Ebert, 2004): Gollum is one of the most
fascinating and convincing characters in the movie because it seems a real
creature but not a creature we have seen before. Gollum presents a really high
level of realism, a kind of realism that could be associated with the second peak
of Mori’s model rather than with the first one. What matters is hence not to avoid
realism in general but realism as human-likeness or in general as imitation of an
existing real creature.
Some preliminary considerations can be extracted from these examples.
First, that animation has broadened the domain of the uncanny valley to
life-like characters in general (such as the animals of “The wild” or non-existing
creatures such as Gollum) and not only to human-like characters.
Second, the examples suggest that two meanings of the term “realism” are
at stake: realism as simulation of human or other existing creatures (such as
animals) and realism as a form of believability of entities that appear realistic
without simulating any existing creature (such as Gollum).
Thirdly, realism seems to constitute a problem when it violates certain
expectations in the spectator: the expectation of distortion of reality and
cartoonist effect related to the context of seeing an animation movie, the
expectations raised by the similarity with well-known real entities, such as human
beings and animals.
We hence have a narrow model of the Uncanny Valley as applied to
realistic robotic artifacts that simulate the features and behavior of human beings
and a broader set of ideas that are issued from this model and that concern the
effects of realism in the reproduction of life-like artificial entities; these entities
can be material robotic artifacts or virtual characters and agents, they can
simulate existing organisms or they can be brand new creatures. The broad set
of ideas connected to Mori’s model implies the existence of a valley of uncanny
in correspondence with certain conditions that raise from an elevated level of
realism in the simulation of existing organisms to the violation of expectations in
the case of artificial creatures that simulate or do not simulate existing
organisms.
These considerations will be developed in this paper in relationship to the
clarification of some notions introduced by Mori, such as the nature of the feeling
that Mori describes as “sense of familiarity”. Some authors, as Hanson (2003),
consider in fact the model of the Uncanny Valley as non-scientific. A problem is
certainly represented by the use of vague, common-sense notions in the
description of the Uncanny Valley. A better understanding of the phenomenon
hence requires a specification of the human reactions described by Mori. It is
possible to extract three components in the non-familiarity effect from Mori’s
description of the Uncanny Valley: emotions related to fear and disgust, which
have been taken into account by the literature in robotics, an epistemic judgment
relative to the believability of the experienced artefact or virtual entity and a
reaction of negative surprise. The problem of believability seems to be generally
related to the violation of expectations and to the violation of the coherence of the
experience, both in mediated and non-mediated conditions. Some exemplary
cases will be described. The other aspect of the uncanny valley, the emotions of
fear and disgust, on the contrary, seem to be more specifically related to specific
experiences, such as the experience with human features. Additional conditions
to the ones that are in cause in the problem of believability could hence be
responsible for the supplementary emotional reactions that are described by the
Uncanny Valley model when human-like artificial entities are at stake.
We can hence add a fourth consideration: that the model of the Uncanny
Valley presents different aspects for what concerns the reactions associated to
the valley of uncanny and that these aspects are all present in the narrow model
but can be analyzed separately as a general problem of believability of artificial
entities and a problem of uncanny emotions raised in specific conditions, such as
in the case of life-like entities.
2. Evidence about the Uncanny Valley
It is auspicated that suitable test procedures are individuated in order to
prove the existence of the Uncanny Valley or to individuate and measure the
conditions that provoke valleys of uncanny in the domains of robotics, animation
or other types of representations.
The model of the Uncanny Valley is in fact still under debate. Brenton et
al. (2005), for instance, affirm that even if there is anecdotic evidence about the
existence of “uncanny reactions”, this evidence does not validate the valley
model. Additionally, the domain of animation in movies is quite complex, so are
the reactions of the public. It is not easy to establish if an animation movie owes
its success to the fact of respecting its cartoonist style because people relate
better to animated figures that are distinctly outlandish than those that approach
human-likeness realism and want animation movies to distort and exaggerate
reality rather than simulating it, or because of other factors connected to the
value of the narration, to the beauty of the aesthetic, etc.
Hanson (2005b) considers the existence of a Valley of Uncanny as related
to the realism of robotic artefacts a mere illusion and puts forward that extremely
abstract robots or even cosmetically atypical human beings can be uncanny; on
the contrary, any level of abstraction and realism can be appealing. There are in
fact many and different ways of deviating from realism and it is not clear that
human reactions are more strongly related to level of realism rather than to good
or bad design.
Ramey (2005, 2006) puts forward that the uncanny valley effect is not
unique to humanoid robots but is a member of a class of cognitive and
perceptual states of uncertainty at category boundaries, such as the boundaries
between humans and robots.
MacDorman et al. (2006b) has recently provided some evidence about the
existence of a curve of uncanny related to the familiarity and realism of
photographed human-like robots (androids and humanoid robots) analogous to
the one described by Mori. The participants to the experiment are asked to rate
31 images (photos) on three scales: a 9-point scale ranging from very
mechanical to very human-like, a 9-point scale from very strange to very familiar
and finally a 10-point scale from strictly eerie to extremely eerie (non-eerie
photos being assigned 0 points). MacDorman (2006a) chooses in fact to make
reference to the feeling connected with the Uncanny Valley and expressed by
Mori with the Japanese term “bukimi”, as “eeriness”. The contents of the photos
are two sets: in the first set the photo of a humanoid robot (Qrio) is morphed into
Hanson’s very realistic P. K. Dick robot which is morphed into the SF writer
photo; in the second set the photo of the robot Eveliee is morphed into a photo of
the android Repliee QI Expo which is morphed into the photo of Repliee’s human
model. The curve resulting from plotting eeriness against familiarity in a graphic
ranging from very mechanical to very human-like presents a valley for both sets
of photos in correspondence of the images between the humanoid robot and the
android robot; the peak of the eeriness matches the trough of the familiarity
ratings, thus reproducing Mori’s results.
