The Stray Kitten That Rewired How I Think About Value

The Kitten in My Garage

A few weeks ago, I heard crying outside my house. Persistent, but oddly hard to place, the kind of sound that makes you stop and listen before you can even locate it. 

I followed it to my garage, where I found a kitten hiding behind a stack of storage boxes. Tiny. Scrawny. Dirty. Terrified. The moment he saw me, he vanished back into hiding, as if the world had already taught him that people weren't safe. 

I put food down and stepped back. Only once I'd walked far enough away would he creep out, eat a few bites, and retreat. 

I did the same the next day. And the day after that. 

Slowly, something started to shift. He stopped bolting so fast. He waited a little longer before disappearing. He started recognising my voice, then came running when I called. Soon he was eating from my hand, rubbing against my legs, purring when I picked him up. 

Weeks later, he's part of our routine. "Has anyone seen him today?" and "Did he finish his breakfast?" are now normal sentences in my house.

Somewhere along the way, he stopped being a stray kitten and became our kitten. 

The strange part is that nothing about him actually changed. Same size, same markings, same mischief. The only thing that changed was our relationship to him, and yet somehow that made him feel infinitely more valuable. 

Objectively, he hadn't become more precious overnight. Psychologically, he had. 

And that is what makes this so fascinating: the things we consider valuable are not always valued purely for what they are, but also for the relationship we have with them once they become ours.   

  Psychological Ownership & the Endowment Effect 

The story of my kitten sits at the intersection of two related ideas: psychological ownership and the endowment effect. 

Psychological ownership is the feeling that something is ours; a sense of possession that can occur even without formal or legal ownership. The endowment effect is more specific: the tendency to value things more highly simply because we own them or perceive them as ours. 

With my kitten, the sense of "our kitten" is clearly present, but the story isn't a neat demonstration of the endowment effect. He is a living being with whom we developed familiarity, affection and a relationship, so the increased value we placed on him could reflect genuine attachment and relational value as much as ownership. The interesting question is where one ends and the other begins.

The endowment effect is usually studied under much cleaner conditions. It was first demonstrated in a now-classic set of experiments by Daniel Kahneman, Jack Knetsch, and Richard Thaler. In one version, participants were randomly given an ordinary coffee mug. Those who received the mug demanded roughly twice as much money to give it up as other participants were willing to pay to acquire the exact same mug. Nothing about the mug had changed; only who held it. 

That single finding, later replicated across dozens of studies and product categories, became one of the clearest demonstrations that human valuation isn't purely objective or "rational". We don't assess value in a vacuum; we assess it through the lens of ownership, experience, context, and what something has come to mean to us. 

This is where the two concepts overlap. Psychological ownership describes the feeling of possession; the endowment effect describes a change in valuation associated with that possession. Psychological ownership can help explain why something starts to feel personally significant, while the endowment effect captures what can happen when that sense of "mine" influences what we are willing to give up for it.

In my kitten's case, all of these forces may have been operating at once. He became ours, we became attached to him, and our relationship with him became meaningful. The endowment effect may be part of that story, but it would be too simplistic to attribute the entire shift in value to ownership alone.

  Why Our Brains Do This   

There isn't one universally settled explanation for why the endowment effect occurs, but several overlapping psychological processes may help explain why ownership can change the way we value something. 

• Loss aversion. One of the most influential explanations is that once something becomes ours, giving it up can be experienced as a loss, and losses tend to carry greater psychological weight than equivalent gains. The same object can therefore feel psychologically different depending on whether we are thinking about acquiring  it or giving it away: before ownership, we are thinking about what we might gain; after ownership, we are thinking about what we stand to lose. Loss aversion is an important part of the traditional explanation for the endowment effect, although research has debated whether it fully accounts for the phenomenon or whether other mechanisms are also at work.   

• Psychological ownership. Value doesn't require legal title to kick in. Simply touching, using, customising, or even imagining owning something is enough to trigger a sense of possession. This helps explain why physical interaction and personalisation can influence how much we value a product. That feeling of "this is mine" can emerge surprisingly quickly, sometimes before anything has actually changed hands. 

• Self-identity. We fold our possessions into our sense of self. A car, a job title, an old jumper, a half-finished side project - these stop being neutral objects and start being extensions of who we are. Letting go of them can feel less like decluttering and more like losing a piece of ourselves. In these cases, however, it is important to distinguish the endowment effect from related processes such as attachment and identity: sometimes we hold onto something because it is genuinely meaningful to us, rather than simply because ownership has inflated its perceived value. 

