Why do you remember song lyrics and movie quotes from years ago when you can’t even remember your password?

Are there things you wish you could remember without fail yet somehow cannot, like extremely important passwords or that item you need to buy?

And do you often wonder why your brain instead still stores the lyrics to a decades-old tune you haven’t heard since you were 12, but a few opening notes are enough to recall the whole song, word for word and in rhythm?

When Norwegian girl group M2M announced their comeback, eagle-eyed fans pointed out that the duo had posted the video on Sep 22, a Sunday, at 9.25am local time. These random numbers wouldn’t mean anything to non-fans, but I immediately knew the significance. 

Without warning, I heard the opening lyrics to the second verse of The Day You Went Away in my head: “I remember date and time, September 22nd Sunday twenty-five after nine.” 

That was all it took to trigger a memory I never knew still existed. It had probably been 20 years since I last listened to the band's teenybopper tunes. I looked up the song, hit play, and surprised myself by singing the entire darn thing. Accurately. 

While this phenomenon may be responsible for many an aggrieved parent or partner when we can’t remember the crucial things despite easily calling up seemingly trivial facts, it is apparently rather common, with research spanning from neuroscience to psychology fields. 

RECALLING ENTIRE SONGS FROM A FEW NOTES

It’s so common that a game is based on this very premise. In Heardle, a spinoff from internet sensation Wordle, players identify a song from the opening few seconds. 

The game taps into the “gating paradigm” – a recognition process that identifies a well-known melody as it unfolds progressively. The more familiar the melody, the fewer notes required for recognition, according to a 2003 study by researchers from the University of Montreal. 

And it seems the existence of a melody matters, the way scents bring to mind a specific memory and its accompanying emotions. Thinking of lyrics as words without a tune might make recalling the song harder.

Case in point: You probably know a fully grown adult who still sings the alphabet song when they need to alphabetise.

BUT WHY DO WE RECALL THESE SONGS SO EFFORTLESSLY?

If you asked how I still remembered the lyrics to M2M's Pretty Boy, my best answer would be: I just do. And that’s not entirely wrong.

According to an associate professor of music psychology from Durham University, a song may become lodged in our “implicit memory” if we’ve sung or heard it sung many times before. So when we hear it again decades later, we are tapping on “procedural memory” to recall the lyrics, says Kelly Jakubowski in The Conversation. 

This type of long-term memory allows you to perform actions without consciously recalling how to do them. For instance, brushing your teeth, riding a bicycle, tying your shoelaces.

How do you know how to do those things? You just do.

THE "REMINISCENCE BUMP" AND WHY IT MATTERS 

But unlike brushing your teeth, music is usually associated with emotion, and hence, so is the ability to recall lyrics from aeons ago. Against your best wishes, you might still remember the lyrics to that ballad you looped countless times during a period of intense infatuation.

What’s worth noting, however, is the “reminiscence bump” in autobiographical memory. This describes the phenomenon where people tend to disproportionately recall memories from when they were 10 to 30 years old. As several explanations have suggested, this life period contains many “novel and self-defining experiences, which may be encoded in the brain more deeply and retrieved more easily”, says Jakubowski. 

A study done by Jakubowski and her colleagues among nearly 500 participants aged 18 to 82 found that music which was in the charts during a person’s adolescence was not only rated as “more familiar”, but also associated with more autobiographical memories. 

The findings also suggested that songs from our adolescence can become closely entangled with past memories, “even if we don’t personally value the music”. 

So you may not have enjoyed a certain overplayed emo song when you were, say, 14 years old. But a breakup at 14 could have fundamentally shaped your life that the song is now invariably linked with that experience and its associated emotions in your subconscious mind.

IS THIS ALSO WHY WE QUOTE ICONIC TV AND MOVIE LINES?

Sure, if you’ve rewatched a beloved TV episode or movie multiple times, you will likely be able to memorise its lines. 

But it is the objectively iconic quotes – the ones that spawn a whole cult following outside the TV or movie fandom – that seem to imply there are factors making certain quotes more memorable than others.

In fact, a 2012 study by Cornell University researchers – You Had Me At Hello: How Phrasing Affects Memorability – suggests that memorable quotes tend to share two properties. The first is “lexical distinctiveness”, in which memorable quotes combine uncommon word choices with familiar sentence patterns. The second is that memorable quotes tend to be “more general”, making them easy to apply in a wide variety of contexts.

In my experience, quotable lines also tend to be reinforced by the TV show or movie’s enduring impact on pop culture, like a gift that keeps on giving. 

A line that instantly comes to mind from a movie that needs no mention is, "On Wednesdays, we wear pink." 

Thanks to another iconic scene from the movie, the date Oct 3 has also been widely recognised as Mean Girls Day. 

“On October 3rd, he asked me what day it was,” says protagonist Cady Heron (Lindsay Lohan) in a voiceover, referring to her crush Aaron Samuels (Jonathan Bennett).

“It’s October 3rd,” she tells him in the scene.

But my personal favourite is the chef's kiss of an answer by Miss Rhode Island Cheryl Frasier’s (Heather Burns) in Miss Congeniality when asked to describe the perfect date: "I'd have to say April 25th because it’s not too hot, not too cold. All you need is a light jacket."

Even though it’s been over a decade since I last watched those movies, I didn’t have to fact-check that I got the quotes right. I know I did.