Designing for human cognitive capabilities. Memory ...cs349/s16/... · Cognitive conscious: processes focused on the relatively few things that you are aware of at the time they occur

CognitionDesigning for human cognitive capabilities.Memory, perception and cognition.

CS349 -- Memory, Perception & Cognition1

Sour

ces


Jef Raskin, The Humane Interface (2000).

Jeff Johnson, Designing with the Mind in Mind (2010)

Ergo

nom

ics

and

Hum

an F

acto

rs • Designing devices that fit human abilities: physical and cognitive.


Cog

nitiv

e En

gine

erin

g, “

Cog

netic

s” • The study of how people mentally work– vs. dominant branch of ergonomics which

studies how people physically work

• “We must master an ergonomics of the mind if we want to design interfaces that are likely to work well.” (Raskin, p. 10)

• “…well-known computer interfaces … are designed as though their designers expect us to have cognitive abilities that experiment shows we do not possess.” (Raskin, p. 10)


Cogn

ition • Faculty for processing

information and applying prior knowledge using mental processes like:– attention– memory– learning– reasoning


Card, Moran, and Newell’s Model Human Processor

Memory

PerceptualProcessor

CognitiveProcessor

MotorProcessor

HCI G

uide

lines • The study of “cognetics” has resulted in many sets of HCI

guidelines.• They are all substantially the same• Why?

– Unlike fashion design, they are not based on the designer’s tastes and whims. They are all based on human psychology: how people perceive, learn, reason, remember, and convert intentions into action.


Memory


Shor

t vs.

Lon

g-Te

rm M

emor

y • Short-term Memory: situations in which information is retained for very short intervals (ε – several seconds)

• Long-term Memory: information is retained over longer periods (minutes, hours, days, years, a lifetime)

• A tempting view:


Perceptions Short-Term Memory

Long-Term Memory

Input RAM Disk

Long

-Ter

m M

emor

y =

Act

ivat

ed N

euro

ns • Perceptions enter via visual, auditory, olfactory, gustatory, or tactile sensory systems– Activate neurons in areas of the brain are dedicated to each sense– Detect low-level features: dark-light edge, diagonal line, high-

pitched tone, sour taste, red colour, etc.• Triggers activation of neurons in other areas of the brain that are not

specific to the sensory system. – Combine lower-level features into higher-level features: animal,

Uncle Kevin, minor key, threat, etc.– The set of triggered neurons depends on the features of the input

and the context.– The more similar two perceptual stimuli are (features and context),

the more overlap there is in the sets of neurons that fire


Long

-Ter

m M

emor

y =

Act

ivat

ed N

euro

ns • Memory formation: long-lasting and perhaps permanent changes to the neurons involved in a neural activity pattern which make it easier to reactivate in the future.

• Remembering: reactivating the same pattern of neural activity that occurred when the memory was formed.– Somehow the brain distinguishes new activations from

reactivations.– Recognition: New perceptions that trigger an existing pattern.– Recall: Triggering an existing pattern without the perception.

• Strength of a memory depends on– How often it’s reactivated– Strength of the original perceptions– Sleep


Shor

t-Ter

m M

emor

y • Not simply neural activations that don’t last long.• Short-term memory is a combination of perception and

attention.– Perceptions make available a collection of neural activations– Attention selects just several of the many activations that

are currently available.– Short-term memory is the currently activated neural patterns

of which we are aware.


