Availability heuristic: when our memory fails animals

Availability heuristic: when our memory fails animals

Heuristics are mental shortcuts that provide fast responses to problems that would otherwise require time to solve. They are psychological ways to save us the trouble of thinking more deeply about complex problems. One example of this is the availability heuristic, which is a shortcut that causes people to make judgments about the probability or frequency of events based on how easily they remember examples of them. The problem with this is that it often drives us to make wrong assessments. This is so in many cases where animals and their defense are involved.

Because of the availability heuristic, we have a tendency to attribute more importance to certain issues according to the ease with which we can remember instances of them. That is, occurrences that are more easily retrieved will appear to us as more relevant or representative than instances that are less retrievable. But it often happens that the more easily retrievable instances are not really relevant or representative of the issue at stake. In this way, the availability heuristic leads us to make biased and wrong decisions.

An example concerning what happens to animals in nature

Let’s consider an example to see how the availability heuristic works. Stop for a moment and try to name, off the top of your head, the most common cause of mortality in sea turtles. It’s very likely that this inquiry will trigger a search of memory, and we can expect that you will recall with relative ease stories about sea turtles entangled in fishing gear, poaching and illegal trade of turtle meat and shells, ingestion of plastic debris, ocean pollution, global warming, oil spills, or turtles accidentally killed as bycatch in fishing trawlers.

The truth, however, is that none of these threats are actually the way the vast majority sea turtles die in the wild. In stable sea turtle populations, it is estimated that only 1 in 1000 hatchlings makes it to adulthood,1 and the vast majority of sea turtles die during their first hours, days or weeks of life. The high mortality rates for hatchlings and juveniles are usually due to attacks by ghost crabs, lizards, snakes, raccoons, seagulls, frigatebirds, fishes, and other marine animals, or simply due to the heat of the sun (if they emerge from nests during daylight).2

The problem here is that when we search our memory for mortality causes in sea turtles we tend to judge their relevance by the easiness with which instances of deadly threats come to our mind. This tendency to rely on the ease of memory search is a case of an availability heuristic error.

The availability heuristic thus helps explain why some problems that affect nonhuman animals are much more prominent in people’s minds while others are totally neglected, even by animal advocates. Our tendency to attribute more importance to certain issues according to the ease with which we can retrieve instances from our memory is largely influenced by the extent of coverage in the media.

The public interest is most easily stirred by unusual, exceptional, or dramatic events. On the other hand, more ordinary forms of suffering and premature deaths caused by harmful natural processes, such as starvation, disease, or predation, are so common they are rarely reported by the media, or when they are, they tend to be trivialized under the biased assumption that deadly or distressful conditions somehow matter less simply because they are “natural,” unlike anthropogenic harms which tend to be overrepresented in news stories. In our example, less than 1% of all sea turtles who are born in the wild are ever affected by pollution or poaching by humans. The overwhelming majority (over 99%) die prematurely due to natural harms without making it to the headlines.

A psychological explanation of the availability heuristic

The availability heuristic, like other shortcuts of judgment that we use when we think, replaces one question for another. So instead of estimating the frequency of an event, we will just report an impression of the ease with which instances come to our mind. The substitution of questions, however, inevitably produces systematic errors.

The study of heuristics was advanced in the 1970s by Israeli psychologists Amos Tversky and Daniel Kahneman. In their seminal paper from 1973, “Availability: A heuristic for judging frequency and probability,” they describe a study on the judgment of word frequency where the majority of subjects reported that there were more words in the English language that start with the letter K than words with K as the third letter. Because it is much easier to recall words that begin with a certain letter than words that have the same letter in the third position, Tversky and Kahneman expected respondents to exaggerate the frequency of letters appearing in the first position, and that is exactly what happened. In reality, there are twice as many words in the English language that have K as the third letter as those that start with K, but words that start with K are brought to mind much more easily. The reliance of respondents on the availability heuristic produced a predictable biased judgment.3

Different factors can affect the retrievability of instances. For example, the impact of seeing a rabbit being killed in person is probably greater than the impact of merely reading news or statistics about rabbits who are dying due a fatal disease in nature. Likewise, recent events are also likely to be more easily retrieved than earlier occurrences, so, for example, if asked to report an instance of intense animal suffering, one may be more inclined to report the recent case of a dog who was brutally murdered in a bizarre ritual rather than the burning of an entire pig farm that killed thousands of animals just a few months earlier.

