Fitts' Law

Fitts Law

It is nice to know that there are actual scientific and quantifiable ways to approach study of interaction. Fitts law shows us that we can actually model people's interaction with systems in a quantifiable way, by relating the number of errors in using an interface element to its proximity and size.

I suspect that microsoft has begun to use Fitts' law in designing some of their newer software, such as the "ribbon" interface of MS Office. I say this because they make use of buttons in the interface whose size is dependent on how important they are. Also the buttons are arranged so that they are closer together, making errors less likely once the system is known.

The Inmates are Running the Asylum

The Inmates are Running the Asylum

Alan Cooper

This book is essentially an argument for the existence of interaction design consultants. It discusses the problems associated with giving the task of interface design to managers, marketers and programmers and argues for the use of interaction designers to completely design the system before any implementation is begun.

I agreed with much of what this book had to say about not only managing projects but also about the design process and attitudes of software engineers. I have seen much of what the author mentions in my own projects, where I get so caught up in what I have to do to program a project that I lose track of how people will ultimately use it. I think in terms of which features I want to have and not necessarily in what is needed to support a specific activity or fulfill a need. When engineering software I feel extremely liberated when I do not have to come up with the interaction design as well and can just focus on getting an already agreed upon design constructed correctly. However I do not feel their should be a complete disconnect between those who implement software and those who design the interactions, and neither does the author. Designers need to understand what is required to implement their designs, and most importantly need to understand what sort of interactions are feasible. That is not to say they should be conservative with their designs just because of their knowledge of the implementation, but they should be able to balance optimal interaction with reasonable implementation.

If and when I go into the software industry, I plan to make sure every software engineer I meet has read this, if only to make sure they acknowledge some of the problems associated with the software engineering mindset.

Providing Dynamically Changeable Physical Buttons on a Visual Display

Providing Dynamically Changeable Physical Buttons on a Visual Display

Chris Harrison Scott E. Hudson

This paper discusses work by the authors to create a simple and versatile system for dynamic buttons on visual displays. Their system involves the use of a malleable latex membrane that can be backlit to act as a screen, a vacuum to distort the latex and a backing that is used to create specific shapes with the distorted latex. The purpose of this interface is to add an element of physical feedback and interaction to touch screens.

While adding their system to generally static touchscreens can be useful in many specific applications (such as car interfaces, ATM pin pads etc.) the lack of dynamism limits its use in my opinion. They make the point that the backing is easy to produce and change, making it simple to create new physical interfaces for systems. However, this is not truly dynamic and almost defeats the purpose of using touch screens for interaction (that interaction can be defined programmatically to support a variety of activities). If you are presented with a "dynamic" pin pad interface, there is only so many different activities you can map onto a pad with 3 rows of 3 buttons, even if those buttons could be enabled or disabled separately.

In spite of these reservations, I feel this could be a significant boon to some of the applications suggested in this paper, specifically car dashboards and control panels. These interfaces do not need to be too dynamic and are significantly easier and safer to use when they can be operated by touch instead of sight. This system combines the advantages of physical interfaces with some of the dynamic ability of touch display systems.

Human Centered Design Considered Harmful

Human Centered Design Considered Harmful

Donald "Don" A. Norman

In this article, Don Norman discusses some of the problems of focusing on the "user" for design. In particular he feels that designing specifically for the user should perhaps be replaced with designing for an activity or task. In designing for the user we often overlook what it is the user is actually trying to achieve and what sort of inherent design issues are present in the activity, and instead focus on trying to make the interface human friendly. As he points out in the article, well used systems such as musical instruments and handwriting are well adapted to their specific activities but are on the whole not very "Human friendly".

I like the points Norman makes in this article. Personally I feel the best interface is the one that supports the quickest and most efficient way to perform an activity or task. Once the interface is constructed with this in mind we can then go back and use Human centered design techniques to refine the interface with human use in mind.

