657 research outputs found
Reasoning about order errors in interaction
Reliability of an interactive system depends on users as well as the device implementation. User errors can result in catastrophic system
failure. However, work from the field of cognitive science shows that
systems can be designed so as to completely eliminate whole classes of
user errors. This means that user errors should also fall within the remit
of verification methods. In this paper we demonstrate how the HOL
theorem prover [7] can be used to detect and prove the absence of the
family of errors known as order errors. This is done by taking account
of the goals and knowledge of users. We provide an explicit generic user
model which embodies theory from the cognitive sciences about the way
people are known to act. The user model describes action based on user
communication goals. These are goals that a user adopts based on their
knowledge of the task they must perform to achieve their goals. We use
a simple example of a vending machine to demonstrate the approach.
We prove that a user does achieve their goal for a particular design of
machine. In doing so we demonstrate that communication goal based
errors cannot occur
Modelling rational user behaviour as games between an angel and a demon
Formal models of rational user behavior are essential for user-centered reasoning about interactive systems. At an abstract level, planned behavior and reactive behavior are two important aspects of the rational behavior of users for which existing cognitive modeling approaches are too detailed. In this paper, we propose a novel treatment of these aspects within our formal framework of cognitively plausible behavior. We develop an abstract, formal model of rational behavior as a game between two opponents. Intuitively, an Angel abstractly represents the planning aspects, whereas a Demon represents the reactive aspects of user behavior. The formalization is carried out within the MOCHA framework and is illustrated by simple examples of interactive tasks
PUMA Footprints: linking theory and craft skill in usability evaluation
‘Footprints’ are marks or features of a design that alert the analyst to the possible existence of
usability difficulties caused by violations of design principles. PUMA Footprints make an explicit link between
the theory underlying a Programmable User Model and the design principles that can be derived from that
theory. While principles are widely presented as being intuitively obvious, it is desirable that they should have a
theoretical basis. However, working directly with theory tends to be time-consuming, and demands a high level
of skill. PUMA footprints offer a theory-based justification for various usability principles, with guidelines on
detecting violations of those principles
Verification-guided modelling of salience and cognitive load
Well-designed interfaces use procedural and sensory cues to increase the cognitive salience of appropriate actions. However, empirical studies suggest that cognitive load can influence the strength of those cues. We formalise the relationship between salience and cognitive load revealed by empirical data. We add these rules to our abstract cognitive architecture, based on higher-order logic and developed for the formal verification of usability properties. The interface of a fire engine dispatch task from the empirical studies is then formally modelled and verified. The outcomes of this verification and their comparison with the empirical data provide a way of assessing our salience and load rules. They also guide further iterative refinements of these rules. Furthermore, the juxtaposition of the outcomes of formal analysis and empirical studies suggests new experimental hypotheses, thus providing input to researchers in cognitive science
Interaction design issues for car navigation systems
We describe a study on the interaction design of in-car
navigation systems. It focused on a commercial
product. Critical incident analysis was performed
based on natural use of the system by a usability
analyst. A cognitive walkthrough was then performed
based on actual scenarios from the natural use. This
is a non-classic application of cognitive walkthrough.
It allowed anecdotal critical incidents to be
theoretically grounded. We draw conclusions about
the interaction design of car navigation systems
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