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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>March</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Can we do beter explanations? A proposal of User-Centered Explainable AI</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Mireia Ribera</string-name>
          <email>ribera@ub.edu</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Explainability; XAI; Conversational interfaces; User centered</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Agata Lapedriza</string-name>
          <email>alapedriza@uoc.edu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Universitat Oberta de Catalunya</institution>
          ,
          <addr-line>Barcelona</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Universitat de Barcelona - Departament de Matemàtiques i, Informàtica. Institut de Matemàtica de la Universitat de</institution>
          ,
          <addr-line>Barcelona, Barcelona</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>design; HCI</institution>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2019</year>
      </pub-date>
      <volume>20</volume>
      <issue>2019</issue>
      <abstract>
        <p>Artificial Intelligence systems are spreading to multiple applications and they are used by a more diverse audience. With this change of the use scenario, AI users will increasingly require explanations. The first part of this paper makes a review of the state of the art of Explainable AI and highlights how the current research is not paying enough attention to whom the explanations are targeted. In the second part of the paper, it is suggested a new explainability pipeline, where users are classified in three main groups (developers or AI researchers, domain experts and lay users). Inspired by the cooperative principles of conversations, it is discussed how creating diferent explanations for each of the targeted groups can overcome some of the dificulties related to creating good explanations and evaluating them.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>CCS CONCEPTS</title>
      <p>• Computing methodologies → Artificial intelligence ;
• Human-centered computing → HCI theory, concepts
and models.</p>
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IUI Workshops ’19, March 20, 2019, Los Angeles, USA
© 2019 Copyright held by the owner/author(s). Publication rights licensed
to ACM.</p>
    </sec>
    <sec id="sec-2">
      <title>1 INTRODUCTION</title>
      <p>Artificial Intelligence (AI) is increasingly being used in more
contexts and by a more diverse audience. In the future, AI
will be involved in many decision-making processes. For
example, in the medical field there will be AI systems that will
help physicians to make diagnoses, whereas in companies
the support of AI will be used in the interviewing process of
recruiting campaigns. In these cases, diferent types of users,
most of them without a deep understanding of how AI is
built, will directly interact with AIs and will need to
understand, verify and trust their decisions. This change of use
scenarios of AI is similar to the one occurred in the ’80s with
the popularization of computers. When computers started
to be produced massively and to be targeted to non-expert
users, a need for improving human-computer interaction
emerged which would accomplish to make technology
accessible to less specialized users. In a similar way, a need for
making AI understandable and trustful to general users is
now emerging.</p>
      <p>In this new broad scenario of AI use contexts,
explainability plays a key role for many reasons, since in many
cases the user interacting with the AI needs more reasoned
information than just the decision made by the system.</p>
      <p>Plenty of attention is being paid to the need for
explainable AI. In the first part of this paper we review the 5 main
aspects that are the focus of recent surveys and theoretical
frameworks of explainability: (I) what an explanation is, (II)
what the purposes and goals of explanations are, (III) what
information do explanations have to contain, (IV) what type
of explanations can a system give, and (V) how can we
evaluate the quality of explanations. This review reveals, in our
opinion, how the current theoretical approach of explainable
AI is not paying enough attention to what we believe is a
key component: who are the explanations targeted to.</p>
      <p>In the second part of this paper, we argue that
explanations cannot be monolithic and that each stakeholder looks
for explanations with diferent aims, diferent expectations,
diferent background, and diferent needs. By building on
the conversational nature of explanations, we will outline
how explanations could be created to fulfill the demands set
on them.
2</p>
    </sec>
    <sec id="sec-3">
      <title>HOW DO WE APPROACH EXPLAINABILITY?</title>
      <p>Defining what an explanation is, is the starting point for
creating explainable models, and allows to set the three
pillars on which explanations are built: goals of an explanation,
content of an explanation, and types of explanations. The
last key aspect reviewed in this section is how explanations
can be evaluated, which is a critical point for the progress of
explainable AI.</p>
    </sec>
    <sec id="sec-4">
      <title>Definition of explanation</title>
      <p>
        Explanations are "ill-defined" [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ]. In the literature the
concept of explainability is related to transparency,
interpretability, trust, fairness and accountability, among others [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
Interpretability, sometimes used as a synonym of explainability,
is defined by Doshi and Kim [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] as "the ability to explain
or to present in understandable terms to a human". Gilpin
et al. [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], on the contrary, consider explainability a broader
subject than interpretability; these authors state that a model
is interpretable if it is "able to summarize the reasons for
[system] behavior, gain the trust of users, or produce insights
about the causes of decisions". However an explainable AI
needs, in addition, "to be complete, with the capacity to
defend [its] actions, provide relevant responses to questions,
and be audited". Rudin [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ] defines Interpretable Machine
Learning in a more restricted sense, as "When you use a
model that is not a black box", while Explainable Machine
Learning is, for this author, "when you use a black box and
explain it afterwards".
