Affordance As Context
Phil Turner
HCI Research Group, School of Computing, Napier University, Edinburgh, EH14 1DJ, UK.
Abstract
The concept of affordance is relatively easy to define but has proved to be remarkably difficult to
engineer. This paradox has sparked numerous debates as to its true nature. The discussion presented
here begins with a review of the use of the term from which emerges evidence for a two-fold
classification – simple affordance and complex affordance. Simple affordance corresponds to
Gibson’s original formulation, while complex affordances embody such things as history and practice.
In trying to account for complex affordance, two contrasting but complementary philosophical
treatments are considered. The first of these is Ilyenkov’s account of significances which he claims are
‘ideal’ phenomena. Ideal phenomena occupy are objective characteristics of things and are the product
of human purposive activity. This makes them objective but not independent (of any particular mind
or perception) hence their similarity to affordances.
The second perspective is Heidegger’s phenomenological treatment of ‘familiarity’ and ‘equipment’.
As will be seen, Heidegger has argued that familiarity underpins our ability to cope in the world. A
world, in turn, which itself comprises the totality of equipment. We cope by making use of equipment.
Despite the different philosophical traditions both Ilyenkov and Heidegger have independently
concluded that a thing is identified by its use and that use, in turn, is revealed by way of its
affordances / significances. Finally, both authors – Heidegger directly and Ilyenkov indirectly –
equate context and use, leading to the conclusion that affordance and context are one and the same.
Keywords: affordance, familiarity, phenomenology, context.
1
Introduction
This is a ‘concept paper’ rather than a report of a case study or the presentation of a new
methodology. The concept in question is affordance which is one of the most ubiquitous in
human computer interaction (HCI).
This paper seeks (a) to review the use of the term affordance and (b) to consider two
contrasting philosophical accounts of how affordance operates. The review concludes that
there is a case for a binary classification of affordance into simple and complex.
Moving beyond Gibson’s psychological account of affordance, two different philosophical
accounts of affordance are considered. The first of these is Ilyenkov’s treatment of
significances which may be thought of as ‘Soviet affordances’. Significances are described as
real and objective but dependent on us as they are a product of our purposive, sensuous work.
For some, Ilyenkov’s writings offer a philosophical underpinning to Activity Theory. Turning
from Soviet thought, Heidegger’s phenomenology is then considered. In the past, selected
aspects of his work have already been used in the related fields of HCI1 and cognitive science
to elucidate a number of the central problems of these disciplines (e.g. Winograd and Flores,
1986; Dreyfus, 1991; Coyne, 1995, 1999; Dourish, 2001). For the present discussion Dreyfus’
observation (ibid:3) that “at the foundation of Heidegger’s new approach is a phenomenology
of ‘mindless’ everyday coping skills as the basis of all intelligibility” is particularly relevant.
This everyday coping with technology must be one of the key interests of HCI.
There was an anecdote published in the magazine interactions some years ago which centred
on a claw-hammer inadvertently being left behind in an orang-utan’s enclosure. The orang1
An interesting review of phenomenology is offered by McCarthy and Wright (2004).
1
utan picked it up, sniffed it, moved it about in its hands and then proceeded to use the claw of
the hammer to scratch the walls of the enclosure; a few minutes later the animal used the head
of the hammer to strike any and all available surfaces. In short, the orang-utan had seen
directly how to use the hammer (Brock, 1996). This anecdote may be regarded as an example
of simple affordance. That is, affordance operating in a classic Gibsonian perception-action
loop. Affordance, however, is not limited to mediating such relatively simple behaviours: a
second, brief anecdote illustrates this. Last year I witnessed a young American (judging from
her accent) failing to open the train door when we arrived at her station. Opening, closing,
pushing and pulling doors are frequently used to illustrate examples of ‘good’ and ‘bad’
affordance but in this case another factor operated, namely familiarity. The American tourist
was unfamiliar with the design of (old) British ‘slam-door’ trains which require a passenger to
open a window, reach outside and use the exterior handle to open the door. Thus the interior
side of the door does not offer the simple affordance of ‘depressing a handle’ and ‘pushing
open’, while the exterior of the door offers the complex affordance of knowing to ‘lean
outside’, ‘depress the handle’ and ‘push’. Figures 1 and 2 illustrate this.
