Wikipedia:Reference desk/Archives/Science/2017 December 14

= December 14 =

Location of mission critical controls
Why do designers place mission critical controls in such a way as to maximise the likelihood of d'oh! moments?

For example
 * I have lost track of the number of times I have wanted to preview a Wikipedia edit and unintentionally pressed the "publish changes" button, simply because the preview button is right next to the publish changes button.
 * When I am composing a text on my iphone the send message arrow is located in the right of the text field in which I compose my message. In the course of composing a text my finger or thumb will sometimes slip to the right and prematurely send the incomplete text.
 * The wireless router that sits behind my TV has the wireless local area network (WLAN) button right next to the router on/off button. In the course of reaching behind my TV to power cycle the modem I accidentally turned off the WLAN instead. When I did manage to complete power cycling the router I could not get a wifi signal to the rest of the house, as I had turned off the WLAN, and had to press the WLAN button again to get the wi-fi going.

I guess the designers involved have little to no awareness of human factors and ergonomics design principles but would be interested to hear others' thoughts. Sandbh (talk) 00:03, 14 December 2017 (UTC)
 * Hearing other's thoughts is not what we do here. This is a desk for getting directed to reading material about a subject.  Also, I should point out that your question contains a problem known as the plurium interrogationum problem: It presupposes an idea which is not yet established, and then asks a question which requires the not-yet-established idea to be true.  Your presupposition, that designers "place mission critical controls in such a way as to maximise the likelihood of d'oh! moments" has not been established yet, so we cannot answer "why" yet.  If one were to try to answer "why", then it turned out the presupposition was wrong, it'd be beyond stupid.  It's like asking "why did you stop beating your wife".  Such a question is impossible to answer because we have not yet established either a) that you beat your wife or b) that you stopped.  I should point out that your personal experience with these design elements is not sufficient evidence as to designers intent, and until you can produce sources which establish that intent your question has no chance of being meaningfully answered by anything except unmitigated bullshit.  Which several people will be along below to provide you with starting... now.  -- Jayron 32 00:37, 14 December 2017 (UTC)
 * I think you are being unduly harsh. I don't see anything in the original question accusing designers of designing controls with the intent of maximizing accidents.  Indeed, the line "I guess the designers involved have little to no awareness of human factors and ergonomics design principles" implies the exact opposite - that its due to ignorance rather than intent.  Also, while we are not supposed to provide our thoughts and opinions, the request "to hear others' thoughts" can be answered by providing references to relevant people's thoughts.  I don't have time now to do a thorough search for literature on this subject, but Googling Binging "reasons for bad design" yielded this page among others.  Its mostly just comparing good and bad designs, but does include a little bit of discussion about why designers tend to do the bad ones. Iapetus (talk) 09:56, 14 December 2017 (UTC)
 * The OP has not established that designers have little awareness of those issues. Information in the article and video I linked below indicate the exact opposite; which again makes the "why" question based on a false premise (even worse than an indeterminate one), which means that "why do they..." is still not answerable.  -- Jayron 32 13:38, 14 December 2017 (UTC)


 * Just a little tangential reading for you as well, directly related to how these things are designed, this video here explains a bit about Fitts's law, which is a useful tool used in designing human-computer interfaces. I will note that it does not answer your direct "why" question (for reasons noted above), but that video, and the Fitts's law article, at least provide you with references to read (and watch), which is the purpose of this desk.  -- Jayron 32 00:42, 14 December 2017 (UTC)
 * For the record, I didn't intend for my post and its speculation to imply that designers deliberately placed mission critical controls in such a way as to maximize d'oh moments. And my speculation was intended to do more than garner answers. Iapetus was on the mark. The Fitts' law article is interesting. The video is too, and the person being interviewed mentions a design decision by Apple to move the X at the top right of some Apple interfaces a few pixels down, and to place it in a circle resulting in the control being harder to get to. So while the interviewee says Fitt's law is more than an academic exercise it is evidently not always observed. Sandbh (talk) 03:36, 16 December 2017 (UTC)