      </p>
      <p>
        Miller [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ], does an interesting review of social science
constructs to find the theoretical roots of the explainability
concept. For example, Lewis [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] states that "To explain an
event is to provide some information about its causal history.
In an act of explaining, someone who is in possession of
some information about the causal history of some event
–explanatory information – tries to convey it to someone
else". Halpern and Pearl [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] define a good explanation as a
response to a Why question, that "(a) provides information
that goes beyond the knowledge of the individual asking
the question and (b) be such that the individual can see that
it would, if true, be (or be very likely to be) a cause of".
After the review, Miller [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] extracts four characteristics of
explanations: "explanations are contrastive" (why this and
not that), "explanations are selected in a biased manner (not
everything shall be explained)", "probabilities don’t matter"
and finally "explanations are social".
      </p>
      <p>
        From these definitions and the recent reviews of
explainability [
        <xref ref-type="bibr" rid="ref10 ref7">7, 10</xref>
        ] we can conclude that there is no agreement on
a specific definition for explanation. However, some relevant
points are shared in almost every definition. For example,
many definitions relate explanations with "why" questions
or causality reasonings. Also, and more importantly, there is
a key aspect when trying to define what an explanation is:
there are two subjects involved in any explanation, the one
who provides it (the system), or explainer, and the one who
receives it (the human), or explainee. Thus, when providing
AI with explainability capacity, one can not forget about to
whom the explanation is targeted.
      </p>
    </sec>
    <sec id="sec-5">
      <title>Goals of explanations (WHY)</title>
      <p>
        According to Sameket al. [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ] the need of explainable systems
is rooted in four points: (a) Verification of the system:
Understand the rules governing the decision process in order to
detect possible biases; (b) Improvement of the system:
Understand the model and the dataset to compare diferent models
and to avoid failures; (c) Learning from the system: "Extract
the distilled knowledge from the AI system"; (d) Compliance
with legislation (particularly with the "right to explanation"
set by European Union): To find answers to legal questions
and to inform people afected by AI decisions.
      </p>
      <p>
        Gilpin et al.[
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] mostly agree with these goals, adding
specific considerations on two of these points: (a) Verification
of the system: explanations help to ensure that algorithms
perform as expected, and (b) Improvement of the system: in
terms of safety against attacks. Guidotti, et al. [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] enforce
for (c) "the sake of openness of scientific discovery and the
progress of research" , while Miller [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] directly considers
"facilitating learning" the primary function of explanation.
Wachter, et al. [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ] describe more in detail three aims behind
the right to explanation. These three aims are "to inform and
help the subject understand why a particular decision was
reached, to provide grounds to contest adverse decisions, and
to understand what could be changed to receive a desired
result in the future, based on the current decision-making
model".
      </p>
      <p>
        Lim et al. [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] add a new goal, relating explainability to:
(e) Adoption: Acceptance of the technology. These authors
state that "[the] lack of system intelligibility (in particular if
a mismatch between user expectation and system behavior
occurs) can lead users to mistrust the system, misuse it, or
abandon it altogether".
      </p>
      <p>
        Doshi-Velez and Kim [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] focus on (b) and (d) and see
interpretability as a proxy to evaluate safety and
nondiscrimination, which can be related to fairness in AI. They also argue
that an explanation is only necessary when wrong results
may have an important impact or when the problem is
incompletely studied. Rudin [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ] agrees with that last view, but
also mentions troubleshooting (a) as an important goal. On a
more theoretical framework, Wilkenfeld and Lombrozo [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ],
cited in [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ], discuss about other functions of explanations
such as persuasion or assignment of blame, and they raise
attention to the fact that the goals of explainer and explainee
may be diferent.