Figure 1: the interior view of a ‘slam-door’. Where the
handle might reasonably be expected only a steel plate
can be seen.
Figure 2: the exterior view of a ‘slam-door’.
This paper will begin by developing this case for a two-fold classification of affordance. The
familiar territory of simple affordance is considered first.
2
Simple Affordance
Gibson introduced the term “affordance” to denote the relation between the organism and its
environment. “The affordances of the environment are what it offers the animal, what it
provides or furnishes, either for good or ill.” (Gibson 1986:127). Specifically on tool use,
Gibson wrote, “An elongated object, especially, if weighted at one end and graspable at the
other, affords hitting or hammering (a club). A graspable object with a rigid sharp edge
affords cutting and scraping (a knife)”. Further examples of affordances include surfaces that
provide support, objects that can be manipulated, substances that can be eaten and other
animals that afford interactions of all kinds. The properties of these affordances for animals
are specified in stimulus information. Even if an animal possesses the appropriate attributes
and senses, it may need to learn to detect this information. An affordance, once detected, is
meaningful and has value for the animal. It is nevertheless objective, inasmuch as it refers to
the physical properties of the animal’s ecological niche and the constraints of the animal’s
body. An affordance thus exists, whether it is perceived or used or not, furthermore it may be
detected and used without explicit awareness of doing so. This description was revised in
2
1986 when Gibson wrote, “An affordance cuts across the dichotomy of subjective-objective
and helps us to understand its inadequacy. It is equally a fact of the environment and a fact of
behaviour. It is both physical and psychical, yet neither. An affordance points both ways, to
the environment and to the observer” (Gibson, 1986:129). Thus affordances hover
uncomfortably in a dualistic netherland between the world and the observer. Yet this was not
how they were originally conceived. The concept of affordance has its origins with the Gestalt
School of psychology. The Gestaltists working in Europe in the 1920’s and 1930’s argued
that we perceive the function of a thing as quickly as its colour or shape. Gibson quotes
Koffka, who publishing in 1935, makes the following point, “Each thing says what it is … a
fruit says eat me, water says drink me”, Gibson (1986:138). Koffka used the term demand
characteristic to describe these (directly perceived) properties of objects, while Lewin, again
quoted by Gibson, preferred the term Aufforderung-scharakter (invitation character). These
properties were seen as being phenomenal in nature and not the physical properties of objects
– that is, we see directly what these objects are for and how to use them - no one taught us to
drink water.
2.1 Beyond the very simple
Fruit and water are a long way from the challenge of designing interactive media but plentiful
examples of simple affordance can be found in Ergonomics. For example, the work of Murrell
in the 1950’s included the design of physical knobs and dials for which ‘up’ meant ‘more’ and
‘down’ meant ‘less’, equally, rotating a knob clockwise ‘afforded’ increasing the volume or
the amount, likewise an anticlockwise direction signified a lessening or reduction (Murrell,
1965). These simple affordance which inform such design principles remain essential to the
creation of tangible, ubiquitous and pervasive devices such as mobile phones, personal digital
assistants (PDAs) and such things as MP3 players.
This simple account of affordance has, of course, been significantly extended and complex
affordance is reviewed in section 3. However Hartson (2003) has also recently proposed a
four-fold division of (simple) affordance for the purposes of designing for interaction. These
four categories are (a) cognitive affordance; (b) physical affordance; (c) sensory affordance
and finally, (d) functional affordance. This four-fold classification maps onto corresponding
functions: for example, physical affordance is synonymous with utility, while sensory
affordances include such things as noticeability, colour, contrast and so forth.
