I judiciously placed one fry in my mouth, and chewed slowly. We had been on the road for nearly six hours now, and it was the only place we could find for miles. Really, it was either this or a bag of Cheetos from the gas station nearby. This was my first McDonald’s French fry in what might have been six years. I ate hesitantly, with facts and figures from the film Super Size Me running through my mind. But right then, after the first fry, with indisputable clarity, my reluctant chewing quickened: Whatever I was eating didn’t matter, I liked it. I liked it so much, in fact, I consumed the whole box, along with the McChicken sandwich slathered in sauce next to it. I then ordered seconds. Gluttony, perhaps, or a moment of intense hunger satiated by the delicious taste of greasy, fatty, sugar-filled food. But I’d known better, hadn’t I? After all, I had read the current research on sodium intake, and seen the YouTube videos of the content that can only be described as “pink slime” presumably forming McDonald’s chicken “meat”. Nevertheless, there I was, French fry in hand. Not only did I like it; appropriately, I was “lovin’it”. Why?

From a biological perspective, in his book, Salt Sugar Fat: How the Food Giants Hooked Us, Michael Moss explains that we humans derive an enormous amount of pleasure from eating specific foods. In fact, we’re programmed to: Before we even consume food, just the sight of it is enough for our mouths to literally start watering. It’s not only the saliva production that acts as a precursor to pleasurable feelings, but when food interacts with our saliva, the taste buds inside our mouths release chemicals into the nerves which signal to the brain that we are consuming something satisfying. While preference for certain tastes begins in utero – such that if your mother ate chocolates, you, too, should enjoy a healthy liking of sweets – this doesn’t only work with sugary foods, but any refined starch – like bread, pizza, even hamburger buns – which our body converts to sugar. While the brain research is still fuzzy, we do know that eating specific foods triggers the “reward circuit” in our brain, mainly controlled through a structure called the Nucleus Accumbens.

In fact, it is this very structure, the Nucleus Accumbens, that isn’t just found to be central when we eat delicious – though likely not so healthy – foods. It is found to be a key player in anything we like, music included. In a 2013 study, researchers from McGill University asked 20 people to listen to music in their preferred genre while in an MRI. The catch was, they had never listened to the songs before, and immediately after each song, they were asked whether they would spend zero dollars, 99c, $1.29 or $2 to purchase the song from iTunes. When a participant in the study really enjoyed the song, the reward center lit up. The really interesting part was that the researchers found that the more the reward center was activated, the more money participants in the study were willing to spend on the song. Though this is important to note – especially when we have a credit card on hand and iTunes open! – where did one’s “liking” of that genre come from?

From a psychological lens, as identified by Tom Vanderbilt, we like things for a number of different reasons: For starters, psychologist Robert Zajonc’s  “mere exposure” effect suggests that “mere repeated exposure of the individual to a stimulus is a sufficient condition for the enhancement of his attitude toward it.”  In fact, the McGill researchers found that while the Nucleus Accumbens lit up, so did a region of the brain called the superior temporal gyrus, which is “the part of the brain that has stored all the templates of the music we’ve heard in the past”. The problem with the mere exposure effect is that as we are exposed to more complex pieces of music or even more complicated meals, we tend to prefer them to simpler tastes. Perhaps this explains why we enjoyed “Twinkle, Twinkle Little Star” as infants, but it would be an unlikely choice to identify as our favourite piece today.

Second, as we might expect, memory plays a hefty role in liking what we like: Choosing the same brand of peanut butter we used to eat as a child, or keeping a raggedy teddy bear on our nightstand, even though it might be 20 years old? We can attribute these behaviours to the memories and nostalgic feelings we get when we see them, because of the fond memories we have attached to them. In fact, a common phenomenon curbed by memory is gradually disliking what we consume when we consume it. For instance, having that first bite of chocolate always tastes better than when you’ve eaten half (or more!) of the bar. Instead of remembering how bland the chocolate tasted after the tenth bite, our memory tricks us into thinking eating the whole bar was as pleasurable as the first.

Third, our expectations play a large role in determining what we like and how much we actually like it. In a study looking at how food labels influence the liking of food, researchers asked their participants to taste two types of corn – one that was from a recognizable brand, and another that went unbranded. They were told which was the brand-name corn immediately before trying both and asked to rate how much they expected to like each kind. Not surprisingly, participants rated that they expected to like the branded corn much more than the unbranded. When eating the corn, they found their expectations to be true – they preferred the taste of the branded corn to that of the unbranded kind. The catch? Both were the exact same corn! Apparently, when a product matches our expected quality of it, we like it.

Evolutionarily, we like what we need. We are programmed to want to survive and reproduce, and our behaviours – including choosing what we like – is directly shaped from this motivation. We like food, water, and sleep because we need it to survive. We like sex because we need it to reproduce. According to Paul Bloom’s book, How Pleasure Works: The New Science of Why We Like What We Like, from the adaptationist theory of pleasure, we humans like weird things – dying our hair purple, painting our nails black, putting tattoos on our face – as a means to “peacock”. In other words, we choose to like strange things because it’s an ostentatious way of attempting to attract a mate.

Whether my eating of McDonald’s fulfilled my evolutionary need to eat, elicited memories of eating Happy Meals as a child, or maybe even overwhelmed my brain’s reward centre upon first bite, we like what we like, and it’s what we like that makes us unique.