Usability Evaluation Considered Harmful

Usability Evaluation Considered Harmful (Some of the Time)

Saul Greenberg Bill Buxton

In this paper, Greenberg and Buxton discuss some problems that are associated with current methods of user interface evaluation, namely an overuse of quantitative usability studies in cases where other methods of evaluation might be more appropriate.

I find this particularly interesting as it brings up the question (to me) of whether CHI truly is a "hard science" where specific testing methods are generally sufficient and indeed necessary to evaluate a solution. Because of the great variety of goals in systems developed in CHI it is easy to see that one testing methodology is not going to be sufficient to test the usefulness of all systems.

A somewhat disturbing point that the authors bring up to support this claim, is the trend of researchers designing systems with the idea of qualitative evaluation in mind. If you are designing a system so that it specifically does well in the tests you plan to put it through, doesn't that really invalidate the tests you are going to perform? What does that prove about the system, that it performs exactly as hoped in the specific highly controlled environment you put it in. Even then, is it actually a system that should be evaluated in this way?

I agree with the authors that testing should be more flexible and actually fit the problem that is being addressed, and thus not necessarily quantifiable. Perhaps a new testing system should be created for each new system instead of recycling old test and trying to recast the problem into an existing mold.

Ethnography Considered Harmful

CHI 2009

Ethnography Considered Harmful

Andy Crabtree, Tom Rodden, Peter Tolmie Graham Button

This paper is essentially a caution written towards interactive designers about the dangers of the wholesale use of sociological ethnographic methods. The authors feel that even though computing is moving into a new level of ubiquitousness it does not mean that designers should throw away old task and work specific study methods. They feel that the new methods being employed are too centered on creating a story and not on focusing on applications and uses of technology.

I feel that these arguments are certainly fair, but that in finding new places to apply technology designers can't just look for existing tasks and work but have to create a broader picture of their target. Just as it makes no sense to only ask a user what they want and not considering what they might need, it makes little sense to study only what people are currently doing without asking what their goals and beliefs are and whether there is some system or solution that could fit those goals better than adapting what they already use.

Still, I can see that it is dangerous to only rely on a highly qualitative study of a group as this can lead to conclusions that are difficult to back up. Without well aimed quantitative study, working results that are gleaned from an ethnography could essentially be considered conjecture and do little to provide scientific proof.

CHI 2007: Software or Wetware

CHI 2007

Software or Wetware? Discovering When

and Why People Use Digital Prosthetic Memory

Vaiva Kalnikaitė , Steve Whittaker

This paper investigates the use of prosthetic memory (both electronic and traditional) vs the use of organic memory. They compared usage of their journaling system, ChittyChatty, an audio recorder, organic memory and pencil and paper notes. They evaluated the four over a period of 1 to 30 days, asking users about the perceived efficiency, usability and accuracy of the systems.

As a result, the studies found that people like the ease of use of organic memory and pencil and paper over the short term, but that these degraded quickly in their usability and accuracy over time. They also found that their system ChittyChatty was generally well liked.

While their studies are interesting, especially for design of memory aid devices, I found their ChittyChatty system most interesting. It is a free hand note taking software that also records audio simultaneously, associating text notes with the audio recorded at the time. I think that would be extremely useful in the context of classes because you could essentially manually index the audio so you know where certain events occurred. Then you can quickly go back and listen to the audio for more details instead of having to write all the details at once.

UIST 2007: Gaze-enhanced Scrolling Techniques

UIST 2007

Gaze-enhanced Scrolling Techniques

Manu Kumar, Terry Winograd

In this paper the authors present several possible ways of using eye gaze detection to make reading text easier, and also present a few other interactions made possible by gaze detection. For the text reading system they had two main types: manual scrolling with gaze enhancement and automatic scrolling of various types.

Manual scrolling with gaze enhancement lets the user use page up and page down to manually go to the next section of text. However as the user pages, the system detects which line they were reading before they paged and highlights it in its new position once the text has finished moving.

