Availability Heuristic

A type of cognitive bias where your judgments are influenced by what most easily comes to mind. How emotionally powerful, eccentric, or recent your memories are can make them more relevant to you. For example, when we see a news report about a shark attack or a plane crash, it can make us believe that these events are much more common than they actually are. These are both emotionally powerful events (i.e., the act of receiving this new, poignant information) as both present threats to life, which is something that most people take very seriously.


1) Allison was recently talking to her group of girlfriends about vaccines and one of them brought up the documentary “Vaxxed” and recommend that everyone in the group watch it. Further, she expounds a bit on the details and how she was alarmed by what she learned. Allison, who values her friend's opinion, as most would as friends carry a high degree of credibility, decides to watch the documentary as she is a new mother herself. Plus, over the next year, her young child will need to receive a number of vaccines as recommended by the CDC's vaccination schedule.

After watching the documentary, Allison now questions the safety of vaccines along with the credibility of the CDC. She then decides to cease her child's vaccinations moving forward even though her child has only had a fraction of the total recommended vaccines.

Explanation: Allison is clearly not thinking critically here. She just finished watching a documentary that essentially told her that vaccines are a threat to her child's life, which is going to elicit a very strong maternal instinct within her to protect her child. Consequently, this strong emotional response is causing her to make an irrational decision that is statistically more likely to cause harm to her child.

*Side note, the documentary “Vaxxed,” which I've seen, is nothing but anti-vaccine propaganda full of lies. Unfortunately, the average individual will watch this and leave thinking that there's some massive conspiracy with scientists and world governments to conceal a vaccine-autism link.

2) Terry is a big supporter of the current President, but is unsure about his claims surrounding global warming. In fact, Terry doesn't know much about global warming other than the scientific community doesn't agree with the President's stance on the issue. Furthermore, there's a special election being held in his state this week where he'll have to decided between a “denialist” (i.e., a common trope for someone who doesn't believe in global warming) or an “alarmist” (i.e., a common trope for someone who believes in global warming). At this point in time, Terry is undecided as he has always considered himself an independent voter.

It just so happens that the President has decided to have a rally in a neighboring town a day before the election. As Terry is a fan of the current President's work, he decides to attend. At the rally, the President goes on and on about how global warming is not caused by man and that it has been changing naturally throughout the Earth's history.

After the rally, charged by the President's claims that global warming is a hoax, he decides to do his own “research” on YouTube and comes across a plethora of videos which further confirm the President's statements. What is more, after all of the information that he has received lately about global warming, Terry has decided that this is a large voting issue for him. Thus, following the rally and his YouTube video “research,” Terry goes to the polls the next day and decides to vote for the candidate who denies global warming.

Explanation: Terry is clearly falling victim to the availability heuristic here. He starts off not knowing much about global warming and, ultimately, decides to vote for an individual who denies global warming as a result of attending a rally and viewing YouTube videos the day before. The rally along with the videos are fresh in Terry's mind as he headed to the voting booth, which absolutely influenced his decision on who to vote for.

3) Jessica is watching the evening news and a segment comes on about a recent scientific publication questioning the safety of GMO foods. While the news is discussing the results of the study, they display accompanying pictures of the rats that were used in the study and the grotesque cancerous tumors that they developed as a result of ostensibly being fed a GMO diet. For Jessica, this view of the tumors elicits a visceral response as cancer is prevalent within her family.

The next day, with the news story still fresh in her mind, Jessica goes grocery shopping and decides to purchase only food that has the Non-GMO Project label as she no longer wants to consume GMO foods.

Explanation: The availability heuristic is at work here again. Jessica, fueled by the recent information that she received from the news last night and the large emotional response evoked by the visuals of the tumors, has decided that she is only going to purchase foods with a Non-GMO Project label. She is doing this an attempt to ensure that she doesn't consume any GMO foods as she is now fearful of her health in regards to consuming these types of food.

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How to Minimize this Bias

Unfortunately, cognitive biases can never be completely eliminated, but they can be minimized. For this particular bias, it is important to stop and try to gain a more holistic perspective of the situation. That is, you're going to want to seek out as much information as possible about the particular topic of concern in an attempt to understand the bigger picture.

What is more, it is important to seek out the science if it exists and seek out multiple, credible scientific authority figures who are informed about this particular topic. These scientific authority figures act as a conduit for the information coming from the community and will be able to tell you the conclusion(s) reached from all of the scientific evidence gathered to date on the topic. Instead of relying on first impressions or doing what your “gut” is telling you, it is important to take these steps before making any decisions.

Now, let's re-evaluate the three scenarios above for the steps that each individual should have taken in order to minimize the effects of this bias.

1) Allison should have talked to her pediatrician before making this rash decision. If she had, the pediatrician would have assured her that all the science points to a very low risk for injury and an extremely high reward (i.e., the prevention of a possible life-ending infectious disease for not only her child, but for other members of the community as well) and that there is absolutely no vaccine-autism link [1].

2) Before choosing to vote for the “denialist,” Terry should have sought ALL information in regards to global warming, which would include the science of why humans are causing global warming. He would have then discovered that ~97% of all the science points to the conclusion that humans are causing global warming [2]. At the very least, Terry should have decided to not weigh global warming as such a large issue for him when casting his vote as he clearly wasn't well informed on this particular topic.

3) Jessica should have sought out the science on this particular topic before deciding to avoid GMO foods. If she had, she would have realized that, overwhelmingly, the science concludes that they're safe to consume [3]. Further, since she was using the Non-GMO Project label to guide her avoidance of GMO foods, she should have done a little research into the veracity of this label as it doesn't actually guarantee that the foods you're consuming are GMO free [4]. Taken directly from the label's website:

“Are products bearing the Non-GMO Project Verified seal “GMO Free”?
Unfortunately, “GMO Free” and similar claims are not legally or scientifically defensible due to limitations of testing methodology. In addition, the risk of contamination to seeds, crops, ingredients and products is too high to reliably claim that a product is “GMO Free.” The Project’s claim offers a true statement acknowledging the reality of contamination risk, but assuring the shopper that the product in question is in compliance with the Project’s rigorous standard. While the Non-GMO Project Verified seal is not a “GMO free” claim, it is trustworthy, defensible, transparent, and North America’s only independent verification for products made according to best practices for GMO avoidance.”


Cognitive biases are a constant threat to critical thinking as they are, unfortunately, always present due to our inherently flawed minds. However, there is still room for hope, as we've discussed here, once you have learned about the particular cognitive bias, there are steps that can be taken to minimize it. Moreover, as we've discussed previously, a cognitive bias is not the same as a logical fallacy.

If you find yourself being influenced by this cognitive bias, it doesn't automatically mean that the argument you subsequently construct will be bad. This does mean, however, that there is a strong possibility that the argument is not the best argument. As a Critical Thinker, you should take a moment to re-evaluate the situation/topic after you've thoroughly conducted a holistic investigation. Only then can you be confident that the availability heuristic isn't leading you down an irrational path.


[1] Taylor, Luke E., Swerdfeger, Amy L., Eslick, Guy D, Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies. Vaccine (2014) Volume 32, Issue 29.

[2] Cook et. al. Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters (2016) Volume 11, Number 4.

[3] National Academies of Sciences, Engineering, and Medicine. 2016. Genetically Engineered Crops: Experiences and Prospects. Washington, DC: The National Academies Press. https://doi.org/10.17226/23395.

[4] Non-GMO Project, Verification FAQs.