David Kirsh UCSD Routines, Cost structure & the Design of environments.

David KirshUCSD

Routines, Cost structure & the

Design of environments

TV Starbucks Microwaves ConclusionsIntroduction

Question

How does redesigning an environment shape routines?

•Artifacts•Technology

•Cue structure •Spatial layout


Relevance

• Cognitive economics– Micro theory of the firm

• Assumption: Well adapted firms have evolved near optimal routines

– Economics needs: • Adequate account of what a routine is (recast in situated/d-cog form)• How routines evolve and how tech or design shapes routinesHow routines evolve and how tech or design shapes routines

Selective forces

Firms in Competition

Surviving Firms

Routine 1Routine 2 . .Routine n


Intuitive answer

Design and tech changes the costs and benefits of activity

Agents then adapt to new cost benefit gradients evolving near optimal strategies


A

B

Technology and routines, Economics and Cognitive Science

• Technology and setting determine a cost function for activity (relative to ideal agent)

• Routines evolve until nearly optimal for a task

• change technology change cost function change best methods for task routines adapt to new cost landscape

Technology1

Independent lights

Best route from A to B

Technology2

Timed lights

Best route from A to B

Setting Constant


Why think this way for design?

• Adapting to cost structure is paradigm in economics, operations research – Hill climbing, or

optimizing or satisficing

• Single routines should be near optimal

• For sets of routines it is the set that is maximized– Weighted average return

(benefit-cost)

n

i

ii

n

)routinereturnavweight

1

(

Frequency of Tasks in Environment

Task 135%

Task 215%

Task 310%

Task 425%

Task 58%

Task 67%


Design evolution is like natural evolution

• Similar cost benefit thinking in evolutionary theory– Adaptation to niche – local maximizing of cost-benefit

functions– E.g. Optimum behavior: 45% foraging 25% exploration, 30%

sleeping– Economic models of animal and human behavior

• Problem is to describe the relevant properties of the niche

– Location and quantity of food– Behavior of predators– Climate, terrain, competitors for food …

• Widespread belief that design evolution and natural evolution have similar explanations


In cognitive science

• Humans adapt to structured environments – Develop efficient routines

• Problem is to describe the environment of activity

– Classical approach environment is collection of task environments

– Formally each task environment is a connected graph of choice points

A single task environment


Activity Space

Activity Space

Activity Space

Activity Space

Activity SpacePure Structure of Task

task environment is abstraction


Task environment assumptions

Environment is abstraction1. System of sparsely distributed choice points –

intersections, nodes

2. Small option or feasibility set at each choice point

• Peg(1, 2), Peg(2, 1), Peg(1, 3) …

3. Consequence function is complete but effortful to compute

• Computing expected time from A to B requires checking all routes from A to B

• Else, use a heuristic estimate of best time

4. Expected distance is modeled using environment internal factors like distance, speed limit, location of lights, speed of agent

• Exogenous factors are excluded– Weather, accidents

A

B


Additional Important Assumptions

5. Independence of E and Ri

– No path through E changes structure of E – connectivity & action repertoire fixed• Task structure is constant

– Routines do not change the cost function• Routines adapt to E• E does not adapt to Routines• E only adapts to agent through tech change

6. Linearity – Small change in Tech small change in routines– Small change in Routines small change in performance

7. Superposable

– For multiple tasks to be in same physical space just superpose on task environment on top of another

8. Codifiable

Real Question

Is this a realistic way to think about design?


Topics

• Example that supports cost structure approach– Watching TV

• Example that shows there are many cost functions to consider– Starbucks

• Problems with entire task environment framework presupposed by cost functions– How good an abstraction?

• Microwaves, GUI design

• Niche interaction

• Multi-tasking

Watching TV


the old days – no remote

Cost to Change Channels

– get up– cover distance to TV– obstruct others view– find channel incrementally

Bothersome to change things

Cost to Change Volume

Cost to turn on/off


Remote

•Portable – distance doesn’t matter

•Random Access

• Easy to change channels, volume, turn off


Remote lowers cost

ProbabilityofError

Time

1

0

Better

Speed Accuracy of Routine

No RemoteRemoteRoutine No Remote Remote

Turn on/off 1. get up2. cover distance to TV3. obstruct others view4. turn on/off button

1. on/off button while seated

Change Volume 1. get up2. cover distance to TV3. obstruct others view4. turn volume knob

1. volume control while seated

Change Channel similar similar

Mute similar similar


So Does cost function work?