Automatic scrolling came in a few different forms. The first is "Eye in the Middle" where the system measures the user's reading speed and adjusts the text scroll to match it. Another technique was smooth autoscrolling which had specific zones of control. If the reader was reading towards the top of the page, scrolling would stop. As the reader moves down the page begins scrolling and if the reader is near the bottom the page scrolls even faster. Finally there is an automatic page up and page down, where if the reader looks at the bottom of the screen for a long enough period (150-200 ms) then the page would page down.

In addition to the text, the researchers also created buttons that would be activated by the user looking off the screen in certain directions.

In a very small user study, the researchers found that the gaze enhanced methods were preferred, specifically the ones associated with discrete page up and page down, as the users found it somewhat difficult to read moving text.

I found the whole gaze assisted scrolling techniques interesting, particularly the use of a short activation period when gazing to determine if that was indeed the user's intention to scroll. There could be some very interesting uses for this (for example switching between windows in a desktop environment or somesuch)

Don Norman gets all Emotional

Emotional Design: Donald Norman

In this book Don Norman goes out to cover how designers can design with the emotions of users in mind. He talks about a number of ways designers can approach and affect the visceral, behavioral and reflective levels. He also talks about emotions in robots both as a human interface and as an AI goal/reward system.

I like that Norman acknowledges the large role that emotional connection plays in how people use objects, and more obviously how they feel about how well those objects/devices work.

Just as Norman says, it not very often that people use the reflective part of their mind, and as such it is rare that people truly use logic to make decisions in real life. Often people are doing things where there is not enough time or information to make a decision based solely on logic, and that is where emotion plays a large part.

Say you are looking to buy a new laptop. If you went in to the process just looking for a complete comparison based numbers and price you would likely go crazy with all the options presented. But then you decide that one laptop looks better than another. Perhaps it is pleasing to look at, this could signify that someone put a lot of thought into the construction. Maybe they keyboard feels good, something that might be important when using it to write a long paper. Maybe when you pick it up, it feels sturdy, possibly indicating good construction. All of these aspects affect how you feel about the laptop, and while these feelings may not be indicative of reality, they are often good heuristics to live by.

Of course if we make the jump and say that emotions are just subconscious, self-adjusting mental heuristics, then we could say that Don Norman's vision of robots with emotions is already a reality. Modern AI systems already have rudimentary learning systems that update heuristics that in essence act in the same way as emotions.

My final thought is on Norman's suggestion that we use emotion as output from systems as a way to quickly convey messages to people. This is pretty much the best idea in the book. Taking advantage of the emotional connotations that people place on everything from colors, sounds and facial expressions, we could create a subconscious vocabulary that would create an efficient way for machines to communicate their status to people.

Say your computer is running out of hard drive space, then perhaps a small face or something representing your computer in the corner of your screen begins to look worried, with its expression getting more severe as the problem gets worse. Now obviously the expressions would have to fit the situation, otherwise a person would just get irritated at the false positives and turn the system off. But at a quick glance the system could quickly inform you as to the status of your machine with more detailed information available on request.

Shocking

The Man Who Shocked The World

by Thomas Blass

This book is a biography of Stanley Milgram, the famed experimental psychologist. As far as biographies goes it was certainly fairly standard, with a mix of interesting character analysis and typical (if bland) biographical details.

I find Milgrams ideas and experimental methods interesting, but I don't know if I feel very sure as to whether his experiments were the best way to empirically prove research points. While his shock experiments were certainly enlightening, it seems unclear as to what exactly he thought this would prove about obedience. It showed that within the circumstance of a procedure perceived to be some sort of experiment people would be obedient to a distressing degree, but he did not seem to dig deeper to find out why people acted like that and whether the results could be reproduced in different sorts of situations.

Milgram most certainly shocked the world, but what he meant to do with his controversial experiments is still somewhat unclear to me.