 * Just decide that there are no mission critical controls on wikipedia, your iphone or your wlan router and your problem is solved. --DHeyward (talk) 08:02, 14 December 2017 (UTC)
 * ...unless your iPhone hosts the app your pilot depends on...
 * 21st-century technology has seen the creation of casual low-cost toys that approximate mission-critical systems so well that we are entering an era of human-factors crisis. Real, actual humans no longer know the difference between a toy and a mission-critical system, and the effects of software-UI only compound this human-factors problem.
 * Even the president of the United States does not appear to appreciate the impact of using a toy chat-app as a means for communicating policy-statements to the entire world. Perhaps the enticing user-interface conditions people to prefer toy UIs over well-engineered systems.
 * Before long, people acclimate - more people get their news from Twitter instead of the actual White House press-statements; more pilots begin to rely on "supplemental electronic flight information system" instead of certified flight instrumentation. The next thing you know, a plurality of people actually believe that iPhone-powered robot cars can drive themselves without human intervention.  We have constructed toy UIs that are sufficiently similar to real mission-critical engineering products that we've completely steam-rolled over the human in human-machine interaction.
 * People who design well-engineered mission-critical systems do spend a lot of time to make sure that humans can interpret and interact with the interface; and a lot of effort is spent to ensure that the view is clear, and the controls are obvious; that incorrect interpretation of a view, or incorrect actuation of a control, is a rare event. People who build toys that approximate well-engineered systems might not have spent such care and effort.  Yet, billions of dollars of economic activity traverse through those toy UIs every single market-day; actual commercial airplane paperwork gets filed and approved through those toy UIs every day; actual news and politics are communicated through those toy UIs every single day.  If there is an impending nuclear strike, or a flood warning, or an active armed-police-action in your neighborhood - the old well-engineered user-interface of the Emergency Broadcast System has been formally replaced with a new UI on your toy smart-phone.  Are these items "mission-critical User Interface"?
 * I found this delightful research project: the Psychology of Trust. They've taken a peer-reviewed piece of their own scientific findings, and ... formatted it as a bad website: partially to see if you'll take it seriously, and partially to demonstrate that most of you will not.
 * Nimur (talk) 18:37, 14 December 2017 (UTC)

This site reviews a book by Don Norman entitled The Design of Everyday Things. Some of the reasons listed for poor design include: "design that ignores the needs and psychology of people"; laziness by programmers; and business constraints (competition, costs, and schedules). Sandbh (talk) 09:28, 15 December 2017 (UTC)
 * Writing in Tragic design: The impact of bad product design and how to fix it, Shariat and Saucier (2017) observe that bad design decisions may come about due to an error of judgement; while this marketing blog refers to, among other reasons, what they call "The hippo factor" or the Highest Paid Person’s Opinion overruling (on the basis of personal preference) an otherwise good design decision. Sandbh (talk) 03:48, 16 December 2017 (UTC)

Cone cell responses to violet
How would File:Cones SMJ2 E.svg look if extended into the violet wavelengths for all three cone types? Is the lingering response of red cones in that range enough to explain why violet is metameric to a mix of red and blue -- despite being a shorter wavelength than either -- or is some other phenomenon responsible? Neon Merlin  09:42, 14 December 2017 (UTC)
 * I'm confused; the graph does extend to the violet range. Violet is from about 380-450 nm or so, and that's on the graph you showed.  -- Jayron 32 13:35, 14 December 2017 (UTC)
 * He must be talking about the red cone line cutting off before 400 or less. Now what confuses me is why there's 3 basic color terms for bluish red and only one looks bluish red (magenta). Females must have awesome color discrimination if purple and violet don't look alike. Sagittarian Milky Way (talk) 15:26, 14 December 2017 (UTC)

Not following an example from the book The Fabric of the Cosmos
I'm reading Brian Greene's book The Fabric of the Cosmos, and trying my best to understand it. In Ch 5 of the book, Greene works up to a hypothetical example which I guess is supposed to illustrate some funky features of spacetime. I'm confused by his example and hoping someone might be able to help me understand it or point me to resources that might do the same.

I may be misinterpreting his example and that may be the source of my confusion. That said I have no choice other than to give my own recap of the scenario:

His scenario involves two characters, you and Chewie, separated by 10 billion light years. For this example to keep things simple he says ignore the motion of the planets, the expansion of the universe, gravitational effects, and so on. He says that if you and Chewie are both not moving relative to each other, then both will agree on what is happening "now" on each other's worlds. (In the context of the full chapter I take this to mean that Chewie would be receiving photons from 10 billion years ago that came from my location & vice versa.) Then he says that if Chewie decided to stand up and walks directly away from you at about 10 miles per hour. Greene seems to explain that the consequence of Chewie walking away with the 10 billion light year separation will result in Chewie sensing things from my location an additional 150 years ago. The author does not state how long Chewie walks or total distance or anything like that.

I'm confused as to how 150 years came about. The only way I can understand this is if Chewie moved a distance equal to 150 light years, but my sense is that is not part of the author's scenario.

Any thoughts?