Cha

ract

eris

tics

of S

hort

-Ter

m M

emor

y • Low capacity– Used to say “7 items plus or minus 2” (George Miller, 1956)– Most current researchers say this is too high– Depends on similarity of items, ability to “cluster” items

• e.g. phone number as 3 sets of digits (vs. 10 digits) – Capacity perhaps best measured in “item-features” rather

than items• Volatility

– Turning attention to a different neural pattern turns it away from some of what it had been focusing on

– Information can be easily lost from short-term memory if not rehearsed to constantly bring it back into attention


Impl

icat

ions

for U

ser I

nter

face

s User interfaces should help people remember information from one moment to the next.Examples:• Modes:

– Allows UIs to have more functions than controls– But… people make “mode errors” – do the wrong thing

because they forget which mode they’re in.– Avoid modes or make it obvious which mode is engaged

• Search results: keep the search terms on screen to help evaluate search results

• Instructions: keep a sequence of instructions visible while being followed


Cha

ract

eris

tics

of L

ong-

Term

Mem

ory • Error-prone:

– Think of it as heavily compressed information– Some features not recorded

• Weighted by emotions• Retroactively alterable


Impl

icat

ions

for U

ser I

nter

face

s • Don’t burden long-term memory more than you have to.• Example:


PerceptionHow we take in information


Perc

eptio

n • Our perception of the world is not a true depiction of “reality”.• To a large extent, we perceive what we expect to perceive.• Our expectations – and therefore our perceptions – are biased

by:– the past: our experience– the present: the current context– the future: our goals


Perc

eptio

n B

iase

d by

Exp

erie

nce Imagine you own a large insurance company. You are meeting

with a real estate developer to discuss plans for a new campus of company buildings. The campus consists of a row of five buildings, some of which include courtyards providing light for the cafeteria and fitness centre. The developer shows you an initial plan:


Perc

eptio

n B

iase

d by

Exp

erie

nce Now imagine that instead of a real estate manager you’re

meeting with the marketing manager about a billboard ad. The advertising manager shows you a suggestion that shows a single, value-laden word to be placed on the billboards:


Perc

eptio

n B

iase

d by

Exp

erie

nce


Perc

eptio

n B

iase

d by

Cur

rent

Con

text • The same phrase is perceived differently depending on the list

in which it appears:

• “The pattern of neural activity that corresponds to recognizing a letter, a word, a face, or any object includes input from neural activity stimulated by the context. This context includes other nearby perceived objects and events, and even reactivated memories of previously perceived objects and events.”

-- Designing with the Mind in Mind, p. 5


Fold napkins. Polish silverware. Wash dishes.French napkins. Polish silverware. German dishes.

Perc

eptio

n Bi

ased

by

Goa

ls • In the following “toolbox”, is there a pair of scissors?

• Was there a wrench?


Perc

eptio

n Bi

ased

by

Goa

ls • This is a fairly famous video. If you’ve already seen it, please don’t blow it for those who haven’t.

• https://www.youtube.com/watch?v=vJG698U2Mvo


Perc

eptio

n Bi

ased

by

Goa

ls There are two ways in which our current goals bias our perception:

1. Influencing where we look– We focus on our goal, ignoring things that are unrelated.

2. Sensitizing our perceptual system to certain features– Our brain will focus on particular features that meet out goal

(e.g. if we’re looking for a “red car”, we’ll scan for red).


CognitionHow we process information


Two

Stat

es o

f Cog

nitiv

e Pr

oces

ses Cognitive unconscious: processes of which you are not

aware at the time they occur. The resources they make available to us are HUGE.Cognitive conscious: processes focused on the relatively few things that you are aware of at the time they occur. The resources they make available to us are tiny (but powerful).


Memory

PerceptualProcessor

CognitiveProcessor

MotorProcessor

cognitiveconscious

cognitiveunconscious

(examples)

movement from unconscious to conscious …

from conscious to unconscious …

Cogn

etic

s “Understanding that we possess these two distinct sets of limited mental abilities and understanding how they work in relationship to human-machine interfaces is as essential to designing interfaces as is knowing the size and the strength of the human hand when we are designing a keyboard.”


-- Jef Raskin, The Humane Interface, p. 11

Com

parin

g Co

gniti

ve S

tate

s


Property Conscious Unconscious

Engaged by Novelty, emergencies, danger Repetition, expected events, safety

Used in New circumstances Routine situations

Can handle Decisions Non-branching tasks

Accepts Logical propositions Logic or inconsistencies

Operates Sequentially Simultaneously

Controls Volition (your “will”) Habits

Capacity Tiny Huge

Persists for Tenths of seconds Decades

Locu

s of

Atte

ntio

n • Locus: The feature, object, or idea about which you are intently and actively thinking (in cognitive conscious).– Related to “focus” but...