Robot control: wiimotes

Exploring the Use of Tangible User Interfaces for Human-Robot Interaction: A Comparative Study

Cheng Guo, Ehud Charlin. University of Calgary

This paper was a comparison of the efficiency in controlling a robot using two different types of input devices: a set of buttons (aka a keyboard) and a 3d Tangible User Interface (aka a pair of Wii-motes).

There were two tasks that users had to perform for the study using either a keyboard system or the wii-mote+nunchuck system to control a sony AIBO. The first was to navigate through a maze, the second was to make the robot pose in a variety of ways.

Overall the researchers found that the Wii-motes worked slightly better than the keyboard for the navigation task and much better for the posing task. This is likely because there was more of a direct conceptual mapping from the wii-mote motions to the actual motions of the AIBO.

Additionally people preferred the Wii-motes because they generally felt it was easier to remember what commands did what.

In summary I would say that it makes sense to use an input device that has similar constraints to what you are trying to do. If you are controlling something in three dimensions you want something that senses 3d control input. If you are performing a task in 2d then all you need is 2d control ability.

The once and future design: or, how I learned to stop worrying and love the robot car.

Don Norman's rambling The Design of Future Things is just as thought provoking as his earlier books, but three times as succinct (I am looking at you Design of Everyday Things) . In it he discusses what he sees as the future of intelligent devices, namely autonomy and human ability augmentation.

I found his discussion of "loose reign" vs "tight reign" control to be one of the most interesting parts of the book. It is an excellent metaphor that could be usefully applied with some sort of literal interpretation. My thought, going to his focus on the intelligent car, would be to have the steering wheel be able to be pulled out or pushed into the dashboard a certain amount, where fully extended would be maximum human control and pushed in could mean more car control (perhaps folding out of sight completely if the car is fully automated). It would be interesting to see what other things this could be applied to, where an automated system continues navigating about (perhaps the web?) until a human grabs hold and shows interest.

RANDOM TANGENT!!
One thing that continued to pop up into my mind while reading this was why noone has tried putting neural networks or the like into videogames to test automated learning techniques. Perhaps people have, but I think it would be fascinating to integrate AI learning into an online game, where an AI could watch players techniques, whether in strategy games or FPS or racing games, learn from them and then try them out itself. It seems that if you wanted to test how effective an AI system is you could first test it for basic design flaws within a virtual environment populated by lots of human users and test it there.

Tapping and rubbing, way better than buzzing.

Tapping and Rubbing: Exploring New Dimensions of
Tactile Feedback with Voice Coil Motors

Kevin A. Li, Patrick Baudisch, William G. Griswold, James D. Hollan

This paper describes two tactile feedback systems built to increase expressive range of haptic systems. The idea is to build devices that will be able to express output in terms of taps and rubbing in addition to traditional vibration used in current phones and game controllers. It is suggested that this would create a much more natural kind of touch feedback that could express a greater range of meaning.

The tapping and rubbing prototypes were constructed using hard drive actuation motors to power the motion. Signals from audio output were then used to control the movement of the motors to make it easier to create smooth motion that could be varied in frequency and amplitude.

The researchers then tested a variety of tips to put on the devices which would create the best tactile sensation. Once these were chosen the devices were tested with users in order to see how well people could distinguish amounts and intensities of movements as well as to get a qualitative assessment of the devices.

While not much of interest was found in the quantitative study (people could distinguish differing amplitudes and amounts fairly well) the qualitative study proved interesting. The test subjects were split on preference of frequency of the rubbing and amplitude of the tapping. Some felt that the faster rubbing felt more natural while others preferred slower. Similarly some subjects thought that soft tapping felt more natural while others thought that harder made more sense.

Another interesting result is that after a certain frequency was reached, the test subjects could not distinguish between tapping and more traditional vibrating sensation.