• BUT: unanticipated consequences of remote

• Emergent behavior: Low cost channel changing created surfing – new type of routine

• Surfing drives search for new designs to lower surfing costs

– better with back button or favorites/memory

• Better still with PIP

– Watch 2 channels

• Mute now usable

– supports conversation during commercials


Moral

• Technology also reshapes conception of goals of what you can do, hope to do

• Changes in cost changes activities and task

• May also reshape how core activity fits in with traditional workflow

– Remotes liberate location of TV

– In kitchens, bars, dining rooms

– Walls, ceiling

• Niche changes, and changes ecology of tasks

– When, where, how watch, doing what else

Goals

Features

Features

Goals Goals

Design Cycle


Upshot

1. Cost function needs to be revised after each design iteration because users want to do new things and these become the driving forces

2. Assumption 5 about task environments is false: • “Environment is independent of routines”

Task structure is independent of routines

• Evidently routines can change the environment

Starbucks

Many costs for design to minimize


Five major Steps in espresso cafés

1. interact with client to specify order

3. take cashmake change offer receipt

2. communicate order

4. prepare the order

5. announce completion of orderqueue for client to collect


Espresso facts

• Called espresso because made for a specific customer and served immediately.

• A double espresso is – 1.5 - 2 ounce liquid extract – prepared from 14-17 grams of (medium) ground coffee – purified water of 88-95°C has been forced through– at 9-10 atmospheres of pressure – for a brew time of 22-28 seconds. – Crema should make up 10-30% of the beverage

• Cappuccino – A shot of espresso topped with equal parts of steamed and

foamed milk (wet cappuccino) – a shot of espresso topped with all foamed milk (dry

cappuccino).• Frothed milk should be 150°• Steamed milk should be 150° to 170°


Design Challenge

• Increase robustness of process– Reduce error– Reduce variance of error– Eliminate disastrous errors

• Process more drinks per hour – Routines and tech support

higher throughput

• Increase quality of service– Better interaction with

customer

• Increase drink complexity• Routines are easier to master

• Error is always lurking– Noisy– Distractions– Surprises

• Interruptions, intrusions

• Multi-tasking, Task

Switching

• Multiple tasks in same

physical space

• High staff turnover

Costs to Minimize Problem Areas


Starbucks Revolutionary Technology

• Changes cognitive efficiency of whole system

• Minimizes costs in most areas

Technology of coordination

Form on cup


Why is it so remarkable?

• Reduces errors

– Losing the order – Confusing one order with another

• Robust to interruption

– If barista forgets order just look it up

– Supports recoverability – increase state

• Tolerates breakdown

– If barista burned another picks it up off the floor

• Supports multi-tasking

– Locks info to object so more modular– Move along as in production like process

• Order complexity can go up

– Cup allows linear process

• Read, execute, read execute …

• Lowers cognitive demands


Recovery of Routines

Design Goals:

redesign the environment to lower recovery time

redesign to facilitate vigilance and error detection


Variance of Routines

Variance

Time

1

0


AcceptableVariance

AcceptableTime

Acceptable

V2V1 V3 V4

• Reduce the variance in output

•For each error rate in the speed accuracy curve the output will be more standardized

•Narrowing the distribution of error size not the number of errors

S e rio u sn e s s o f e r ro r

D is trib u tio n o f E rro rs

0


Complexity

• Allow user to handle more complex drinks– Lowers cognitive costs (memory, computation,

attention)

Wet grande cappuccino• extra shot of ½ decaf• fat free milk • sugar free hazelnut syrup

• drop of vanilla• extra froth• lower temp


Learnability

Expertise

Time to learn

Great design

Good design

Average design

Starbucks has a lot of turnover


Variance

Time

1

0


AcceptableVariance

AcceptableTime

Acceptable

V2V1 V3 V4

ProbabilityofError

Time

1

0

Better

Speed Accuracy of Routine

No RemoteRemote

Expertise

Time to learn

Great design

Good design

Average design

• To save cost function approach to environment design necessary to find the right parameters to assign cost to

