Jeremy Smith Feb 19, 2019 11:32:14 AM 24 min read

Ambiguity Effect and How to Keep it From Hurting Conversions

Everybody likes a sure thing. Life is easier if you know what’s going to happen next or what you can expect in return for your investment, or for any effort. It just seems fair: If I do this, I know I’ll get that.

It’s different when “that” is not well defined. We’re less likely to put our effort or money toward something that is ill-defined, ambiguous or unknown. If there’s a choice, we’ll go elsewhere.

This is known as the “ambiguity effect.” It suggests that people prefer to choose an option with a known probability of a favorable outcome over an option where the probability is unknown. The “ambiguity,” or lack of information, creates a cognitive bias. Missing information makes the probability of the outcome “unknown,” and people tend to avoid it.

warning mass confusion aheadOthers have described it as most folks having a rule of thumb (a heuristic), which says to simply avoid anything they don’t have enough information about.

Ambiguity and other cognitive biases are a type of “friction,” which is bad for conversions. As I’ve written elsewhere, friction is anything that gets in the way of conversions. There are many types of cognitive friction, but quite often they boil down to issues of trust or mistrust.

Ambiguity breeds mistrust. Is this intentionally unclear because they’re hiding something? Is this a trick? Is this unclear because they don’t really know what they’re doing? What’s really going to happen to me? What will I wind up with if I click on or agree to this?

Most people would rather not find out.

Ambiguity Breeds Avoidance


economist Daniel Ellsberg Image from


The ambiguity effect was first described in 1961 by the economist Daniel Ellsberg (at left). And if you’re thinking, ”I know that name …” you’re right. But before the Pentagon Papers and his continued social activism, Ellsberg was an academic at Harvard who, among other things, published a breakthrough paper on decision theory and behavioral economics.

Chip Heath and Amos Tversky, psychologists at Stanford University, describe Ellsberg’s supposition much more concisely than the original paper does:

“The simplest demonstration of this effect involves two boxes: one contains 50 red balls and 50 green balls, whereas the second contains 100 red and green balls in unknown proportion. You draw a ball blindly from a box and guess its color. If your guess is correct, you win $20; otherwise you get nothing. On which box would you rather bet? Ellsberg argued that people prefer to bet on the 50/50 box rather than on the box with the unknown composition, even though they have no color preferences and so are indifferent between betting on red or on green in either box.

Ellsberg’s suppositionThis pattern of preferences, which was later confirmed in many experiments, violates the additivity of subjective probability because it implies that the sum of the probabilities of red and of green is higher in the 50/50 box than in the unknown box.

“Ellsberg’s work has generated a great deal of interest for two reasons. First, it provides an instructive counterexample to (subjective) expected utility theory within the context of games of chance. Second, it suggests a general hypothesis that people prefer to bet on clear rather than on vague events, at least for moderate and high probability. For small probability, Ellsberg suggested, people may prefer vagueness to clarity.”

Here’s another explanation of the ambiguity effect, also known as the “Ellsberg paradox”:

“I know that there is at best a moderate chance of my winning a local singing competition, because the local singers are good. There is a competition in the next town, but I do not know how good the singers are there. Rather than 'risk it,' I enter the local competition.”

In both illustrations, people avoid the choice they know less about, though it could very well provide better odds of a good outcome. The second box of red and green balls could be 90 percent red, and quickly indicate that “red” is a winning bet. Singers in the next town’s competition could be terrible. But … Nope.

Another study found that people will even pay to avoid having to make a choice if they can’t determine the probabilities.

So, what does this have to do with online marketing and conversion optimization?

Plenty, I tell you.

One of several cognitive biases that may be plaguing your website and other marketing channels is ambiguity. Most simply, if a potential buyer knows less about you but more about the other guy, she’ll go with the other guy – just because of a hard-wired bias against the ambiguity in your ad or site.

