Biomedical Engineering Reference
In-Depth Information
in the development process, including the planner, the designer, the advertis-
ing people, the salesperson in the retail market, etc., who may not have the same
image regarding the system. In this way, the designer is forced to integrate their
design skills with their ability to simulate the user's behavior. The application of
standard models offered by several international guidelines on accessibility and
usability, indeed, although it is able to represent the typical user's behavior to a
certain extent, is not enough to grant the success of a product. Therefore, to deliver
a satisfactory product, the designer needs to possess to a certain extent the abil-
ity to “simulate” the possible user's behavior. However, the ability to “simulate”
someone else's behavior consists of one of the hardest and most complex cognitive
processes that a human being can perform (Meltzoff and Decety 2003; Decety and
Jackson 2004).
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The user's cognitive process:
The user's interaction with the system is quite differ-
ent from the designer's process. First of all, it is a fact that, by interacting with the
interface, the user applies the same cognitive processes used by the designer in
the creation of the interface (i.e., problem-solving, representation of knowledge
and expertise). Thanks to these shared processes, the user is able to “operate” in
the interface (i.e., the interface is understandable and usable). However, whereas
the designer applies these shared cognitive processes during their simulation of
a hypothetical user's behavior (i.e., in the design of the information architecture),
the actual user does not need any simulation of the designer's intention: Their
cognitive processes are used only to perform actions in the interface and they do
not need to forget about their mental model. Therefore, the actions performed by
the user in the interface are not based on an “imagined” or “simulated” developer;
the actions are experienced directly.
The distance separating the designer and the user in the interaction mostly depends
on the different ways of applying their mental model: the designer's simulation of the
interaction and the user's interaction with the system. The distance between designer
and user can be reduced by the actors' competences to adapt the mental model to the
action required (i.e., simulate and interact). The more competent a designer is in simu-
lating the hypothetical user, the smaller the distance separating their mental model
from that of the actual user; the more competent a user is in the system functioning, the
smaller the distance from the conceptual model of the interface (and therefore from the
designer's model).
Both the user and the designer are part of the object we need to measure (the interaction).
Therefore, we cannot use as standards of measurement either the expectations on how the
system should work (i.e., the designer's perspective) or the experience and the satisfaction
perceived by the users in the interaction with the system (i.e., the user's perspective). In
fact, both of these perspectives are only a part of what we need to measure. In this sense,
we need to find an external unit of measurement able to generalize the relation between
the two. This standard unit we want to introduce can be observed only by introducing
an external model (i.e., evaluator's model) able to estimate the distance between the two
actors involved in the intrasystemic interaction. This model should be created on the base
of the available guidelines—e.g., Web Content Accessibility Guidelines 2.0, Heuristic list,
and design principle etc.—and usability evaluation methods (UEMs) for subjective- and
objective-oriented observation. An evaluator's model so created will be able to introduce
a new conventional unit of measurement, the reliability of which will be granted by the