      </p>
      <p>
        Regarding to the need and utility of explanations, Abdul
et al.[
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] see explanations as a way for humans to remain in
control. This view is questioned by Lipton [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ], who warns
against explanations "to simply be a concession to
institutional biases against new methods", arising a more deep
relfection on how AI fits our society: to empower people or to
surpass people. Finally, Rudin [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ], in her controversial video
seminar, questions the utility of explanations, and states that
they only "perpetuate the problem of bad stuf happening",
because they act somewhat as a disclaimer. Furthermore,
some authors agree that the explainee will only require
explanations when the system decision does not match her
expectations [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ].
      </p>
      <p>
        Despite the disagreement of some experts on the need of
explanations, there are more reasons supporting their need
than the opposite. In particular it is very likely that users
expect an explanation when the decision of an AI has
important economical consequences or it afects their rights.
However, trying to cover all goals with a unique explanation
is overwhelming [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. If we take into account the explainee ,
maybe a practical solution could be to create several
explanations serving only the specific goals related to a particular
audience.
      </p>
    </sec>
    <sec id="sec-6">
      <title>Content to include in the explanation (WHAT)</title>
      <p>
        Lim et al. [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] say that an explanation should answer five
questions: "(1) What did the system do?, (2) Why did the
system do P?, (3) Why did the system not do X?, (4) What would
the system do if Y happens? , (5) How can I get the system
to do Z, given the current context?" . These questions are
very similar to the explanatory question classes introduced
by Miller [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. Gilpin et al. [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], on the contrary, add a new
question related to the data stored by the system: (6) "What
information does the system contain?"
      </p>
      <p>
        Lim et al. [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] relate their five questions to Don Norman
gulfs of evaluation and execution, solving questions 1-3 the
separation between perceived functionality of the system and
the user’s intentions and expectations, and questions 4-5 the
separation between what can be done with the system and
the user’s perception of its capacity. These authors tested the
questions on an explanatory system with final users and they
concluded that "Why questions" (2) were the most important.
      </p>
      <p>
        Some authors categorize the explanations depending on
whether they explain how the model works or the reason of
a particular output [
        <xref ref-type="bibr" rid="ref10 ref7">7, 10</xref>
        ]. Although both aspects are
connected, explanations can be more specific when focused on a
local result. In the first case, the explanation is more global,
and can help users to build a mental model of the system. This
global explanation includes also the representation learned
by the model (for example, in a Neural Network, what are
the roles of layers or units), that allows users to understand
the structures of the system. In the latter, the explanation
focuses in a specific output and allows users to understand
better the reasons why that specific output occurred or the
relation between a specific input and its output.
      </p>
      <p>Overall, there are multiple questions that good
explanations should provide answers to. We observe, however, a
quite consistent agreement on the importance of the "Why"
questions. Furthermore, some explanation contents are more
interesting or important for some users than others. For
example, researchers developing the AI system might be
interested in technical explanations on how the system works
to improve it, while lay users, with no technical background,
would not be interested at all about these type of explanation.</p>
    </sec>
    <sec id="sec-7">
      <title>Types of explanations (HOW)</title>
      <p>In this section we review the diferent ways of classifying
explanations according to how they are generated and
delivered to the user.</p>
      <p>
        In terms of generation, explanations can be an intrinsic
part of the system, which becomes transparent and open
to inspection (for some authors this is called
interpretability). For example, CART (Classification and regression trees)
[
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] is a classical decision tree algorithm that functions as a
white box AI system. On the contrary, explanations can be
post-hoc, built once the decision is already made [
        <xref ref-type="bibr" rid="ref17 ref20">17, 20</xref>
        ].
For instance, LIME by Ribeiro et al. [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ] consists of a local
surrogate model that reproduces the system behavior for a
set of inputs. Detailed pros and cons of each of these two
types are discussed in [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ]. In particular, while intrinsic
explanations need to impose restrictions on the design of the
system, post-hoc explanations are usually unable to give
information on the representation learned by the system or
on how the system is internally working.
      </p>
      <p>
        Regarding to the explanation modality, we can find
explanations in natural language with "analytic (didactic)
statements [...] that describe the elements and context that
support a choice", as visualizations, "that directly highlight
portions of the raw data that support a choice and allow viewers
to form their own perceptual understanding", as cases or
"explanations by example", "that invoke specific examples or
stories that support the choice", or as rejections of alternative
choices or "counterfactuals" "that argue against less preferred
answers based on analytics, cases, and data" [
        <xref ref-type="bibr" rid="ref11 ref17">11, 17</xref>
        ].
Currently visualizations are probably the most common type
of explanations (see [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ] for a recent review), with a longer
tradition of interaction and evaluation methods [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ].