Nevertheless, an experiment conducted by Hanson (2005b) with a similar
series of morphed photos arranged with the aim of making them appealing and
not eerie shows the following result: while reactions to the control figures show
the uncanny valley trend, attractively-tuned figures show a low level of eeriness
thus demonstrating that the sense of eeriness does not only depends on the level
of realism but at least also on aesthetic considerations. According to Hanson
(2003, 2005a, 2005b) and Hanson et al. (2005) the Uncanny Valley can be
avoided and realism can be maintained as an objective for robotics if aesthetic is
well.
Additionally, in another experiment of MacDorman (2006b) where the
participants are exposed to short films (30 to 60 seconds) of a wide range of
human-like and android robots (a mobile robot, a manipulator arm, android
heads, android robots, a human being), the results are more concordant with
Hanson’s statement that the uncanny occupies a continuum ranging from the
abstract to realism; the curves extracted from the same kind of evaluation
described for the previous experiment in fact do not show the presence of a
single valley of uncanny; the lines corresponding to strange versus familiar and
of eeriness are almost mirror images. MacDorman (2006b) hence suggests the
presence of multiple causes affecting the perception of realistic robotic artefacts
and eventually provoking a sense of eeriness. These causes range from the
deviation from the norms of physical beauty to the sense of disgust which is
provoked by the perception of illness, disease, bad genes, to the elicitation of the
fear if death and to the defences for coping with death’s inevitability. Hanson
(2003) presents a survey of. studies in neurophysiology and neuro-imaging
intended to confirm the following hypothesis alternative to the Uncanny Valley
model: that the uncanny effect is the result of an alarm system which detects
anthropomorphic entities and rings when patterns that signal crises are detected
or when patterns that signal healthy presence are not detected. It is also
proposed
that
the
system
produces expectations
for
more
advanced
verisimilitude cues in presence of anthropomorphic entities; if these expectations
are encountered social interaction can be initiated; if they are not, a response of
fear is triggered. But Hanson also insists that no warranty is given that all the
kinds of deviation from verisimilitude will have the same effect on human
reactions.
All these causes are especially related to what I have called the narrow
model of the Uncanny Valley, because they make reference to human-like or at
least life-like contents of experience. MacDorman (2005a, 2005b, 2006a, 2006b)
and MacDorman et al. (2006a, 2006b, 2006c) consider in fact that humanoid
robots and androids in particular elicit expectations about the behaviour of the
android (including social behaviour in interaction with human beings) that are
based on the experience with human beings. In this way human-like robots
become a precious instrument for the understanding of social behaviour of
human beings but they are also subject to negative reactions when the raised
expectations are frustrated by imperfect realism. The violation of expectations in
itself is not considered by MacDorman (2005b, 2006c) as a sufficient condition
for explaining the sense of eeriness provoked by realistic robots: in fact, not all
forms of expectations violation result in a sense of eeriness. Thus, additional and
probably multiple causes must be individuated that are specifically related to the
expectations and other mental states provoked by human-like or at least life-like
artefacts.
It is proposed here that necessary actions to for the development of
suitable test procedures for demonstrating the existence of an uncanny valley
and for individuating the causes of the uncanny valley consist in the clarification
of the different aspects of the phenomenon, and preliminary, in the clarification of
the human mental state that Mori indicates with the term “sense of non-
familiarity”2. This is in fact a term issued from commonsense language but it is
not clear which are the psychological dispositions and attitudes at stake.
3. Sense of non-familiarity
Mori’s description of the sense of non-familiarity can be factored into
different components, in part emotional in part epistemic and propositional. Mori,
in fact, presents two main examples of the uncanny.
The first example is represented by a prosthetic hand which reproduces all
the features of the visual aspect of a real hand. Mori sustains that people are
shocked when they touch the prosthetic hand because it is cold and it lacks of
soft tissue: the experience reveals uncanny, no more familiar and a sense of
strangeness arise.
The second example concerns prosthetic arms and in general human-like
robots that are not only realistic in their aspect but can also move. Human
movement is nevertheless perfectly reproduced. Mori hypothesizes that the view
and touch of such moving artefacts is shocking and that it might provoke a sense
of horror.
We can hence extract the following components of the sense of nonfamiliarity:
2
Another aspect of the phenomenon to be clarified is indicated by Ramey (2005, 2006) in the similitude
between humans and robots. According to the results of an experiment conducted by the author it seems
that humand and robots are considered by the participants to share a number of analogies but it also seems
that these analogies lay more in the components f the body than in those of the face.
-
non-familiarity/strangeness indicates the presence of an epistemic
judgment relative to the believability of the experience: the experience with
the uncanny entity is unbelievable, it evokes falsehood; shock reactions
can be assimilated to strong reactions of surprise, and notably to a
negative surprise or a surprise which is associated with negative,
unpleasant emotions;
-
non-familiarity/fear/repulsion: negative emotions include a sense of
horrible that has a shocking effect; the sensation of uncanny can be
considered as composed of fear and repulsion.
The two components are present also in the definition of the English term
“uncanny” and of the Japanese term “bukimi”, which synonyms are: weird,
ominous, eerie, strange, unfamiliar, bizarre, abnormal, alien, creepy, freakish,
ghastly, horrible, spine-chilling (see MacDorman, 2006a).
These components can hence be candidate for constituting the object of
suitably developed measurement instruments and for further psychological and
philosophical investigation.
Another confirmation of the presence of two different components in the
sense of non-familiarity is represented by the answers of the participants to an
experiment effectuated by MacDorman (2005b) with humanoid robots and
android heads; the test investigates the presence of defences normally provoked
in human beings by reminders of death. The comments of the participants after
having viewed the android head in fact make reference to emotions related to
fear and disgust (“Scary female image”, “The first two images were disturbing”, “It
made me feel sick just looking at it”, “The woman was frightening”) and also to a
different kind of impressions that are in relation with strangeness rather than with
fear (“Strange”, “I thought it was kind of bizarre”, “Weird lady”).
