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Fig. 7.3
Comparing goals and directives. Goals are linear with a series of steps whereas directives
are vague and gradually refi ned through a process of interacting with the environment and defi ning
tasks that explore the problem space outlined by the directive
(improvisation and affordance-based interactions) or using any number of search
and planning procedures defi ned in goal-based AI.
Once the painter takes a step back to understand his last contribution in terms of
the overall picture, however, he may fi nd that his last contribution actually disrupted
the overall balance of the piece. Although he doesn't have a specifi c end state for the
painting in mind, one of the directives guiding his work may relate to achieving an
overall balance in the composition. This directive does not tell him what contributions
to make, but it helps point out inconsistencies and visual tensions that need to be
addressed.
Let us suppose that the artist found fi ve areas of the drawing that all violated his
sense of balance due to his last contribution. He then selects one of those areas and
defi nes a specifi c painting tasks that he predicts will help achieve balance. Once the
fi rst of those fi ve areas is complete, the artist could take another step back and real-
ize that his latest contribution makes the left side of the artwork look kind of like a
face, which he likes. The artist might then update his overall directive to creating
some kind of abstract face. Once this directive is adopted, the entire canvas is ana-
lyzed with respect to face-like features. Given this new constraint, he sees additional
opportunities to change the drawing and would then select specifi c painting tasks
that contribute toward the current directive. Here, the directive is dynamic and
always evolving through interaction with the environment. The feedback offered by
actually producing a change in the environment spurs new ideas and interpretations
that can change the overall directive. The directive determines the constraints and
affordances that are consciously available to the painter's perceptual processes.
Ultimately, it is the continuous perception-action feedback loop that actually
determines actions. Instead of thinking of action as a series of behaviors executed