Stories about cruel experiments with lab animals or the appalling situation of chickens cramped in factory farms attract much attention from animal advocates, and those instances will come more easily to mind than other cases of animal suffering and violent deaths that are either downplayed or go underreported by the media, such as the mass killings, for conservation purposes, of animals who belong to “invasive species.”

Several influential studies of availability biases were also carried out by psychologists Paul Slovic, Sarah Lichtenstein, and Baruch Fischhoff. In their studies, tornadoes, for instance, were seen by overconfident respondents as “more frequent killers than asthma, although the latter causes 20 times more deaths. Death by lightning, on the other hand, was judged less likely than death from botulism even though it is 52 times more frequent.”4

The main lesson from their studies is that estimates of causes of death are warped by media coverage that shapes what the public is interested in. There is a bias toward novelty and toward poignancy,5 due to which unusual events receive more attention than they would actually receive according to their relevance or of how representative they are.

The availability heuristic and our failure to make informed decisions that impact nonhuman animals

The availability heuristic can seriously affect our perception about nonhuman animals and hinder our ability to tackle problems that affect them in an effective way. For instance, because humans commonly share their homes with cats and dogs or may have also had intense personal experiences in rescuing and rehabilitating abandoned “companion” animals, their expectations about the frequency of events that affect cats and dogs may be distorted by the emotional intensity of their own experiences. One may therefore feel more inclined to perceive the situation of abandoned animals such as cats and dogs as a more pressing issue that requires more support than other issues that affect a much greater number of nonhuman animals. According to Animal Charity Evaluators, “of all animals used and killed by humans in the United States, over 99.6% are farmed animals, about 0.2% are animals used in laboratories, 0.07% are used for clothing, and 0.03% are killed in companion animal shelters. However, about 66% of donations to animal charities in the United States go to companion animal shelters, 32% go to groups with mixed or other activities, and just 0.8% of donations go specifically to farmed animal organizations, while 0.7% go to laboratory animal organizations.”6 (Note also that this assessment sets aside animals living in the wild, which are significantly more numerous than the ones exploited by human.)

The takeaway here is that, among other things, we shouldn’t just trust our personal experiences, as they may catch a disproportionate amount of our attention and cause us to make bad judgments. We should instead look more carefully at statistics and allocate resources accordingly in order to make better-informed decisions, which can potentially impact a lot more animals.

But it is not just the animals humans exploit that are affected by our biased assessments. As we have seen in the case of sea turtles, we can easily overlook issues that affect a large amount of animals simply because they don’t attract much attention from the media. Another example relates to the reasons why so many people still hold the unrealistically optimistic view that animals live good lives in the wild: most people don’t have an accurate image of the animals who live in nature, in particular, their relative population numbers.

The public tends to be heavily influenced by images and narratives reported by the media, which help create and reinforce a distorted view of animal populations. When people think of an animal living in the wild, most of them visualize a big adult mammal, or maybe some other vertebrate. But they are a tiny minority of the animals living in the wild. Most mammals are small rodents, most vertebrates are fishes, and most animals are invertebrates. Moreover, the overwhelming majority of animals are very young ones who have just begun to exist and who die shortly afterwards. This inaccurate view is detrimental to animals, as it contributes to the misconception that animals live mostly good lives in nature. This view leads to a lack of concern about the harms they suffer and a consequent lack of interest in discovering ways to help them.

Animal advocates themselves may also feel inclined to give more attention to certain problems that victimize nonhuman individuals while completely overlooking others. For example, if we were to ask animal activists to list three different places where animals are routinely harmed and killed, most of them would probably find the question very easy and could promptly mention slaughterhouses, vivisection laboratories, or fur farms. But this is not really representative of the number of animals killed by humans in different fields. If we wanted to list the fields where more animals are killed, we would have to mention first commercial fishing and fish factories, and then slaughterhouses and recreational fishing. Moreover, if instead we would ask the same people to name the main reasons why animals suffer in nature, that would probably be perceived as a more difficult question. And it would be much harder to mention, say, three diseases from which animals in the wild typically die.

But because we hope that in the future animals in nature will suffer and die less from terrible common diseases such as rabies, mange, or tuberculosis, we have very good reasons to raise awareness about their unfortunate situation now, just like we do in the case of exploited animals. Building a deeper understanding about the situation of animals in nature can both decrease the neglectedness and help increase the tractability of many problems that affect those animals. This is because making the plight of wild animals more visible to the public eye challenges the speciesist status quo that prevails in the scientific and academic communities, which delays our ability of safely helping more and more animals in need due to a lack of progress in research.