• Cannot completely control where our locus will be• We can have at most one locus of attention

– Maybe none– More than one locus is actually multi-tasking, not multi-

processing• Why is this not optimal?

– Multi-processing can be achieved by combining one locus and one or more automatic activities...• Driving and talking, …CS349 -- Memory, Perception & Cognition29

Seei

ng D

oesn

’t M

ean

We

See • A single locus of attention filters out many perceptions

– Tuning out sounds and smells...– Implications: some aspects of a UI may be tuned out as

well

• Perceptions persist briefly and then decay quickly– Many perceptions do not automatically become memories– Implications:


Seei

ng D

oesn

’t M

ean

We

See:

C

hang

e B

lindn

ess • Change Blindness: a change in a visual stimulus is

unnoticed by observer– http://www2.psych.ubc.ca/~rensink/flicker/download/


Cont

ext S

witc

hes • There is a significant cost to switching from one locus of

attention to another– Context switch: about 10 seconds

• More for intense tasks, less for lightweight tasks• If the same context switch is performed repeatedly...

• Implications: – Protect users (yourself!) from context switches– Research in interruptability– Exploit single locus/context switches

• Magician• Canon Cat/Some Apps (next slide)


New message from Feridun …

Cano

n Ca

t


Abso

rptio

n • You can be more or less absorbed in your locus of attention– More absorbed:

• More difficult to transition to another locus• Requires greater stimulus to effect such a change• Examples: reading a book, playing a game

• Absorption is essential to productivity– Implications for UI: don’t interrupt this state!– Encourage flow (being “in the zone”)


Abs

orpt

ion’

s N

egat

ive

Con

sequ

ence

s • Eastern Airlines Flight 401 story• Proportional to stress: “As stress increases, people

concentrate more and more on but a few features of their environment, paying less and less attention to others... You become less likely to see hints, help messages, or other user aids as you become increasingly agitated about the problem.”

-- Raskin, p. 27

• Implications for UI: prevent errors, easy-undo


Auto

mat

ic A

ctio

ns • Automatic Action: any activity done without conscious thought (routines, habits, skills) … in cognitive unconscious

• Performing a task repeatedly makes it easier– Eventually, don’t need to give it conscious thought– Conscious thought may impede the action

• Automatic tasks enable simultaneous actions– If we are doing more than one activity at a time, all but at

most one of them are automatic• Automatic actions are essential to higher life forms


Lear

ning

and

Con

trol

ling

Aut

omat

ic A

ctio

ns • Humans cannot avoid developing automatic responses– “Practice makes perfect” vs. “Practice makes permanent”

• Sequences of actions become clumped into a single action– Cannot interrupt a sequence of less than 1-2 sec.– Long sequences can only be interrupted with conscious

thought• Unlearning automatic

actions


Goo

d A

utom

atic

Act

ion

Impl

icat

ions • Persistent use of any interface will develop automatic actions

that are difficult to unlearn– Can be good (e.g. consistency and similarity leads to quick

interaction)


Bad

Aut

omat

ic A

ctio

n Im

plic

atio

ns • Can be bad (e.g. dangerous automatic actions)– Example: File deletion confirmations– Any confirmation step that elicits a fixed response soon

becomes useless– Alternatives?


The action you have requested cannot be undone. It will cause permanent loss of the file. If you are sure you wish to delete the file forever, type backward the tenth word in this box.

Sum

mar

y • Introduction to perception and how it is biased• Introduction to human cognition capabilities

– cognetics – cognitive conscious vs. cognitive unconscious– locus of attention– automatic actions

• Implication of cognition for design


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Designing for human cognitive capabilities. Memory ...cs349/s16/... · Cognitive conscious: processes focused on the relatively few things that you are aware of at the time they occur