Miller’s Law – A Rule in Product Design and Life Management | Hacker News Reader

Miller’s Law – A Rule in Product Design and Life Management

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130 pointspdevine59 comments

You know how people say: “on a scale of 1-10”?

I’ve used the principle of Millers law to start asking people to measure on a scale of 1-7.

Universally, people balk at the scale. But I explain to them that most people can’t tell the difference between 2 and 3 on a ten point scale. If you can’t articulate a difference, there’s no use in the measurement.

Seven is great because you get more than the simplicity of 1-5. So... 1 - the worst 2 - bad 3 - below avg 4 - average 5 - above average 6 - good 7 - the best.

And don’t even THINK about responding with “5.5”. ;)

There is research into this - your intuition is pretty much in line with best practices (though 7 isn’t magic compared to 5 or anything). Eg http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.839...

This is very close to one of the key criticisms behind Net Promoter Score when we was looking at implementing it for a client.

Basically it uses an 11 point scale and your net promoter score is the proportion of 0-6 (negatives) subtracted from the positives (8 or 9-10). I may have got ranges wrong but the idea is the same. This was touted as "the only number you need to improve" for business success.

Chile's education system uses a 1-7 scale for grades

It could be argued that most western system do also, anything below a D is a fail. Depending on how you look at it we either have a 5 or 8 level system if +/- is used.

I'm not sure why you were DV'd, but in grad school in the US a C is considered failing.

in the UK a C would be considered a good grade even with the grade inflation -at uk unis a third aka gentleman's degree Is the failing grade

When I was at school in the UK getting an A meant you where really good and a triple A at A level was super rare and less than you would need to get into Oxbridge

While this might be very true, I'm not sure it's in any way related to Millers Law.

The 7 +/-2 rule is, in part, about the design and layout of information so as to better aid the end user in leveraging the way their memory stores information spatially.

In short, it's about how to best design a system to give information TO a user.

What you're talking about is pretty much the reasoning behind methods like 'Fist of Five', 'five star' or '5 face' voting systems. These are methods well grounded in psychology and I might argue going up to 7 is unnecessary.

0-6 FTW

There is actually a whole theory around this, and has lots of implications for the designs of hedonic and sensory scales.

I work on modeling human sensory perception and preference of food and beverage products, and have had to design scales that work as a true "metric";

Most scales suffer from 3 primary problems:

1) avoidance of the endpoints

2) tendency towards the mean

3) minimum information gain

For example; on a 10 point scale, very few (> .5% of respondents) will mark a 1 or 10 (this is problem 1). In addition, 5's are over represented VS the expected amount of 4's and 6's (problem 2).

These problems together reduce the amount of information inferable from the collected data. There is a number of ways to measure this, including information theory (think of the avoidence of the end points and tendency towards the mean as a lossy compression algorithm for the true signal) or as a sampling of an unrepresentative population to infer the posterior distribution.

A 100 point scale has the same problems as above, and in addition suffers from a lack of consistency (reproducibility) - respondents are likely to give a product a different score (say a 92 and 94) when asked about the same product multiple times. This will frequently lead to non-parametric rank reversals, which 1) prove that a 100 point scale is not a "metric" and 2) show that the amount of information is further reduced at higher optionality.

Thus - the discrete scales that work best are:

A) 1 - 7

B) 1 - 13

as they both do not suffer from avoidance of the end points, both have no selectable mid-point (forcing respondents to choose a point above or below the median), and are highly replicable (very few respondents will switch rank orders).

I must be missing something... why isn't 4 a midpoint of 1-7 and 6 a midpoint of 1-13? I'd think you would want an even number of points to prevent over-selection (like 0-7 or 1-8).

The psychological effect is "tendency towards the mean", and in this case, the mid-point isn't the mean.

Forcing individuals to choose a score above or below the mean yields a better sampling of the true distribution in this case.

What? 1+2+3+4+5+6+7 = 28. 28 / 7 = 4. So 4 is both the midpoint and the mean?

Perhaps people don't differentiate between 1-7 and 0-7 and assume that 3.5 is always going to be the midpoint?

That is correct.

So when they pick 4 on a 1-7 scale, it's not neutral but good, because it's above 3.5?

Perfect, I’m screenshottimg this answer and showing it to my friends when they get weird when I ask them how much they like their beer on a scale of 1-7.

Because science.

One place I worked we changed the scale from 1-5 to qualitative descriptors (I don't remember the exact words but something like "poor, average, good, great, perfect") and it significantly increased the information we got. Previously we almost never got any scores other than 1,4,5. Afterwards we started seeing more 2s and 3s. It seemed that people only needed one value for "bad" so putting "average" at 2 was very helpful.

