Search for why this happens, and you’ll find claims about twin flames, telepathic bonds, and the universe sending you a message. Those ideas might feel reassuring. But they don’t actually explain what’s going on inside your brain or theirs. Psychologists have been studying persistent thoughts about other people for decades, and what they’ve found is more grounded and more interesting than any spiritual explanation.
Some of those reasons are entirely about you, about unfinished emotional business your brain won’t let go of. But a few of them might actually be about what’s happening on the other person’s end, too.
They’re Probably Thinking About You Too
The most common assumption is that you’re the only one still circling. That they said what they said, walked away, and haven’t thought about it since. But a team of social psychologists led by Gus Cooney and Erica Boothby found that this is almost always wrong.
Their research, published in the Journal of Experimental Psychology, asked more than 2,100 people across 8 studies to report how much they’d been thinking about a conversation partner after an interaction, and then estimate how much that person had been thinking about them. People consistently believed they were thinking about the other person far more than the other person was thinking about them. Cooney and Boothby called this the “thought gap,” and it held between strangers meeting for the first time, friends having personal conversations, and romantic partners after arguments.
The reason is access. During a conversation, you can read someone’s mind a little through their words, their tone, and their body language. The moment that conversation ends, the line is cut. You still know exactly how much you’re thinking about them because the conversation is right there in your head. But you lose all certainty about what’s happening in theirs. So you default to assuming the gap is bigger than it actually is. The research says it isn’t. They’re probably replaying it too.
Something Between You Was Left Unfinished
The thought gap explains why the thinking is probably mutual. But it doesn’t explain why some people stick more than others. For that, you need to go back to a café in Vienna in the 1920s.
Psychologist Bluma Zeigarnik was sitting with colleagues when she noticed something about the waiters. They could recall every detail of an open order, drinks, dishes, and special requests, without writing anything down. But the moment a bill was paid, the order vanished from their memory entirely. It was as though settling the tab closed a loop in their brain and freed up the space.
Zeigarnik tested this in her lab and found that people recalled interrupted tasks nearly twice as well as completed ones. The brain creates a kind of cognitive tension around anything left unfinished, and that tension stays active until the task is resolved. Psychologists now call this the Zeigarnik Effect, and it extends well beyond restaurant orders.
Think about the people who take up the most space in your head. They’re almost never the ones where things ended cleanly. It’s the friend who stopped responding and never said why, or the relationship that dissolved before either of you said what needed to be said. These sit in your mind like open tabs, pulling your attention back because nothing was ever properly closed.
You Might Be Trying Too Hard to Forget Them
So your brain won’t release unfinished business, and the natural instinct is to force the thought out. Just stop thinking about them. Move on. Social psychologist Daniel Wegner spent years studying why that strategy almost always backfires.
In 1987, Wegner ran what has since become one of the most referenced experiments in cognitive psychology. He asked participants to verbalise their stream of consciousness for 5 minutes with a single instruction. Don’t think about a white bear. Every time the thought crept in, they rang a bell. The harder people tried to suppress the thought, the more frequently it returned.
The explanation is in how the brain handles suppression. When you try not to think about something, 2 processes run at the same time. The first is a conscious effort to distract yourself, to fill your mind with anything other than the forbidden thought. The second is an automatic monitoring system that checks whether the thought has crept back in. But the monitor has to hold onto the very thing you’re trying to avoid so it can scan for it, and that’s what pulls it back to the surface. Basically, the two processes work against each other.
When it comes to people, this means the harder you try to stop thinking about someone. The more persistent they become. It isn’t a failure of willpower. It’s the architecture of suppression working exactly the way it was built to work.
What You’re Feeling Might Not Be Love
Everything we have covered so far could apply to almost anyone. But if the person occupying your thoughts is someone you have romantic feelings for, there’s a name for what might be happening.
In the late 1970s, psychologist Dorothy Tennov spent years interviewing people about their romantic experiences and identified a state she called limerence. It looks like love on the surface because it involves constant thoughts about another person, intense longing to be near them, and a consuming need for reciprocation. But where love tends to deepen with familiarity and survives contact with someone’s real flaws. Limerence feeds on uncertainty and distance. It is involuntary, obsessive, and built on idealisation rather than genuine knowledge of who the other person actually is.
The person experiencing limerence often constructs an entire version of the other person in their head, and that version rarely matches reality. You’re not thinking about who they are. Instead you’re thinking about the person your mind has assembled from limited information, and that person is almost always flawless. Researchers have also found that limerence shares neurological features with addiction, including cycles of craving, withdrawal, and dependency. Which is why it can feel less like affection and more like an obsession.
