dcc2010 cascini del_frate_fantoni_montagna

Gualtiero Fantoni – [email protected] UNIVERSITÀ DI PISA

Beyond the design perspective of Gero's FBS framework

Gaetano Cascini (Politecnico di Milano)

Luca Del Frate (TU Delft)

Gualtiero Fantoni [email protected] (Università di Pisa)

Francesca Montagna (Politecnico di Torino)

FOURTH INTERNATIONAL CONFERENCE ON DESIGN COMPUTING AND COGNITION12–14 July 2010

University of Stuttgart, Stuttgart, Germany

mailto:[email protected]


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Summary

Motivation and approach to research

Discussion on the situated FBS framework FBS model and main processes

Observations from literature

Proposal for an extension to user modeling

Exemplary application

Conclusions and further developments


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Motivation and approach to research (1)

Affordances and the role of the users are of particular interest

FBS is a designer centric model

Open issues Can the FBS framework be used to represent the user

perspective? Do we need some new variables for the model (goals,

manipulation, plans, etc..from Brown&Blessing2005)? By doing that, is it possible to model also affordances, misuses,

alternative uses, failures, etc..? Are there some consequences? Is the model still stable?


Entities to be managed within the extended framework

1. Actors and relations in the External World. (e.g. user needs, “the working environment”, “rest of the world”, the interpretations of artifacts).

2. Product usability and use context. The concept of “guess” has been used for describing the implicit assumption of context for making use of a device.

3. Product affordance. “Affordances are possible actions” and in particular “the affordances A of a device are the set of all potential human behaviors (Operations, Plans, or Intentions) that the device might allow”.

4. Failures and their perception. 5. Alternative Uses. “Product alternative uses are all the possible uses

connected to the context and to the material decomposition of the device.”

6. Misuses are defined as those conditions in which the user manipulates the product in ways that were not intended by the designer, still keeping the same goal.


Analysis of Gero et al. works from 1986 to 2009

Gero’s numbers: more than 49 books and over 600 papers and book chapters from 1986 to 2009259 papers (675,408 words) downloaded from http://mason.gmu.edu/~jgero/

After tokenization and lemmatisation ~22,000 lemmas

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

design

agent

structure

designer

knowledge

behaviour

function

action

memory

situatedness

problem

environment

interaction

F-B-S

interpretation

ontology

user

failure

affordance

interface

From year 2000

From year 2002


… a problem with the year 2010

Gero’s numbers: more than 600 papers from 1986 to 2009 (2010)270 papers downloaded from After tokenization and lemmatisation ~22,000 lemmas

0

100

200

300

400

500

600

user failure affordance interface

Kannengiesser, U and Gero, JS, 2010?, A PROCESS FRAMEWORK OF AFFORDANCES IN DESIGN

52 times

136 times

.. in this paper the word designer appares only 6 times


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Discussion on the situated FBS framework (1)Three classes of variables: Function (F) variables: teleology of the object, i.e. what it is for Behavior (B) variables: what the object does Structure (S) variables: components and their relationships, i.e.

what it is

Eight elementary steps in design: 1. Formulation 2. Synthesis 3. Analysis 4. Evaluation 5. Documentation 6-8. Reformulation steps

Gero and Rosenman, 1990


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Three interacting environments (the interaction between designer and environment impacts the course of designing): External world: things and their representations outside the

design agent Interpreted world: internal, interpreted representation of that

part of the external world that the designer interacts with Expected world: environment in which the effects of actions are

predicted according to current goals and interpretations of the current state of the world

Three classes of processes: Interpretation: Xe Xi (push-pull) Focusing: Xi ⇔ Xei

Action: Xei → Xe (transformation)

Discussion on the situated FBS framework (2)

Gero and Kannengiesser, 2004


Designer centric vs User centric FBS representation

Can we introduce, as is, the user in the FBS framework?Since “a user designs how to use an artifact for herself/himself [..] it is not surprising that the FBS framework can be used to describe a user's behavior”. REVIEW 2Nevertheless, the goal of the authors is to propose a comprehensive representation of the cognitive aspects related to the product use context, in order to strengthen the design process, thus still with a close link with the designer’s perspective.The idea is that the FBS framework can be used to describe other processes related with design (e.g. use, failures) and other entities (e.g. affordances).


Designer centric vs User centric FBS representation

From the designer’s point of view the designed device is a: user acting on a structure in a certain environment in a certain way

From the user’s point of view the device is an:interface on which he/she can act (properly and improperly) and from which he/she can receive a feedback


Affordances 1 from literature

Norman [1988] believes “that affordances result from the mental interpretations of things, based on our past knowledge and experience applied to our perception of the things about us.”Maier and Fadel [2003] (M&F) consider affordances to be “potential uses” of a device.

Q1 Can I say that affordances are mental representations of possible uses (or better, uses the user believes as possible)?