I think that these two inputs could be useful in hand held devices. For example if a phone could tap on your leg when you get a text (when it is in your pocket) it would be much more noticeable and quieter than current vibrating systems. Also rubbing feedback when the device is in your hand could provide much more intuitive than vibrating in some situations. The authors of the study also suggest that it could convey a better way to convey human emotions in messages as these inputs often felt like human interaction.

Elevator Algorithm: Ethnography, going down.

Eric, Drew and I did a most excellent and seemingly pointless exercise in ethnographical study: watching people in elevators (and stairs). 

But I assure you, it was not in fact pointless. No, we wanted to get a better sense of the relative usage of elevators vs stairs at the West Campus Garage, a site of much comings and goings, where it is easy to observe people's movement habits. In watching this we hoped find patterns which would be interesting or could be used to help improve the parking garage's efficiency and utility.

At first we thought we would try to observe several elevator/stairway sets and count how many people used one versus the other, how far they travelled and whether they were female or male (the only personal trait distinguishable from a distance). However after a few minutes we realized that one person could not watch both a set of stairs and an elevator, so we had to limit our observations to a single set: those on the North-East corner of the garage. Even with two people this was difficult, as we had to both take notes and track people as they moved from floor to floor. However once we had 3 people on one set of elevators and stairs, we were successful.

We watched the garage over the course of one day at three different times of day. We tried to catch the busiest hours: 8, 12 and 5, but were a little bit late for the early morning and early evening. Still I think those would be the best hours, particularly if watched over a whole week (results might differ on TR vs MWF).

In the end a lot of our results were fairly straight forward. The only one of real interest was the cutoff point for stair usage vs elevator. When traveling a distance of 2 floors, a large portion of people used the stairs, but at 3 floors, the percentage almost flipped. I wonder if this is similar to most buildings or specific to the garage.

Well with more watching and data i bet we could find out more.

The Mole People: one big underground party

The Mole People is a book about the homeless who inhabit the subway and train tunnels of New York City. In it Toth explores the loose groups and societies built up by the people in the tunnels, what sent them into the tunnels and why they stay.

While this book is well written, intriguing and a good read, it does not seem like a very good example a proper ethnography. 

The author certainly put enough effort into investigating her subject, but when she presents the material it is often difficult to determine where specifically the stories she relates are coming from. Sometimes it is obvious that it comes from first hand experience, such as her interviews with Bernard, where other times it is impossible to tell who the story is coming from, for example the piece on the group of graffiti artists and their attempt to tag an entire train. In such cases she weaves in a huge amount of description, but it is hard to believe that all this detail could possibly have been related to her. 

I would argue that the artful story telling is both the most compelling aspect of the book as well as the most bothering. It gives the entire book a feeling of a loose interpretation of what she learned and felt, with poetic license taken where detail is sparse. Unfortunately this makes it difficult to tell what true, what she actually observed, and what is hearsay and stories she learned about in her dealings with the tunnel dwellers.

If she was indeed trying to create a compelling argument about how these tunnel dwellers see themselves and how they want to be treated, it is undermined by the way she presents itself. However if we see her book instead as an evocative narrative which gives a general feeling about what a tunnel dweller's life is like then perhaps these shortcomings are not a problem at all.

Media = Reality

The Media Equation

The Media Equation is a discussion on the lengths to which humans perceive the mediated as the real. Humans have been found to treat all media, from books and films to computers, like people to a certain extent. Even though it is a mediated view, the experience is subconsciously treated the same as if it were real.

I have already discussed what bothered me about this book so I will skip immediately to what I found interesting and useful, namely the latter half of the book.

Source Orientation

I feel that the discussion of source orientation is key to understanding the results of the research mentioned earlier in the book. It pokes holes in the concept that people think of the programmer when using a program, a concept which I had considered an explanation for why people are polite to computers. After reading the section it makes sense that this would not be the case. In fact I would say there are several different hierarchies of source orientation.

