Cognition: Mental Representations, Problem Solving, and Decision Making - Foundations for Designing User-Centered Systems - page 167

relationship to other objects (e.g., sorting them, or looking for relationships). When
the process is based on the number of objects, the algorithm is linear. When the
process for each item is based on the number of other objects as well, the algorithm
is nonlinear (e.g., based on the square of the number of objects which represents the
number of possible comparisons). Sometimes there are algorithms that are not too
bad with increasing numbers of objects, and other times the costs quickly expand
beyond the capabilities of even modern computers. This area is addressed by
algorithm complexity, and your users will not understand it well.
Further illustrative examples of problems in interfaces caused by a mismatch
from the designer's view of the task and the user's mental model (such as doors
that open the wrong way, and buttons that are hard to find) can be found in books
such as Norman ( 1988 , 2013 ) and on web sites of interface bloopers.
6.2.3 Feeling of Knowing and Confidence Judgments
Users will vary in how confident they are in their representations. So they will ask
themselves questions about objects such as ''Is this a clickable region?,'' about
processes such as ''Is this the right way to do it?,'' and results such as ''Is this the
right answer?.''
The way that confidence judgments are analyzed varies across contexts and
research domains. Computer science and artificial intelligence (AI), for example,
have tried to provide algorithms for computing a confidence level based on the
available evidence. Psychology has studied feeling of knowing, about word
retrieval, strategy selection, and how close you are to the answer. Business has
studied confidence in decision making. In each of these cases, the measures of
confidence form another part of a mental representation.
Users will base their feeling of knowing on a wide range of information. This
includes having successfully used the answer before, being familiar with the
domain, social expectations from the person asking (do you know the way to….?),
and social comparison (others would know the answer, so I probably should also
know it). Good interfaces will help users develop appropriate levels of confidence
in their representations and decisions. Often, this means providing information to
support learning, including feedback on task performance, and also providing
information to build a mental model. If users do not get feedback, their calibration
about how well they are doing will be poor to non-existent; this applies across
many professions and businesses (Dawes 1994 ).
6.2.4 Stimulus-Response Compatibility for Mental Models
One aspect of mental models that can be applied to interface design is the idea of
stimulus-response (S-R or SR) compatibility. This aspect of behavior is that the