An alarm that squirts essence of wasabi, yawning tortoises and an analysis of why people sigh have won Ig Nobel prizes

How do you wake a deaf person in the middle of the night if there's a fire? Squirt a cloud of wasabi at them, of course. For the Japanese researchers who came up with the horseradish-based alarm system, it was a lifesaving piece of work, but on Thursday night they entered the history books with the award of the Ig Nobel prize for chemistry.

Their research was one of 10 areas celebrated at the 21st Ig Nobel prizes at Harvard University. The awards, a spoof on the Nobel prizes, which will be announced next week, honour achievements that "first make people laugh, and then make them think".

Other winners included researchers who looked at whether people make better decisions when they have a strong urge to urinate, whether yawning is contagious in tortoises, and an analysis of why people sigh.

The Japanese scientists and engineers who came up with the 50,000-yen (£400) wasabi alarm tried hundreds of odours, including rotten eggs, before settling on the Japanese condiment – a favourite of sushi lovers. Its active ingredient, allyl isothiocyanate, acts as an irritant in the nose that works even when someone is asleep. "That's why [people] can wake up after inhalation of air-diluted wasabi," said Makoto Imai of the department of psychiatry at Shiga University of Medical Science, one of the team that won this year's Ig Nobel for chemistry.

Mirjam Tuk of the University of Twente, winner of the 2011 Ig Nobel for medicine, investigated how well we make decisions when faced with painful or stressful situations, such as a powerful need to urinate. She found that people who are better at resisting the urge to urinate are also better at controlling their impulses on cognitive tasks. For example, her subjects were stronger-willed when it came to resisting a small reward promised for tomorrow, in order to receive a bigger reward further in the future.

Tuk's work is part of a bigger question examining self-control. She shared her award with a team of American scientists that included Professor Peter Snyder, a neurologist at Brown University. "We did not expect this honour, but we are pleased by it," he said. "We are most pleased because the goal of the awards is to nurture and increase interest in science by the public (particularly for students). It is important to show that science can be fun and entertaining, as well as important."

Karl Teigen of the University of Oslo, winner of this year's Ig Nobel in psychology, was celebrated for a paper that considered the question: why do we sigh? He wanted to give his students a project that would teach them about the research method. "We decided to choose a theme where we could do original work, and it turned out – to our surprise – that in psychology there were no empirical studies on sighs and sighing."

They discovered that most people believe others' sighs are a sign of sadness or disappointment. But they reported that their own feeling when they sighed was more often resignation. How did Teigen react to the award? "Surprise. Embarrassment. Amusement. A sneaking pride. And then, of course, I sighed."

Academic research is often seen as trivial when viewed from the outside, he added. "It must be allowed to make fun of scientists, because they have a lot of fun themselves."

Dr Anna Wilkinson of the University of Lincoln, winner of the 2011 Ig Nobel in physiology, spent six months training a red-footed tortoise called Alexandra to yawn on command. She then used the trained tortoise to work out whether other tortoises would yawn whenever Alexandra did.

Contagious yawning is common in humans and scientists think it might be controlled by empathy, since it requires an understanding of the emotional state of another individual to "catch" a yawn.

"With tortoises we've found evidence of social learning, fantastic spatial cognition and brilliant visual perception, so we wanted to know what else can they do," said Wilkinson. "I thought it would be really interesting to test one of these high-level hypotheses with a species which, it is very clear, do not possess empathy."

Her tortoises, however, showed no evidence of contagious yawning. The result lends weight to the idea that the behaviour is indeed controlled by higher-level cognitive mechanisms.

Other winners included a team of French and Dutch researchers who were given the physics Ig Nobel for studying why discus throwers become dizzy whereas hammer throwers do not. The world's doomsayers – including Harold Camping – who have predicted the end of the world on various dates were collectively awarded the mathematics Ig Nobel "for teaching the world to be careful when making mathematical assumptions and calculations".

Almost all the winners turned up to collect their awards and make 60-second speeches at the ceremony in Boston. They were handed their trophies by real-life Nobel laureates including Prof Roy Glauber (physics, 2005), Prof Dudley Herschbach (chemistry, 1986) and Prof Louis Ignarro (physiology or medicine, 1998).

Ignarro was himself given away in a competition to win a date with a Nobel laureate.

Marc Abrahams, the editor of the Annals of Improbable Research, a regular Guardian writer and the founder of the prizes, ended the ceremony with his customary congratulations: "If you didn't win an Ig Nobel prize tonight – and especially if you did – better luck next year."

2011 Ig Nobel prizewinners

Physiology

Anna Wilkinson, Natalie Sebanz, Isabella Mandl and Ludwig Huber for their study ""No evidence of contagious yawning in the red-footed tortoise Geochelone carbonaria".

Chemistry

Makoto Imai, Naoki Urushihata, Hideki Tanemura, Yukinobu Tajima, Hideaki Goto, Koichiro Mizoguchi and Junichi Murakami for determining the ideal density of airborne wasabi (pungent horseradish) to awaken sleeping people in case of a fire or other emergency, and for applying this knowledge to invent the wasabi alarm.

Medicine

Mirjam Tuk, Debra Trampe and Luk Warlop, and jointly to Matthew Lewis, Peter Snyder, Robert Feldman, Robert Pietrzak, David Darby and Paul Maruff for demonstrating that people make better decisions about some kinds of things – but worse decisions about other kinds of things – when they have a strong urge to urinate.

Psychology

Karl Halvor Teigen of the University of Oslo, Norway, for trying to understand why, in everyday life, people sigh.

Literature

John Perry of Stanford University for his Theory of Structured Procrastination, which states: "To be a high achiever, always work on something important, using it as a way to avoid doing something that's even more important."

Biology

Daryll Gwynne and David Rentz for discovering that certain kinds of beetle mate with certain kinds of Australian beer bottle.

Physics

Philippe Perrin, Cyril Perrot, Dominique Deviterne, Bruno Ragaru and Herman Kingma for trying to determine why discus throwers become dizzy, and why hammer throwers don't, in their paper "Dizziness in discus throwers is related to motion sickness generated while spinning".

Mathematics

Dorothy Martin of the USA (who predicted the world would end in 1954), Pat Robertson of the USA (who predicted the world would end in 1982), Elizabeth Clare Prophet of the USA (who predicted the world would end in 1990), Lee Jang Rim of Korea (who predicted the world would end in 1992), Shoko Asahara of Japan (who predicted the world would end in 1997), Credonia Mwerinde of Uganda (who predicted the world would end in 1999), and Harold Camping of the USA (who predicted the world would end on 6 September 1994 and later predicted that the world will end on 21 October 2011), for teaching the world to be careful when making mathematical assumptions and calculations.

Peace

Arturas Zuokas, the mayor of Vilnius, Lithuania, for demonstrating that the problem of illegally parked luxury cars can be solved by running over them with a tank.

Public safety

John Senders of the University of Toronto, Canada, for conducting a series of safety experiments in which a person drives an automobile on a major highway while a visor repeatedly flaps down over his face, blinding him.