The international Baccalaureate uses a 7 point scale: http://www.isnsz.com/media/images/Assessment_6.width-800.png

I generally like my scales to be logarithmic. At work, I made the following scale to explain difficulty of technical items to non-technical people. It works quite well:

  Effort Scale

  1: Easy peasy
  2: Trivial but time-consuming
  3: Some invention required and non-trivial
  4: Invention required
  5: Lot of invention required 
  and for special occasions:
  6: This is a whole new startup

Yelp and Uber ratings, and other 5-star ratings bother me. There is no generally agreed upon standard. Sometimes people give 5 stars only for exceptional service, however, most of the time, people give 5 stars if they weren't wronged in any way. It's a mess! Also, most people aren't qualified to differentiate between five different levels of service/food. It should either be generally agreed upon logarithmic scale, or it should be a yay-meh-nay scale with no guilt in giving a meh.

With Uber I considered a 4 to be "nothing wrong", and reserve 5 for "amazing service above and beyond".

However it seems that drivers who have an average of say "4.2", despite being perfectly fine and giving above and beyond service 1 in 5 times, gets kicked off. This means that 5 is acceptable and there's no way to mark above acceptable.

I'm odd, I don't expect every trip I get to be above average. That's clearly not possible.

I'm the same way. My instinctive reading of a 5 star system maps it onto a bell curve. So if I received exactly the service I expected, with zero complaints, that's obviously a 3 out of 5. 5 stars means two standard deviations above my expectations. It feels to me like a company that gets nothing but 4 and 5 star reviews should be taking issue with their marketing department for setting expectations way too low.

But in an Uber, giving less than a perfect score can get someone fired. So it's 5 stars unless the driver literally spits on me, and then it might be 5 stars and a complaint. Anything lower than a 5 star rating feels unethical, like stiffing a waiter on a tip.

What I can't figure out is how this is of any use to Uber. They have created a "metric" where a large chunk of their customers regard answering honestly as a social faux pas, at best, so what do they think they're measuring?

People know this and the"real" Uber rating scale is a ten point scale between 4 and 5. Same with Amazon product reviews. Anything under 4 doesn't get a look.

I think a simple thumbs up/thumbs down would be just as effective.

That 4.2 thing really disturbed me. Most people driving for Uber aren't doing it because they want to over their alternative to nothing. I couldn't, in good conscience, give out a rating that puts someone's livelihood at risk.

I only gave out one 3 star, but that was because the driver was very bad, though not taxi-driver bad, which is what I would consider 1-star.

Off topic: I got all 20. What you do is invent a story in pictures.

A cat was playing with a ball under the tree. An apple fell from tree on cats head. The cat squared around the apple and ran inside the house through a small door into her box. King dad drove in his car, took out huge hammer from the trunk and hit the box of milk. Milk sprayed all over the house and inside the fish tank. Fish got restless and caused a cross bow from the wall to fire an arrow through the book that was all taped over. Mom in her red shoes came and took the key under the flower.

I forgot my pimping king with thor hammer was riding in a car so 19/20 for me. I wonder when Miller's law is gamed with this narrative technique how information design is tailored to this long tail of users. Story as the new UI.

Tangential, but I was able to recite all the words, but only because memorized them in a nonsensical, but easier to remember story. I like the exercise because it forces me to be creative.

The CAT looked at me eating an APPLE, I threw a BALL outside to see if it would chase it instead it climbed a TREE...

Me, too. Instead of having to remember all 20 words, I just had to remember a few stories: the cat eating an apple on a ball in a tree, the square face whose house is a boxcar, etc.

Same here. I too managed to recall all words in the correct order using the same technique.

How many stories? If you had three or so words per story, that would give you about seven stories, which fits the notion of 7 +/- 2 "chunks" of information.

Yeah, that was a poor example/text he posed in the article. That's not how we consume data in menus or similar 'chunks' of digital information we interact with.

I also started to do that, but it is pointless except for specific purposes or memory competitions. In real life you can’t go creating memory palaces or funny stories for everything. And it distracts from other more important points in the article, like remind how bad is our memory.

I use memory palaces for a lot of different tasks. I'm certainly not great at it, but you can train this skill to be quite quick. It's great for learning names, vocab words, remembering to do lists, among other things.

The couple key strategies for a memory palace are:

1. Ensure your palace is as real as possible. Spend some time mentally mapping out every detail of your palace in your mind so that you don't have to later.

2. The more animated or "human" the better. Our minds are better at remembering faces.

3. The dirtier the better. Our brains are also way better at remembering sexual imagery.

I got about 13 words on this test using this technique poorly and it only took a couple seconds (and I didn't memorize the second half of the list).

I love how they end with a call to reduce your levels of electronic distraction, then have a list of different social networks you can contact them at.

Related to the idea of chunking, I remembered 15 words easily, using a clever technique that I read about a few years ago. Instead of trying to remember each word individually, I remembered scenes. This enabled me to remember more than 7 words, because the chunks no longer were words, but were combinations of words.

For example, for the words "king" and "hammer", I imagined a king hammer ruling over his subjects. For "milk" and "fish", I imagined a fish with udders. They're silly, but they work.