2.2 Breakdown analysis
Rather than the Ergonomic approach of matching the “machine to the man”, an alternate
approach to designing for affordance has been adopted by De Souza and her colleagues who
among have modelled the breakdowns in the communication between the user interface and
the user (de Souza et al., 1993, 1999 and 2000; Prates et al., 2000a and 2000b). Their analysis
uses ‘tags’ - which represent an utterance that expresses a user's reaction to what happens
during interaction such as “Where is?”, “What now?” and “Where am I”. This use of tags
parallels the taxonomy of potential breakdowns in using a tool as presented by Dreyfus. It will
be recalled that Heidegger famously classified tools as being either ready-to-hand or presentat-hand (the former implying transparent, un-thought use, the latter suggesting some measure
of uninvolved reflection). Hubert Dreyfus, an important commentator on Heidegger has
extended this treatment to deal with the range of breakdowns in our day-to-day use of tools.
Table 1, which has been adapted from Dreyfus (1991) holds a description of these
breakdowns and their consequences. As with most philosophers, the hammer is the artefact of
choice.
3
Available-ness
Un-availableness
2
What happens
Dasein’s stance
What is encountered
Equipment functioning
smoothly
Transparent coping.
Absorbed in practical
activity.
Transparent functioning,
readiness-to-hand.
Get going again (picking
up another hammer)
Context-dependent aspects
or characteristics of
“objects” (“hammer” as “too
heavy”)
The inter-connectedness of
equipment. The towardswhichs 3.
Equipment problem:
1. Malfunction
(conspicuous:
hammer too heavy)
2.
Temporary
breakdown
(obstinate: head
comes off hammer)
3. Permanent
breakdown
(obstructive:
unable to find
hammer)
Occurrent-ness Everyday practical
activity stops
Pure
Rest.
Occurrent-ness Getting finished.
Practical deliberation.
Eliminating the
disturbance.
Helpless standing before, The worldly character of the
but still concerned.
workshop, including the forthe-sake-of-whichs.
Detached standing
before, theoretical
reflection.
Skilled scientific
activity.
Observation and
experimentation.
Pure contemplation.
Just looking at
something (curiosity)
Just occurrent and no more.
Isolable, determinate
properties.
The universe as a lawgoverned set of elements.
Bare facts, sense data.
Table 1 – modes of being of entities other than Dasein (after Dreyfus, 1991:124-5)
While this is an interesting treatment of Dasein’s ‘relationship’ with hammers it does leave a
number of questions open with respect to our use of more complex and, perhaps, socially
constructed tools such as those outlined early in this essay.
3
Complex Affordance
Norman (1988) sought to adapt the original, direct unlearned formulation of affordance with
one which is at one remove, namely perceived affordance. He suggested that an individual
could be said to perceive the intended behaviour of, say, interface widgets such as the sliders
and buttons. The intended and perceived behaviours of such widgets are, of course, very
simple, including sliding, pressing and rotating leaving him to conclude that ‘real affordances
are not nearly as important as perceived affordances; it is perceived affordances that tell the
user what actions can be performed on an object and, to some extent, how to do them’ (ibid).
Though like Gibson he subsequently modified his position on perceived affordances to
observe that they are ‘often more about conventions than about reality’ (Norman, 1999:124)
citing scrollbars as examples of such a convention. While he has remained resolute that
2
Heidegger’s use of language is notoriously challenging, for example, Heidegger uses the term Dasein which
means ‘there is’ to indicate a human being. It is the convention to use the term un-translated. To add such
difficulties, commentators have offered a range of different translations of key terms. Dreyfus is no exception. In
the following table readiness-to-hand (Zuhandenheit) is translated by Dreyfus as availableness and present-athand (Vorhandenheit) as occurrentness.
3
Heidegger also uses the expressions towards-which to mean something like a goal, and for-the-sake-of-which to
indicate purpose..
4
perceived affordances are not real affordances this discussion opened the door to the wide
spread adoption of the term. Indeed the literature is replete with examples the extended the
use of the concept (e.g. Gaver, 1991 & 1992; Robertson, 1991; Hudson and Smith, 1997;
Norman, 1999; St. Amant, 1999; Silveira et al., 2001; among numerous others). Typical of
these, Robertson (1997) has reported on an ethnographically-informed study of a distributed
design team. One of the themes she considered were the affordances a technical system must
have to support remote cooperation. From the perspective of embodied action she considered
the aspects of a system which should or must be present to afford communication. She
identified a number of generic, embodied actions and their relevant affordances: for example,
pointing at something, emitting signs and monitoring of signs, moving in and out of shared
space. An example of one of these affordances is ‘highlighting some aspect of an object’.
