The cat slow blink — that languid, heavy-lidded half-close of the eyes your cat sometimes aims in your direction — is one of the most studied feline signals in behavioral science. For years, cat owners called it the “cat kiss” or “eye kiss” and assumed it meant contentment. As of a 2020 study published in Scientific Reports, they were right. The slow blink is a genuine positive-emotion signal, and it works in both directions: cats do it toward humans they trust, and humans who do it back are more likely to get one in return.
What the 2020 Study Actually Found
Researchers at the University of Sussex, led by animal cognition scientist Karen McComb, set out to answer what had always been folk knowledge: does the cat slow blink mean something specific, or is it just a random muscle movement?
They ran two experiments. In the first, owners were instructed to slow-blink at their own cats while seated nearby, then remain neutral — no eye contact, no slow blink. Cats slow-blinked back at their owners significantly more after the owner slow-blinked first. In the second experiment, an unfamiliar researcher slow-blinked at cats they had no prior relationship with. Those cats were not only more likely to return the slow blink; they were also more willing to approach the researcher afterward compared to cats who received only a neutral, open-eyed gaze.
Both findings point to the same conclusion: the slow blink is a bidirectional signal of positive affect. It isn’t random, and it isn’t just a sign that a cat is sleepy. It communicates something — and cats can receive it from humans as well as produce it themselves.
Why a Half-Closed Eye Signals Trust
The logic becomes clear when you consider what a cat’s open, unblinking stare actually means in feline social dynamics. A direct, sustained stare is a threat display. Cats use it with rivals and with prey. Holding eye contact with another cat, especially a strange one, is confrontational by default.
Closing the eyes partway — even briefly — is the opposite. It makes a cat momentarily less alert, less defensive, more exposed. Doing it in the presence of another animal is a low-stakes signal that says, roughly, I am not a threat, and I don’t perceive you as one. The slow blink is essentially a cat choosing to be visually vulnerable, on purpose, in your direction.
This is why the signal tends to appear in relaxed, familiar contexts: a cat lounging on a favorite perch, a cat that has just been petted and settled. You rarely see it in a tense, alert animal. The physical state and the signal are linked.
Is It the Same as Blinking During Sleep?
Worth clarifying: the slow blink isn’t the drowsy half-close of an animal drifting off. A sleeping or pre-sleep cat may close its eyes fully and gradually, but the communicative slow blink is more deliberate — a pause, a soft narrowing, sometimes held for a beat, directed at a specific individual or point in space. Behaviorists distinguish between involuntary eye closure associated with sleep pressure and the oriented, context-dependent slow blink. The key indicator is orientation: a slow blink aimed at you is different from eyes that simply droop shut.
How to Use It With Your Own Cat
The practical takeaway from McComb’s research is that humans can initiate this exchange, not just receive it. If you want to try it with your own cat:
- Sit or crouch at roughly the cat’s level — not looming over them.
- Wait until the cat is calm and already looking at you.
- Narrow your eyes slowly, hold the half-closed position for a moment, then look away or let them drift fully closed briefly.
- Give the cat time to respond — sometimes it comes back immediately, sometimes after several seconds.
Forcing eye contact or staring intensely while waiting for the blink tends to backfire, because the wide-open stare is the signal you’re trying not to send. Relaxed eyes and a slightly averted gaze give the cat more room to respond.
The study also found that cats were more likely to approach researchers who slow-blinked compared to those who maintained a neutral open gaze. So beyond the exchange itself, the signal appears to shift the social temperature of an interaction — it makes an unfamiliar human marginally safer, in the cat’s assessment.
What the Research Doesn’t Tell Us
Science supports the slow blink as a positive-affect signal, but a few things remain genuinely open. Researchers don’t know whether cats slow-blink at each other in the same way they do at humans — most documented observations involve cat-to-human or human-to-cat exchanges, not cat-to-cat. It’s possible the behavior was shaped partly through domestication, as an extension of the non-threatening gaze cats use with familiar conspecifics, repurposed for human interaction. The original Scientific Reports paper by Humphrey, Lestrelin, and McComb notes the mechanism behind why slow blinking triggers positive associations in cats is still not fully worked out — the researchers propose it may relate to the calming function of narrowed eyes in appeasement signaling across felids, but this is not yet confirmed.
It’s also worth noting that individual cats vary considerably. A very anxious or undersocialized cat may not respond to slow-blinking from a stranger at all, or may interpret any direct attention as pressure. The signal works within a relationship — or helps build one — but it isn’t a universal override for a frightened cat.
Where the Slow Blink Fits in the Broader Picture of Feline Communication
Cats communicate through a surprisingly layered system of posture, tail position, ear angle, scent, and vocalization. The slow blink sits within the visual-signal layer alongside flattened ears, the puffed tail, the exposed belly (which is not an invitation to touch, contrary to popular belief), and the full vocabulary of feline body language that most owners only partially read.
What makes the slow blink particularly interesting is that it’s one of the few feline signals that transfers across species and appears to be learnable by humans with basically no training. Most cat signals require context and familiarity to interpret correctly. The slow blink is different: once you know it exists, you can produce it and receive it without any special expertise. That’s a rare thing in cross-species communication.
It may also explain why cats who have been slow-blinked at by their owners from kittenhood often seem unusually sociable with strangers — they’ve had the signal modeled consistently and are more likely to extend a version of it outward. Whether this is genuine learning or simply reflects that well-socialized cats are calmer across all metrics is a question the research hasn’t yet disentangled. But the correlation is worth noticing, especially for anyone bringing a new kitten home and wondering how to build a calm, trusting relationship from the start.
Frequently Asked Questions
Does the slow blink always mean a cat is happy?
It reliably indicates a relaxed, positive state rather than active happiness in a bouncy sense. Think of it as a signal of trust and calm — the cat is at ease enough to lower its guard. A very stressed or threatened cat won’t slow-blink.
Can I teach my cat to slow-blink?
You can’t train it like a trick, but you can create conditions where it’s more likely to happen: calm environment, relaxed body language on your part, no forced eye contact. The more often you initiate with your own slow blink during low-key moments, the more likely your cat is to reciprocate over time.
What if my cat never slow-blinks at me?
Not all cats display it frequently, and some — particularly those with limited early socialization — may rarely produce the signal. Absence of slow blinking doesn’t mean your cat dislikes you. Look for other relaxed signals: loose body posture, slow tail movements, the full range of calm feline body signals that indicate ease in your presence.
Do cats slow-blink at other cats?
Possibly, but this is much less documented than the human-directed version. Most of the peer-reviewed evidence focuses on cat-human exchanges. Whether it plays the same social role between bonded cats living together remains an open research question.
The cat slow blink is one of those behaviors that rewards a second look. It seems small — just a pair of half-closed eyes — but it carries real information about trust, emotional state, and the surprisingly rich social world cats navigate every day. The fact that you can participate in it, not just observe it, makes it one of the more accessible windows into what a cat is actually experiencing when it shares a room with you.