      </p>
      <p>We can see there exist many types of explanations and,
although visualizations are among the most adopted, it is
not clear when or why one type is better than another. In
some cases the most suitable modality will depend on the
content of the explanation. Furthermore, the user should also
play an important role on deciding what type of explanation
is the most appropriate according to background, specific
expectations or needs.</p>
    </sec>
    <sec id="sec-8">
      <title>Evaluation of explanations</title>
      <p>
        Evaluating explanations is maybe the most immature aspect
on the research on explainable AI. Lipton [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] and Miller
[
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] openly question the existing practices for evaluating
explanations. Lipton says that "the question of correctness
has been dodged, and only subjective views are proposed".
Miller [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] argues that most explanations rely on causal
relations while people do not find likely causes very useful,
and states that simplicity, generality and coherence are "at
least as equally important".
      </p>
      <p>
        In a promising direction, Doshi-Velez and Kim [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] criticize
the weakness of current methods for explanation evaluation,
and suggest grounding evaluations on more solid principles,
based on Human Computer Interaction (HCI) user tests. The
authors suggest three possible approaches, from more
specific and costly to more general and cheap: (1)
applicationgrounded evaluation with real humans and real tasks; (2)
human-grounded evaluation with real humans but
simpliifed tasks; and (3) functionally-grounded evaluation without
humans and proxy tasks; all of them always inspired by real
tasks and real humans’ observations.
      </p>
      <p>
        The Explainable AI DARPA program (XAI) [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ], started
on 2017, tries to cover current gaps of this topic and opens
many scientific research lines to solve them. The program
conceptualizes the goals of explanation as to generate trust
and facilitate appropriate use of technology (focusing mainly
in adoption, the (e) goal of explanations). The project relates
the explanation goals with several elements to evaluate, each
one linked to a corresponding indicator.
      </p>
      <p>
        On the Open Learning Modelling domain, Conati et al [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ],
based on Mabbot and Bull[
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] previous experiments, point
out some key considerations on designing explanations such
as considering the explainee, as we suggest, and also the
reason to build the system, which aspects to made available
to the user and the degree it can be manipulated by the user.
      </p>
      <p>
        On a more technical vein, Gilpin et al.[
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], after a review of
the literature, cite four evaluation methods. The first two are
related to processing (completeness to model, completeness
on substitute task), while the last two related to
representation (completeness on substitute task, detect biases) and
explanation producing (human evaluation, detect biases).
      </p>
      <p>
        Setting clear evaluation goals and metrics is critical in
order to advance the research on explainability and more
eforts are needed in this area. How can we say that a system
is better than another if we do not know why? Doshi-Velez
and Kim [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ], and DARPA [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] proposals have strong points,
but they do not cover all the goals set on explainable systems,
nor all the modalities and explanation contents.
3
      </p>
    </sec>
    <sec id="sec-9">
      <title>CAN WE DO BETTER?</title>
      <p>In this section we critically review the previous sections and
give insights on new directions to create better explanations.
We build our proposal upon two main axes: (1) to provide
more than one explanation, each targeted to a diferent user
group, and (2) making explanations that follow cooperative
principles of human conversation.</p>
      <p>
        In order to better contextualize current developments in
explainability, we suggest to take into account the
communicative nature of the explanations and to categorize
explainees in three main groups, based on their goals,
background and relationship with the product [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ],[
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]:
• Developers and AI researchers: investigators in AI,
software developers, or data analysts who create the
AI system.
• Domain experts: specialists in the area of expertise
where the decisions made by the system belong to. For
example: physicists or lawyers.
• Lay users: the final recipients of the decisions. For
example: a person accepted or rejected on a loan demand,
or a patient that has been diagnosed.
      </p>
      <p>Starting with explainability goals, if we take a closer look
to the listed goals, we can detect diferent needs and
explainee profiles for each of them. (a) verification and (b)
improvement goals, clearly appeal to a developer or researcher
profile, who wants to improve the algorithm’s parameters or
optimization. These goals can be attained with the help of
domain experts to whom the tool is intended to help: they
will be the ones that detect possible failures of the system.