Robertson quotes Goodwin (1994) in defining highlighting as those ‘methods used to divide a
domain of scrutiny into figure and ground, so that events relevant to the activity of the
moment stand out’. Highlighting embodies not only one’s perception but serves to direct the
attention of others.
A second example of the extended use of the term affordance can be seen in a study reported
by Silveira et al. (2001) entitled, Augmenting the Affordance of Online Help. There are two
things to note from this title alone: firstly, that a high level online interactive system like the
help system might have affordances; and secondly, that affordances can be subject to
augmentation, indeed this augmentation is managed by a process of ‘semiotic engineering’.
A further example is an extension of the concept of affordance to partition the evaluation of a
collaborative virtual environment - CVE (Turner and Turner, 2002). In their study they create
an explicit three layer model of affordance: ‘basic level’ equating with simple usability /
ergonomics, a ‘middle layer’ matching user tasks (and/or) embodiment and finally, a ‘top
level’ corresponding to the purpose of the activity for which ‘cultural affordance’ are
appropriate. This extended use of the concept of affordance reaches a fuller flowering in the
discipline of computer supported cooperate work (CSCW) where the social organisation of
work is often spoken of in terms of affordance. Indeed, the use of the term affordance in
anthropology is not unusual (e.g. Cole, 1996; Wenger, 1998; Holland et al., 2001). Cole
(1996), for example, identifies a range of affordance offered by a variety of mediating
artefacts including the life stories of recovering alcoholics in AA meeting (affording
rehabilitation), patients’ charts in a hospital setting (affording access to a patient’s medical
history), poker chips (affording gambling) and “sexy” clothing (affording gender
stereotyping). Cole notes that mediating artefacts embody their own “developmental
histories” which is a reflection of their use. That is, these artefacts have been manufactured or
produced and continue to be used as part of, and in relation to, intentional human actions.
Holland and her colleagues add to this with a discussion of how the men of the Naudada
(native to Nepal) use of the pronoun ta (you) to address their wives. This pronoun is the least
respectful of all forms of address and is usually reserved for children, dogs and other
“inferiors”. As Holland notes, “ … pronouns, through their collective use in common practice,
have come to embody for, and so impose on, people […] in Naudada a conception of the tasks
to which they are put, and a conception of the person(s) who will use them and be the
object(s) of them” (Holland, ibid:62). Thus the use of the least respectful form of the pronoun
places women as inferior to men, that is, their use affords the maintenance of social structure
in their society. In a closely related vein, researchers in the field of CSCW have noted that
artefacts mediating cooperation are frequently socially constructed and their affordances can
be seen to differ from one workplace to another. These so-called boundary objects (Star,
1989) are resources or artefacts which support the work of separate communities such as
different departments within an organisation or even between very different communities of
practice. To be useful by these different communities they must be sufficiently flexible to be
5
used in different ways, by different people for different purpose in a range of contexts. The
term ‘boundary object’ is, of course, primarily descriptive rather than a design imperative as
they are seen to develop or ‘evolve’ within and between communities by embodying custom
and practice. There are numerous examples of boundary objects, descriptions of which are
frequently couched in terms of affordance. For example Berg et al, (1997) have described the
shared use of patient records by a range of clinicians and nurses and again more recently
Reddy et al. (2001), while Bødker and Christiansen (1997) describe the use of scenarios as
boundary objects between users and designers. Of further interest is Sellen and Harper’s
(2002) extended study of the affordances of paper. Their analysis of the affordances of paper
include: reading, being easy to navigate through a [paper] document; being able to read more
than one document at once; writing notes upon / annotating; ease of filing; portability; joint
viewing and so forth. Examples of complex affordance are clearly very diverse - the challenge
now is to account for them.