The availability heuristic and the unjustified disregard for the future

Most people have a tendency to focus on what happens in the present or what will happen in the near future, rather than on the far future. However, it’s likely that sentient beings will exist for many, many years from now, and there’s a risk that they may be facing very bad situations. This is something we should worry a lot about, as the harms future sentient beings may suffer are potentially much more significant than the ones that present ones endure.7

Unfortunately, many people don’t care about what will happen in the far future. In fact, most aren’t even aware that this is a serious issue. One of the most important reasons why this happens is the availability heuristic, because when they think of possible beings who we may benefit, what comes to their minds are beings who currently exist, rather than future ones.

Resisting the availability heuristic and giving equal consideration to all sentient beings

Psychologists warn that, although possible, resisting potential availability biases is mentally strenuous. The conscious exercise for avoiding systematic cognitive errors may require more effort than usual. We must, however, try to regularly evaluate our impressions and gut feelings by asking important questions that may challenge our perceived knowledge or beliefs in relation to problems that victimize nonhuman animals. Memories fade over time and so do our carefulness and criticism.

The availability bias makes us feel overconfident about certain issues that affect a large number of animals and completely indifferent or complacent about many others. For that reason, in order to improve our efforts to defend sentient beings we should be more vigilant against potential biases due to the pitfalls of our memory.

Further readings

Carroll, J. S. (1978) “The effect of imagining an event on expectations for the event: An interpretation in terms of the availability heuristic”, Journal of Experimental Social Psychology, 14, pp. 88-96.

Caruso, E. M. (2008) “Use of experienced retrieval ease in self and social judgments”, Journal of Experimental Social Psychology, 44, pp. 148-155.

Fox, C. R. (2006) “The availability heuristic in the classroom: How soliciting more criticism can boost your course ratings”, Judgment and Decision Making, 1, pp. 86-90 [accessed on 4 January 2018].

Gilovich, T. D.; Griffin, D. & Kahneman, D. (2002) Heuristics and biases: The psychology of intuitive judgment, New York: Cambridge University Press.

Greifeneder, R. & Bless, H. (2007) “Relying on accessible content versus accessibility experiences: The case of processing capacity”, Social Cognition, 25, pp. 853-881.

Greifeneder, R. & Bless, H. (2008) “Depression and reliance on ease-of-retrieval experiences”, European Journal of Social Psychology, 38, pp. 213-230.

Greifeneder, R.; Bless, H.; Pham, M.T. (2011) “When do people rely on affective and cognitive feelings in judgment? A review”, Personality and Social Psychology Review, 15, pp. 107-141.

Harvey, N. (2007) “Use of heuristics: Insights from forecasting research”, Thinking & Reasoning, 13, pp. 5-24.

Hayibor, S. & Wasieleski, D. M. (2008) “Effects of the use of the availability heuristic on ethical decision-making in organizations”, Journal of Business Ethics, 84, suppl. 1, pp. 151-165.

Hulme, C.; Roodenrys, S.; Brown, G. & Mercer, R (1995) “The role of long-term memory mechanisms in memory span”, British Journal of Psychology, 86, pp. 527-536.

Keller, J. & Bless, H. (2008) “Predicting future affective states: How ease of retrieval and faith in intuition moderate the impact of activated content”, European Journal of Social Psychology, 38, pp. 1-10.

Manis, M.; Jonides, J.; Shedler, J. & Nelson, T. (1993) “Availability heuristic in judgments of set size and frequency of occurrence”, Journal of Personality & Social Psychology, 65, pp. 448-457.

Ofir, C.; Raghubir, P.; Brosh, G.; Monroe, K. B. & Heiman, A. (2008) “Memory-based store price judgments: The role of knowledge and shopping experience”, Journal of Retailing, 84, pp. 414-423.

Read, J. D. (1995) “The availability heuristic in person identification: The sometimes misleading consequences of enhanced contextual information”, Applied Cognitive Psychology, 9, pp. 91-121.

Riddle, K. (2010) “Always on my mind: Exploring how frequent, recent, and vivid television portrayals are used in the formation of social reality judgments”, Media Psychology, 13, pp. 155-179.

Ross, M. & Sicoly, F. (1979) “Egocentric biases in availability and attribution”, Journal of Personality and Social Psychology, 37, pp. 322-336.