Nass and Reeves suggest that people are thinking of the computer when they are interacting with its software. That may have been true of their test examples where there might have only been on type of software on the computer. However, from my experience I would have to say that there are several conceptual source levels between what I am doing on a computer and the actual physical computer itself. Just as is the case in their examples, I notice this when something goes wrong.

First I blame the piece of software I am using right now. That is the entity I am interacting with, not any other software, not the operating system, not the computer. Each application I use has its own quirks, its own personality, I am interacting with them. For example, if you have ever heard someone say "I hate Microsoft Word!" after something messes up. They don't blame the computer, they don't blame the operating system, they blame the application itself.

Now this may be a function of the level of technical sophistication of the user. It could be that if one were less experienced with computers that the computer would take the blame of any software failing, or perhaps instead of the computer, the operating system. I suppose its all in how you perceive the relationship between application, operating system and hardware. You are not interacting with your computer, the physical device, it is much more layered and nuanced than that.

Other Thoughts

There were a few other sections that piqued my interest. One was the section on gender assumptions from voices out of computers. That was all very well, but I wonder how much more information and assumptions they could get from analyzing different accents of male and female voices. They listed a whole host of assumptions (er conclusions) made about the nature of the speaker based on their gender, but what about their accent? If for example we changed the comparison to being between a female British accent versus a male Californian accent. I think that could be just as enlightening (I am pretty sure the British accent would increase perceived intelligence)

I had a quick thought on screen sizes which I am surprised they did not actually do any formal studies on. Namely, is a computer (perceived to be) faster and more capable if it has a larger screen. I can tell you from experience that it is absolutely faster, no question. Next time your computer is bogged down, get a new screen, it will make you feel so much better about your computer.

Finally I found the section on fidelity interesting, and I feel that they could now expand it from just being about visual and audio fidelity to include tactile fidelity. For example on touch screens, to what extent does a lag between finder motion and computer reaction mess with people.

The media equation: A quick thought

The writers of this book seem to think that every single one of their findings would defy the logic of any normal person, even though many things they have found seem perfectly reasonable. Particularly their insistence that humans reactions to media are surprising. I think we have known for a long time that people become psychologically engaged with media even though they consciously know that it is not real. I mean that is what theater is, is it not? People have been going to plays for millennia, knowing full well that what they are watching is in fact not real, but they become engaged in it nonetheless. I would argue that this is just an early form of media, a way of presenting information like stories. People have known for a long time then that media can deeply affect how people feel. The idea that the media equation is a new idea is somewhat surprising to me considering this.

What is new is understanding how people deal with interactive media. However it seems that in many cases, the author's studies elicited responses from people by anthropomorphising the study devices (using voice or human-like text). What might be more interesting is how people react to non-anthropomorphic interactive media. Do people react in a social way to computers if computers act nothing like a person? How is it surprising that people react to computers like people if computers are acting like people?

I feel it has been well known for a while that a conscious knowledge that something is not real does not in any way lessen the feeling of reality if media is presented correctly.

Favorite Interface: Canon XSLR

Oddly enough one of my favorite interfaces (besides my ipod touch) is control system for my Canon XS dslr.

Now obviously there is a fair amount of learning that must be done if you are completely new to cameras and digital cameras.  But compared to several digital cameras I have used (particularly cheaper, snapshot digitals) this camera has one of the best and simplest sets of controls.

The key advantage of this camera is input mapping. When you are taking a picture and want to adjust any standard camera control (zoom, focus, exposure or f-stop) there is a button or input specifically for that function. On many smaller cheaper cameras which are geared for automatic function, you must dig through a series of menus on the camera to adjust those settings.

Another advantage is the inputs are not just labelled buttons. If you wish to change zoom, you don't just press a zoom button, you can actually physically control it with your lens. If you want to change the exposure length or f-stop there is an actual wheel mechanism that feels similar to using a standard film camera. Similarly, use of the flash is controlled by whether or not the flash mechanism itself is extended. If the flash is closed then the camera will not use flash, period. This is particularly nice when you are in a museum as you can know with certainty whether or not the flash will go off when you take a picture.

