To add: non-tech error stuff
Attention blindness demos Speech errors and disfluency Emotion and design (3 teapots) Just noticeable differences (JNDs) Add Strayer cell phone study
Relevant topics
Perception Motor abilities Attention Reading Sensory memory Working memory
Long-term memory Reasoning Decision-making Speech perception
and production Discourse
Perception
Vision Rods and cones Visual acuity Color: hue, intensity, saturation Distance estimated by size (+intensity) Gestalt principles
Gestalt theory says perception is:
Emergent Constructive Multistable Invariant
Subjective contour
can “create" a figure.
Figure-ground segregation (stable)
Figure more thing-like, more memorable, smaller seen as being in front of the ground
Ground seen as unformed material extends behind the figure
Perception
Vision
Hearing Pitch, loudness, and timbre Pitch range: 20 Hertz - 15,000 Hertz Resolution Speech vs. other sounds
Perception
Vision
Hearing
Touch Mechanoreceptors, thermoreceptors,
nociceptors (pain) Different resolution at different points Feedback is important
Modalities; speed/accuracy; practice effects
Reaction times differ by modality Integrating 2 modalities into 1 percept Speed trades off with accuracy Skill increases with practice
(Power Law of Practice)
Attention
Pop-out and serial vs. parallel search
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 V 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
Attention
Pop-out and serial vs. parallel search
0 0 0 0 0 0 0 0 0 0 | | | | | | | | | |
0 0 0 0 0 0 0 0 0 0 | | | | | | | | | |
0 0 0 0 0 0 V 0 0 0 | | | | | | | | | |
0 0 0 0 0 0 0 0 0 0 | | / | | | | | | |
0 0 0 0 0 0 0 0 0 0 | | | | | | | | | |
Attention
Pop-out and serial vs. parallel search
O N N N O O O N N O N O
O O O N O O O N N O N N
N O O N O O N O O N N O
O N O N O N O O O N O N
N O O N O O O N N O O N
Change blindness
Inability to detect what should be obvious changes in a scene
| 400 ms | 40-80 ms | 400 ms |
Original Image Blank Modified Image
Change blindness
Inability to detect what should be obvious changes in a scene. This is affected by Interrupting with a blank screen Distraction such as the “mud” (captures attention)
| 400 ms | 40-80 ms | 400 ms |
Original Image Blank/Mud Modified Image
Conversations and cell phones
Auto accidents increase during cell phone use
Yet people safely talk to their passengers all the time
So it follows that the problem must be due to dialing, handling the phone, etc.
Or does it?
Strayer & Johnston’s expts (in press)
Visual tracking task with joystick Conditions: hands free or handheld
Converse with someone in another room Listen to the radio or books on tapeShadowingPrompted word generation task
Results:
Performance was worse for subjects on cell phones than for subjects listening to radio, books on tape, or shadowing. Twice as many red lights were missed, and RTs increased!!
Whether the phone was hand-held didn’t matter at all!
What do you think causes the poor performance of people on cell phones?
Inattention Blindness (IB)
When observers fail to notice an unexpected object or event
Occurs when attentional resources are directed toward another task
Attention Influences Perception
Inattentional Blindness: involves missing a (remarkable!) change because you’re not expecting it and not attending to it.
Example: Man/office/phone moviehttp://viscog.beckman.uiuc.edu/grafs/demos/23.html
Notice anything strange?
Simons & Chabris (1999)
Attention Influences Perception
Inattentional Blindness: involves missing a (remarkable!) change because you’re not expecting it and not attending to it.
Example: http://viscog.beckman.uiuc.edu/grafs/demos/15.html
Count passes made by the white team or the black team (easy task)
Count bounce passes and also count aerial passes (hard task)
Simons & Chabris (1999)
Attention Influences Perception Inattentional Blindness: involves missing a
(remarkable!) change because you’re not expecting it and not attending to it.
Example: More people see gorilla
with easy task More people see gorilla
when attending to black team (83%) than white team (42%)
Similarity matters!
Simons & Chabris (1999)
Inattentional Blindness - another ex.
Pilots landing an aircraft simulator Experimenters were interested in a new
heads-up display Pilots didn’t notice a large plane placed
on the runway at the last minute
Haines (1991)
Sensory memory
Iconic memory - fleeting, hi-res buffer
Must be attended to to be remembered Echoic memory Haptic memory
(Characteristics vary with context)
Working memory
Rapidly accessed, rapidly decays Capacity limitation: “7±2” (Miller) Baddeley’s 3 part model
Visuospatial sketchpadPhonological loopCentral executive
Interference
Long Term Memory
Unlimited capacity, slower to access Interference and forgetting Encoding specificity,
transfer-appropriate processing Levels of processing theory
retrieval depends on encoding!
graph. < rhyme < semantic < personal
Visual imagery, dual coding theory
Long Term Memory (cont.)
Semantic organization Tip-of-the-tongue effect (interference) Schemas Distortions in memory
Decision making
Framing effects
Program A: save 200 peopleProgram B: 1/3 probability of saving all 600
2/3 probability of saving no one
Decision making
Framing effects
Program A: save 200 peopleProgram B: 1/3 probability of saving all 600
2/3 probability of saving no one
72% choose A; 28% choose B!!
Decision making
Framing effects
Lose a $50 ticket 46% YES, 54% NO Lose a $50 bill 88% YES, 12% NO
Would you buy another ticket?
Decision making
Framing effects Anchoring effects
Do you think Dr. Brennan is older or younger than 20/60?
Please give your best estimate of her age.
Decision making
Framing effects Anchoring effects
Do you think Dr. Brennan is older or younger than 20/60?
Please give your best estimate of her age.
Anchored at 20: 37.7 years old
Anchored at 60: 39.3 years old (p < .05)
Conclusion:
Review your knowledge of cognitive and perceptual psychology!
You can distill principles of human-computer interaction and explain people’s performance and errors from what you know about human cognition and perception!