How many animals are killed every year for food in the U.S., and worldwide? If you have no idea, you are not alone: people are still finding these numbers hard to grasp.

Let’s start with the answers: every year approximately 10 billion terrestrial animals are slaughtered in the U.S. (data from 2011). For comparison, 7.5 billion are killed in the European Union (data from 2014), and 65 billion worldwide. This is, of course, if we exclude fish, who are killed by the trillions.

The numbers are staggering, which is probably one of the reasons why they can be difficult to remember. However, according to this study, there are other, more complex explanations. Educators, as well as the animal advocacy and veg*n movements, must take these explanations into account if they want to improve their effectiveness in driving positive change for animals.

According to the study, there is institutionalized pressure on consumers – from the livestock industry as well as from governments – not to reflect too much on how food is produced. Farmed animals live and die away from public scrutiny, and the final products no longer resemble in shape or name the animal(s) from whom they are obtained. The author of the study contends that the other negative effects of livestock farming beyond animal suffering, such as environmental degradation or climate change, also appear to have a limited effect on the degree of awareness of U.S. citizens.

According to the authors, previous studies have reported that most people in the U.S. are still oblivious to the consequences of industrial livestock production. Apparently, the same applies to university students. The study reports the results of an experiment carried out at one private New Jersey University, where seven groups of 1st year sociology students were given a lecture on speciesism that included data on the number of animals slaughtered for food annually in the U.S. and worldwide. The students were advised that they would earn extra academic credits by answering one exam question on the speciesism lecture.

Of the 155 students that answered the question in the final test, 66% underestimated the number. The median response was 65 million, which represents a tiny 0.006% of the real number of terrestrial animals killed for food in the U.S. in 2011 (10 billion). Even more surprisingly, the bottom 10% of the students averaged 24,667 animals as an estimate. There were no differences in the responses based on gender, but students with higher scores in the exam overall gave the most realistic responses.

The scope of the experiment was limited, but one conclusion was that even within the intellectually privileged population of university students there is a high resistance to acquiring new information on the scale of livestock farming. In this case the author did not use graphic images to illustrate the lecture. However, even extra college credit did not motivate the students enough to retain information on slaughter rates of farmed animals. This gives an indication of the difficulty of, in the words of the author, “putting a dent in the dissonance” of average citizens and consumers.

The study suggests that a continuous effort to educate the general public via multiple sources (media, scientific evidence, advocacy) could have strong results in the long run. Even concerned citizens who declare a genuine interest for the way farmed animals are treated may eventually become affected by what the author calls “enlightenment fatigue”, being tired of too much (harsh) truth. This fatigue can lead some people to disengage with animal suffering and continue in their habits without further questioning them. Changing the situation will require constant work on the part of educators and advocates.