On Being Human

1. On Being Human ITEC 4130 Fall 2009

2. Understanding humans • Humans evolve much more slowly than technology • There are limits to human capabilities • - knowing what they are helps us understand what is going on

3. Three Views of Humans How to model a human! • Humans are interpreters/predictors • - cog. psych. & AI • Humans are sensory processors • - sensory psych., EE & CS systems • Humans are actors in environment • -activity Th., ethnog., ecol. psych.

4. Humans as I/O machines • Senses • vision • hearing • touch • smell/taste • proprioception (positional feedback) • requires time to propogate back to brain • kinesthesia (muscle memory) • instantaneous • golf swing or catching a ball

5. Vision • Two stages in vision • - physical reception of the stimulus • - processing and interpretation of stimulus • - red arrow green arrow problem • The physical apparatus: the eye • - mechanism for receiving light and transforming it into electrical energy

6. More about the eye • The eye: • - the light it picks up is light that reflects from objects • - images are focused upside-down on retina • - retina contains rods for low light vision and cones for color vision • - ganglia distribution on the retina varies by species (African plains vs tree dwellers)

7. Depth and Size PerceptionIt is a complex suite of clues • visual angle indicates how much of field of view object occupies • Is your visual field circular? • Test this using a marker on the board • visual acuity is ability to perceive fine detail • predatory birds have very high visual acuity • Eagles: 600,000 cones/sq mm • Humans: 150,000 cones/ sq mm

8. Depth and Size PerceptionIt is a complex suite of clues • familiar objects perceived as constant size • law of size constancy • as someone walks toward you you don’t think: Man, that guy is getting taller by the second! • Cues help perception of size and depth • Accommodation (lens stretches) • Occlusion • Motion parallax • Relative size (tied to size constancy) • Aerial perspective (atmospheric)

9. Brightness • Brightness is a subjective reaction to levels of light • Measured by just noticeable difference • Visual acuity increases with luminance • Pinhole camera • Reading is improved in bright light

10. Color Perception • Color made up of hue, intensity, saturation • Cones sensitive to color wavelengths • Blue acuity is lowest • Green acuity is highest • 8% males and 1% females color blind (Red/Green confusion most freq)

11. XXXXXGraphical Representation at the Interface • Graphical modeling and 3-D • Graphical coding • Graphical coding for quantitative data • Color coding • Color versus monochrome coding • Icons

12. Compensation & Illusions http://blindspottest.com http://en.wikipedia.org/wiki/Image:Gradient-optical-illusion.svg http://en.wikipedia.org/wiki/Same_color_illusion http://en.wikipedia.org/wiki/Grid_illusion http://en.wikipedia.org/wiki/Ponzo_illusion http://en.wikipedia.org/wiki/Image:Revolving_circles.svg

13. Reading… it’s pretty complicated • “Stage” model of reading • (1) visual pattern perceived • (2) decoded using internal language representation (pick out the words) • (3) interpreted using knowledge of syntax, semantics, pragmatics • (what do these words mean?)

14. Perception in reading • Reading involves saccades and fixations • Saccades are rapid movements of the eye • Without them, the retina would “saturate” and you wouldn’t see anything • Fixations are the stops in that movement • Perception occurs only during fixations • Otherwise the world would be blurred! • AKA: saccade masking • Word shape is important to recognition.

15. Hearing • Two stages in hearing • - physical reception of the stimulus • - processing and interpretation of stimulus • -someone speaks to you • -you say “what?” • -but you figure out what they said before they can answer

16. Hearing • Provides information about environment: • Distance • Direction (but you can’t distinguish between directly in front and directly behind you!) • People can hear from 20Hz to 15kHz(I wish!) • less accurate distinguishing between high frequencies • Auditory system filters sounds • We can attend to sounds even in the presence of background noise • “cocktail party phenomenon”

17. Touch • Receptors in the skin: • - thermoreceptors (heat and cold) • but you can’t distinguish which! • - nociceptors (pain) • - mechanoreceptors (pressure) • Unevenly distributed across the body • Some areas more sensitive than others • fingers are more sensitive than your back

18. 6th, 7th and 8th senses • Proprioception • internal awareness of your body position • (Through feedback) • Kinesthesis • awareness of body movement • (Through muscle memory) • Balance • vestibular organ of inner ear • visual cues as to orientation • awareness of body orientation • through proprioception

19. Movement & perception • Tight integration of • -perception & motor planning, • -movement execution • -feedback • proprioceptive, kinesthetic, vestibular and visual • Response time = reaction time + movement time • -Movement time depends on age, fitness … • -Reaction time depends on modality • visual: 200ms • auditory: 150 ms • pain: 700ms (slow and distance related)

20. The Box Model of Memory Sensory memories vision touch auditory Short-term/ working memory Long-term Memory Episodic Semantic Sensory buffers are constantlyoverwritten Driven by attention Semantic: facts, meanings, skills, concepts, understandings… Episodic: events, time, place, emotion… Scratch-pad for temporary recall * rapid access (70ms) * rapid decay (200ms) * limited capacity (7 ± 2) Recency effect: recall of recent items best Evidence for several working memories

21. The Box Model of Memory Long-term Memory Episodic Semantic Semantic memory structure -provides access to information -represents relationships between information -supports inference -associative: -recall based on meaning -gives rise to meaning-related confusions -eye witness testimony…

22. Attention • Focused • Sustained • Divided • Selective • Alternating

23. Attention • How to focus attention at an interface? • Structure the information • Others…

24. Consolidation • Moving information from STM to LTM? • Need to provide: • Structure • Meaning • Become familiar (through rehearsal)

25. Forgetting • Decay • Information lost gradually but slowly • Interference • New information replaces old (retroactive) • Old may interfere with new (proactive) • Inhibition • You can ‘choose’ to forget • Example: • Parking your car… • You intentionally forget all but the most recent episode

26. Retrieval • Recall • * Information reproduced from memory • * Can be assisted by cues, (e.g. categories, imagery, auditory input…) • Recognition • * Information gives knowledge that it has been seen before

27. Knowledge representation • Declarative knowledge = knowing that • Semantic networks • Frames • Scripts • Procedural knowledge = knowing how • Scripts • Production rules

28. Semantic networks

29. Frame-based model of semantic memory • Knowledge is organized in data structure • Slots in structure are instantiated with particular values for a given instance of data • ...translation for CS people: • frames classes in the head; • slots  variables/methods in the head)

30. General knowledge as frames

31. Script-based memory • Scripts = using frames for stereotypical processes (e.g. eating in a restaurant) • * used for interpreting situations • * generalize episodic-memory events

32. Production rules • Representation of procedural knowledge • Condition/action rules • if condition is matched, rule fires

33. Slips and Mistakes • Slips are errors in execution of correct intention • Capture errors • Errors of attention • Mistakes are errors in selection of goal or method for accomplishing it • Errors of knowledge