This attribute gives the agent control over the visual and auditory attention spotlights. The range of functions supported is based on extensions of Mark Wiesmeyer's thesis work, An Operator-Based Model of Human Covert Visual Attention.
Substructure of the attribute:
(<top-state> ^attention-link <al>)
(<al> ^identifier <id>
^<< nearest furthest >> << auditory visual >>
^direction << ul l dl u c d ur r dr >>
^width <num>)
Not all of these attributes are required. If the identifier is
specified, the modality and location is determined from the modality
of the identifier. Otherwise, the nearest or furthest attribute is
checked (in that order) and the modality is determined from the value
of that attribute. The direction is evaluated, and if valid, the
target location is then determined by searching the appropriate input
field in that direction at the appropriate distance. If no such
feature is found, the processing terminates. If the other processing
has been successful and a width is present, the width of the spotlight
is changed, but otherwise it is left the same. Implementation of output function: ShiftAttention in attention.c