Another nice touch is that when switching through shooting modes (such as going from manual mode to full automatic) some inputs gain or lose constraints according to what you will probably want to do in that mode. For example in automatic mode the camera does not allow you to try to adjust any settings like exposure and f-stop and also does not allow you to do continuous photo shooting. If you are in automatic mode it is evident that you wish the camera to do all sensing and adjust accordingly, so you dont need to set any of those and won't need to take several shots in a row as nothing will change from one to the next. In manual mode, however, all the complex controls can be used, as it is supposed that the user knows what they are doing and wants to have this extra flexibility and risk (that the photos may be under exposed). Similarly continuous shooting can then be enabled in manual mode as the user will likely want to take photos while adjusting settings (if they want to bracket a shot for example.)

Design of Everyday Things: Summary

The Design of Everyday Things

Posted comment on Drew's blog

This book covers the psychology of daily human interactions with objects and how designers can use an understanding of this create better designs. It covers some basics of human explanatory systems, human memory and common ways the human brain can create errors. The book is replete with examples of designs that are either successful or fail at interacting with particular parts of the human mental system. At the end of the book is a summary of the design process with what amounts to a checklist for making a good human interface for your device or system.

I would have to say that the most enlightening and fascinating part of this book was the analysis of everyday interactions and the mental processes associated with them. I was particularly interested in the section on internal vs external memory as I see this as very important for software. If a piece of software can use concepts and mental models that are already used in other pieces of software it makes it much easier for users to learn new software. Then for concepts that are new the software can provide explicit written or visual clues as to how new, unknown functionality can be used.

This shows why it is so important for pieces of software to use mostly standard UI elements of the windowing system they reside in. I know as a mac user this used to be problematic, as very often pieces of software would be quickly ported from windows and would use windows-like interface conventions instead of switching to more Aqua like UI layout. In these applications none of the conventions that I knew were followed and so I had to learn a new set. Now of course if I had used Windows it would have all been very natural.

Another section I found particularly interesting was the discussion of forcing functions. The idea of forcing a user into a certain set of operations so they are unable to create errors is very useful. It is (or should be) very easy to apply this in software design and, with the advent of display input systems, hardware too. With devices such as iPods we can remove controls dynamically to make sure that only relevant input is possible. However that seems to be more the exception than the rule as very often software is engineered so that extraneous input is still possible. In some cases, however, the inclusion of forcing functions is entirely dependent on who will be using a system. For a novice user, we may want to allow them to perform only safe operations, whereas a more advanced user will likely want more power over the system at the risk of possibly damaging the system (perfect example being sudo.)

On the concept of control mapping.

Random thought...

I just realized one of the worst (or best) examples of terrible control mapping:

Cable box remotes.

I was trying to set up my grandfather's tv/dvd/cable system a year ago. The cable guy had already come through and hooked everything up to 'work' with his cable box. He had even set up one of those universal remotes. Those things are TERRIBLE, for not only are there more buttons on them than are possible to count, but each button serves quadruple duty. There are something like four buttons across the top that serve as selectors for which device you would like to control, like CABLE, TV, DVD, or AUX. The only thing that tells you that you are on a particular device is a small red light next to the corresponding button.

Then, in order to begin watching tv you must go through a complicated routine. Switch the remote to the cable control to turn on the cable box, then switch to TV to turn on the tv. Now if you want to change channels you need to switch back to CABLE before pressing the channel buttons (labelled + and -). If you forget to do this then you will change the channel on your tv off of the channel that connects it to your cable box which in some cases won't seem to be a problem as you can still surf channels on your tv. However your speakers and DVD are hooked up through the cable box so if you want to use that and are on the wrong TV channel you are SOL.

In summary, too many buttons, too many functions, impossible to achieve what you want.