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Ambiguity Bias

Ambiguity Bias


The ambiguity bias refers to where people avoid options with missing information because it makes the choice feel risky. The effect suggests that people have a preference for options where there is a known probability of a favourable outcome.

In conversion the ambiguity bias means people may abandon a site or choice if they don’t understand the product/offer or are uncertain about the next step. People hate uncertainty and will avoid it at all costs.

Unclear call to action labels can result in the ambiguity bias reducing your conversion rate. Text such as “Submit”, “Continue” or copy that does not relate to the information being requested can cause confusion and friction in the user journey.

Image of submit call to action from Ladbrokes.com

Image source: Ladbrokes.com

Not having consistent messaging throughout a user journey may also create a lack of clarity. Here is a deposit user journey from Guts.com. The first screen after registration clearly indicates that a deposit bonus is available. However, once the customer selects their payment method (2) and lands in the cashier (3) there is no mention of a deposit bonus, but there is an empty “Enter bonus code” field.

Image of user journey with empty bonus code field which could suffer from ambiguity effect

Image source: Guts.com

This creates uncertainty about whether a bonus code needs to be entered or will the bonus be automatically allocated. This is unclear and could result in customers abandoning making a deposit as they go in search of a bonus code.


People hate uncertainty and the ambiguity bias is a demonstration of this human trait. Ensure you use clear language on your CTAs that relates to the action that results from clicking on the button. Consistent messaging throughout the user journey can also reduce uncertainty.

Further, pre-fill discount code input fields if possible or remove them from sign-up forms altogether unless they are absolutely necessary. It is better to automatically apply discounts if users qualify for them to minimise uncertainty and maximise customer satisfaction with the process. Getting users to manually enter discount codes may reduce redemption rates but it will reduce satisfaction among those customers who forget to apply the code.


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