--128.229.4.2 (talk) 16:54, 14 December 2017 (UTC)
 * I'd need to see directly what Greene writes to know what he's talking about, but I think I can tell you where the 150 years come from: Chewie's speed is 10 miles/hour = 4.5 meters/second. Divide that by the speed of light (0.3 billion meters / second) and multiply by 10 billion years gives you 150 years. He may be talking about special relativity where the axes (actually spaces) of simultaneity in two reference frames that are moving with respect to each are slightly tilted with respect to each other by an angle v/c. By moving away from you, Chewie's "simultaneity space" would cut your world line about 150 years in your past. Not sure where Greene is going with that... --Wrongfilter (talk) 17:54, 14 December 2017 (UTC)
 * Thank you. Yes, this seems to fit in with the text surrounding the example. Thank you, I'll read up on Relativity_of_simultaneity and hope for a better understanding.
 * --128.229.4.2 (talk) 20:41, 14 December 2017 (UTC)
 * This book example is ugly: because it's trying to use simple language, it's confusing you by losing detail.
 * The author is attempting to illustrate two totally different pieces of physics that are both very complicated, and to show that they combine.
 * First, there is a Lorentz transform, caused by relative motion. If you worked that math out, you would get time dilation, but 10 mph does not yield 150 years.  The standard math for a Lorentz contraction is found in almost every book on special relativity.  Here's a nice summary from Oxford University that pulls no punches: course notes for Relativity from the Oxford Department of Physics.  Using standard equations, the time dilation is essentially negligible.
 * Secondly, in this example by Brian Greene, there is a non-flat universe. Over the distance of 10 billion light-years, the shape of the universe varies (in his example problem).  Your meter is not the same as the meter that "Chewie" measures!  (That's... the subtle detail of new physics that is the core thesis of his whole book!)
 * When you combine these effects, you get a bizarre and non-standard Lorentz-transform. The author doesn't give you equations; he gives you sloppy plain-English descriptions; so to the casual reader, it is hard to see which parts are "standard" relativistic physics, and which parts are "Brian Greene's curved space-time theory" physics.
 * It is the combination of these effects that yields the weird "150 years" number. Regrettably, neither the author nor I write out the details of the combined-form equation!
 * Though these types of book make for casual fun reading, they don't give you a lot of the formal preparation, nor the specific mathematical tools you need, to actually do anything with modern theoretical physics. Like always, if you're really interested, I recommend a real textbook!  A good place to start - if you haven't got it already - is any of the Stewart calculus books.  These are great introductions to modern mathematics in a format that a real student can actually use.  Specifically, the third section of Multivariable Calculus will give you the exact tools you need to study mathematical representations of non-flat universes.  At the end of the day, "curved space-time" is just u-substitution by a fancier name!
 * Nimur (talk) 18:08, 14 December 2017 (UTC)
 * Thank you. I guess it is good to know that the author is playing a little more fast and loose than is useful to the uninitiated. Not what I was hoping for when I bought the book and started reading, but probably not a huge surprise. My curiosity wants to understand the nature of the universe but my brain isnt as eager when it stumbles upon anything beyond basic math symbols. But I guess that is often the rub.
 * --128.229.4.2 (talk) 20:41, 14 December 2017 (UTC)


 * See also Relativity of simultaneity. Loraof (talk) 19:28, 14 December 2017 (UTC)
 * Thanks, this graphic from that page was very helpful in trying to follow this example.
 * [[File:Relativity_of_Simultaneity_Animation.gif]]
 * And now that I think about it & see the visual, the author did introduce this topic earlier in the book. So I missed the connection upon first reading.
 * --128.229.4.2 (talk) 21:29, 14 December 2017 (UTC)
 * Be aware that this is a silly, pure academic example to prove or illustrate some simplified theory. In reality it is already wrong because everything moves. "A" moves and "B" stands still on the plain of our Space-Time Continuum does not exist. Even black holes move. --Kharon (talk) 02:56, 16 December 2017 (UTC)


 * The thing to bear in mind is that "now" (spacelike interval) is not something that can be seen. So if you start walking relative to Chewie, "now" may change by 150 years -- in the sense that in 10 billion years, when the light from "now" arrives where you were, you will have walked 150 light years!  (note: I didn't check that math)  But what you actually see is only the slightest decrease in the apparent speed of events at Chewie's location because the light takes an iota longer to get to you with every step. Wnt (talk) 16:00, 17 December 2017 (UTC)

Organ connection
What is connection between the artery and the right hemisphere of the brain? 119.30.38.179 (talk) 17:47, 14 December 2017 (UTC)
 * Which artery? The body is full of arteries...  The one going to the brain is one of the carotid arteries.  -- Jayron 32 19:45, 14 December 2017 (UTC)


 * My bad, should've specified it more. Talking about model-like pictures of skeletons like such images. Point is - I'm looking for images like that in a "standing" position as if an xray if the thorax is going to be taken. --62.214.191.65 (talk) 20:47, 14 December 2017 (UTC)
 * Actually there is no direct connection. Read Blood–brain barrier. --Kharon (talk) 02:44, 16 December 2017 (UTC)