Strangeness, bizarreness, weirdness are aspects of the sense of nonfamiliarity different from fear and disgust: they make reference to a judgment that
is not necessarily connected with negative emotions but to the reaction in face of
something new and unexpected: the judgment that a certain creature appears
wrong and hence unbelievable.
I will put forward a general hypothesis for explaining the aspect of fall of
believability related to the phenomenon of the Uncanny Valley, general in the
sense that the fall of believability can be observed in different types of
experiences and not only in the case of the perception of human-like or life-like
artefacts. This hypothesis is grounded on observations and experimental results
in the domain of VR and also of normal perception and makes reference to the
role of coherence and expectations in perception and to the effects of the
violation of coherence and expectations.
For what concerns the second aspect of the sense of non-familiarity, I
suggest that negative emotions of the type fear/disgust are associated to the fall
of believability in particular conditions, for instance when the content of the
experience is represented by human-like or life-like artefacts.
These considerations are transversal to different types of experiences
such as non-mediated experiences in the perception of natural objects and
events, non-mediated experience with robotic artefacts, mediated experiences
with virtual or fictional objects and artefacts.
4. Believability
Believability seems to be connected with coherence and with the respect
of expectations activated during the experience. Discrepancy between the level
of realism achieved for the physical aspect and the level of realism achieved for
the motor behaviour or between the level of realism which is presented to
different sensory modalities seems in fact to produce falls of believability.
4.1 Coherence between behaviour and physical aspect
Mori suggests that realism in the sense of human-likeness does not
depend only on the physical aspect of the artifact, but also on its movement. In
particular, the presence of movement changes the shape of the uncanny valley:
peaks and valley result exaggerated. Additionally, the variations in movement
that cause human-like artifacts to fall into the uncanny valley are very slight:
slight variations in speed or in the relation between the characteristics of velocity
and acceleration produce the uncanny reaction.
Bunraku puppets are cited as examples because even if they are not very
realistic in their features they are felt as human-like thank to the characteristics of
their movement.
There is evidence since the ’50 that human figures can be identified from
patters of biological motion obtained by placing light points at the joins of a
human being and by showing the light points dynamic behavior against a black
background. The considerations about the role played by movement in humanshape perception can be extended to the recognition of human emotions, style,
gender (see for instance, Pollik, 2004) and also beyond the perception of human
figures to general mechanisms of perception (Viviani, 1990). There is evidence in
fact that the dynamic cues play an important role in the identification of the shape
of the dynamic object. Viviani and colleagues (Viviani, 1989, 1997), for instance,
have explored the effects of trajectory and velocity in the visual and kinesthetic
perception of circular shapes and have demonstrated that varying the
relationship between trajectory and velocity produces variation in shape
perception and illusions that tend to re-establish a certain law that connects the
two characteristics.
Recent studies conducted in VR environments seem to confirm the role of
behavioral cues in the evaluation of human-like figures (in this case of humanlike avatars). These studies also highlight the fact that, when the aspect and
behavior of human-like figures is reproduced, the existence of an accord or
consistency between the level of realism developed for the physical aspect and
the level of realism developed for the behavior counts more than the
achievement of high realism in one of the two aspects (for a review see
Vynayagamoorly, 2005).
The two following examples inquiry the impact of
human-like avatars’ realism on the perceived quality of communication during a
social exchange in a virtual environment. Both studies reveal that realistic aspect
is not necessarily positively appreciated by users asked to enter in social
interaction with virtual characters, and both studies argue that more
anthropomorphic characters elicit elevated expectations toward the virtual
character’s behaviour: when the expectations are not attended social interaction
and the sense of presence or co-presence are diminished in respect to the
condition in which the user interacts with very abstract virtual characters.
Consistency between levels of realism seems hence to be more effective on
believability, sense of presence and social interaction with virtual characters than
high realism in the aspect or in the behavioural cues.
In Nowak et al. (2003) it is put forward that human beings tend to project
mental states such as beliefs and desires into many entities; this overgeneralization of intentionality has been described by Dennett (1996) as the
intentional stance. Not every entity of the real or virtual worlds can trigger the
intentional stance, but only entities that appear self-propelled, self-guided or
volitional. This consideration might explain the reason why behaviour is so
important for the believability of virtual agents as life-like entities: only an entity
that shows behavior and movement can eventually show self-guided behaviour
and volition. The fact that an entity is an avatar (a virtual entity animated by a
human) or an agent (a virtual entity animated by the computer) is not so relevant
in order to trigger the intentional stance and social reactions in the user when
interacting with virtual characters: in an experiment conducted with three levels of
anthropomorphism of avatars and agents (high aspect realism, low aspect
realism and no aspect cues at all), in fact, the participants show the same level of
co-presence, physical presence, social presence for avatars and agents; the high
level of anthropomorphic aspect seems to have a positive effect on all the
conditions. Nevertheless, the results also indicate that the absence of physical
aspect raises the same responses of the anthropomorphic characters: it is hence
argued that the tendency to project human characteristics in the other is made
possible by high realistic simulations or by no simulations at all but not by lowlevel simulations. The low level simulation, in fact, would frustrate expectations
about the human aspect that are not frustrated by the very realistic or not realistic
at all conditions.
In Garau et al. (2003) 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 nonrealistic physical aspect is represented by a sort of sticky human and the
behaviour is the avatar’s 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 lessrealistic 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 copresence 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.
The result is somewhat surprising also in view of the statement about the
importance of movement for realism advanced by Mori.
Nevertheless this result suggests a hypothesis of explanation of the
disruptive effects of the Uncanny Valley: 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. The consequence is not necessarily a
sense of fear or disgust, but the entity does not capture the audience or users as
it would do if the different domains were consistent for what concerns their
realism.
The importance of the consistency between levels of realism in order not
to fall into the Uncanny Valley is also affirmed by Tromp et al. (1998) and Slater
et al. (2001).