4
A Very Soviet View of Affordance
Evald Ilyenkov was a Soviet philosopher who is often portrayed as one of the key thinkers behind
Activity Theory. Among his many contributions, Ilyenkov sought to provide a materialist account of
non-material phenomena, significances being one such non-material phenomenon.
Significances, as will be seen, have remarkable similarities to affordances. Ilyenkov4 begins
his argument by identifying two classes of nonmaterial phenomena namely:
1. mental phenomena such as thoughts, beliefs and feelings and
2. phenomena that are neither material nor mental – meaning and values, such as
goodness.
This second class he calls ideal [ideal’noe]. Ilyenkov then goes on to contrast two opposing
accounts of these ideal phenomena. An objectivist account might argue that such ideal
phenomena are external to us and constrain our actions, e.g. many religions present these
phenomena as ‘god-given’. In contrast, subjectivists would argue that these phenomena are
the product of our human nature and as such are merely projections having no existence
independent of us. Rejecting both of these accounts Ilyenkov proposed a classic dialectic
position arguing that a thing can be objective without being independent of us. Through
human activity we idealise our world (i.e. endow it with meaning) and in so doing we also
endow it with properties that come to exist completely independently of us. As Ilyenkov puts
it:
Ideality is a characteristic of things, but not as they are defined by nature, but by
labour, the transforming, form-creating activity of social beings, their aim-mediated,
sensuously objective activity. The ideal form is the form of a thing created by social
human labour. Or conversely, it is the form of labour realized [osushchestvlennyi] in
the substance of nature, “embodied” in it, “alienated” in it and “realized”
[realizovannyi] in it, and thereby confronting its very creator as the form of a thing or
as a relation between things, which are placed in this relation (which they otherwise
would not have entered) by human beings, by their labour.
Ilyenkov, 1979: 157
Ideal properties such as significances are thus real, objective but not independent of us as
they are products of meaning-endowing in human activity. This clearly echoes many of the
insights from anthropology and CSCW. However the most problematic part of this argument
(excepting the obscurity of Ilyenkov’s expression) is the issue of ideality’s complete
4
The following description of Ilyenkov’s work draws heavily on Bakhurst’s commentary (1991).
6
independence from the individual mind. The key to understanding this is the expression
‘individual mind’ rather than mind per se. The ideal exists in the collective not the individual
mind – a concept reminiscent of distributed cognition (e.g. Hutchins, 1995). Thus while social
life is a product of the collective, it is experienced by individuals as a set of given rules,
practices, tools and artefacts. We, individually, grow up among pre-existing and apparently
objective phenomena. From this perspective human development can be seen as the process
of becoming enculturated into this objectified, historically developed world. Ilyenkov offers a
specific example of this: ancient mariners saw the stars as a pre-existing navigational aid,
while priests regarded them as pre-existing guides to future events (astrology). These
interpretations, that is, the need to find one’s way at sea or the need to predict future events,
were subsequently attached to the stars as the result of their incorporation into human activity.
Ilyenkov (1977) describes the creation of artefacts as a further illustration of how ideal
properties could be held to exist objectively in the world. He uses the example of a table. A
table is part of objective reality and yet can be distinguished from a block of wood because it
has been objectified by the human activity shaping it. This is how we distinguish wood from
tables; and wood from footwear – see
Figure 3.
Wood affords a variety of uses, for
example, burning, throwing, shaping,
trading and so forth. Through purposive
use objects acquire significance. Shaping a
block of wood into a pair of clogs, endows
the wood / clogs with the significances of
wearing, being purchased as a souvenir or
being thrown into machinery5. Ilyenkov
notes that activity is the source of the
world we inhabit and the principal
expression of how we inhabit it. This is
Figure 3: making clogs - or objectifying wood
more
than
saying
simply
that
by way of human purposive activity
objectification is the source of the ideal
properties of this or that thing – Ilyenkov was proposing that objectification is the source of
human culture. So, for example, we non-archaeologists are unable to distinguish between a
shard of flint and an ancient stone tool while a student of the discipline who has been
successfully enculturated can. Ideality is like a stamp or inscription on the substance of nature
by social human activity:
it is the form of the functioning of a physical thing in the process of social human life
activity … [it is] human social culture embodied (objectified or reified) in matter, that
is, [a quality] of the historically formed modes of activity which confront individual
consciousness and will as a special non-natural [sverkhpriroda] objective reality, as a
special object, comparable with material reality, and situated in one and the same
space as it and hence often confused with it.
