The Digital Signage Insider

Making great digital signage content: The serial position effect

Published on: 2008-03-18

Back in January, I taught a POPAI webinar about how to create effective content for digital signage networks (and some readers may have seen the short version that I presented during the Digital Signage Expo or my related article on the importance of keeping your content simple).  I learned so much about what makes good content while researching this presentation that I plan to share it all on the blog over the course of several upcoming articles.  We'll be covering everything from the psychology of memory and copywriting techniques to color, contrast, fontography and a host of other relevant topics, all with practical examples from the field.  Hopefully you'll find it as useful as I did.  Today we're going to start at the beginning, and that means probing deep into the human psyche to understand how our memories work.

Obviously, this is going to be just a bit of a simplification of things, since (a) there are whole shelves in your local library full of books about memory, and (b) despite all of those aforementioned books, nobody really has a solid understanding of how it all works.  Nonetheless, in the course of our investigation we found a few principles of human memory that can make the difference between a message that gets remembered and one that does not.  Luckily, these principles are both easy-to-understand and easy-to-exploit. First and foremost is something called the serial position effect.  This effect notes how an element's position in a list affects the proportion of readers who are able to recall it later.  As a rough guideline, say that you're working with a relatively short list, perhaps five to seven items of equal length and complexity. The serial position effect says that the typical viewer will recall the items at the very beginning and the very end of the list about twice as often as those items in the middle of the list. Further, they'll be able to recall the very last elements a bit better than the ones at the beginning. (This is actually called the recency effect, since our recall is better for those items that we saw most recently.)

So how can digital signage content creators take advantage of the serial position effect?  Simply arrange the information that you're presenting to increase the odds that the most important messages will be remembered.  For example, consider the following list of features that might appear on an in-store signage clip:
  • More widgets than the competition
  • 2 out of 3 experts recommend it
  • Does twice the work in half the time
  • Get 33% more for free
  • Less costly than our competitors
Now suppose the manufacturer decided that "Get 33% more for free" and "2 out of 3 experts recommend it" were the most important messages, and the rest were secondary.  Instead of arranging the messages in the order above, we can take advantage of the serial position effect and present them as follows:
  • Get 33% more for free
  • More widgets than the competition
  • Does twice the work in half the time
  • Less costly than our competitors
  • 2 out of 3 experts recommend it
Statistically speaking, viewers will be about twice as likely to remember the first and last items of our list (which are now the two most important messages) compared to the ones in the middle, assuming that they actually see the entire list of items. Additionally, since the recency effect usually trumps the primacy effect, our most important message should go at the end. This gives it a slightly better chance of being recalled than the first item. In other words, the first and last message in a list will have the best recall, but last typically beats first.

Can we optimize these effects even further?

You betcha! To begin with, present the first items on the list at a slower speed to enhance the primacy effect.  By giving your viewers' brains a bit more time to process those early messages, there's a better chance they'll move them from the short-term store (a very temporary part of our memories) into a more permanent storage area.  Likewise, leaving ample time at the end of a list can enhance the recency effect for the same reason.  Also, the recency effect is greatly diminished when an interfering task is given. Thus, showing your most important list item and then asking a viewer to write down a phone number or perform some other task will significantly reduce the recall rate of that last item (and all of the other list items, to some extent). In other words, if you have a call-to-action at the end of your content, keep it short and simple so it won't compete with your core message.

Here's another rule of thumb: when in doubt, choose your two best messages and leave it at that!  Of all the content we looked at, the simplest designs had the best viewer recall. Since virtually everyone can remember a two-item list, see if you can whittle your core message down to two items, and use the full length of your clip to focus on those.  And last but not least, we've been assuming that your audience will be able (and willing) to watch your clip all the way through.  But since many of them won't, if there's one message that's more important than the rest, keep it on the screen for as long as possible.  This makes sure that it's available to be seen by the greatest number of people.

Having fun yet?  I know you'd probably find this same info in any Psych 101 textbook, and it can certainly be a bit dry, but consider this: of the hundreds of media clips that we studied, our number one conclusion was that readability, recognition and recall are far, far more important to the success of a digital signage project than aesthetics, form or the "sophistication" of the content.  Sure, we'll be covering those "fun" topics like color and animation in the coming weeks, and you can find some earlier recommendations in our article on what TV and print can teach us about digital signage ads. But when creating your next digital signage masterpiece, you might get more practical benefit by using the serial position effect. It's also quite effective when combined with memory chunking and coding, which we'll be covering next week. Until then, I encourage you to try out the strategies we discussed today, and see if your key metrics show a measurable improvement.  As always, if you have any experience working with content for signage, leave a comment to let us know what you think!


+2 # Jason Goldberg 2008-03-19 03:20
I'll certainly echo the sentiment that when in doubt... choose fewer messages. I'm willing to bet the serial position effect is greatest on lists of 1 item :) It's especially true when you consider the POPAI MARI data that found: "This translates into a shopper being exposed to 1.5 pieces of marketing at retail material every second, then looking at and engaging with an individual display every 4.3 seconds." In that kind of environment you just don't have time to spam the audience with a lot of secondary value propositions. I ask my designers to assume they are designing/writing for a billboard that will be viewed at highway speeds. Of course the real beauty of dynamic content is that we have the opportunity to tailor the message for different consumers and try to hit each one with the one "right" value proposition.
+1 # effie 2008-03-19 18:41
I totally agree, less is more in the digital signage industry. I'm curious what experience that others have had with getting an advertiser to trim their messages and focus on just the most important ones? Trying to talk them into less wording, is usually the start of each new ad (or at least with new advertisers). Most seem to feel cheated if I don't dump all the crap from a print ad into their digital ad. I usually ask that they try to read all the information they want in the ad, in the time that it's set to run. If they can't read it all, then they need more time or less words. Even if they can read it, it does nothing for retention. Any advise on effective methods to counter this? Seems like the advertisers need to be educated before the designers, but of course that's not going to happen.
0 # Paul Costen 2008-03-19 20:15
Effie, I find the easiest way to condition advertisers is during the initial sales pitch. Some clients are easier to convince and work with than others, but that's how it is with everything else. In trying to convince the client this is a better way to advertise, it's important to stress the fact that this is not TV, even though that's the delivery method. Once they give you their ad that they run on TV or print, they've already set their expectations about how much effort they need to put into honing their message (read: none). One of the most important things to impart to the client is the fact that the designer and the advertiser share the same goals; when they're successful, you are too, and it works both ways.
0 # Bill Gerba 2008-03-20 13:49
I think Jason's example of a roadside billboard is also a great way to hone both your pitch to potential advertisers and your request to designers. The notion of driving past a billboard at 55 MPH is such a good analogue -- everyone has done it, and when you explain it to someone, (s)he'll immediately understand that there are a hundred other things that **must** be paid attention to, the billboard being one of the least important. Bottom line: if the text/message reads well in a billboard-esque format, it will probably work well on a digital sign. Starting with that, you can then work on the content's visual design using all of the flexibility and functionality that a digital medium gives you.
0 # Ian 2008-03-25 07:09
Dear Mr Gerba, I am a marketer from South Africa and would like get in direct contact with you via e-mail would this be possible.

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