Cognitive Biases — Ambiguity effect

Michael Gearon
4 min readOct 6, 2019
Photo by Joshua Sortino on Unsplash

If the result of two options were the same but you know the probability of one and with the other option it’s unknown the probability of success then we prefer to go with the option of known probability. The ambiguity effect closely ties into the loss aversion bias in which our natural bias is avoid risk and stick with safer options.

“Better the devil you know than the devil you don’t”

The ambiguity effect bias comes from our association of missing information with negative information. If we are not told something it’s usually because it’s negative or it doesn’t benefit us. You can think of cases where this is true such as buying a product or voting for someone.

For the most part the ambiguity effect is a fairly rational bias we have, however it can also hold us back from trying new things and potential have longer term impacts on our life or in the simplest form it could stop us trying something new at a restaurant as something familiar may also on the menu.

An example of the ambiguity effect

In a study by Heath and Tversky, subjects were asked to pick a green or red ball from a container and then guess its colour.

If they guess correctly, they won money.

One container had 50 red balls and 50 green balls, while the other had a random proportion of both balls.

While it was equally likely to pick either colour of ball from either container, most subjects chose the container with 50 balls of each colour, the option with known probability.

A modern example of the ambiguity effect

Research conducted by Buddy Media, which is now part of Salesforce looked into the use of URL shorteners. They found that although URL shorteners are cleaner to look at it was actually full-length URLs that were by popular by a staggering 3 times.

But you can understand why this would be the case, we are quickly making decisions everyday and if we looked at a URL which was clear what was behind it compared to one that isn’t clear then it’s easier to make the decision as it’s a safer choice which results in the same outcome.

How to counter ambiguity and why you shouldn’t get confused with curiosity

The main remedy of the ambiguity bias is clarity. If you are clear to people what they get from something you present them then they will feel more at ease. By giving them the information clearly and simply they will have higher confidence in your option over someone/something else. This can be achieved through:

  • Statistics that are relatable. Statistics are a great way to prove the success of a service or product as they demonstrate historical what has happened. However the important part is something that is relatable to the person, don’t reference something the person doesn’t care about or isn’t applicable to them.
  • Guarantee to provide confidence and build trust. Something which I’ll mention later is about by providing a guarantee can give that reassurance to a person
  • Clarification and answering questions. Great customer service is a must and building that relationship between you and the person is important

However, don’t confuse ambiguity with curiosity. Curiosity is a good thing and when used right can be a powerful option to persuade someone as naturally we are curious and want to find out more. Sometimes it’s disappointing when we know everything. Where ambiguity comes into play is when there are two options available but both have the same outcome.

It is a fine balance between curiosity to entice people and then holding too much back that the user loses trust.

Cases where ambiguity could be impacting your business

If you are in marketing this bias should be taken in account as if you had a potential buyer and they knew a few companies who provide the same service then they may opt to go with the competitor over you. Even if you have the superior product, if the buyer doesn’t feel comfortable or has the level of trust needed then that could be the thing that loses you the deal.

If you are in design and user experience then think about call to action buttons, when you see the word “continue” and “click here” this doesn’t explain to the person what happens once they are clicked. This vagueness is not only confusing but can be off putting and could be impacting the experience the user has with your service.

If you are a sales person then be aware that the person you’re pitching to may know nothing or not enough to make a decision about you and your business. Sometimes it’s easy to forget that you know your product, business and offering inside and out but others may know nothing. Businesses offering “money back guarantee” and “free trial periods” are examples of where they remove the ambiguity and also tap into the curiosity bias because people would be curious to try a service out.

Further reading of cognitive biases

Thanks for reading about the ambiguity effect. As well as this bias I’ve also covered other cognitive biases that are available to read. I would recommend looking at the loss aversion article next as that is closely linked to the ambiguity effect:



Michael Gearon

Senior Interaction Designer and Co-Author to Tiny CSS Projects