Affordance 2 from literature

Brown & Blessing 2005: affordance ~ function but affordances do not include the notion of teleology (what the artefact is for) “Thus, unlike functions, affordances may or may not be associated with a goal. Also, if a goal is specified, affordances may or may not support it [..] In fact, as M&F point out, some affordances may be undesirable, clashing with the goal: what they call “negative affordances””

Q2 But if now Affordances may or may not be associated with a goal, were they in the past associated with a goal?

Gero 2010: “Affordances also appear similar to behaviour. [..] Affordances are an agent’s potential actions that interact with an artefact structure and thereby produce artefact behaviours of relevance (with positive or negative consequences).”

Q3 Artefact behaviours of relevance is something that can be interpreted in the space of GOALS?


Consequences

If Q1, Q2, Q3 are true: Affordances are mental representations of expected (by the user) possible uses of an artefact. Therefore each possible use can be connected with possible consequences that can be exploited or avoided (~ goals).

Therefore affordances can be “functions with a weak link with goals”.

Maier & Fadel 2009: structure ⇒ affordance ⇒ behaviourBrown & Blessing 2005: affordance ~ function Therefore we can affirm: structure ⇒ ~ function ⇒ behaviourBut in Gero 2003: structurei ⇒ behaviouri ⇒ functioni

So, do we miss some arrows in the FBS model (e.g. from structure to function)? Can we add AFFORDANCES in the FBS framework? And if yes, where?


A starting proposal

Our proposal is that:The user manipulates a structure. The structure produces a set of behaviours. The user interprets (via his/her knowledge) some of them as functions. B=M(S); F=K(B). Repeated experiences bring the user to simplify the

process: S ⇒ B and B can be used for potential F = A.The user sees a structure. The user imagines (knowledge) to manipulate the structure, imagines it produces some behaviours that he can use for achieving a goal (potential function = affordance). The entire process is in the user’s mind (expected world) In time the process can become: S ⇒ B ⇒ potential F = A But, the direct link S↔A is useful “to spend less cognitive effort and make

fewer errors” and it also increases the speed in decision making.


Affordance and learning

Bei

Aedi

Bi

AdiAe

Be

UIe

UIdi

UIed

From the designer’s perspective From the user’s perspective

AeuiAui

AeSe

Inti

Intei

Bei

Bi

Be

UI: the part of a product which has been intentionally devised by the designer for hosting the user-product interactions.


Consequences

Affordances can be introduced in the FBS A connection between Si and Ai can be added

There is a difference in the interpeted affordances. Both the desinger and user perceive both true and false affordances, but Ad and Au can be different. E.g. Sliding or turnable door?

HP: Au:turnable. M(S)Bsui≠Beu

i. Fui is interpreted and Au is updated. (See after)

UI differs from Int (the actual used interface) UI can contain Int (the case of REC key in the remote of VHS) UI can be contained in Int (the case of the fan in case of CUP

overclocking)


Use

Bei

FeiAei

Bi

FiAui Inti

Ae

Be

Se

Fe

Me

Mi

Mei

Intei

From the designer’s perspective From the user’s perspective

For the designer user’s Manipulation is a behavior.He/she consider the artifact as an “user using his machine”


Comparing designer and user perspective ..

The alternative uses are the possible behaviors B (interpreted by the user as possibilities of achieving goals G) of the system coming from its structure, but totally disconnected from the goals the designer interpreted as user needs and the product was designed for. alternative uses can be described as Gu ≠ Gd, Bsu ≠ Bsd. M(S)Bsu

i=Beui

The misuses. 1- The user believes the product affords A, but A was not intended by the designer. 2- User and designer agree on the product affordances. Misuses are the possible behaviors (interpreted by the user as possibilities of achieving goals) of the system, coming from the manipulation of its structure and linked to the goals the product was designed for. misuses can be described as: Gu = Gd, Bsu ≠ Bsd. There is at least a

problem in Meu and the manipulation forseen by the designer.


Conclusion and open questions?

The introduction of the user seems able to explain in some way also affordances, misuses, alternative uses, etc.Some of them (affordances?) can (?) be introduced also in the desinger perspective.Some of them can be explained by comparing the user point of view and the designer point of view.

1. Do we miss something?2. Are the variable, we want to introduce, really independent?3. Is it necessary to introduce manipulation or can it be integrated

in B?4. If we introduce the goal, what is the consequence?


The unforeseen consequence

Function (F) of an artefact is defined as its teleology. It is ascribed to behaviour by estabilishing a teleological connection between a human’s goal and measurable effects of the artefact. (Kannengiesser 2010)If we introduce goals in the framework, we do not need Functions anymore, because they can be expressed as a behaviour interpreted through (linked to) the goals.

And .. what if “Functions do not exist”. Is it bad or it is good?