Routines, Cost structure & the Design of environments

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

2. Question How does redesigning an environment shape routines? • Artifacts • Technology • Cue structure • Spatial layout

3. Routine 1 Routine 2 . . Routine n Selective forces Surviving Firms Firms in Competition 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 routines

4. Intuitive answer Design and tech changes the costs and benefits of activity Agents then adapt to new cost benefit gradients evolving near optimal strategies

5. 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 Setting Constant Technology2 Timed lights Best route from A to B Technology1 Independent lights Best route from A to B

6. 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)

7. 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

8. 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

9. task environment is abstraction Activity Space Activity Space Activity Space Activity Space Pure Structure of Task Activity Space

10. Task environment assumptions Environment is abstraction • System of sparsely distributed choice points – intersections, nodes • Small option or feasibility set at each choice point • Peg(1, 2), Peg(2, 1), Peg(1, 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 • Expected distance is modeled using environment internal factors like distance, speed limit, location of lights, speed of agent • Exogenous factors are excluded • Weather, accidents

11. Additional Important Assumptions • 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 • Linearity • Small change in Tech  small change in routines • Small change in Routines  small change in performance • Superposable • For multiple tasks to be in same physical space just superpose on task environment on top of another • Codifiable

12. Real Question Is this a realistic way to think about design?

13. 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

14. Watching TV

15. Cost to Change Channels get up cover distance to TV obstruct others view find channel incrementally the old days – no remote Cost to Change Volume Cost to turn on/off Bothersome to change things

16. Remote • Portable – distance doesn’t matter • Random Access • Easy to change channels, volume, turn off

17. Remote lowers cost

18. 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

19. Moral Design Cycle • 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 Features Goals Goals Goals Features

20. Upshot • Cost function needs to be revised after each design iteration because users want to do new things and these become the driving forces • Assumption 5 about task environments is false: • “Environment is independent of routines” • Task structure is independent of routines • Evidently routines can change the environment

21. Starbucks Many costs for design to minimize

22. prepare the order • interact with client to specify order • communicate order • take cashmake change offer receipt • announce completion of orderqueue for client to collect Five major Steps in espresso cafés

23. 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°

26. 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 Design Challenge Costs to Minimize Problem Areas

27. Starbucks Revolutionary Technology • Changes cognitive efficiency of whole system • Minimizes costs in most areas Form on cup Technology of coordination

29. 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 Why is it so remarkable?

30. Recovery of Routines • Design Goals: • redesign the environment to lower recovery time • redesign to facilitate vigilance and error detection

31. Variance of Routines • 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

32. 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

33. Learnability Starbucks has a lot of turnover

34. Summary • To save cost function approach to environment design necessary to find the right parameters to assign cost to • Upshot: Cost structure has many dimensions • E1 is better than E2 along some but worse along others

35. Microwaves Changes to microwave design are driven by the ecology of other cooking devices

36. Stove Blends Oven Blends Microwave Blends Ecology of Cooking Devices

37. Lessons • 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 • Relevant context of use is larger than the task environment of microwaves in isolation • Niches interact

38. 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 functionality different Interface

39. 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

40. 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

41. Conclusions

42. 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)

43. Problems with cost functions • Visual design affects performance by reducing cognitive costs • 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

44. Problems with cost functions • Niches or task environments interact with each other when the same users inhabit them all and work in them at the same time • 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)

45. Problems with cost functions • 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

46. End