Whether it is the next iPhone model, a new flat TV screen, or a more fashionable collection of a favorite line of clothes, everyone tends to be very excited when big upgrades come out. Between the date of the announcement and the release date, we spend time weighing options and thinking through the potential purchase: what are the new features of the product? Is the upgrade a significantly enhanced product in comparison to the version we own? And, even more important, do we actually need an upgrade in the first place?

But there is another important thing we do: we treat our current products in ways that may break them, often unconsciously, so as to have a proper justification to upgrade. In a sense, we behave like the people depicted in a recent Virgin Mobile TV commercial, named “Happy Accidents” — a consumer microwaves his cell phone instead of a burrito, a lab worker drops his mobile into a vat of toxic sludge, and a commuter throws her phone into the backseat of a departing taxi. Oops! As becomes clear at the end of this commercial, these phone owners are all looking forward to “accidentally” destroying or losing their devices, thus necessitating an upgrade purchase. The advertisement has an element of truth. Research I have done with two colleagues (Silvia Bellezza of Harvard Business School and Josh Ackerman of the University of Michigan), shows that knowing a product upgrade is available leads consumers to mistreat the products they own.

Why? As human beings, we are wonderful storytellers. We want others to believe we are responsible, fair, and logical, and it’s also important for us to view ourselves this way. For this reason, when we behave in ways that are not consistent with the rosy image we hold of ourselves, we come up with all sorts of justifications to rationalize our behavior. In fact, we go as far as treating our possessions—and even our romantic partners—carelessly when an “upgrade” is on the market.

A well-established body of research, dating back at least as far as Freud’s 1894 elaboration of defense mechanisms, suggests that people’s perceptions of the world—and of themselves—are self-serving. Think about the last time you got onto your bathroom scale and were surprised by some bad news. You likely got off and then on again, just to make sure you didn’t misread the display or put too much pressure on one foot. Of course, when the scale delivers good news, we smile and dress up for the day. We are more than happy to accept evidence that makes us look good. When it doesn’t, we come up with justification so as to subtly tip the scales in our favor.

Research suggests that the way we weigh ourselves mirrors the way we behave in general. Consider a well-known study conducted by Snyder, Kleck, Strenta, and Mentzer in the late 1970s. Participants had to choose one of two rooms in which to watch a movie and fill out a questionnaire. In one room, participants were told, there was a handicapped person; in the other, there was a non-handicapped one. When the same movie clip was being shown in both rooms, people were more likely to choose to sit with the handicapped individual. But when different movies were being presented, a situation that created a justification for selecting one room over the other, the majority avoided the handicapped person. Thus, the presence of a justification allowed and promoted less virtuous behavior.

As consumers, we are often faced with the opportunity to purchase a new, enhanced product—such as an upgraded cell phone—even though the device we currently own is still fully functional. To justify the purchase to ourselves, we behave in rather strange ways. Here is how my colleagues and I showed this. In one laboratory experiment, we gave participants a basic ceramic mug that was worth about $1 and told them they could keep it. We then asked them to play the game Jenga. In Jenga, players try to remove individual blocks from a pre-assembled tower of relatively small wooden blocks without collapsing the tower. To encourage participants to keep playing, we offered them extra payment for each block removed. Before the game began, we placed their mug on top of the tower. To emphasize the risk of each decision to remove a block, we told participants that they were not allowed to catch the mug if it fell and that they would not receive a new mug if theirs broke.

We had two conditions. In the upgrade condition, participants were shown a nicer-looking mug (with a retail value of about $10), which they inspected before playing the game. They were told they would have the opportunity to purchase the upgraded mug at a special price at the end of the study. In contrast, participants in the no-upgrade condition were not shown another mug before playing the game. The result? Among those in the upgrade condition, 61% dropped the mug during the game, as compared to only 37% of those in the no-upgrade condition. It seems that exposure to mug upgrades led participants to become more careless with their owned mugs. Why? Careless behavior allowed participants to justify buying an upgrade without having to consciously admit to themselves or others that they had been intentionally wasteful.

In search of other evidence, we turned to the field. We acquired an international dataset of about 3,000 lost Apple iPhones. Every Apple iPhone in the world has a unique code, known as the IMEI number. After losing a phone, consumers can visit the IMEI Detective website to report the loss and check if their phone has been found by anyone. We used not reporting a loss on the IMEI Detective website as a proxy for carelessness. We found that fewer people go online to look for their phones when a newer iPhone model is about to be released or is newly available for purchase. For example, we observed fewer reported losses of the iPhone5s when the iPhone6 was about to be released or was newly on the market.

And what if there was a crack on your phone? Our research shows that you’d consider the damage to be much more serious if an upgrade is available on the market than if it is not. Interestingly, the effect of upgrades applies beyond durable goods. In fact, there is evidence of similarly careless behavior when “better models” are available in the romantic domain. Research in the interpersonal relationships literature shows that people often denigrate their romantic partners when exposed to partner “upgrades”—attractive opposite-sex others. As we become aware of these improved options, we start being less careful and attentive toward our current partner.

All this evidence supports what Benjamin Franklin once observed: “So convenient a thing it is to be a reasonable creature, since it enables one to find or make a reason for everything one has a mind to do.”