4.2 Coherence between different cues of the agent’s psychology
In the domain of animation the quest for realism and the existence of
specific applications with human-like avatars lead designers to try to produce rich
agents, for instance agents that show emotions and personality. In addition to
physical aspect and motor behaviour, these agents can be linguistic; additionally,
the physical features, postures and motor actions are designed to work as cues
for cognitive, emotional and motivational states and for personality.
An interesting study about consistency in artificial agents by Nass et al.
(2000) relate that the lack of consistency between cues that indicate the
personality has negative consequences at least in the case of real human
beings.
The possibility of inconsistency is produced by the fact that human beings
judge the personality of another agent (real, fictional or artificial) on the basis of a
certain number of cues: way of speaking, way of moving, etc.
Negative consequences are represented by the negative appreciation of
users: users will like a character that presents inconsistent cues less than a
character that presents consistent cues. Some possible reasons for this
preference, or anyway, some advantages of consistency are indicated:
consistency allows people to predict what will happen during social interaction
(Fiske and Taylor, 1991), makes it easier to remember a person accurately
(Cantor and Mischel, 1979), lightens cognitive load (Fiske and Taylor, 1991). Like
and dislike can be instantiated by the fact that people prefer to engage with
agents that can be labelled consistently.
Dislike is not the same thing as non-believability. Nevertheless, there is a
common point between non-believability of inconsistent entities and dislike
toward inconsistent characters. It seems in fact that people turn to nonverbal
cues to see if they are inconsistent with the verbal ones when they want to detect
deception (Ekman and Friesen, 1974) (Ekman, 1980). This means that
inconsistency between verbal and non-verbal cues alerts to falsehood and
makes the inconsistent speaker untrustworthy.
In the design of artificial fictional characters the requirement of consistency
is pragmatically respected (Field 1994; Thomas and Johnston 1981). An
experiment conducted and described by Nass et al. (2000) and Isbister and Nass
(2000) on the appreciation of artificial characters with consistent and inconsistent
personality cues (verbal personality and non-verbal personality) confirms that
users like consistent character more than inconsistent ones and also that they
find consistent characters as more useful, more fun to interact with, and more
charismatic than the others.
It is worth noticing that consistency in this case concerns verbal and nonverbal cues that are used by human beings as indications of personality and not
realism as applied to the couple represented by physical aspect and motor
behaviour, as it is the case for Mori’s model and the discussion about the
Uncanny Valley in general.
This consideration suggest that when believability is at stake, coherence
plays a general role which is not bound to the style in which agents or characters
are presented (more or less realistic) and to the aspects of the agent that present
some form of inconsistency (such as physical aspect and motor behaviour).
4.3 Coherence between physical aspects that affect different sensory modalities
The first case of strangeness and uncanny described by Mori is the
prosthetic hand which has a very realistic visual aspect but is cold and lacks of
softness. This case can be considered as an example of experience of
multisensory conflict: a discrepancy subsists between the information for the
visual sensory modality and the information for the touch sensory modality.
According to Mori’s example, the subject who attributes the two inconsistent
sensations to one and the same object experiences a sense of non-familiarity. An
associated behavioural reaction is constituted by surprise.
This remark is supported by a number of studies in the domain of
perception concerning the experience of intersensory conflicts and a number of
studies about the effects of violations of coherence in perception. Intersensory
conflicts are the effect of the exposition to discrepant stimuli for different sensory
modalities and of the combination of these discrepant stimuli into one and the
same perceptual outcome. The experience of intersensory conflicts is quite rare
in normal perception, even in presence of discrepant information. In fact, when
faced to discrepant information the perceptual system shows a tendency to solve
the conflict in favour of intermediate solutions between the discrepant stimuli or
of dominance solutions in favour of one of them (Welch and Warren, 1981). This
tendency suggests a sort of preference of the cognitive system for coherence. In
the rare situations in which discrepancy cannot be solved, the subject
experiences an explicit conflict. The experience of conflict is associated to a
reaction of surprise and to the judgment that the experience in cause is
impossible, hence wrong.
For instance, when certain muscles of the limbs are vibrated by a suitable
instrument, a discrepancy is produced by information from the receptors within
the muscles and tendons and the receptors within the joints (Goodwin et al.,
1972) (Craske, 1977). In this situation the subject experiences an illusion as if the
vibrated limb was moving toward a certain position; but if the vibrated limb is in a
specific position at the beginning of the experiment and the experimenter
prevents the limb from moving, the subject experiences a movement which goes
beyond the anatomic possibilities of the joints, an impossible movement. The
movement is immediately identified as impossible by the subject, who hence
judges that there is something wrong in his experience, that what he perceives
cannot be true: “the arm is being broken”, “it is being bent backwards, it cannot
be where it feels” and the arm is felt as being “in two places at once”. Thus, the
subject is put into the condition of emitting an epistemic judgment concerning his
experience (there is an error in this experience) on the basis of the
characteristics of the experience itself.
Other violations of perceptual coherence are represented by the
experience with perceptual paradoxes, in particular with impossible and
ambiguous figures. As in the case of intersensory conflicts the presence of a
violation of coherence provokes a reaction of surprise and also a sense of
bizarreness and wrongness.
The perception of the Penrose two-pronged triangle (both in the twodimensional and in the three-dimensional versions), for instance, immediately
provokes a sense of wrongness, even if no error can be attributed to the
perception of the figure or of the object. Also in this case, the sense of
wrongness is associated with a sense of impossibility. According to Gregory
(1973, 1997) impossible figures make use of pictorial rules in order to create the
impression of the third dimension, but then some of these rules are broken by
other cues in the figure, so as to make the object impossible to construct. The
illusion of an impossible figure is thus explained as the application of opposite
rules for one and the same depiction. The two-pronged triangle, for instance, is a
possible drawing following the rules of two-dimensional depiction, but becomes
an impossible object when the rules of three-dimensional depiction are applied.