But how do you free working memory when you're done?

I use my hp48 every so often. The UX is primitive, 5 generic keys, slow refresh lcd. But the RPL (lisp/forth) system has only a few bits of builtin constructs, which means you'll have maybe 3 level deep worst case. Most things are below the 7 figure. It's smooth as f. With just a bit of upgrade I wouldn't mind programming on this at all.

More and more I believe that ignorance thus space exploration and Miller's "level 1" cache has a huge role in our enjoyment of things.

A psych professor claimed, years ago, that the number is actually 5 +/- 2, but I can't remember his argument. Something about including error of measurement from the experiments, maybe? Regardless, he said it is why 7 phone # digits is often difficult for some people, because it is on the high end of what most people can remember.

I managed to remember the first 18 elements of the list.

On a more relevant note, it's easier to remember a large number of things when they're related to each other in meaningful ways. So the results of this little memory test aren't very good predictors of your ability to remember things in a real-world setting.

Worth pointing out how great (and easy to learn and master) a mnemonic device it is to create a story from the list...

The skinny cat with an apple on it's head ran after the ball that led it to the tree with square leaves. Each leaf was actually a picture and if you looked closer you could see a head (of a fat cat) in the picture. You zoom in and the picture becomes a movie and you see the fat cat walk up to a house and open the door... etc etc

The more absurd the image you create the easier it is to remember. You also have much better long term memory. It's been half an hour since I memorized the list and I've drawn my attention to 5 other HN posts, but here I am able to recite the list 100% accurately and without hesistation...

Cat apple ball tree square head house door box car king hammer milk fish book tape arrow flowers key shoe

This is nothing against Miller's Law though... as who goes about creating visual stories to memorize user interfaces :)

What does memory have to do with how many things are on screen at one time? Do UI elements get turned into a memorized list or something? But longer term you can store longer lists. I'm not sure how this limited short term memory phenomenon relates to UI?

Exactly.

Seven plus or minus two refers to working memory. When you encounter say a navigation menu with 10+ unstructured items, it becomes impossible to consider all the options at once.

But when you look at a menu, you know what you're looking for so it's a matter of identifying one thing. Aside from convenience I don't think the length of a menu matters much.

The point is when you don't know what you are looking for exactly. The Abobe products are a good example of this. I don't use Photoshop often so I forget where stuff is. Having a lot of menus and each menu having a large number of options makes it difficult for a novice user (like me) to find the resize image dialog, for example. To be fair, Photoshop is designed for experts and expert users will learn an interface no matter how crappy it is so it isn't a big deal in this case. But the endless options and menus do make it harder for novice users.

If the menus and options were grouped in way that is in line with human psychology, it would be easier for novice users to find that one option. I know the Office ribbon gets flack on HN but Miller's Law is one of the big reasons for the Office ribbon and how it is designed which makes it a lot easier for novice and intermediate users to find that one option in Office.

Miller’s law says that people can remember 7+/-2 things at a time. I think that’s why people usually like structured lists much better than a unstructured, unsorted laundry list.

People can remember only 4 things. The few who can remember more are the exception.

That would be a much better goal for product design. You don't want designers to pack things by 7 or 9. It's too many.

I think the average is 5, one of the diagnostics for Dyslexia is not being able to remember less than this in short term memory

I tend to remember 3 things when it comes to things like shopping or tasks. Add a fourth and I usually end up getting something wrong or forgetting it.

Similar to the story method of memorization mentioned, using the Method of Loci makes it easy to memorize all twenty.

https://en.wikipedia.org/wiki/Method_of_loci

https://www.ted.com/talks/joshua_foer_feats_of_memory_anyone...

This is why phone numbers are 7 digits long: xxx-xxxx. Then, add another "chunk" for the area code: (xxx) xxx-xxxx.

Phone numbers are 11 digits long, usually split into 5 and 6, but sometimes 4/7 or 3/8, and even 6/5 and 7/4.

Not that anyone remembers phone numbers nowadays.

It was even shorter before when the exchange was represented with a word and a number (e.g. KLondike 5 for 555).

Hacker News desperately needs a "Saved You a Click" feature.

I think 5-9 words is much more than 7 bits of information...

It's possible they mean bits as in small parcels rather than bits as in 0 || 1.

If "cat" is a foreign language word that you just learned, it is definitely more than a bit of information. If you are a native speaker of English, "cat" is now for you a single "chunk", or piece of information.

Not sure why you were downvoted.

The comment below mine, about "bit" being used as "piece", was my first thought too. But then the author contrasts with a quote using the actual entropy definition of a bit.

And chunking doesn't work as an explanation either, even with Huffman encoding, unless half of all words you ever use are "cat".

Note that even if the word was used incorrectly, it makes no difference on the author's argument.

Isn't there a law of UX that the viewport should be large enough for the user to see the article's text? I can see like half a paragraph between the top stuff and the bottom stuff.

Jack of all trades. Master of none.

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