Ilyenkov 1979: 139-140 cited by Backhurst, 1991:180
In other words, a significance makes a thing knowable. For Ilyenkov, nothing about the
physical nature of a thing in itself explains how it is possible that it can be knowable.
However, significance is not merely a synonym for affordance. In order to be knowable some
significance has to be attached to the thing through the process of the object’s incorporation
5
Clog = sabot, throwing a sabot into machinery, sabotage.
7
into the sphere of human activity which is not necessarily true of an affordance – particularly
simple affordances. The ideal properties of an artefact represent to the individual a reification
or embodiment of the practices of the human community that has historically developed the
thing. In other words, objects acquire this ideal content not as the result of being accessed by an
individual mind, but by the historically developing activities of communities of practice.
5
Familiarity and Equipment
Heidegger’s philosophy focuses on the nature of being – human being in particular (who he
describes as Dasein – a term we have already seen in table 1). In doing so, he distinguishes
and distances himself from those who are concerned with epistemology which he regarded as
disinterested and theoretical knowledge. Dasein is ‘in-the-world’, a world comprising
everyday practices, equipment and common skills shared by specific communities. Despite
the richness and volume of Heidegger’s work, it has not been widely quoted and applied, for
example, Winograd and Flores (ibid) have (only) brought the concepts of readiness-to-hand,
present-at-hand and throwness to our attention. This is now extended to consider Heidegger’s
treatment of familiarity and equipment.
Commercial training courses often specify as a pre-requisite ‘familiarity with Microsoft
Windows™’; the safety briefing on a commercial jet often includes the warning that
passengers may not be familiar with this specific aircraft. Familiarity has a central role in
everyday life. More than 20 years ago Bewley et al. (1983), writing of the four design goals
which were adopted in the design of the legendary Xerox Star’s user interface, noted that the
first of these was, “There should be an explicit user’s model of the system, and it should be
familiar (drawing on objects and activities the user already works with) and consistent.” User
model, familiarity and consistency. Similarly Raskin (1994) discussing the rise of intuitive
user interfaces concluded that by intuitive we really meant familiar. While familiarity is
generally understood to refer to a knowledge of something, for Heidegger, it primarily
encompasses the ideas of involvement and understanding. Here involvement may be taken as
something approaching a synonym for ‘being-in-the-world’ while understanding should be
interpreted as the tacit knowledge of our everyday activities. We daily demonstrate our
familiarity by coping with situations, tools and objects by our understanding of the referential
whole. A world, according to Heidegger, has three key characteristics:
1. A world comprises the totality of inter-related pieces of equipment. Each piece of
equipment being used for a specific task – hammers are for driving nails into wood (it
is not meaningful to consider a hammer without reference to other equipment, for
example, nails); a word processor is used to compose text.
2. The second ‘component’ of a world is the set of purposes to which these tasks are put.
Of course, while we cannot meaningfully separate out purposes from tasks in these
(non-Cartesian) worlds we can recognise that the word processor is used to write an
academic paper for the purpose of publication and dissemination. Similarly nails are
driven into wood to provide illustrations for philosophical discourse.
3. Finally, in performing these tasks we acquire or assume an identity (or identities) as
carpenters, academics and so forth. Thus by worlds we mean cultural worlds. In using
these concepts and viewpoints we are moving away from thinking in terms of what are
the nature of things (and ourselves) to how we manage and cope with things.
‘My encounter with the room is not such that I first take in one thing after another and put
together a manifold of things in order then to see a room. Rather, I primarily see a
referential whole ... from which the individual pieces of furniture and what is in the room
stand out. Such an environment of the nature of a closed referential whole is at the same
8
time distinguished by a specific familiarity. The … referential whole is grounded precisely
in familiarity, and this familiarity implies the referential relations are well-known.’