Your Brain Is Using Them as Emotional Comfort
Where limerence attaches to someone current or recent, nostalgia reaches further back, to someone who belonged to a completely different chapter of your life. Nostalgia used to be classified as a kind of psychological weakness. A sign that someone was stuck in the past. Researchers Constantine Sedikides and Tim Wildschut at the University of Southampton have spent the last two decades studying it. And their findings say otherwise.
Psychological discomfort, things like loneliness and stress, and major life transitions, actually trigger nostalgia. Nostalgia then acts as a buffer by boosting self-esteem, increasing feelings of social connectedness, and reinforcing a sense of continuity between who you were and who you are now.
This is also different from the unfinished business Zeigarnik identified. Where the brain loops on something that was never resolved. Nostalgic recall draws on a memory that already feels complete and safe. So when someone from your past keeps surfacing during a difficult period, your brain might not be telling you to call them. It might be borrowing the emotional warmth of that connection to stabilise you in the present.
You Might Be Avoiding Something Closer to Home
There’s a difference between your brain reaching for comfort and your brain running from something. Nostalgia soothes. But sometimes the person circling your thoughts isn’t soothing at all. The thoughts feel repetitive and consuming; they loop without leading anywhere, and they don’t leave you feeling any better when they pass. That’s not comfort. That might be avoidance.
Psychologist Susan Nolen-Hoeksema spent her career studying rumination, the tendency to cycle through the same thoughts about the causes and consequences of your emotional state without ever arriving at anything useful. Her Response Styles Theory, first proposed in 1991, found that rumination doesn’t just happen alongside emotional distress. It can function as a form of cognitive avoidance where the thinking feels productive because it’s intense and all-consuming, but actually prevents you from solving the problem underneath.
Applied to people, this looks like fixating on someone during a period when something else in your life isn’t working. A stalled relationship, a draining job, a quiet sense that something needs to change but you can’t name what. The person in your head becomes what your brain chews on instead of the harder, less defined problem sitting right in front of you. And the same cognitive tension Zeigarnik identified helps explain why this works so well as a diversion. Your brain treats the unresolved person like an open task demanding attention, and that demand fills enough cognitive space to keep you from sitting with whatever is actually bothering you.
If thinking about someone doesn’t bring comfort and never leads to resolution, it’s worth asking what that thinking might be standing in for.
Your Attachment Style Might Be Running the Show
Then there is rumination. The tendency to cycle through the same thoughts about the causes and consequences of your emotional state without ever arriving at anything useful. Psychologist Susan Nolen-Hoeksema spent her career studying it, and her Response Styles Theory, first proposed in 1991, found that rumination doesn’t just happen alongside emotional distress.
It can function as cognitive avoidance. Which is what psychologists call it when your brain uses one problem to keep you from facing another. The thinking feels productive because it’s intense and all-consuming, but it’s actually running interference against whatever you don’t want to look at directly. And unlike nostalgia, which draws on memories that feel warm and complete, rumination loops without soothing.
Nolen-Hoeksema also found that rumination tends to be self-reinforcing. The more someone ruminates, the worse their mood becomes, and the worse their mood becomes, the more they ruminate. That cycle can run for weeks or months because the thinking feels like processing. It is constant and consuming, and it mimics the texture of working through something, but nothing actually moves forward.
Applied to people, this looks like fixating on someone during a period when something else in your life isn’t working. The person in your head becomes what your brain chews on instead of the harder problem sitting right in front of you, and the same cognitive tension Zeigarnik identified helps explain why it works so well as a diversion. Your brain treats the unresolved person like an open task demanding attention, and that demand fills enough space to keep you from sitting with whatever is actually bothering you.
They Liked You More Than You Realized
That covers 7 things, but there’s an 8th that ties back to Cooney and Boothby’s thought gap. The same team found something else. They looked at what happens when people try to estimate how much their conversation partners actually liked them after an interaction.
Across multiple studies, participants consistently underestimated how much the other person enjoyed the conversation, how much they liked them, and how warmly they remembered the whole exchange. Boothby and Cooney called this the “liking gap,” and it held between strangers meeting for the first time, college dorm mates getting to know each other over weeks, and members of the general public at a personal development workshop. The gap didn’t fade quickly either. It persisted for months.
The pattern is consistent with everything else in the research. We don’t have access to other people’s internal states after an interaction ends. So we fill in the blanks with our own self-criticism and assume the other person landed somewhere harsher than they actually did. If part of what’s keeping someone in your thoughts is the nagging sense that you came across badly, the data says you probably didn’t. And if they’re thinking about you at all, there’s a good chance it’s fondly.
