Biomedical Engineering Reference
In-Depth Information
be done by the subject as part of artifact use). It is this coupling between
the artifact and the schema as defined below, which is carried out by the
worker himself, in a specific situation and in pursuit of a specific goal, that
makes it possible to determine the instrument.
The artifact may take on various forms and may be produced by the
worker himself, or by other people for the worker's benefit. In some cases,
only a part of the artifact will turn into an instrument - such as in the case
of using only some of its functions or some of its display screens.
The concept of schema is derived from the works of Piaget (1952). In
the end, it refers to the concept of 'use' as we have used it thus far. Schemas
constitute the means whereby workers are able to apprehend the situa-
tions and objects to which they are confronted as part of their interactions
with their environment. Schemas respond to two different processes:
• Accommodation: Workers may draw from the schemas that they
have constructed throughout the course of their own personal histo-
ries, and transform or reorganize these schemas in order to respond
to the new situations they encounter. Hence, for example, to use new
artifacts, workers will transform their own schemas by operating a
process of differentiation.
• Assimilation: The worker may thus apply similar schemas to arti-
facts despite their being very different from one another, and imple-
ment them in a suitable manner as part of a process of generalization.
Schemas present another dual feature. They are also of a private and a
social nature. Throughout their own personal histories, workers will con-
struct their own schemas (through assimilation and accommodation). Yet,
each of them is not in complete isolation, and other workers may take part
through practices aiming to share schemas and to hand them down, for
example, between peers belonging to the same community (Bourmaud,
2006) or to a work collective.
The instrument as a construct
The example below may help us introduce the proposal made here. A
walking stick purchased in a store presents some intrinsic features that
guide the use that can be made of it in a ramble: its adjustable height, its
moulded handle, its strap, the pick that is fixed at the end, etc. all strongly
guide how it can be manipulated and used for support in walking paths.
However, all of us have experienced forms of use that are less expected
for this stick, and yet very practical: using it to pick a fruit by reaching out,
extending the arm and swiping at it can prove quite an enjoyable experi-
ence. The concept of affordance (Gibson, 1979; Norman, 1988) is useful