The antidote to ambiguity is clarity. If you want to diminish a potential bias against buying whatever you are selling, make sure your customers have all information necessary for them to be confident in the probability of their success.

Show people, that, Yes, this click will take you where you want to go. Yes, this product will fill your need or solve your problem. Yes – what you expect to happen next is absolutely what is going to happen.

zen payroll

Ambiguity can arise anywhere in the user experience and, when it does, you need to wipe it out.

Eduardo A. Schilman, Ph.D, illustrates the ambiguity effect for Singulariteam by referring to a study that found people like longer URLs as opposed the shortened ones you can get from Bitly, Owly and other services. This is because full-length URLs provide more information and lessen ambiguity, or uncertainty.

full-length URLs

“So while might be shortened to, a quick glance at the long URL entails trust and understanding – we know where we are being led to: the iTunes store, to get an app. Getstocks app. The short URL on the other hand has no data at all. People distrust vagueness,” Schilman writes.

example of full-length URLsThere you go: make sure your URLs are clear. As Moz says, “The URL of a web document should ideally be as descriptive and brief as possible. … Individual pages' URLs should also be descriptive without being overly lengthy, so that a visitor who sees only the URL could have a good idea of what to expect on the page.”

Did you catch that: a good idea (known probability) of what to expect (outcome).

‘Clarity Affords Focus’ – Thomas Leonard

Here are four more steps to reducing ambiguity in your online marketing:

1. Use keyword phrases (or long-tail keywords).

This is a means of clarifying what you have to offer from the start. It also will help you get more qualified leads.

Here’s what I mean. If you have a restaurant, you know there are a bazillion restaurants, so “restaurant” is useless alone as a keyword. Yours is a “Mexican restaurant.” Better, but there are about four dozen Mexican restaurants in town, so you’re still not cutting it keyword-wise. You run a Mexican restaurant specializing in Oaxacan tlayuda, which is commonly referred to as “Mexican pizza.”Oaxacan tlayuda,

Great, but “Oaxacan tlayuda” is too specific (and too not in English). On the other hand, “Traditional Mexican pizza” leaves no ambiguity as to what you’re about, and “pizza” – well, that’s gonna probably pick up a lot of searchers who didn’t realize they want Mexican tonight.

But you still have an ambiguity tlayudaproblem among those who don’t know what a tlayuda is. And those hungry searchers looking for a Mexican restaurant may now be thinking, You know, I haven’t had pizza this week ...

2. Write informative ad copy.

Your next opportunity to keep hungry diners who love Mexican food and pizza headed your way for tlayuda is in your ad copy. In a standard Google ad, in addition to a 25-character headline (Traditional Mexican Pizza = 25 characters), you have two lines of 35 characters each for descriptive copy, as well as your display URL.

So here, you want to explain just what you are offering. This is where “Oaxacan tlayuda” (15 characters) is useful for the uneducated user and serves as a secondary keyword phrase for those in the know. What else would be good marketing and good descriptive copy (which are one and the same) for this restaurant? Off the top of my head ...

  • Authentic
  • Flavorful
  • Variety
  • Family
  • Fun
  • Enjoy
  • Treat
  • Affordable.

So …

Traditional Mexican Pizza


Authentically made Oaxacan ‘tlayuda’

makes a flavorful family treat

Traditional Mexican Pizza


Enjoy authentic Oaxacan ‘tlayuda,’

a fun, affordable family dinner treat

Two things: We’re assuming a “family” restaurant; you wouldn’t use “family” for a place that catered to a college crowd or late-night after-closing hipsters. On the other hand, you could target “late night” (10 characters) or cite a nearby college in other ads. Second, you could swap “traditional” and “authentic” (among other terms), to get more mileage out of the copy. (And, third – you’d thoroughly test all of this to find out whether any of it works. Right now, we’re just talking about eliminating ambiguity.)

Ok, we have Mexican pizza, which is some kind of traditional food called “Oaxacan tlayuda” – Oh, yeah, Oaxaca; Sure, I get it. And it’s kinda fun, flavorful and/or affordable to eat.


