Cognition: Mental Representations, Problem Solving, and Decision Making - Foundations for Designing User-Centered Systems - page 164

Table 6.1 Some propositional representations
Letters example—canonical
A is to the left of C
C is to the left of D
B is to the immediate right of A
Letters example—non-canonical
M is to the left of Y
Y is to the left of S
R is to the immediate right of M
Workshop expenses
Gross income was $3,500. Expenses for coffee breaks were $1,218; copying was $400, and
AV rental was $1,200. Net profit was $882
Puzzle sequence
A series of numbers is 8 5 4 9 1 3 2 7 6
What comes next?

Letters example—canonical: A B C D

Letters example—non-canonical: M R Y S

Workshop expenses:

3,500

3500

3,000

3000

2,500

2500

2,000

2000

Costs Series1

1,500

1500

1,000

1000

500

500

0 0

Gross income Coffee breaks Copying AV rental Net profit

Gross
income

Coffee
breaks

Copying AV rental Net profit

Fig. 6.2 Some graphical representations of the material in Table 6.1

6.2.2 User's Mental Models

The mental models that people use in performing tasks affect how they perceive
and interact with the world. There are several different meanings of the term
mental model, however, and the different ways in which it is used can be confusing
(e.g., Gentner and Stevens 1983 ; Johnson-Laird 1983 ; Moray 1996 , 1999 ; Norman
1983 ; Wilson and Rutherford 1989 ). For our purposes we think of mental models
as a representation of some part of the world that can include the structures of the
world (the ontology of the relevant objects), how they interact, and how the user
can interact with them.
As an example, work out how many windows there are in the place where you
live. The way that most people arrive at an answer is by referring to a structural
mental model of their home. They then imagine walking around their model of the