Summary

• Upshot: Cost structure has many dimensions– E1 is better than E2 along some but worse along others

Microwaves

Changes to microwave design are driven by the ecology of other

cooking devices

Microwave with Toaster

Convection Microwave

(Microwave, Toaster Oven & Fan)

Microwave with Coffee Maker

Microwave

Toaster

Convection Toaster Oven

Gas StoveElectric Stove Induction Stove

Electric Skillet George Foreman

Grill

Crock Pot

s

Electric OvenGas Oven

Toaster

Rotisserie

(Toaster Oven & Rotator)

Light Microwave

Gas StoveElectric Stove Induction Stove

Electric Skillet/Grill

George Foreman Grill

Crock Pot

Rice Cooker

Coffee Pot Electric Water Kettle

Heat Lamp

Microwave with Toaster

Rotisserie(Toaster Oven &

Rotator)

Microwave

Convection Microwave

(Microwave, Toaster Oven & Fan)

Light Microwave(Microwave, Toaster Oven,

Fan, & Halogen Lamp)

Gas OvenElectric Oven

CombinationOven & Stove

Toaster Oven[small]

Convection Oven

Electric Oven & Fan

Convection Toaster Oven

[small] & fan

Toaster Oven

Microwave with Coffee Pot

Microwave Toaster

(Microwave & Toaster Oven)

Microwave Toaster Oven

(Microwave & Toaster Oven)

Toaster

Oven BlendsStove Blends

Microwave Blends

Ecology of CookingDevices


Lessons

1. Microwaves have a context of use. In kitchen the cost structure of the microwave is not independent of the other devices because– Substitutability

• Cook in microwave or oven or toaster or crock pot?

– Motivation to learn• Even if harder to do in oven users know how so won’t

incur the startup cost to learn– Design forces often involve hybridization or changing

the cost function for multiple devices

2. Relevant context of use is larger than the task environment of microwaves in isolation– Niches interact

Same functionality different Interface

If functionally equivalent interfaces make a difference then a relevant part of the activity space of users is not reducible to task environment - bad abstraction


Same state space different cognitive efficiency

• Different cognitive costs

• Structures interaction by visual cue– Planning: What do I have to do? Where am I, what’s left?

• Facilitates review, verification, error discovery


Properties of Real environments

• Cue structure• Affordances• Constraints• Annotations

Design Challenge

Discover principles that lower cognitive costs of:

• Recognizing what can be done – live options• Recognizing where we are in a task • Recognizing consequences of actions in advance of

doing them• Recognizing what ought to be done

Conclusions


Problems with cost functions

• Cost functions are at best instantaneous and may have to be changed with every design change in the environment– Task environments are not independent of routines and design

changes (lesson from TV)

• There are many cost functions available and not clear that we can reduce them all to a single number

Cost = f (c1, c2, c3, c4, c5, c6 …)

– New designs may reduce some costs while raising others and we may not be able to say which is preferred (lesson from Starbucks)



• Visual design affects performance by reducing cognitive costs

• These are not well representedas costs defined over a task environment

– These costs have a lot to do with interactive cognition and are not mentioned in option set (lesson from Microwaves)

– Agents make many more decisions than enumerated in sparse choice point set



• Niches or task environments interact with each other when the same users inhabit them all and work in them at the same time – not independent– Interactions mean that estimates of cost function for a

given task environment when made in isolation will be incorrect for that environment when embedded with other environments (lesson from microwaves and ovens)



• Multi-tasking in the same space can lead to destructive interference between two tasks that can only be prevented by performing actions that are not in either task

• Adding annotations, reminders, marking by putting cup in certain orientation

• Speaking to partners (‘remember its soy milk’, .. )

• UPSHOT: Understand ecology of activity and how task and artifacts fit together in the larger system of activities

David Kirsh UCSD Routines, Cost structure & the Design of environments.

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Transcript of David Kirsh UCSD Routines, Cost structure & the Design of environments.