1 ISE 412 ATTENTION!!! From page 147 of Wickens et al. ATTENTION RESOURCES

2 ISE 412 ATTENTION!!! A "flexible, sharable, processing resource of limited availability". Our ability to attend to several things at once (time-sharing) depends on:  Controlled vs automatic processing  Skill  Which resource(s) required Attention “tasks” can be divided into 4 categories...

3 ISE Selective Attention "requires the monitoring of several channels (sources) of information to perform a single task.”  Example: scanning cockpit instruments Limitations: – As the number of channels of information increases, performance declines (even when the overall signal rate is the same). – Can select inappropriate aspect(s) of the environment to process. – "Cognitive tunnel vision" in complex environments with many displays, especially under stress. (Example: 1972 Eastern Airlines crash in the Everglades). Errors associated with Selective Attention are generally the result of an intentional, but unwise choice.

4 ISE 412 Selective Attention Design Guidelines:  Place frequently sampled displays together.  Place sequentially sampled displays together.  Use external aids/reminders to help people remember when the display was last sampled.

5 ISE Focused Attention Requires attending to one source of information at the exclusion of all others  Examples: Trying to study while someone else is talking on the phone Trying to enter numerical data into Excel while others are discussing basketball scores and stats. Limitations:  Impossible to ignore a visual stimulus within 1 degree of visual angle of the visual information you are interested in.  Auditory stimuli sufficiently loud with respect to the signal you are interested in, and/or similar to it, can interfere with the signal. Errors associated with focused attention are generally unintentional, driven by the environment.

6 ISE 412 Focused Attention Design Guidelines: Parallel vs serial processing  Parallel processing is helpful when: two tightly coupled tasks are performed simultaneously  e.g., control roll and pitch of aircraft two or more information sources imply common action (redundancy gain)  Parallel processing is harmful when similar aspects of different stimuli must be processed (resource competition)  e.g., listen to air traffic control and input waypoints into the onboard computer two or more stimuli imply different actions  e.g., a batter distracted by a moth

7 ISE Sustained Attention "the ability of observers to maintain attention and remain alert over prolonged periods of time."  Example: Security guard watching monitor for intruders. Limitations:  Vigilance decrement - a decline in the speed and accuracy of signal detection with time on the task (found more in the laboratory than in real world tasks).

8 ISE 412 Sustained Attention Design Guidelines:  Appropriate work-rest schedules and task variation.  Increase the conspicuity of the signal.  Reduce uncertainty as to when and where.  Training.

9 ISE Divided Attention "two or more separate tasks must be performed at the same time, and attention must be paid to both.”  Example: Driving and talking to a passenger. Limitations:  Time-sharing...

10 ISE 412 The Resource Metaphor of Attention Time-sharing (or doing two tasks simultaneously) is difficult because we have limited attention resources. The Performance-Resource Function (PRF)

11 ISE 412 The Performance Operating Characteristic (POC) Performance Operating Characteristic Curve Task A Task B

12 ISE 412 Limitations of the "single-resource" theory of attention Difficulty insensitivity  In some experiments it has been shown that making one time- shared task more difficult has no effect on the performance of the other. Perfect time-sharing Structural alteration effects  In some experiments it has been shown that altering the structure (but NOT the difficulty) of one task affects performance on the other.  Example: Manual vs vocal responses to a tone discrimination task while tracking.

13 ISE 412 Multiple-Resource Theory Instead of one "pool" of resources, there are several different capacities of resources:  Codes: spatial or verbal  Modalities: visual or auditory  Stages of processing: early (encoding/central processing) or late (responding) The more resources are shared, the more tasks will interfere.

14 ISE 412 Multiple-Resource Theory To the extent that tasks demand separate rather than common resources:  Time-sharing will be more efficient  Difficulty insensitivity will be observed  The POC will be more "boxy"

15 ISE 412 Limitation of Multiple Resource Theory The three proposed dimensions (stages, codes, modalities) do not account for all experimental findings. For example:  Tasks with different rhythmic requirements are hard to time-share.  Control dynamics affect the efficiency of time-sharing a manual tracking task with another task.

16 ISE 412 Implications & Design Recommendations Since spatial and verbal codes draw upon separate resources, time-sharing manual and verbal responses is highly efficient (assuming that the manual response is spatial in nature and that the vocal response is verbal). Example: pilots fly the airplane (spatial, manual task) and simultaneously talk to air traffic control (verbal, vocal task). This example also demonstrates different modalities (visual and auditory) which also draw from separate resources; therefore … Design systems to support a mix of manual and vocal responses for time-shared tasks.

17 ISE 412 Multiple Resource Theory The effect of training  Training can make tasks data limited rather than resource limited Data limited tasks can coexist more easily than resource- limited Reasoning behind “part-task training” paradigms  People can also be trained to timeshare tasks more efficiently Rapid switching between tasks True multi-tasking