However, for the domain experts, the main goal can be to
learn from the system (c), to understand the mechanisms
of inference or correlation that the system uses in order to
improve their decision methods or to hypothesize possible
general rules. For domain experts the explainer goal
providing explanations is to grant the system adoption (e). The last
goal mentioned by Samek, the right to an explanation, is
clearly targeted to lay users because the system decisions
may have economical or personal implications for them,
although this goal can be also relevant for domain experts,
who might have the legal responsibility of the final decision.</p>
      <p>
        Related to explanation content, Doshi-Velez and Kim [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]
argue that diferent explanations are needed depending on
global versus local scope, thematic area, severity of
incompleteness, time constraints and nature of user expertise. We
can delve a bit more on this idea, particularly in the need to
tailor explanations to user expertise, and exemplify it with
the following scenario. Let’s say we have a system that ofers
explanations at the representational level, describing data
structures; these should clearly not be communicated in the
same language for developers as for domain-experts. Even
diferent area domain-experts will require diferent kind of
explanations [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ].
      </p>
      <p>
        In terms of types of explanations, Lipton [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] states that
humans do not exhibit transparency, sustaining that human
explanations are always post-hoc. On the other side, many
authors are concerned about the high complexity of machine
learning algorithms and the limits of human reasoning to
understand them [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ]. This relates to Nielsen heuristic of
progressive disclosure or Shneiderman visual
informationseeking mantra: "Overview first, zoom and filter, then
detailson-demand" as techniques to cope with complex
information or tasks. To make explanations more human, Naveed,
Donker and Ziegler [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] introduce an interesting framework
of explanations based on Toulmin’s argumentation model.
This model proposal is to communicate decisions giving
evidences, like facts or data, that support the decision, and
relating both the evidences and the decision with contextual
information. Other authors suggest interaction as a way to
explore the explanation space: "allowing people to
interactively explore explanations for algorithmic decision-making
is a promising direction" [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] "By providing interactive partial
dependence diagnostics, data scientists can understand how
features afect the prediction overall" [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>
        Likewise, Miller [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] criticizes the current proposed
explanations as being too static, he describes them ideally as "an
interaction between the explainer and explainee". Delving on
the fourth feature he identified in social science theoretical
constructs: "explanations are social", this author parallels
explanations to conversations . Therefore explanations must
follow the cooperative principles of Grice [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] and its four
maxims: 1. Quality: Make sure that the information is of
high quality: (a) do not say things that you believe to be false;
and (b) do not say things for which you do not have suficient
evidence; 2. Quantity: Provide the right quantity of
information. (a) make your contribution as informative as is required;
and (b) do not make it more informative than is required;
3. Relation: Only provide information that is related to the
conversation. (a) Be relevant. This maxim can be interpreted
as a strategy for achieving the maxim of quantity; 4.
Manner: Relating to how one provides information, rather than
what is provided. This consists of the ’supermaxim’ of ’Be
perspicuous’, and according to Grice, is broken into various
maxims such as: "(a) avoid obscurity of expression; (b) avoid
ambiguity; (c) be brief (avoid unnecessary prolixity); and (d)
be orderly".
      </p>
      <p>
        We observe that (1), (2), and (3) refer to the content of the
explanation, while (4) refers to the type of explanation.
Notice that these 4 cooperative principles can also be related to
other wanted properties of explanations [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ], such as fidelity
or comprehensibility. Our claim is that Explainable AI for
domain-experts and lay users can benefit from the theoretical
frameworks developed for human communication.
Finally, considering evaluation, we can also observe that
diferent metrics appeal to diferent needs and audience.
For example, testing completeness or functionally-grounded
evaluation are targeted to developers or AI scientists, task
performance and mental model appeal to domain experts
whereas trust is intended for domain experts and lay users. If
we deliver diferent explanations, targeted to a specific of the
above mentioned groups, it will be easier to evaluate them,
since we can use the most suitable metric for each case.
4
      </p>
    </sec>
    <sec id="sec-10">
      <title>USER-CENTERED EXPLAINABLE AI</title>
      <p>From the literature review and discussions above presented,
we conclude that explanations are multifaceted and cannot
be attained with one single, static explanation. Since it is very
dificult to approach explainable AI in a way that fulfills all
the expected requirements at the same time, we suggest
creating diferent explanations for every need and user profile.
The rest of this section gives more details on this idea and
discusses the diferent reasons that support our proposal.</p>
      <p>As argued above, we suggest that AI explanations should
follow the 4 cooperative principles previously described.