Ambiguity is the main characteristics of the experience with other patterns of
lines such as the perception of the Necker cube: the observer is not able to judge
the orientation of the cube, since the cube alternatively appears to have two
different orientations. A similar phenomenon is instantiated by the figure of the
Woman of Boring, the figure of the Vase of Rubin and the duck-rabbit figure, just
for citing some well-known figures. In all these cases, the perceptual experience
is ambiguously double: for instance, the same figure can be interpreted as a duck
and as a rabbit.
It is interesting to notice that the two interpretations cannot be synchronic:
the visual system seems to have no choice but to access one aspect at a time.
Even if the subject has experienced both the interpretations, and thus knows that
two interpretations are possible, he cannot perceive them simultaneously.
Human beings seem hence to have a special attitude through stimuli that can be
‘interpreted’ as being two different entities or figures at the same time: they
separate their descriptions, saying that they see, now, the stimulus as one object,
and, then, as another (Wittgenstein, 1958).
Following these examples, we can suggest that in the case of the perception
of paradoxes, there seems to be no error, in the sense of a departure from the
reality of the pattern of lines which is perceived. In fact, the subject correctly
perceives all the features of the figure. But the fact that two possible
interpretations are both present in the one and the same perceptual experience,
and that they are not reciprocally compatible, provokes a reaction of wrongness,
surprise and indecision. Even if one interpretation can be primed, the subject
experiences indecision between the two interpretations.
We can hence advance the following considerations: that the wrongness
or bizarreness of the experience appears to be related to the presence of a
discrepancy between the contents of two present experiences, hence to what we
can call a synchronic violation of coherence; and that the presence of a
synchronic violation of coherence makes the experience feel bizarre and even
impossible.
4.4 The reaction of surprise
Another consideration concerns the reaction of surprise that accompanies
violations of coherence. Surprise reactions are typically associated with the
presence of unfulfilled expectations. The frustration of expectations can be
considered as a violation of a diachronic form of coherence because
inconsistency stands between the content of the actual experience and the
content of an expectation based on past experiences or knowledge. But it is also
possible that the experience in a certain sensory modality activates a
corresponding expectation for the other sensory modalities: that the visual
experience of a square shape activates a corresponding expectation for the
touch modality, that if the object which is actually seen would also be touched the
touch modality would reveal the presence of a square. When multisensory
discrepant information is combined in one and the same percept the violation of
coherence is connected to the frustration of cross-modal expectations.
MacDorman (2005b) cites the possibility that elicitation and violation of
expectations might occur cross-modally, but he asserts that in this case the
sense of eeriness which he considers specific of the Uncanny Valley model is
absent.
Even in absence of sense of eeriness, the violation of coherence between
different sources of information or between expectations activated by different
sources of information can be judged as negative or unpleasant in virtue of the
negative adaptive value of violations of coherence. In this case the reaction of
surprise provoked by the detection of an error can be accompanied by negative
emotions (even if not necessarily fear or disgust) because of the fact that, as
when an error is committed, the subject who is faced with ambiguity cannot act
properly, since perception cannot guide his action toward a non-ambiguous well
identified target.
Different studies indicate in fact that violations of coherence (as the ones
related to illusions we are immediately aware of) present a negative adaptive
value. Coherence and the recognition of violations of coherence could, on the
contrary, have a positive adaptive value for the subject. In the domain of
neurophysiology Stein and Meredith (1993), for instance, underline the
importance of the coherence of the perceptual experience for the action and the
adaptation of the organism with regard to the environment. The integration of
information from different sources presents a positive effect on the neural
activation even for low stimulations; in general, coherence seems to present an
important adaptive value, especially for the correct programming of action when
information is inconsistent, on the contrary, the effect is disrupting upon action:
the action is either inhibited or directed toward a wrong target.
It is plausible
to hypothesize that the consequence of an explicit conflict or of a violation of
coherence in general is the inhibition of action, a break in decision making
because of the ambiguity of the sensory information available. The subject
prepares himself for action (at a personal or at a sub-personal level) in a way that
is attuned with the perceptual characteristics of the object that is the target of the
action. When the content of perception is ambiguous or when some of the
qualities of the object are actually perceived as mutually inconsistent, then the
indications or the action might be ambiguous too.
As for what concerns the emotions of disgust and fear, we can
hypothesize that they are evoked only by special situations, such as the
perception of human-like agents. When human characters are the objects of
perception the presence of synchronic violations of coherence and violations of
expectations might present an additional negative value connected with the
special place occupied by the perception of faces or of human beings in the
cognitive and emotional functioning. The sense of non-familiarity would hence be
present in its complete formulation (judgment of non-believability with negative
value of the experience associated to negative emotions of fear and disgust) only
in the case of human-like agents that present some form of resemblance with
humans and in the case of the violation of the expectations aroused by this
resemblance. But the idea of a negative valley with no fear and disgust (negative
judgment of believability and negative surprising effect) could be extended
toward a more general condition including entities that are not necessarily
human-like or toward characteristics of human-like entities that do not
necessarily concern the realism of their aspect and behaviour.
4.5 Believable agents
Even in absence of considerations concerning emotions of fear and
disgust, the production of human-like believable agents is strongly concerned
with considerations about realism. The aim of producing believable agents is a
primary objective in computer animation, both for films and VR; but it has been a
crucial question even for more traditional media displaying stories with
characters, such as classic animation, dramas, films, comics, books, etc. The
problem of the opportunity of seeking for realism in order to produce believable
characters has been faced in particular for animation, comics and VR. In each of
these domains we can find positions that are next to Mori’s advice to robots’
designers of avoiding the first peak of the uncanny valley and of seeking for new
forms and features.
