Skip to main content

Verified by Psychology Today

Horoscopes, Conspiracy Theories, and Your Left Hemisphere

Humans excel in pattern matching—even when those patterns are not there.

Key points

  • Humans love finding patterns in data, even if these patterns are not there.
  • Whereas (non-human) animals go for rational choices, humans stay with irrational choices even when the environment is uncertain.
  • Neuroscience research suggests that humans confabulate stories due to a left-hemisphere interpreter.

It took me a while, but I managed to identify your zodiac sign as determined by the sign the sun was in at the time of your birth. Knowing your zodiac sign, I managed to construct your horoscope for today:

You have feelings of uncertainty at the moment. You may wonder whether you are able to handle your family life and your work and even feel overwhelmed by the problems of the world. These feelings, however, will soon transform into feelings of empowerment, where you feel you take back control of your family and work life and are able to face the world’s problems. You and your strength are what matters today.

If you indeed felt empowered by today’s horoscope, you might also wonder how I was able to know your sign. You might even wonder how I predicted what day you would be reading your horoscope as this blog was not written knowing when you read it (though if I were able to predict your zodiac sign, I might also be able to predict when you are reading this page). And yet, today’s horoscope seems so applicable to you.

From horoscopes to conspiracy theories turns out to be a small step

Like horoscopes, conspiracies seem to work best if they seem applicable to you. If somebody told us there was a potential problem with the 2021 election results in a voting office in Georgia, it may pique our interest, particularly if the outcome of the election nationwide is not yet certain. And if we were also to learn about a problem in a voting office in Arizona, we might get more interested. Two problems in one day; that can hardly be a coincidence.

In fact, these two incidents, whether they are true or not, might indicate something more substantial. If there is smoke, there is fire! There might be a more general and more substantial problem with the 2021 election! And if somebody were to claim the elections are rigged, it just adds up to the evidence. It is easy to buy into that conclusion, particularly if the party we so believe in is losing. From bits and pieces of information, we start to slowly but surely build a pattern, and once we see that pattern, we will not let go. Whether it is a horoscope or a conspiracy theory.

The problem is that we do so well with picking up patterns that we are even able to find patterns when they are not there. Let’s illustrate this with a pattern unrelated to your personal life and sign, and unrelated to your political beliefs. Imagine you are presented with a series of lights being flashed at you, alternating between green and red, like the first row in the picture below. If an experimenter asked you what the most likely color would be at the end of the first-row sequence, you likely have little difficulty giving the right answer: green. The lights alternate from green to red, and quickly a pattern emerges. You might not even need 11 colors flashed at you to come to that conclusion.

Source: MaxLouwerse

Now consider the second row. What is the more likely color at the end of this sequence? Most of us will answer the most likely color is green. After all, the color red has been flashed at us for so long that the next obvious color needs to be green. That doesn’t seem too hard either.

Pigeons come to a very different conclusion. They would choose the color red. And that is a much more rational answer. If 82 percent of the colors being flashed at you are red, the most likely successor in the sequence is red. Whereas (non-human) animals go for frequency, humans will go for a pattern. Whether the pattern is there or not, we desperately work towards a pattern we may think is there. And the more uncertain the environment we operate in, the more likely we will go for a pattern even though frequency is the more rational choice.

Pattern matching and the brain

It may be a stretch, but hey, we are talking patterns here, so let me link this to some neuroscience research. In extensive neuroscience research on split-brain patients, Michael Gazzaniga found that patients confabulated stories from pieces of information they hardly had access to. He came to the conclusion that these patients are involved in a post-hoc sense-making activity. They make up a pattern even if it is not there. Moreover, Gazzaniga and his team were able to identify the location of this post-hoc making-sense activity: in the left hemisphere of these patients. He called this activity the left-brain interpreter. This left-hemisphere interpreter is responsible for confabulating stories, making things up from pieces of information, for finding patterns even if they are not there.

There is also a right-hemisphere interpreter. However, the right hemisphere creates an accurate record of the past, for instance making sense of the visuospatial world, the left hemisphere confabulates and guesses. The right hemisphere is visually more intelligent than the left, but the left hemisphere makes sense of the linguistic and cognitive world.

I find our post-hoc sense-making, pattern-matching ability fascinating. It shows that even though we think we are very rational, in fact, we are only rational to make sense of the world post-hoc. For instance, it might explain how we understand the stories we hear and see. Even if the chronology of a movie is interrupted, we have little difficulty piecing together the story trying to make sense of the bits and pieces of information, and form a pattern. If you missed that one episode in your favorite television series—unlikely these days thanks to our streaming services—you would be able to reconstruct the storyline in a heartbeat, thanks to a post-hoc sense-making, pattern-matching ability.

So, the next time you consider believing that conspiracy theory, you may have found somebody to blame. Next time you start paying attention to today’s horoscope, you know who may be responsible for knowing you so well. Your left-hemisphere interpreter.


Gazzaniga, M. S. (2018). The consciousness instinct: Unraveling the mystery of how the brain makes the mind. Farrar, Straus and Giroux.

Louwerse, M.M. (2021). Keeping those words in mind: How language creates meaning. Prometheus Books.

More from Psychology Today

More from Max Louwerse Ph.D.

More from Psychology Today