Among the various model based theories, the Gero's FBS framework is acknowledged as a well-grounded, effective and tested reference for describing both analysis and synthesis design tasks. Despite its design-centric nature, the FBS model can provide a valid support also to represent processes and tasks beyond its original scope. The specific interest of the authors is to extend the FBS application to model also uses and misuses of objects, interpretations of the users, needs and requirements. In fact, as partially addressed also in literature, some issues arise when the classical FBS framework is adopted to model particular aspects such as the user's role, values and needs, as well as to produce an explicit representation of failures and redundant functions. The full paper presents an extended classification of aspects, beyond the design perspective, which currently cannot be represented by the FBS model and some directions for its possible extension. Several examples clarify the scopes and the characteristics of the proposed model. The current state of development of the author’s work still cannot be considered an integrated model, but relevant possibilities to extend the domain of applicability of the FBS framework emerge.

1. FOURTH INTERNATIONAL CONFERENCE ON DESIGN COMPUTING AND COGNITION
12–14 July 2010
University of Stuttgart, Stuttgart, Germany
Beyond the design perspective of Gero's FBS
framework
Gaetano Cascini (Politecnico di Milano)
Luca Del Frate (TU Delft)
Gualtiero Fantoni g.fantoni@ing.unipi.it (Università di Pisa)
Francesca Montagna (Politecnico di Torino)
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

2. 2/16
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
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

3. 3/16
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?
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

4. 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.
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

5. 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 2009
259 papers (675,408 words) downloaded from http://mason.gmu.edu/~jgero/
After tokenization and lemmatisation ~22,000 lemmas
20000
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
design
agent
structure
designer
knowledge
behaviour
function
From year 2000
action
memory
situatedness
problem
environment
interaction
From year 2002
F-B-S
interpretation
ontology
user
failure
affordance
interface
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

6. … 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
Kannengiesser, U and Gero, JS, 2010?, A PROCESS FRAMEWORK OF AFFORDANCES IN DESIGN
600
500
400
300
200
100
0
52 times
136 times
user failure affordance interface
.. in this paper the word designer appares only 6 times
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

7. 7/16
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
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

8. 8/16
Discussion on the situated FBS framework (2)
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 Û Xei
Action: Xei ® Xe (transformation)
Gero and Kannengiesser, 2004
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

9. 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 2
Nevertheless, 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).
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

10. 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
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

11. 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)?
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

12. 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?
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

13. 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 Þ affordance Þ behaviour
Brown & Blessing 2005: affordance ~ function
Therefore we can affirm: structure Þ ~ function Þ behaviour
But in Gero 2003: structurei Þ behaviouri Þ 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?
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

14. 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 Þ 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 Þ B Þ 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.
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

15. Affordance and learning
From the designer’s perspective From the user’s perspective
Bei
Aed
i
Bi
Ad
i
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA
Ae
Be
UIe
UId
i
UIed
Aeu
i
Au
i
Ae
Se
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.

16. 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)Bsu
i≠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)
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

17. Use
From the designer’s perspective From the user’s perspective
Me
Mi
i Inti
Mei
Bei
Aei
Fei
Bi
Au
Fi
Ae
Be
Se
Fe
Intei
For the designer user’s Manipulation is a behavior.
He/she consider the artifact as an “user using his machine”
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

18. 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 G≠ G, Bs≠ Bs. M(S)Bsi=Bei
u du du
u
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.
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

19. 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?
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA

20. 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?
Gualtiero Fantoni – g.fantoni@ing.unipi.it UNIVERSITÀ DI PISA