From "Got Milk?" to "What's in your wallet?" to "Are you a Mac or a PC?" promotional phrases consisting of a simple question have proven to be quite effective, but are they more effective than a simple statement? That depends. Henrik Hagtvedt, Ph.D., a Marketing professor at the Carroll School of Management at Boston College, has just finished investigating what happens when you replace a period with a question mark, or vice versa, and how that affects whether a consumer makes a purchase.

"I've long been interested in ambiguity and uncertainty," says Hagtvedt, whose study is forthcoming in the Journal of Consumer Psychology. "And raising a question has that kind of connotation to it - a little bit of uncertainty because you're asking the consumer to think about this - to reach his or her own conclusion."

Hagtvedt looked at this phenomenon through the lens of one's arousal - if someone was excited or nervous, would they respond more favorably to a question or a statement? Conversely, if a prospective consumer was calm, which type of phrase would they now prefer?

Using pens, strawberries, pictures, and an ad display with music and visual images, Hagtvedt compiled data from more than 400 prospective consumers over the course of three studies. He measured how participants, who were under various states of arousal, responded to promotional phrases that were framed as questions or statements. A statement such as, "The Pen For You" was compared to a question of, "The Pen For You?" Exciting or dull photographs were utilized, as was various kinds of music, to induce high or low arousal. The first result? Marketing statements were more effective and well received if the consumer was aroused (i.e., stimulated or excited in some way).

"If consumers are experiencing high arousal for some reason, and there may be many reasons for this - they could be at a sports event, watching TV or some kind of action movie, it could be the content of the magazine or webpage they're looking at - if there is stimulating material around the consumers, they will tend to be aroused and respond less favorably to a question," found Hagtvedt. "If you are highly aroused, you tend to want clear information and know exactly what's going on - you don't really want to think about it, hence a statement does better. Under high arousal, the statements led to more purchases than the questions did."

That's because highly aroused study participants preferred clear, straightforward communication. But under low arousal, questions were received more favorably because the phrase was perceived as interesting. As Hagtvedt notes, "questions often engage the mind more than straightforward statements do, and even rhetorical questions can enhance consumer elaborations on a given message."

"A question mark can peak interest because you're asked to think about things on your own," says Hagtvedt. "You're so used to getting all these statements that being asked to actually think about it on your own might be slightly more interesting. Under normal circumstances, where consumers might be relatively relaxed or calm, marketers may therefore benefit from framing their promotional phrases as questions rather than statements. "

Given the takeaway of the research - aroused consumers appreciate clarity, while calm consumers appreciate stimuli that peak their interest - the lesson for marketers is this: Know where your message is being seen.

"If it's a supermarket or shopping center on a typical, slow-moving day, then it may make sense to spark the consumer's curiosity a little bit by framing promotional phrases as questions. A question mark can cause the consumer to wonder - what's this about?"

However, if the ad display is in the middle of say, holiday hustle and bustle or a big sale that's creating a frenzy, a simple declarative statement is best, according to the research.

Says Hagtvedt, "Aroused consumers don't want to think about it - they just want simple information that they can act on. Consumers tend to experience questions as less clear communication than statements. Hence, they have an adverse reaction. It doesn't have to be strong, and consumers might not even be aware of it, but it can nonetheless be enough for them to have a slightly lower evaluation of the brand or product than they otherwise would have. It might cause them not to purchase just because that little uncertainty is slightly disturbing to them."

Going forward, advertisements might be customized for magazines, television or the internet, depending on the level of arousal they encourage: "If the ad itself or the material in which it is imbedded involves topics of a sexual, competitive, dangerous, or thrilling nature, the current research suggests that a statement style is likely to be more effective, even if a question style could appeal to consumers' curiosity under other circumstances," according to the research. "The same logic holds for public policy communications. A question style regarding behaviors to achieve desirable health outcomes might draw consumers in under calm conditions, but it may be less effective at the physician's office if they are feeling nervous."

Hagtvedt observes, "Consumers may not always consider the implications of language details of this kind, but such details can make a big difference in the efficacy of marketers, ranging from business managers to politicians."