History of the Concept of Time (187)
This contradicts the view which assumes that we have to synthesize a ‘manifold’ of things,
perspectives and sense data. Instead Heidegger argues that we simply perceive the room’s
Gestalt and in doing so we are able to deal with its contents through our familiarity with other
rooms. Familiarity is then a ‘readiness’ to cope with, say, chairs (e.g. by sitting on them)
which has developed from our earliest days. Heidegger describes this readiness as:
‘the background of … primary familiarity, which itself is not conscious or intended
but is rather present in [an] unprominent way’
History of the Concept of Time (189)
And in the Basic Problems of Phenomenology he calls it the ‘sight of practical circumspection
[…], our practical everyday orientation’ (163). Assuming that we are enculturated into the
world of modern computing, when we enter our places of work we see desks, chairs,
computers, network points and so forth. We do not perceive a jumble of surfaces, wires and
inexplicable beige boxes (unless we have just been burgled). We demonstrate our familiarity
by coping with situations, tools and objects.
6
Discussion
In reviewing the use of the concept of affordance it has been observed that researchers have
moved far beyond Gibson’s original account. He saw affordance as a reciprocal relationship
between object and action and that this could be characterised as part of the perception-action
loop. This mechanism alone cannot account for the very wide range of affordances which
have been discussed.
Instead and in their own very different ways, both Ilyenkov and Heidegger have argued that
we understand the world in terms of use. Ilyenkov has also argued that we understand our
historically constructed world in terms of significances. These significances are ideal that is,
they are subjective and independent of an individual mind existing instead in the collective –
affordances /significances are the visible manifestations of our culture.
Heidegger’s perspective on equipment also forces us to conclude that an affordance cannot
exist in isolation. He has argued that we perceive / experience the world as an inter-connected
mesh of things which we can use. The totality of equipment means that each tool occupies a
specific position in the system of forces that makes up the world. The totality of equipment is
the world. Harman illustrates this point well in his discussion of a bridge …
… in turn, the bridge as a whole is not a self-evident, atomic finality; rather, it
functions in numerous different equipmental ways, swept up into countless larger
systems. Usually, it enacts an official plan of efficiency, shaving ten minutes from the
drive around the bay. But in certain regions of the world, separating hostile factions,
it is monitored by snipers. The bridge can be the unforgettable site of a fateful
conversation (nostalgia-equipment), the location of a distant relative’s suicide
(memorial-equipment), or perhaps it is simply stalked in a troubling insomnia. It is an
object of study for architectural critics or material for sabotage by vandals. In the
lives of seagulls and insects, it takes on different aspects.
Harman, 2002:23
This is not to suggest that things have different meanings in different contexts. For Heidegger,
equipment is context. So, it would appear that on affordance, Ilyenkov and Heidegger, despite
9
differences in language, are of one mind. A thing is identified by its use – that is, we identify
it through its affordances or significances – so as equipment is context, affordance and
context must be synonyms. Interestingly, Brézillon and Pomerol (2001) also equate context
with knowing how which Heidegger regards as the basis of understanding – to understand
something is to know how to use it.
So, what does this mean for the design and evaluation of interactive systems, devices and
media? The difficulty of trying to apply this reasoning to everyday HCI engineering is that it
is necessarily holistic. Use, affordance and context are treated as a Gestalt by both Ilyenkov
and Heidegger and to date no one has managed to create holistic forms of design. The design
of interactive systems requires the designer not to be involved with ‘use’ per se but to be
engaged with ‘design for use’. Much the same is true for evaluation. This is the difference
between specifying the materials and dimensions of a hammer and the act of hammering.
In conclusion, from a holistic or phenomenological perspective, affordance, use and context
are one. From a design perspective affordance is not an intangible, elusive property of
interactive systems, it might better be thought of as a boundary object between ‘use’ and
‘design for use’ recalling Wenger’s (1998) remarks that all designed artefacts are boundary
objects both between and within the communities of practice of designers and users.
Acknowledgements
Thanks to the anonymous reviewers of this paper for their constructive comments.
7
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