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

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. For example, the overkill effect could cause someone to reject a complex scientific explanation for a certain phenomenon, because a certain myth that is often used to explain it is easier to accept.

Accounting for this bias is important, because it means that past a certain point, presenting additional evidence in support of your argument can actually make people less likely to accept it. As such, in the following article, you will learn more about the overkill effect, understand why people are susceptible to it, and see how you can reduce the risk of people being influenced by this bias when you present them with an argument.


Understanding the overkill backfire effect

The overkill backfire effect could mean, for example, that presenting someone with 10 arguments that explain why their misconception is wrong, could be less effective than only presenting them with 3 arguments on the topic, since people generally prefer explanations that are simpler and easier for them to process.

Since the overkill effect represents a situation where an attempt to change someone’s opinion by providing them with new information ends up backfiring, it is considered to be a subtype of the 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, favor, interpret, and remember information in a way that supports their preexisting beliefs.


Why people experience the overkill backfire effect

Simply put, since 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 stance.

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 belief in 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 backfire effect

Simplify your argument

To avoid the overkill backfire effect, you want to simplify your arguments as much as possible given the circumstances, while still presenting a cogent stance overall. This means that when you present your argument, you need to ensure that it is clear and concise, and doesn’t contain any unnecessary technical jargon. Furthermore, if you’re presenting any statistical information, you should 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, a 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 a statistically-significant level during L2 acquisition (at p < .05). Furthermore, this study also showed that the L1 transfer will occur throughout the A1-B2 CEFR range of L2 proficiency levels.

Instead, try to avoid using complex jargon and statistics, by saying something along the lines of:

Studies show that your 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 your proficiency in the new language improves past a certain point.

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

Simplifying your argument 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 of doing this is that if you start with a simple explanation, you can always add more details later on, if you see that the people you are talking to has questions, or wants 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 necessarily be shorter than a longer one. Sometimes, it takes more words to explain something in simple terms, especially if you end up omitting a lot of the technical terminology. This is okay, and while you should strive 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 on your strongest evidence

In order to minimize the chance of an overkill effect, you should also make sure to focus on only a few key points when presenting your stance. This ensures that you give your recipient enough information in order to convince them successfully, without causing them to feel overwhelmed.

One advantage of starting with only your key arguments is that you can always add more evidence later on if you find that it’s necessary. On the other hand, if you provide too much evidence from the start, you will find it relatively difficult to retract that evidence later, especially if the person that you are talking to ends up feeling overwhelmed.

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 involves focusing on weaker aspects of your claim, and arguing against them as if they represent your entire stance. Therefore, 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 helps ensure that your argument is strong and easy to understand, while also ensuring that it contains enough supporting evidence.


Remember that you are also susceptible to the overkill backfire 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 therefore more appealing, without giving full consideration to the more complex arguments that you heard. Then, make sure to actually consider the more complex arguments, and try to simplify them, using the same techniques that you would use if you were presenting them to someone else.


Caveats about the overkill backfire effect

While there is evidence of the overkill backfire effect in some cases, research also indicates that it isn’t expected to occur in every situation.

For example, one study on the topic found that providing people with a relatively large number of counterarguments (4-6) led to equal or better belief reduction than providing people with a relatively small number of counterarguments (2).

This suggests that whether or not the overkill backfire effect will occur depends on various factors, such as the people involved, the topic being discussed, and the nature of the counterarguments being provided.


Summary and conclusions

  • The overkill backfire effect is a cognitive bias that causes people to reject arguments that are complex in favor of arguments that are easier for them to understand.
  • People experience the overkill effect because they often prefer to select an argument that is less taxing for them to process from a cognitive perspective.
  • The overkill effect means that, past a certain point, seeing additional evidence in support of a certain stance could make people less likely to accept that stance.
  • To avoid the overkill effect, you should 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.
  • You should also make sure to focus on only the strongest pieces of evidence that you have, rather than mentioning all the available evidence from the start. In addition to reducing the likelihood of an overkill effect, doing this also makes it more difficult for your opponent to use strawman arguments against you.