  Beyond the Physical 

The psychology of ownership doesn't stop at physical objects. Research on psychological ownership shows that people can develop a sense of possession toward both material and immaterial targets, including things such as ideas, work, organizations and places (Pierce, Kostova, & Dirks, 2003). 

This is why founders resist killing features they spent months building, even when the data says no one uses them. Why we overrate our own ideas in a meeting, purely because they're ours. Why selling our first car feels unexpectedly emotional. Why  clearing out an old wardrobe takes more willpower than buying a new one. Why outgrowing a job can feel, quietly, like losing part of your identity. It may be the endowment effect at work, but it could also be sunk-cost thinking, status quo bias, attachment or identity. The interesting part is that these different forces can produce the same outward behaviour: we don't want to let go. 

Interestingly, the effect doesn't even require current ownership. Strahilevitz and Loewenstein (1998) found that people place inflated value on items they used to own, which is why an old toy from your childhood can suddenly feel worth far more than its market price the moment you spot it online. 

  The Business of Ownership 

The psychology of ownership also offers a useful lens for understanding familiar marketing practices. Companies often give customers an opportunity to experience, customise or interact with products through free trials, product customisers, "build your own" configurators and hands-on experiences. These practices can create opportunities for customers to imagine a product as theirs or develop a sense of personal ownership, although the presence of these practices alone is not evidence that the endowment effect is operating.

The same principle can also help us understand why giving something up can feel very different from never having it in the first place. A free trial that ends can feel more painful than a service we simply chose not to subscribe to, for example, because the first experience can create a sense that something we had is now being taken away. That doesn't mean every successful free trial or product demonstration is evidence of the endowment effect, but it illustrates why the psychology of ownership matters to businesses designing customer experiences. 

One interesting experimental example comes from Carmon and Ariely's (2000) study of basketball tickets at Duke University. Across four studies, they examined the differences between what buyers were willing to pay (WTP) and what sellers were willing to accept (WTA) for tickets, noting that sellers' valuations were more closely tied to what they would be giving up, while buyers' valuations were more influenced by what they would have to spend. Rather than treating this gap as simple evidence of ownership alone, the authors argued that buyers and sellers focus on different aspects of what they would forgo in the exchange.

When Ownership Doesn't Win

Perhaps the most important thing to remember is that the endowment effect isn't a one-size-fits-all rule that says we always overvalue whatever we own.  

Research suggests its strength varies considerably with context. For example, List (2003) found that experienced market participants often show a significantly reduced, and in some cases eliminated, endowment effect, implying that repeated market exposure and trading experience can dampen the bias. More recent work by Smitizsky, Liu, & Gneezy (2021) even challenges the central role of loss aversion in certain environments, finding no evidence for it and instead pointing to more strategic buy–sell decision processes rather than psychological attachment. Cross-cultural studies also found meaningful variation in the effect across societies (Maddux et al., 2010), indicating it may not be a universal feature of human psychology. Taken together, these findings do not invalidate the endowment effect, but they do suggest it is more context-dependent and more complex than originally theorised.

The strength of the effect can depend on what we own, how meaningful it is, how ownership is established, how familiar we are with the object, the context in which the decision is made and how value is measured. In some situations, people may show little or no endowment effect, while in others, genuine attachment or identity may explain their reluctance to let go better than ownership itself. 

That distinction matters because not every difficult decision to give something up is an endowment effect. The same behaviour can arise from sunk costs, status quo bias, genuine attachment or identity, which is why the context behind the decision matters. 

  Breaking Free From What We Own 

None of this means ownership is irrational or bad - attachment to our things, our work, and our ideas is part of what makes them meaningful. But it's worth noticing when that attachment is quietly overriding good judgment. 

Next time you're struggling to part with an old possession, defending an idea more fiercely than the evidence warrants, or clinging to something purely because it's familiar, it's worth pausing to ask: 

If I didn't already own this, would I choose it again today? 

If you would choose it again, ownership may not be distorting your judgment at all. You may simply value the thing. 

But if you wouldn't choose it again, and the main reason you're holding on is that giving it up feels painful, that is a signal worth paying attention to. 

The question isn't whether something is "really" valuable. It's whether ownership has quietly become part of the evidence you're using to decide how valuable it is. 

The kitten in my garage taught me something I didn't expect a stray animal to teach a behavioural scientist: sometimes the most powerful forces shaping our decisions aren't the things we actually own. They're the things we merely believe we own.