A classic approach to believability in animated agents in fact was provided
by Thomas and Johnston in their famous book “Disney: the illusion of life”:
believability is conceived as the illusion of life, the illusion that even the oddy,
caricatural, unrealistic characters of animation movies are alive. The same
approach has been adopted for comics, as testified by McCloud’s reference book
“Understanding
comics”.
McCloud
underlines
the
role
of
abstraction,
simplification and amplification in the depiction of comics characters: the effect of
the practical requirement in traditional animation where thousands and
thousands of drawings have to be produced, the necessity of using extremely
simple, non-realistic imagery and to seek to abstract and extract the essential
features of a character, reveals to be a theoretical requirement for producing
more believable characters. Abstraction allows in fact to highlight the essential
characteristics of the depicted agent.
This line of thinking is re-taken in the domain of VR, the new interactive
medium, by the researchers of the Oz Project, a project for creating believable
interactive dramas with believable agents. Agents are interactive characters.
Bates (1992, 1994) states that believable characters and agents are designed in
such a way as to provide the illusion of life and as to permit the suspension of
disbelief. In general believability is identified with a feeing of reality or an illusion
of reality: the (false) sensation that the world and agents the user is interacting
with are real even if not realistic.
Realism, Bates re-affirms, is in fact rarely effective in producing the sense
of reality. Scott-Reilly (1992, 1995) motivates this consideration on the basis of
the expectations that are evoked in the spectator or user: realistic, human-like
characters activate in the spectator or user expectations that are connected to
human beings. Since it is very difficult, or even impossible, to produce characters
that are exactly like human beings, a way to produce believable characters is to
lower the spectator or user expectations by presenting him with cartoonist or
alien characters. In the first way the expectations about the physical aspect are
lowered, in the second way even the behavior of the agent can diverge
substantially from those of human beings. The idea behind this suggestion is that
it is much more difficult to disappoint or deceive a spectator or a user with few
expectations than a spectator or user with a lot of expectation about how the
agent should look and behave.
Nevertheless, additional premises should be added in order to justify the
invitation to the lowering of expectations: that spectators and users hold a certain
number of expectations based on their experience with the real world or even
with fictional and virtual worlds; that some of these expectations are activated by
the characteristics of the artificial world and agents they are exposed to; and that
the respect or frustration of these expectations matters for their believability. We
can call this a case of diachronic coherence or violation of coherence in that the
experiences that are respected or frustrated are activated in the context of the
experience but are based on beliefs and knowledge that the spectator or user
holds from his previous experience. These premises constitute an hypothesis
about the factors that enhance or depress believability and this hypothesis is
consistent with the considerations we have drawn in the case of conflicts
between the realism of the physical aspect and the realism of behavior, that is
that synchronic violations of coherence provoke a fall of believability. We can
hence advance the following general hypothesis: that violations of coherence and
frustration of expectations at the synchronic and at the diachronic level are fatal
for the believability of fictional and virtual agents and worlds. It follows that
minimal requirements for enhancing believability in general consist in the respect
of the expectations that are activated by the context of the interaction, by the
characteristics of the virtual or fictional world and by the characteristics of the
virtual or fictional agents. In addition to respect internal coherence, designers
should hence consider the expectations that are hold by the users or spectators
and that can be activated during the designed experience.
Mateas, Loyall, Bates, Reilly and the other representatives of the Oz
project, for instance, suggest that believable characters must be rich, in the
sense of showing (through the aspect and behavior) a rich psychology (Mateas,
1999, 2002), (Loyall, 1997). Characters’ psychology includes the same aspects
we expect to find in normal, natural agents: personality, emotion, self-motivation,
change, social relationships. Nevertheless, the manifestation of these states
cannot be as shaded is it can be fro natural entities of the real world: also in the
case of internal states exaggeration, isolation and a suitable timing is required in
order to make emotions, personality, etc. recognizable to the users and viewers.
Even in this case realism works against believability because it prevents the
identification of the psychological state which is represented.
The indicated requirements are not necessarily the minimal requirements
for creating believable characters and agents. Their effect can be double. On one
side, adding more or less rich psychology can make agents with minimal physical
aspect look more believable. On the other side, other opportunities for the
production of incoherence (in addition to incoherence between physical aspect
and motor behaviour) are created by adding components to the agents’
characterization. Experimental research only can provide indications about which
of the two effects dominates and how contextual circumstances, aims,
applications can eventually produce shifts from one effect to the other.
4.6 Different meanings of realism
Two meanings of “realistic” emerge in connection with the notion of
believability: realism in the sense of simulation of the real world, of faithful
reproduction of the physical features of the world and entities; and realism as a
mental state, a feeling based on a form of deception: the fictional or virtual world
and entities are taken as being as real as the real world is, even if they do not
share many resemblances with the real world.
We can make reference to the first meaning as photorealism, but we
should consider that the aim of faithfully reproducing the physical characteristics
of the real world might concern other sensory modalities than vision. New,
multisensory interfaces for VR in particular aim at producing believable
experience for different sensory modalities, such as vision audition and touch. It
seems hence better to make reference to this form of realism as to realism as
simulation. This is the kind of realism which is implied when the agents are not
only intended to produce an illusion of life or to be generally human-like, but they
also intended to resemble to real human beings or other existing entities of the
real world.
The second meaning of believability is a mental state of illusion of reality
and of life: agents look real or alive without resembling to any existing entity of
the real world. This meaning is far for being conceptually and psychologically
clear. It can be understood as an illusion of non-mediation: the illusion of being
there in the fictional or virtual environment or the illusion that there is no medium
between the user and the fictional or virtual environment. But it is not evident that
users and film or other media audience mistakenly take a fake world for real or
that believability require this error. When children play with a stick and pretend it
to be a sword they do not take the stick for a real sword, they just pretend and
make-believe. Why shouldn’t adults do the same thing when interacting with
fictional or virtual worlds? In other words believability might be revealed by the
appropriate behaviors of an adult who acts as if the virtual or fictional agents
(whatever their similarity to existing creatures of the real world) were real.
