The students in my negotiation classes are very rarely surprised to learn that negotiators sometimes lie. Deception, they assume, is central to negotiation. “And why do negotiators lie?” I probe—a question that usually elicits eye-rolls and answers related to one of two obvious motives: greed (e.g., “to get a better deal”) or fear (e.g., “to avoid a bad deal”). And the students are partially right, in that greed and fear can explain a fair portion of negotiators’ deceptions.

But the students are wrong in one critical respect: some of the most common reasons why negotiators lie have little to do with either motive. Indeed, although research has not and may never ascertain the proportion of lies attributable to each specific cause, lies born of greed or fear are probably—and surprisingly—in the minority. So let’s consider some of the most common reasons why negotiators lie, in hopes of making ethically challenging situations negotiable:

1. A lack of preparation: The most common source of deception in negotiation, most likely, is a distinct lack of forethought. How will I answer that tough question about my alternatives? What will I say if they ask me, point-blank, about my bottom line? We often fail to consider such questions in advance, which can tempt us to deceive when our counterpart actually asks them.
2. A lack of creativity: Negotiators often lie because they find themselves in a tough spot and perceive a false dilemma: to lie or not to lie? In reality, even a small dose of creativity often suggests a third way. What if the recruiter asks if I have a competing offer? Could I focus on the fact that I just hit the job market and am expecting great success, instead of fixating on a yes or no?
3. A lack of time: Negotiators often lie because they don’t take the time to consider the situation carefully, opting for the simplest and often the most self-serving option, which is the most deceptive.
4. Confusion between competition and deception: Negotiation scholars like to distinguish between competitive and deceptive negotiation behaviors. Put simply, real negotiators often don’t. They see deception as just one more competitive arrow in the quiver, appropriately attached to the bow whenever a value-claiming opportunity arises.
5. Subtle environmental cues: Believe it or not, negotiators may be tempted to lie by the objects, substances, or physical spaces around them. As I’ve recently summarized, psychology offers many reasons to suppose that environmental cues as innocuous as money, fake sunglasses, or ominous colors can heighten the temptation to lie.
6. Mythical images of the negotiator: Relatedly, and as I’ve also described before, negotiators and negotiation are steeped in mythology. Our most common image of the successful negotiator—the aggressive, competitive, no-holds-barred, take-no-prisoners, wheeler-and-dealer (no names)—is incomplete at best and wrong at worst. Incorrect images lead to inappropriate behaviors.
7. Agreement bias: Put simply, we don’t feel very good walking away from our negotiation counterparts, even when we know we should. So when we see that one little lie is all that’s required to seal the deal and walk away smiling—when we tell the counterpart the sweet words they want to hear or omit the treacherous words they don’t—well, then we often end up lying.

In sum, my negotiation students are quite right that greed and fear underlie some of the deception we see in negotiations. But they—and probably most other people—are wrong in thinking that greed and fear are the only or even the primary sources of lies in negotiation. They’re not! People lie for manifold and diverse reasons, not that any of those reasons excuse them for doing so. Here’s hoping that knowing the reasons can help you detect deception from others and wholeheartedly avoid it yourself.