Instructing Real World Va, cuumers

Early views of Natural Language il~slr~tclio~s corresponded to the early views of plates: instructions were interpreted as speci~’ing nodes of a hierarchical plan that, when completely expanded (instructions having been recognized as only being partial specifications of activity), acts as a control structure guiding the behavior of an agent.. This view, for example, enabled SIIRDLU’s uccessful response to instructions such as "Pick up the green pyramid and put it in the box" [29], a response that. attracted early public at.tention to the emerging field of Artificial httelligence. That plal~s should not be viewed as control structures has already been well argued by others in the field, including Agre and Chapman [1], Pollack [2:3], and Suchman [25]. Agre and Chaplnan, for example, point to the fact that when people form plans in response to instructions given theln before the start, of a task, they appear to use those plans as resources: the actual task situation may lead them to interpolate additional actions not mentioned in t.he instructions, to replace actions specified in the instructions with other ones that seem better suited to the situation, and to grotmd referring terms as a consequence of their actions rather than as a precondition for them, all of which are very differmtt from how COlnputers use programs to control their operation. Agre and Chapman do not actually distinguish between instructions and plans in [1]. IL is in subsequent work that distinctions emerge. For example, looking at instructious given as advice to agents already engaged in an activity, Chapman [7] treats iustructions as additional evidence for action alternatives already identified by the agent as being relevant to its current situation, but that might not he followed ilnmediately (or ever) if other alternat, ives have more evidence in their favor. Chapman argues that this is how arcade game players follow advice given