The Overkill Backfire Effect: on the Danger of Having Too Much Evidence

The Overkill Effect


The overkill backfire effect is a cognitive bias that causes people to reject arguments that they think are too complex, in favor of arguments that are easy for them to understand. Often, this means that past a certain point, presenting additional evidence in support of your argument can actually make people less likely to accept it.

In the following article, you will learn why people are susceptible to this effect, and how you can reduce the risk of them being influenced by it when you present an argument.


What is the overkill effect

The overkill backfire effect is a cognitive bias that causes people to prefer explanations which are easy for them to understand, over explanations that are difficult for them to process.

An example of the overkill effect would be that if you gave someone 10 pieces of evidence that explain why a certain belief of theirs is wrong, then they would be less likely to change their mind on the topic than if you gave them only 3 pieces of evidence.

Since the overkill effect represents a situation where an attempt to change someone’s opinion by providing them with information ends up backfiring, it is a type of a backfire effect, which is a cognitive bias that causes people to strengthen their support for their original belief when they are faced with evidence that suggests that those beliefs are wrong.

The backfire effect in itself represents a type of a confirmation bias, which is a cognitive bias that causes people to search for, interpret, and remember information in a way that supports their preexisting beliefs.


Why we experience the overkill effect

Simply put, because it is more cognitively taxing to process a large number of complex arguments, the more information you present in support of your stance past a certain point, the lower the likelihood that the person you are talking to will be able to successfully internalize that information, and the lower the likelihood that they will agree with your overall argument. As such, while you might intuitively want to present as much evidence as possible in order to support your stance, adding a lot of arguments is often counterproductive.

For example, in one study on the topic researchers asked participants to think of reasons that could explain why a certain belief of theirs is wrong. They found that while asking people to generate only a few reasons was often effective in getting them to change their belief, asking them to generate many reasons had an opposite effect, meaning that it often caused participants to reinforce their original stance.

This is especially an issue when trying to refute common myths and misunderstandings, since many of them offer a simple and compelling truth, which contrasts sharply with the large amount of complex scientific evidence needed to debunk them. As one paper on the topic states: “simple myths are more cognitively attractive than lengthy, complicated refutations”.


How to avoid the overkill effect

Simplify your argument

To avoid the overkill effect, you want to simplify your arguments as much as possible given the circumstances, while still presenting a cogent stance. This means that when you present your argument, you need to ensure that it is clear and concise, without any unnecessary technical jargon. Furthermore, if you’re presenting any statistical information, try to explain it in simple terms, in order to make it easier for your recipient to understand.

For example, if you are in a situation where you need to use a simple explanation, don’t say:

SLA studies on L1 transfer during L2 acquisition show a crosslinguistic influence from the L1. For example, recent study which examined transfer of definite and indefinite articles showed that 68.3% of the population (based on a representative sample) will experience transfer on statistically-significant level (at p < .05) during L2 acquisition, and that this phenomenon appears throughout the A1-B2 CEFR range of L2 proficiency levels.

Instead, try to avoid the complex jargon and statistics in the above explanation, and say something along the lines of:

Studies show that you native language influences you when you learn a new language. For example, a recent study which looked at the acquisition of articles, which are words like “the” and “a”, showed that two-thirds of the people learning a new language will experience such a “transfer” effect from their native languaguage, and that this occurs primarily for people who have not yet mastered the new language.

If you find that you need to simplify this explanation even further, you can try saying something along the lines of:

Your native language often influences you when you learn the words and grammar of a new language, though this is less likely to happen once you get really good.

Remember that how much you should simplify your arguments depends on the circumstances. As such, you would use a slightly different explanation when talking to a random guy in a bar than you would when giving a talk at an academic conference.

Doing this properly ensures that you present your argument in a way that the other person can easily understand, which makes them more likely to accept your stance. An added advantage is that if you start with a simple explanation, you can always add more details later, if you see that the people you are talking to have questions, or want to know more. However, if you start with an overly complex explanation, people will often lose interest in the topic.

Finally, keep in mind that a simpler explanation will not always be shorter. Sometimes, it takes more words to explain something in a simple, especially if you end up omitting a lot of the terminology. This is okay, and while you do want to be concise, your main focus should be on explaining things in a way that is easy to understand.


Focus on your key points and your strongest evidence

In addition, you should make sure to focus on only a few key points when supporting your stance. This ensures that you give your recipient enough information to convince them, without causing them to feel overwhelmed by all the new information.

One advantage of doing this is that you can always add more evidence later on if necessary. Conversely, if you start by providing too much evidence, you will find it relatively difficult to retract the things you said, both because it is perceived as negative by listeners, and because the people that you talk to will have already felt that your argument was too overwhelming.

Focusing on your strongest evidence also has the added advantage of making it harder for your opponent to use strawman arguments against you. This is because using strawman arguments often involve cherry-picking the weaker aspects of your claim, and arguing against them as if they represent your entire stance. When you only include the strongest pieces of evidence in your argument, it makes you less vulnerable to this rhetoric technique.

Based on this, if you have 5 pieces of evidence in support of your stance, 3 of which are “strong” and 2 of which are “weak”, you will generally be better off discussing only the 3 “strong” points, while avoiding the weaker ones. This also helps simplify your argument overall, which, as we saw earlier, should be presented in a clear and concise manner, and if necessary, simplified in order to make it easily intelligible to your target audience.


You are also susceptible to the overkill effect

It’s important to remember that we are all human, and are therefore all susceptible to the overkill effect. As such, it’s important to take the potential influence of this cognitive bias into consideration when you’re listening to arguments presented by other people.

Specifically, try to identify cases where you automatically accept the argument which is simpler and appealing, without giving full consideration to the more complex arguments that you heard. Then, make sure to actually consider the complex arguments, and try to simplify them, using the same techniques that you would use if you were presenting them to someone else.


Summary and conclusions

  • The overkill effect is a cognitive bias that causes people to reject arguments that are complex in favor of arguments that are easy to understand.
  • This occurs because it is cognitively taxing to process a large amount of complex information, and people often reject arguments that are difficult for them to process.
  • This means that for a lot of people, once they reach their cognitive saturation point, seeing more evidence in support of a certain argument might actually reduce the likelihood of them being convinced by that argument.
  • To avoid the overkill effect, simplify your arguments as much as possible given the circumstances, and make sure to use clear language, while avoiding unnecessary technical terminology and overly-complex statistics.
  • In addition, make sure to focus on only the strongest pieces of evidence that you have, rather than mentioning all the available evidence from the start. Doing this will not only reduce the likelihood of an overkill effect, but will also make it more difficult for your opponent to use strawman arguments against you, where they focus on your weakest pieces of evidence in order to attack your overall stance.