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 systems

Humans are actors in environment-activity Th., ethnog., ecol. psych.

Humans as I/O machinesSenses

visionhearingtouchsmell/tasteproprioception (positional feedback)requires time to propogate back to brainkinesthesia (muscle memory)instantaneousgolf swing or catching a ball

VisionTwo 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

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

* Eagles: 600,000 cones/sq mm* Humans: 150,000 cones/ sq mm

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)

XXXXXGraphical Representation

at the InterfaceGraphical modeling and 3-DGraphical coding

Graphical coding for quantitative dataColor 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 (pick out the words)(3) interpreted using knowledge of syntax, semantics, pragmatics

(what do these words mean?)

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.

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

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”

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

6th, 7th and 8th sensesProprioception

internal awareness of your body position(Through feedback)

Kinesthesisawareness of body movement(Through muscle memory)

Balance vestibular organ of inner earvisual cues as to orientationawareness of body orientation

through proprioception

Movement & perception

Tight integration of -perception & motor planning, -movement execution-feedback

proprioceptive, kinesthetic, vestibular and visualResponse 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 MemorySensory memories

visiontouch

auditory

Short-term/workingmemory

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 bestEvidence for several working memories

Semantic: facts, meanings, skills, concepts, understandings…Episodic: events, time, place, emotion…

Long-termMemory

Episodic

Semantic

The Box Model of MemoryLong-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?

Need to 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

episode

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

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