In this context, if diferent explanations are specifically
designed for diferent audiences or users, we can design each
one with a particular purpose, content, and present it in a
specific way. This procedure makes it easier to follow the
principles of (2) quantity: deliver the right quantity of data
and abstraction, and (3) relation: be relevant to each
stakeholder. Concretely, taking into account the current research
in explainability we suggest these 3 big families of
explanations:</p>
      <p>- Developers and AI researchers: Model inspection and
simulation with proxy models. These two types of
explanations are very well suited to verify the system, detect failures
and give hints to improve it. The mode of communication
ifts well the audience, who are able to understand code, data
representation structures and statistical deviations.
Completeness tests covering diferent scenarios can be set to
evaluate the explanation.</p>
      <p>- Domain-experts: provide explanations through natural
language conversations or interactive visualizations, letting
the expert decide when and how to question the
explanation and led her discovery by herself. Explanations must
be customized to the discipline area of the domain experts
and to the context of their application, be it legal or medical
decisions, or any other, in order to be clear and to use the
discipline terminology. Test of comprehension, performance
and survey of trust can be set to evaluate the explanation.</p>
      <p>
        - Lay users: outcome explanations with several
counterfactuals [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ] with which users can interact to select the one
most interesting to their particular case. This explanation
is parallel to human modes and it is very likely to generate
trust. Satisfaction questionnaires can be set to evaluate the
explanation.
      </p>
      <p>Our proposal is that explanations need to be designed
taking into account the type of user they are targeted to,
as shown in the pipeline for explanation of Figure 1. That
means to approach explainable AI from a user-centered
perspective, putting the user in a central position. Approaching
explainability in that way has two main benefits. First, it
makes the design and creation of explainable systems more
afordable, because the purpose of the explanation is more
concrete and can be more specifically defined than when we
try to create an all-sizes all-audiences explanation. Second,
it will increase satisfaction among developers or researchers,
domain-experts and lay users, since each of them receives a
more targeted explanation that is easier to understand than
a general explanation. Finally, it will be easier to evaluate
which explanation is better because we have metrics that are
specific to each case.</p>
      <p>
        Wachter et al. [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ] proposal of counterfactual explanations
fulfilling the right of explanation is a good example that
supports the implementation of these principles. In their paper
they abound in the need to make explanations adapted to lay
users (user-centered design) "information disclosures need
to be tailored to their audience, with envisioned audiences
including children and uneducated laypeople" , "the utility of
such approaches outside of model debugging by expert
programmers is unclear". They also emphasize the need to give
a "minimal amount of information" (be relevant),
"counterfactual explanations are intentionally restricted". Moreover,
when the authors talk about the suitability of ofering
"multiple diverse counterfactual explanations to data subjects",
they could benefit from a conversational approach.
      </p>
      <p>While the proposed scheme of user-centered explainable
AI particularly benefits the quantity and relation principles,
the manner can also be chosen to be as appropriate as
possible to the user. For example, although natural language
descriptions can be a suitable modality for any of the three
user groups, the specific vocabulary should be adapted to
the user background. In particular, technical terms are not
a good choice for explanations targeted to a lay user, and
explanations for domain-experts should use their respective
area terminology. Finally, regarding to the quality principle,
we think it has to be always applied in the same way, and it
is not necessary to take into account the specific user group.
5</p>
    </sec>
    <sec id="sec-11">
      <title>CONCLUSION</title>
      <p>While there has been a great progress in some aspects of
explainability techniques, we observed that there is a key
aspect that is being misrepresented in several of the current
approaches: the user to whom the explanation is targeted to.
Putting explanations in the user context makes explainability
easier to approach than when we try to create explainable
systems that fulfill all the requirements of a general
explanation. In addition, the user-centered framework gives clues on
how to create more understandable and useful explanations
for any user, because we can follow the principles of human
communication, thoroughly studied.</p>
      <p>More generally, the increasing demand of explainable AI
systems and the diferent background of stakeholders of
machine learning systems justify, in our view, to revise the
concept of explanations as unitary solutions and to propose the
creation of diferent user-centered explainability solutions,
simulating human conversations with interactive dialogues
or visualizations that can be explored.</p>
    </sec>
    <sec id="sec-12">
      <title>ACKNOWLEDGMENTS</title>
      <p>This work has been partially supported by the Spanish project
TIN2016-74946-P (MINECO/FEDER, UE) and CERCA
Programme / Generalitat de Catalunya. Icons used in Figure
1, are from Flaticon, made by Freepik and Smashicons. We
thank Jordi Vitrià for his review and suggestions on the
whole article.</p>
    </sec>
  </body>
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