A model for a motivational system grounded on value

based abstract argumentation frameworks

Eugenio Di TullioUniversity of Bari

Italy

Floriana GrassoUniversity of Liverpool

UK

The problem• Digital interventions to promote healthy

lifestyles• More successful if grounded in robust

behavioural theory– Variety of techniques to impact different stages

of the planning process– Use of different styles of interaction

• New insights from recent research areas in AI:– Persuasion technology– Argumentation Theory

Argument & Computation• Over the last decade a core and autonomous

discipline within AI, as opposed to permeating reasoning research– Emphasis on what persuades, not proofs– Hypothesis that the extent of acceptance is

subjective, depending on the view of the audience• Crucial aspect within practical reasoning, as

opposed to theoretical reasoning– Presumptive schemata– Embraced by recent research in MultiAgent

Systems

Application areas• Multi-agent dialogue interactions– E.g. negotiation scenarios

• Legal reasoning– E.g. tools to model and support case-based

reasoning• Healthcare advice– E.g. changing attitudes to healthy eating

• Medical treatment– E.g. automated argument over organ transplants

• Finance– E.g. automated stock market exchanges/contract

Directions of research• Abstract argument systems: formal

exploitation of simple notions of “attack” and “defense”.

• Logics for argumentation: formal models for automated reasoning.

• Dialogue protocols: emphasis on the rules that should govern the argumentation process and the participants to it.

• Argument schemes: stereotypical patterns for presumptive reasoning, fallacies.

Abstract ArgumentationAn argumentation framework (AF) is a pair F = (A, R) whereA is a set of argumentsR ⊆ A × A is a relation representing “attacks” or “defeats”.Different semantics to establish which arguments are “in” and which are “out”.

Transtheoretical model of change

Motivational dialogues• A subclass of argumentative

dialogues• Main feature: a discussion around a

behaviour, and the considerations of pros and cons of such behaviour– Can’t be based on “facts” only– Highly entrenched in the “value system”

of the parties engaging in the discussion– There is no right or wrong answer –

things change when perspectives change

ExampleA1: You should exercise twice a week because it improves your health. B2: Why is it good for my health?A3: Because exercise improves your stamina.B4: But then I might as well go to work by bike.A5: No, exercising is better for your health.B6: But exercise is boring.A7: What is more important: your health or having fun?B8: I find my health is more important. I guess I should exercise.

(from van der Weide et al 2010 “Practical Reasoning Using Values”)

Practical Reasoning on Values and Perspectives• Values: “desirable trans-situational goals,

varying in importance, that serve as guiding principles in the life of a person or other social entity”

Schwartz,S, Advances in experimental social psychology 25 (1992)

• Value Based Argumentation Framework (VAF) (Bench-Capon et al, Argumentation Research Group, University of Liverpool)

– Tuple <AR, attack, V, val, P>– AR set of arguments; attacks relation on AR, V set of

values, val function mapping from AR to V P set of possible audiences.

– An argument relates to value v if accepting it promotes or defends v.

• Values are discussed in terms of what condition promotes or demotes them– E.g. treating people the same promotes the

value of equality, exercising promotes the value of being healthy

• Conditions and values can be promoted in degrees– Not exercising is not healthy, exercising once a

month is healthier, once a week is healthier still• Perspective: preorder on states representing

a “topic” for discussion (e.g. health, fun)

Practical Reasoning on Values and Perspectives -ctd

• Perspectives can positively or negatively influence other perspectives forming chains– (E.g. health positively influence wellbeing)

Practical Reasoning on Values and Perspectives -ctd

• When an agent has a “preference” over a perspective, this perspective becomes a “value” – used as a “guiding principle” by the agent– agent will try to reach as state maximally preferred

from that perspective

Example

(from van der Weide et al 2010 “Practical Reasoning Using Values”)

Health, Fun and Conformity perspectives are also values

Exercise perspective is not a value, but influences values

Motivational System• Ultimate aim:– Build an environment for digital

interventions, based on motivational dialogues

– Authoring tools for creating user profiling, communication plans/strategies, styles of interaction

–Mobile technology to acquire user’s preferences and lifestyles

– Centred around the notion of “Value System”

Prototype implementation

• A prototype built on top of Aspic (Argumentation Service Platform with Integrated Components - 6FP - Opensource)– A platform to manage argumentation dialogues, which

also provides services like reasoning, decision-making, learning.

• Concentrates on the managing of the value system and the practical reasoning on perspectives– Left aside: user’s profiling and behavioural strategy

implementation

System architecture

Value System Ontology

Managing values• Two value systems are maintained– For the user and for “the system”– Typical for dialogue systems representing “mutual”

beliefs• Interaction driven by a plan or “strategy” based

on the user’s behavioural profiling (e.g. Transtheoretical model)– E.g. topic of discussion based on the stage of change

• System attempts to “utilise” user’s own beliefs and value system to maximise motivation impact

Example• The system contains the states:

1. Eating junk food less than 4 times a month; 2. Eating junk food between 4 and 8 times a month; 3. Eating junk food more than 8 times a month

• And the perspectives to evaluate the states are Healthy eating; Fitness; Health; Social life

• Initial value systems are:

Evaluation of Transition A

• System attempts to make user “aware” of influences which could impact the evaluation of transition A

New evaluation of A

New connections

Screenshot

Conclusions• Preliminary work towards an argumentation

based motivational system• Attempt to combine insights from

argumentation theory and behavioural theories

• Still prototypical: need to include more reliable user model and full blown communication strategies

• Adherence to standards (e.g. Aspic) looks beneficial in terms of cross-discipline evaluation