5. The uncanny as repulsion and fear
The sense of fear or repulsion raised by humanoid robots is discussed in
particular by MacDorman (2005b) and a measurement instrument is suggested.
This instrument is directed to understand if the view of uncanny robotic figures
elicits in human beings the same kind of reactions they would have in presence
of death reminders, hence if the sense of uncanny is related to the fact of raising
thoughts about death and mortality. Other hypotheses advanced by MacDorman
in order to explain the specificity of the reaction of human beings face to humanlike robots include, as we have previously seen, the presence of cues that remind
illness, bad genes, or of cues that deviate from the norms of beauty. In some
way, androids could remind us the possibility of being substituted by a sort of
Doppelganger, they could evoke the image of a disassembled body or even of a
soulless living entity (MacDorman, 2006a). In all these cases death is reminded
to the human subject and could evoke specific defences.
5.1 Reminders of death
MacDorman (2005b) attributes the sensations associated with the
Uncanny Valley to the violation of unconscious expectations, and specifically to
the violation of human-directed expectations. In fact many non-biological
phenomena can violate our expectations without provoking the sensation that
MacDorman characterizes as “eeriness” and which is associated with the
experiences that fall into the Uncanny Valley. MacDorman sought to explain the
specificity of the expectations and sensations provoked by human forms rather
than other kinds of artefacts. The model of explanation of the Uncanny Valley
proposed by MacDorman is hence strictly related to the artefacts that represent
human beings or their parts and that specific form of realism which is humanlikeness. Human-like robots are supposed to elicit the same kind of expectations
raised by the sight of human beings. A hypothesis suggested by MacDorman for
the explanation of this aspect of the Uncanny Valley phenomenon is hence that
humanoid robots which do not perfectly resemble to human beings work as a
reminder of mortality. Human-like robots that are not animated, or that are
animated in a non-fully realistic way, may look dead because they are not able to
satisfy all the human-directed expectations they elicit. As zombies and other
entities that remind death, these robots might raise in the human being the same
defences raised by reminders of death, defences that are related to death
thought and to the awareness of death, and that can be conscious or
unconscious. MacDorman (2005b) hence adopts a behavioural test based on the
Terror Management Theory and displays the relative instruments of evaluation of
the presence of reactions of defence toward death and mortality thoughts.
Another hypothesis emitted by MacDorman, which is not tested, makes
reference to human-directed expectations but not to reminders of mortality; it is
suggested that, in analogy with human beings, androids elicit expectations and
context-appropriate behaviour in people interacting with them and that imperfect
androids might violate the other’s expectations about how to go on. This disturb
in the expectation-action process might be at the origin of the uncanny sensation.
Nevertheless no proof is given of the fact that a feeling of uncanny is
associated with humanoid figures and no specification is provided about which
characteristics of the realistic human figure would be responsible for the
emerging of the feeling of uncanny.
5.2 Return of familiar emotions and beliefs that have become unfamiliar
The effort of explaining the psychological causes of the feeling of
repulsion, disgust, uneasy, eeriness which arises in response to certain situation
in life and fiction is at the centre of Freud (1919). The uncanny is in this case the
translation of the German Unheimlich. Freud criticizes the idea that the sense of
uncanny is caused by a form of cognitive incertitude, by situations that are new
and not clear, as in the paradigmatic case in which a subject is taken by the
doubt that a certain animated creature is really alive or that an object is
animated. This paradigmatic case is exemplified by dolls and automats ad in
particular by a fictional figure: Olympia of Hoffmann’s Sandman. As
MacDorman’s test uncanny robotic heads and Mori’s imperfect human-like
robots, Olympia is a human-like automat with no movement. The reader is hence
disturbed by the incertitude relative to the fact that Olympia is a real person or an
automat. Freud rejects both the idea of the cognitive incertitude and the idea of
the ambiguity between real life and imitation of life, reality and representation.
Even in the case of Hoffmann’s tale, the sense of uncanny is attributed to the fact
that something which is familiar to the subject (Heimlich) but which should have
been stayed hidden (again a meaning of Heimlich) has become overt. In the case
of the Sandman tale, a complex of castration is associated to different elements
in the story in which is present the fear of loosing one’s own eyes (Olympia’s
eyes are provided by a strange, paternal figure who extracts the eyes to
children); the fear of castration is a familiar feeling which has been removed and
which Hoffmann tale evokes. Dolls, doppelgangers and automats are particularly
effective in producing a sense of uncanny because they evoke an early stage of
life characterized by animistic thoughts (such as the possibility to give or
annihilate life by thought, or the fact that even objects are animated, or the fact
that everyone of us has a doppelganger or soul).
5.3 Face recognition mechanisms
In view of providing a scientific explanation of the reaction of fear and
disgust associated to imperfectly realistic robots it seems useful to question
cognitive neurophysiology and also pathology. Human faces and figures
constitute in fact special objects for perception: not only specific areas of the
brain are dedicated to their identification, but these areas are activated even from
little details. Comic artist McCloud (1993) offers a nice illustration of the salience
of few details for face perception and of the strong bias toward the perception of
simple figures with some evoking details as faces: if one draws a series of closed
figures of different, even very irregular, shapes and then places a little two circled
form within the shapes the resulting drawing will strongly evoke a face.
Hanson (2003) proposes a survey of studies on human face perception
and indicates neuro-imaging on human face perception as the most suitable
source of evidence for individuating the conditions that provoke uncanny
reactions. Pathology constitutes a rich domain of evidence about the specificity of
the perception of human figures too and it designates some of the conditions
that make human-like figures perception become uneasy, creepy and frightening.
