MEMOS: An Interactive Assistive System for Prospective Memory Deficit Compensation — Architecture and Functionality
Hendrik Schulze · 2003 · Proceedings of the 6th International ACM SIGACCESS Conference on Computers and Accessibility (Assets '04) · doi:10.1145/1028630.1028645
Summary
This paper presents MEMOS (Mobile Extensible Memory Aid System), a distributed electronic memory aid designed to compensate for prospective memory deficits following brain injury. Prospective memory — the ability to remember future intentions and tasks — is a frequent and disabling outcome of brain damage that significantly affects patient autonomy and quality of life. MEMOS consists of two components: a Personal Memory Assistant (PMA), a palmtop computer (HTC Wallaby/T-Mobile MDA running PocketPC) carried by the patient, and a stationary Base System (BS) server running J2EE on Linux. The PMA delivers structured, interactive reminding "cards" grouped into task "decks" — each card shows a simple message with large soft buttons, and the patient progresses through cards by pressing buttons or is automatically advanced after timer events. Tasks are modelled as graph structures that can branch based on the patient's responses, adapting to individual needs and abilities. A critical design innovation is the bidirectional GPRS cellular connection: unlike unidirectional pagers used in prior research, MEMOS can not only push reminders to the patient but also receive confirmation of task completion and alert caregivers when critical tasks are missed or the patient fails to respond. The system uses a custom XML-based markup language (M2) rather than HTML/WML to handle the specific requirements of memory aid interaction, including automatic activity initiation and multi-card display.
Key findings
The system was designed around six key requirements derived from neuropsychological research and clinical experience: structured interactive reminding (not just alarms), flexible schedule rescheduling, intuitive interface for cognitively impaired users, integration in everyday life, patient self-determination, and detection of critical situations with caregiver alerting. Early patient feedback revealed that flexible time management was the most important feature — patients with moderate memory disturbances insisted on having control over postponing and rescheduling tasks, stating they would not use a system that was "remote-controlled." Postponement options were restricted to practical intervals (10 minutes to "evening") to maintain a consistent schedule. In the first evaluation at the Daycare Clinic for Cognitive Neurology at the University of Leipzig, 9 patients with mild to moderate memory problems were tested. Patients with pure prospective memory deficits benefited most, fulfilling 94% of experimental tasks with MEMOS compared to 80% with conventional aids (phone and palm pilot) and 72% without any electronic aid. Patients with motivational problems tended to ignore the memory aid entirely. Practical challenges included patients attaching the PMA to its docking station incorrectly (preventing recharging and next-day task loading) and the phone's operating system automatically turning off the cellular radio at low battery, silently disconnecting from the Base System.
Relevance
MEMOS addresses a problem that has grown more relevant with aging populations: supporting independent living for people with memory impairments through technology. The system's design principles remain highly applicable: structured multi-step task guidance (not just simple alarms), bidirectional communication enabling caregiver oversight without removing patient autonomy, flexible scheduling that respects the user's sense of control, and adaptive task complexity based on individual cognitive abilities. The finding that patients with motivational problems did not benefit highlights an important limitation of cognitive prosthetics: technology cannot compensate for all aspects of executive dysfunction, and designers must distinguish between "forgetting to do" (prospective memory, addressable by reminders) and "not wanting to do" (motivational deficit, requiring different interventions). For contemporary accessibility practitioners, the tension between patient autonomy and caregiver oversight that MEMOS navigates is directly relevant to the design of smart home systems, medication management apps, and other technologies for cognitively impaired users. The practical failures around charging and connectivity also serve as lasting reminders that assistive technology reliability in the home environment is as critical as feature functionality.
Tags: cognitive prosthetics · memory · brain injury · mobile technology · assistive technology · caregiving · rehabilitation · independent living · cognitive accessibility · healthcare technology