Problems with Intent Recognition for Elder Care

Christopher W. GeibHoneywell Labs3660 Technology DriveMinneapolis, MN 55418 USA{ geib,goldman}@htc.honeywell. comAbstractProviding contextually appropriate help for elders re-quires the ability to identify the activities they areengaged in. However, inferring agent intent in thesekinds of very general domains requires answers to anumber of problems that existing AI research on intentrecognition/task tracking has not addressed. This pa-per identifies some of these limitations, sketches someof the solutions and points at some promising direc-tions for future work.lIntroductionTo provide contextually relevant aid for elders, as-sistant systems must be able to observe the actionsof the elder, infer their goals, and make predictionsabout their future actions. In the artificial intelligence(AI) literature this process of deducing an agent’s goalsfrom observed actions is called plan recognition or tasktracking. We argue that plan recognition must be acentral component in assistant systems for elders:However, most existing AI literature on intent recog-nition makes a number of assumptions preventing itsapplication to the elder care domain. In this paperwe will discuss the requirements of this domain, inour previous work (Geib & Goldman 2001b; 2001a;Goldman, Geib, ~: Miller 1999) we have described anapproach to plan recognition that does not make manyof the restrictive assumptions of other intent recogni-tion systems. In this paper we briefly discuss its ap-plication to the recognition of elders plans in relativelyunconstrained environments.Requirements on Plan RecognitionThe domain of plan recognition for elder care requiresconfronting a number of issues that have not been ex-amined in more theoretical or academic domains. Thefollowing is a list of issues, properties or assumptions1This work was performed under the support of the U.S.Department of Commerce, National Institute of Standardsand Technology, Advanced Technology Program Coopera-tive Agreement Number 70NANBOH3020made by some or all previous AI plan recognition re-search that are critical in the elder care domain.Abandoning plans: All people abandon plans atone time or another. They forget what they are doing,the get distracted by other events, or due to changingcircumstances they explicitly decide to abandon a goal.In the case of providing care to elders failing memoryand mental faculties may cause the elder to uninten-tionally abandon goals that we would like the systemto remind them of. Consider an elder that begins totake their medicine but then gets distracted by a phonecall and does not return to the medication. To remindthe elder that they need to finish taking their medi-cation, a system will first have to recognize that theyhave abandoned that goal. We will discuss this in moredetail in the second half of the paper.Hostile agents: Most previous work in plan recog-nition has assumed cooperative agents, that is agentsthat do not mind or are even helpful in having theirplans recognized. Unfortunately it is unrealistic to as-sume that all elders will be willing to have their actionsobserved by an assistant system. Like all adults, eldershighly value their independence and may be willing totake extensive measures to prevent an assistant systemfrom observing them.To correctly handle agents that are hostile to hav-ing their goals recognized it is critical that we removethe assumption of a completely observable stream ofactions. The assistant system must be able to infer theexecution of unobserced actions on the basis of otherobserved actions and observations of unexplained statechanges.Observations of failed actions: Observations offailed actions can tell us at least as much about theintent of the elder as successful actions, however mostcurrent work in plan recognition has not consideredobservations of failed actions in inferring intent.Partially ordered plans: The plans for the dailyactivities of an elder are often very flexible in the or-dering of their plans steps. Consider making a peanut-butter and jelly sandwich, do we put the jelly on breadfirst or do we put peanut-butter on bread first? In fact,13