Lessons learned from manual systems: designing information systems based on the situational theory of agency - Information Systems Foundations: Constructing and Criticising - page 168

To illustrate the situational theory and how it differs from the deliberative theory, con-
sider a rat searching for food in a connected maze without cycles (Figure 14.1 (a)). The
rat could:
1. explore and build a mental model by conceptually lifting the roof off the maze; or
2. use a left-hand, wall-following rule to reach the food.
The first requires the rat to gather and hold a representation of the maze, as viewed from
above and which includes all objects in the maze, before deducing a plan of action that
is to be effected by it. The aerial view in Figure 14.1 (a) shows this (deliberative) view.
The second is a situational approach, shown in the ground view in Figure 14.1 (b), where
the rat notices a limited range of situations relevant to its activity and of which it becomes
aware by sensing these aspects - the absence and presence of walls. To act, the rat only
needs to be aware of the absence and presence of walls near it, and it is not interested
in anything else in its environment. In this way representation is purely indexical
(centred on the rat) and functional (for its acting).
Figure 14.1. The two views of 'Rat World'.
In the 'ground view' there are three aspects, numbered 1, 2 and 3. These three aspects
completely determine the situation the rat is in, at least in relation to its seeking food.
The rat will then select the action appropriate for the situation. All possible situations
and their associated responses can be grouped into an activity (called 'seeking food in
a maze').
As stated earlier, myopic-situated actions rely on environmental affordances for their
efficacy. In this example, the environmental affordance is that the maze is singly connec-
ted and does not have cycles. It is the existence of this structural property of the maze
that ensures that if the rat invokes the activity it will reliably reach food. This maze-
navigating example illustrates the general point made by advocates of the situational
theory (Agre and Horswill, 1992) and ecological theories of behaviour (Gibson, 1977;
Schoggen, 1989) that environmental structures, or affordances, make a significant con-
tribution to the production of goal-directed behaviour of real agents in real environments.
As Agre and Horswill (1992) put it: 'it is almost as if these surroundings were an extension
of one's mind'.
There are three ways in which a situational system is brought into being. First, a situ-
ational system could evolve so that agent actions and the effects of actions knit perfectly
with the environment and situations to make activities reliable. Biological organisms are
excellent examples of evolved situational systems. In many cases, such as social activities,