Lecture Slides - Lesson 1 Foundations

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Lecture Slides - Lesson 1 Foundations

  1. 1. Psychology 446 Engineering Psychology & Human Performance 1 Week 4-1: Displays, Perceptual & Attentional Constraints
  2. 2. Psyc 446 – Engineering Physiological and Human Performance 2 Week 4 Topics • Lecture 4-1 • Perceptual Filters • Displays and Attention • Visual Search • Lecture 4-2 • Perceptual Organization • Spatial Proximity and pre-attentive processing • Object Displays
  3. 3. Psyc 446 – Engineering Physiological and Human Performance Perceptual Systems • How does energy become a perception? • Perceptual systems act as filters (HT < HS) • Some data filtered due to limitations of perceptual systems, e.g. resolution of fine detail • bottom-up (or passive) filtering • Some data filtered due to current goals: we “choose” to ignore the data and attend something else, e.g., the hardness of the chair you’re sitting on • top-down (or active) filtering with attention 3
  4. 4. Psyc 446 – Engineering Physiological and Human Performance Filters in the Visual System • Visual Field: roughly 150 deg. (varies) • Useful Visual Field • Task dependent • Visual resolution (acuity) is heterogeneous • Fovea • Peripheral Vision • Resolution vs. sensitivity relativevisualacuity Nasal Blindspot Temporal Degrees from the fovea 4
  5. 5. Psyc 446 – Engineering Physiological and Human Performance Filters in the Visual System Visual Field: roughly 150 deg. (varies) Useful Visual Field – Task dependent – Visual resolution (acuity) is heterogeneous Fovea Peripheral Vision Resolution vs. sensitivity 5
  6. 6. Psyc 446 – Engineering Physiological and Human Performance Filters in the Visual System • Top-Down (Goal Driven) or Active Filters • may be applied voluntarily or involuntarily • Types • Movements of the Body • bring objects into field of view (FOV) • very slow (relative to head and eye) • Movements of the Head • bring objects into FOV and orient fovea toward objects of interest • slow relative to eye movements 6
  7. 7. Psyc 446 – Engineering Physiological and Human Performance Filters in the Visual System • Types of Active Filters (cont.) • Movements of the Eye - orient fovea more quickly • Saccades: fast (e.g., 100 deg./s), jerky  2-4 per second, separated by fixations  fixation dwell typically related to stimulus complexity or difficulty of information extraction • Smooth Pursuit: slow (0 -10 deg./s), smooth • Movements of Focal Attention • fastest enhancement of processing • typically lead eye movements 7
  8. 8. Psyc 446 – Engineering Physiological and Human Performance Focal Visual Attention • Function: selects (filters) information for further processing • Thought to provide temporal priority or additional resources for processing particular stimuli • limited capacity -- unattended stimuli are ignored and may not be processed • difficult to divide attention (especially under stress-tunnel vision) 8
  9. 9. Psyc 446 – Engineering Physiological and Human Performance Focal Visual Attention • What is attention? • Literally? ????? (we don’t know yet) • Attention may be the phenomenal experience resulting from synchronization of firing of cell assemblies in different cortical modules, perhaps coordinated by activity in the frontal lobes • Allows dynamic links between processes of perception, action, and working memory • Metaphors for understanding attention • Spotlight -- attention distributed in space • Zoom lense -- processing advantage trades off with spatial extent • Resources 9
  10. 10. Psyc 446 – Engineering Physiological and Human Performance Perceptual and Attentional Limitations 10
  11. 11. Psyc 446 – Engineering Physiological and Human Performance Perceptual Filtering and Supervisory Control • Supervisory Control: any task involving scanning of displays and selection of relevant stimuli • Operator’s display sampling is based on their mental model of event probabilities • High event rate channels sampled more often • Design to minimize scan times and errors • locate high event channels centrally • locate channels with related information (that often require sequential sampling) in close proximity • Probability adjustment not as extreme as needed for optimal performance (similar to sluggish beta) 11
  12. 12. Psyc 446 – Engineering Physiological and Human Performance Perceptual Filtering and Supervisory Control • Sampling behavior reflects imperfections of human memory • may result in forgetting to sample a channel • may sample a channel too often • explains “oversampling” of low event rate channels • having channels which aren’t visible (in the Norman sense) increases the probability that they will be forgotten • can be overcome with “sampling reminders” • Sampling becomes more optimal if preview is available -- helps provide accurate mental model 12
  13. 13. Psyc 446 – Engineering Physiological and Human Performance Visual Search • Examples: industrial inspection, football quarterback, radiologist, air traffic control • Serial vs. Parallel Search • serial search: sequential scanning of stimuli needed to detect target (attentive processes) • search time increases as # of display elements increases (positive time-numerosity slope) • parallel search: target “pops-out” of multi- element display without scanning (pre- attentive processes) • search time is constant as # of display elements increases (zero time-numerosity slope) 13
  14. 14. Psyc 446 – Engineering Physiological and Human Performance Visual Search • Typical Human Performance • Expectancy Effect: search where we expect targets to occur • Abernethy (1988): football quarterbacks • Kundel and La Follette (1972): radiologists • Mourant and Rockwell (1972): drivers • Availability Effect: search where it is easiest and most obvious (can overcome expectancy) • inexperienced drivers may not check mirrors because they are not obvious 14
  15. 15. Psyc 446 – Engineering Physiological and Human Performance Visual Search • Typical Human Performance (cont.) • Saliency: some types of stimuli tend to draw our attention • motion or flickering • bright, colorful (high contrast) •large size (global) • Why? These stimuli are processed preattentively -- they “pop out” of the stimulus 15
  16. 16. Psyc 446 – Engineering Physiological and Human Performance Visual Search and Perceptual Organization • Perceptual systems organize incoming data to more effectively extract meaning • How? • Mental models guide expectations • Expectations guide search strategies • Search strategies actively filter information in a manner consistent with expectations • Information from search is linked to mental model and new expectations are formed (back to top) 16
  17. 17. Psyc 446 – Engineering Physiological and Human Performance Perceptual Organization 17

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