Rotliman, A. & Schwarz, N. (1998) “Constructing perceptions of vulnerability: Personal relevance and the use of experiential information in health judgments”, Personality and Social Psychology Bulletin, 24, pp. 1053-1064.

Ruder, M. & Bless, H. (2003) “Mood and the reliance on the ease of retrieval heuristic”, Journal of Personality and Social Psychology, 85, pp. 20-32.

Schwarz, N.; Bless, H.; Strack, F.; Klumpp, G.; Rittenauer-Schatka, H. & Simons, A. (1991) “Ease of retrieval as information: Another look at the availability heuristic”, Journal of Personality and Social Psychology, 61, pp. 195-202.

Shedler, J. & Manis, M. (1986) “Can the availability heuristic explain vividness effects?”, Journal of Personality and Social Psychology, 51, pp. 26-36.

Sjöberg, L. & Engelberg, E. (2010) “Risk perception and movies: A study of availability as a factor in risk perception”, Risk Analysis, 30, pp. 95-106.

Stepper, S.; Strack, F. (1993) “Proprioceptive determinants of emotional and nonemotional feelings”, Journal of Personality and Social Psychology, 64, pp. 211-220.

Vaugh, L. A. (1999) “Effects of uncertainty on use of the availability of heuristic for self-efficacy judgments”, European Journal of Social Psychology, 29, pp. 407-410.

Wänke, M.; Schwarz, N. & Bless, H. (1995) “The availability heuristic revisited: Experienced ease of retrieval in mundane frequency estimates”, Acta Psychologica, 89, pp. 83-90.

Weick, M. & Guinote, A. (2008) “When subjective experiences matter: Power increases reliance on the ease of retrieval”, Journal of Personality and Social Psychology, 94, pp. 956-970.


1 Spotila, R. (2004) Sea turtles: A complete guide to their biology, behavior, and conservation, Baltimore: Johns Hopkins University Press.

2 Dial, B. E. (1987) “Energetics and performance during nest emergence and the hatchling frenzy in loggerhead sea turtles (Caretta caretta)”, Herpetologica, 43, pp. 307-315 [accessed on 19 January 2018]. Frick, M. G. (2003) “The surf crab (Arenaeus cribrarius): A predator and prey item of sea turtles”, Marine Turtle Newsletter, 99, pp. 16-18. Hammerschlag, N.; Broderick, A. C.; Coker, J. W.; Coyne, M. S.; Dodd, M.; Frick, M. G.; Godfrey, M. H.; Godley, B. J.; Griffin, D. B.; Hartog, K.; Murphy, S. R.; Murphy, T. M.; Nelson, E. R.; Williams, K. L.; Witt, M. J. & Hawkes, LA. (2015) “Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape”, Ecology, 96, pp. 2117-2126. Moran, K. L.; Bjorndal, K. A. & Bolton, A. B. (1999) “Effects of the thermal environment on the temporal pattern of emergence of hatchling loggerhead turtles (Caretta caretta)”, Marine Ecology Progress Series, 189, pp. 251-261 [accessed on 12 January 2018]. Tomillo, P. S.; Paladino, F. V.; Suss, J. S. & Spotila, J. R. (2010) “Predation of leatherback turtle hatchlings during the crawl to the water”, Chelonian Conservation and Biology, 9, pp. 18-25. Witzell, W. N. (1981) “Predation on juvenile green sea turtles, Chelonia mydas, by a Grouper, Promicrops lanceolatus (Pisces; Serranidae) in the Kingdom of Tonga, South Pacific”, Bulletin of Marine Science, 31, pp. 935-936 [accessed on 21 January 2018].

3 Tversky, A. & Kahneman, D. (1973) “Availability: A heuristic for judging frequency and probability”, Cognitive Psychology, 5, pp. 207-232.

4 Kahneman, D. (2011) Thinking, fast and slow, New York: Farrar, Straus and Giroux.

5 Kahneman, D. (2011) Thinking, fast and slow, op. cit..

6 Animal Charity Evaluators (2016) “Why farmed animals?”, Animal Charity Evaluators [accessed on 13 January 2018].

7 Tomasik, B. (2011) “Risks of astronomical future suffering”, Foundational Research Institute [accessed on 18 January 2018]. Beckstead, N. (2013) On the overwhelming importance of shaping the far future, New Brunswick: Rutgers [accessed on 9 January 2018]. Baumann, T. (2017) “S-risks: An introduction”, Reducing Risks of Future Suffering, August 15 [accessed on 20 January 2018].