Interruption Management:The Use of Attention-Directing Tactile Cues

Pamela J. Hopp, C. A. P. Smith, Benjamin A. Clegg and Eric D. Heggestad

Human Factors: The Journal of the Human Factors and Ergonomics SocietySpring 2005 Issue

Eliza Weber

Article Overview• Forms of interruptions• Interruption management• Task switching and the use of directional cues• Case study• Application and future directions of research

Forms of Interruptions•Internally Generated•daydreams, intrusive thoughts

•Externally Generated•phone call, arrival of an e-mail, alarm, questions

Interruption Management

• Definition: The detection, interpretation and integration of interruptions within ongoing task performance

• Ideal interruption• Minimally distracts ongoing task performance• Provides clear signal of secondary task

Task Switching and Cues • Research shows that

people struggle to remember to switch between operations unless there is a reminder in the environment

• Suggestion: Provide individual with a cue signaling when secondary task requires attention

Task Switching and Cues

• Visual Cues• Use may not be optimal• Visual fatigue from overdependence

on visual channel

• Auditory Cues• Difficult to identify or recognize• Too intrusive and difficult to

suppress

Tactile Cues• Advantages

• Tactile channel not heavily used• Readily detected• Not highly intrusive• Omnidirectional and perceived

along with visual and auditory information

• Disadvantages• Overstimulation• Effects of signal intensity and time

uncertainty are additive.

Case Study: Directional Tactile Cues

Do directional tactile cues that prompt users to switch their attention provide performance benefits or create additional interference within a multi-task environment?

61 Undergraduate Students20 Men

39 Women2 Unidentified

32 – Control Group29 – Treatment Group

Case Study: Directional Tactile Cues

Aircraft Monitoring Task• Presented on radar screen

displayed on computer monitor placed directly in front of participant

• Computer mouse used to respond to aircraft monitoring task

Gauge-reading Task• Presented on computer

monitors positioned laterally, one on each side of participant

• Computer keyboard, placed in front of participant, used to respond to gauge-reading task questions

Case Study: Directional Tactile Cues

• Control Group – Instructed to remember to check the side screens for potential interruptions

• Treatment Group – Received directional tactile cues delivered through pager buzzers sewn into shoulders of a vest.

Hypothesis

• Treatment group should demonstrate more efficient switching between tasks• Should attempt greater proportion of interrupting

tasks• Average time to give correct response should be

shorter• Tactile cues not expected to cause decrements in

overall performance• Lower workload and stress

Hypothesis

• Multiple Resource Theory – Tasks that require non-overlapping resources should not interfere with each other– Number of errors on gauge-reading task expected

to be equal in both groups– Number of hits, misses, false alarms and correct

rejections on aircraft monitoring task expected to be equal in both groups

Aircraft Monitoring3 Scenarios, each 10 minutes in length, designed to be of equal difficulty

Task consisted of visual input and required a considerable manual response load

On average, 2/3 of planes that crossed screen required action from participant

Computer tracked all actions taken by participant and displayed a summarized count of correct decisions and errors made at end of each scenario

Gauge-reading15 gauge-reading task interruptions were presented in each scenario

6 possible question types requiring a “Yes” or “No” response Question types and locations (left or right monitor) were counterbalanced

Time between questions ranged from 20-70 secondsDuration that questions were displayed ranged between 10-20 seconds

Computer recorded accuracy of each response as well as response time Number of questions answered correctly was displayed at the end of each scenario

Subjective Workload

• Subjective Workload Questionnaire– Time pressure– Mental effort – Stress– Physical discomfort– Treatment group answered extra questions on use

of tactile cues

Results – Gauge-reading Task

• Treatment group attempted significantly greater proportion of gauge questions and responded faster than the control group

• No difference in error rates– Task switching was more effective in treatment

group– Tactile cues did not interfere with information

processing requirements of interruptive task

Results – Aircraft Monitoring Task

•No significant difference in task performance•Addition of tactile cues did not adversely impact performance

Results – Workload Questionnaire• No significant effect of group on subjective

workload perceptions • Tactile cues did not create substantial

additional workload

Discussion• Treatment group participants did not respond

to ALL gauge task questions – Failure to recognize cue– Negotiated interruption• Lead to task not being handled in timely manner

Applications • Aviation Industry – Pilots and Air Traffic Controllers• Military – Soldier decision making• Spatial Orientation• Navigation• Obstacle Homing/Avoidance/Evasion• Medicine• Alternate Communications• Sensation Feedback

Future Directions of Research• Incorporate information about nature and urgency of a task• Ongoing research – Type of information that can be effectively transmitted

via tactile cue– Nature of tactile localization depending on body

placement• Examine different task environments and types of users• Other possible applications?– User-interface development, vigilance tasks, team

environment

Questions?