Some pathological phenomena in fact can be explored in which the feeling
of uncanny is related to human-like figures with particular characteristics; these
phenomena are mainly classified as delusional misidentification syndromes. The
following pathologies constitute some examples that present a certain affinity
with the eerie sensations of the uncanny valley:
-
Capgras syndrome or delusion is a disorder characterized by the belief
that a close relative has been replaced by an impostor, robot or alien; the
misidentification seems to be related to a loss of emotional response
toward familiar faces (there is no differential autonomic response to
familiar and unfamiliar faces).
o An interesting fiction example of this form of misidentification is
represented by the novel and movies dedicated to invasions of
body snatchers who come as seeds from another planet and
replace human beings with duplicates that are identical to the victim
but lack of human emotions; relatives are frightened when they
notice this lack of emotional response which is indicated as the only
way for recognizing alien impostors.
-
Another phenomenon related to Capgras delusion is the so called
Syndrome of subjective doubles: the subject beliefs in the existence of a
doppelganger of himself, with the same appearance but different
character. The doppelganger is a double of an individual who is not that
individual.
o Two exemplar movies based on the existence of doubles are
Doppelganger (1969) and Mirror image (1959).
-
In Fregoli delusion the subject holds the belief of being persecuted by a
person who takes different appearances. As in the two previous
syndromes the subject is hence faced to impostors.
Other delusional misidentification syndromes exist, but what is interesting
in the cited cases is that appearance is no more related to identity and that the
subject is frightened by the impostor. The syndromes are attributed to disruptions
in the mechanisms of face perception caused by different forms of brain damage
or other neurological disorders.
A hypothesis for explaining the sense of fright produced by imperfect
human-like figures based on perceptual and cognitive mechanisms is the
following: when seeing a human face certain specific brain area connected with
human face recognition are activated. There is evidence that these areas are
activated also for very poor or blurred images of human faces. Nevertheless,
when human-likeness is not perfectly achieved or when the human-like figure
presents certain characteristics a disruption is produced in the mechanisms for
face recognition. This disruption is in some aspect analogous to the one which is
present in the cited misidentification syndromes. Hence the figure is perceived in
some sense as an impostor and the impostor is associated to fear as it happens
in the cited misidentification syndromes.
6. Conclusions
The model of the Uncanny Valley can be inquired from different points of
view, and in particular it can be considered in a narrow or broad sense.
The narrow sense consists in the specific mathematical curve proposed by
Mori for describing human beings’ reactions to realistic human-like robots; this
curve still needs experimental investigation in order to be confirmed or
disconfirmed. Any experimental investigation concerning the Uncanny Valley
model requires preliminary clarification of the problems at stake, in particular for
what concerns the psychological states that are supposed to be provoked by the
spectacle of realism (such as the sense of familiarity or non-familiarity), the
meaning of and quantification of realism, the theoretical hypotheses that are
presupposed by the model.
Broadly intended, the model of the uncanny valley expresses a number of
interesting suggestions for lines of inquiry in the domain of mediated interaction,
some of which find local experimental or at least anecdotic confirmation in the
literature about old and new media, such as comics, classic animation, computer
animation and VR. The elements that compose the broad problem of the
uncanny valley are in fact real, virtual or fictional agents or other entities that
populate real, virtual or fictional worlds and that present some form of realism;
the term “realism” can be used in two ways: as simulation of the properties of
existing entities of the real world or as believability with more or less realism. On
the side of the subjects of the experience, the components of the problem are
constituted by the emotional, cognitive and behavioral reactions exhibited by the
users or spectators; these reactions have been described in different ways: Mori
used the generic term “sense of familiarity” but other terms have been used for
describing the behavioral and cognitive effects (such as “sense of presence” or
“co-presence”, “enjoyment”, “engagement”, “illusion of reality”, “illusion of nonmediation”, etc.) and the feelings or emotions evoked (eeriness, uncanny, fear,
disgust, etc.); what is common to the different views presented is the idea of a
negative valley of appreciation in response to a certain level of realism or to the
presence of discrepancies between the level of realism achieved for certain of
the agents’ aspects .but not for other.
It has been suggested here that the cognitive-behavioral components of
the spectators’ or users’ response should be considered separately from the
emotional components. In fact, the negative valley of appreciation (referred here
as a negative judgment of believability associated with negative surprise) is
present even in absence of the sense of uncanny (fear and disgust) in all the
cases in which certain expectations are frustrated and the coherence of the
experience is violated. These expectations are activated by the context of the
interaction (the real, fictional or virtual world, eventually the narration or story
which is presented) and by the entities that populate the real world (such as
material robotic artifacts) or fictional and virtual worlds (such as fictional
characters or virtual agents, but also fictional and virtual objects or
environments). The violation of coherence can happen at the synchronic level, as
when realism (simulation) in the physical aspect of an agent is inconsistent with
realism (simulation) in the behavior of the agent, or when one object is realistic
(simulates properties of a real object) in its visual aspects but not in what
concerns its haptic properties. Violation of coherence can also happen in
absence of realism as simulation: when the expectations raised by the
experience with one sensory modality are frustrated by simultaneous
experiences with other sensory modalities, the effect is a conflict which is
perceived as impossible, wrong and hence non-believable. The violation of
coherence can also happen at the diachronic level: some of the characteristics of
the context and entities, in fact, can activate expectations that are held by the
subject and that are frustrated by other aspects of the experience. Realism as
simulation and agents represent special cases within this general model.
When both agents and realism are concerned (simulation of human
beings), special emotional reactions of fear and disgust can be provoked by the
violation of synchronic and diachronic expectations. The reasons for this
additional reaction can be indicated in the special nature of the social interactions
with other human beings and in the special perceptual nature and symbolic
meaning of the human figure.
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The phenomenon of the Uncanny Valley is the object of debate between researchers from
several domains ranging from robotics to VR to psychology and sociology at “Toward Social
Mechanisms of Android Science. A CogSci-2005 Workshop”, ICCS/CogSci-2006 Long
Symposium (special session dedicated to Uncanny Valley), see androidscience.com, and
Interaction
Studies
7:3,
bin/t_bookview.cgi?bookid=IS%207%3A3.
see
http://www.benjamins.com/cgi-