See the flaw – the ambiguity? Never said it was a restaurant. Could be frozen food. Could be a recipe website. Let’s try …

Traditional Mexican Pizza


Come enjoy our Oaxacan ‘tlayuda’

an authentic & flavorful family treat

Authentic Mexican Pizza


Enjoy traditional Oaxacan ‘tlayuda,’

served in a fun, family atmosphere

“Come enjoy” and “served” indicate that they’re going to make it for you, no?

So now we know Mexican “pizza” is a traditional food from Oaxaca called “tlayuda,” which is a flavorful dinner that’s kind of fun to eat, like “regular” pizza, and it’s this family restaurant’s specialty. All clear? Worth looking into? Don’t see why not ...

3. Create a relevant and informative website.

Once you’ve enticed potential customers to your website, once again you want to make sure there’s as little ambiguity as possible so you don’t lose them. Your landing page should reflect what’s in your ad through words and images. Describe, explain and show your product, as well as who you are (especially in a hospitality business, like a restaurant). This creates understanding and trust while eliminating ambiguity.

Your landing page should reflect what’s in your ad through words and images

If your ad is about tlayuda, it absolutely has to direct users to a landing page about your tlayuda. Especially if you serve other dishes, you’ll create tremendous uncertainty – if not downright hostility – if a potential diner who is interested in Mexican pizza is suddenly looking at an array of burritos, rellenos, tacos, etc. Those dishes should certainly be on your site if they’re on the menu, but not where the tlayuda ad brings people.

And, as the user moves through your site’s decision funnel, each step should be clear and yield expected results – “get directions” goes to a map and/or written directions; “make reservations” goes to a working form and/or phone number and shows hours of operation; and “menu,” please, for goodness sakes, goes to an up-to-date list of your variety of scrumptious, traditional and fun-to-eat tlayudas.

It’s interesting (to me, anyway) that Ellsberg said people might actually prefer a little ambiguity in a low-risk proposition. That works out well for our tlayuda business.

No matter what you’ve written, people who haven’t had tlayuda are going to be uncertain as to whether Mexican pizza “works.” But there’s a little bit of an adventurous appeal in the newness, while the risk is very low. It’s just one meal, plus it’s bound to be made with ingredients that a Mexican food eater generally knows he likes. Hey, let’s try this!

4. Use Negative Keywords.

This is a conversion optimization tool that is too often overlooked. Negative keywords added to an account exclude certain words or phrases from searches that return your ads. They narrow the search parameters and, by doing so, they potentially save you money.

Think of all the pizzas that tlayudas are not: Italian, Sicilian, New York-style, deep-dish … Each should be added to your inventory of negative keywords for your tlayudas campaign. Add “recipes,” “frozen” “taco stand” and anything else that doesn’t represent you or your product.negetive keyword search using google

Google’s AdWords Keyword Planner suggests keywords for the product name you enter. From that list, you can select terms that don’t fit your product. Look for "negative keywords" below the main table in the AdWords Keywords tab. (In "Display Network only" campaigns, you “exclude keywords” from your campaign or ad group.)


Right now, I’m not sure whether I’ve taught you about ambiguity and getting it out of the way of your conversion rate, or given you a new business idea, or simply flung a craving on you. Maybe all three.

But before you go to lunch or your loan officer, let’s review: the ambiguity effect is a cognitive bias that causes potential customers to bail if they don’t have enough good information about a product or service. This is a problem for marketers that can be overcome through clarity – clear information about your product or service, and your company, as well as clear intentions as to where your ad, URL or other online features will take the user.

Clarity eliminates ambiguity and builds trust, which increases the potential for conversions.

Now, let’s eat.

Category: Heuristic Analysis


Jeremy Smith

Digital marketer with a penchant for dance; helping clients see the light through the jungle of tweets since before Twitter was cool.