On Being Human
ITEC 4130Fall 2009
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
Three Views of Humans How to model a human!
Humans are interpreters/predictors- cog. psych. & AI
Humans are sensory processors- sensory psych., EE & CS
systemsHumans are actors in environment
-activity Th., ethnog., ecol. psych.
Humans as I/O machines
Sensesvisionhearingtouchsmell/tasteproprioceptionkinesthesia
VisionTwo stages in vision- physical reception of stimulus- processing and interpretation of stimulus
The physical apparatus: the eye- mechanism for receiving light and transforming it into electrical energy
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)
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
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)
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
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)
Graphical Representation at the
InterfaceGraphical modeling and 3-DGraphical coding
Graphical coding for quantitative data
Color codingColor versus monochrome coding
Icons
Compensation & Illusions
http://blindspottest.comhttp://en.wikipedia.org/wiki/Image:Gradient-optical-illusion.svghttp://en.wikipedia.org/wiki/Same_color_illusionhttp://en.wikipedia.org/wiki/Grid_illusionhttp://en.wikipedia.org/wiki/Ponzo_illusionhttp://en.wikipedia.org/wiki/Image:Revolving_circles.svg
Reading… it’s pretty complicated
“Stage” model of reading(1) visual pattern perceived(2) decoded using internal language representation(3) interpreted using knowledge of syntax, semantics, pragmatics
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!
* Word shape is important to recognition.
Hearing* Provides information about environment:
* Distance* Direction
* People can hear from 20Hz to 15kHz* 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”
Touch
* Receptors in the skin:- thermoreceptors (heat and cold)- nociceptors (pain)- mechanoreceptors (pressure)
* Unevenly distributed across the body* Some areas more sensitive than others
* fingers are more sensitive than your back
6th, 7th and 8th senses
Proprioceptioninternal awareness of your body position
Kinesthesisawareness of body movement
Balance vestibular organ of inner earawareness of body orientation w.r.t. vertical
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: 200msauditory: 150 mspain: 700ms (slow and distance related)
The Box Model of Memory
Sensory memoriesvisiontouch
auditory
Short-term/workingmemory
Long-termMemory
Sensory buffersareconstantlyoverwritten
Driven by attention
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
Declarative memory:semantic + episodic
Semantic: facts, meanings, skills, concepts, understandings…Episodic: events, time, place, emotion…
The Box Model of Memory
Long-termMemory
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…
Attention
FocusedSustainedDividedSelectiveAlternating
Attention
How to focus attention at an interface?Structure the informationOthers…
Consolidation
Moving information from STM to LTM?
Provide:Structure Meaning Become familiar (through rehearsal)
Forgetting
DecayInformation lost gradually but slowly
InterferenceNew information replaces old (retroactive)Old may interfere with new (proactive)
InhibitionYou can ‘choose’ to forgetExample:
Parking your car…You intentionally forget all but the most
recent
Retrieval
Recall* Information reproduced from memory* Can be assisted by cues, (e.g. categories, imagery…)
Recognition* Information gives knowledge that it has been seen before
Knowledge representation
Declarative knowledge = knowing thatSemantic networksFramesScripts
Procedural knowledge = knowing howScriptsProduction rules
Semantic networks
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)
General knowledge as frames
Script-based memoryScripts = using frames for stereotypical processes (e.g. eating in a restaurant)
* used for interpreting situations
* generalize episodic-memory events
Production rules
Representation of procedural knowledge
Condition/action rulesif condition is matched, rule fires
Slips and Mistakes
Slips are errors in execution of correct intention
Capture errorsErrors of attention
Mistakes are errors in selection of goal or method for accomplishing it
Errors of knowledge