Australian scientists who discovered that a species of beetle makes love to a beer bottle and delaying a trip to the toilet causes people to make bad decisions are among the winners at this year's IgNobel Prizes.

The IgNobels are awarded each year by the Harvard-based Annals of Improbable Research as a light-hearted counterpart to the Nobel Prizes, which will be awarded next week.

The prizes are intended to celebrate the unusual, honour the imaginative, and spur people's interest in science, medicine and technology - once they stop laughing.

Most of the winning researchers appear happy to go along with the joke.

Dr David Darby, Director of the Behavioural Neurobiology Laboratory at the Mental Health Research Institute of Victoria, says winning an IgNobel is a mixed honour.

"We're delighted to have the research recognised, but the fact that people are laughing at it is a bit disconcerting," said Dr Darby, who is part of the team that received the IgNobel prize for medicine.

The study, published in Neurology and Urodynamics earlier this year, was the first time anyone had looked at how delaying the need to urinate might impact on mental processes.

"Our discovery was part of a whole line of research that looked at things that might impair cognition, including alcohol, prolonged sleep deprivation and white noise," Dr Darby said.

"In a situation where people can't void their bladder for any length of time, their attention to detail and ability to manipulate information is equivalent to someone with a .08 blood alcohol level."

Dr Darby says there are several possible explanations.

"One possibility is the amount of pain felt by someone with a full bladder; another explanation is that the brain function involved in inhibiting urine flow is located in the inner frontal part of the brain, in close proximity to the areas responsible for motivation, attention and working memory," he said.

"The final possibility is that people simply become obsessed with holding on and can't think of anything else."

Dr Darby says the study has serious workplace implications: "If people are forced to stay on the job when they need to go, there can be safety and other ramifications."

Love affair with the bottle

Entomologists Dr Darryl Gwynne, from University of Toronto Mississauga, and Dr David Rentz, an adjunct professor at James Cook University in Queensland, received the biology prize for their 1983 study that showed male jewel beetles copulate with empty, discarded beer stubbies. Their study was published in the Australian Journal of Entomology.

Confused by the colour and reflection of the small bumps on the bottom of a glass beer bottle, male Julodimorpha bakervelli beetles mounted the bottles and attempted to copulate with them.

"Some of the more attractive bottles had corpses of several beetles around them," Dr Rentz said.

In one case, the beetle was unwilling to let the bottle go even when it was attacked by ants.

Jokes aside, the researchers say that apart from polluting the environment, discarded bottles are a potential threat to the beetles' mating system. The researchers wrote to the local brewery, and while they received no response, the bottles were modified to remove the dimples.

"Whether this was done to protect the beetles, we have no idea," Dr Rentz said.

A team of European researchers received the physics prize for determining why discus throwers become dizzy while hammer throwers don't. The mathematics prize was awarded to a group of doomsayers who over the past 50 years have erroneously predicted the day the world would end.

Lithuanian mayor Arturas Zuokas was presented with the IgNobel peace prize "for demonstrating that the problem of illegally parked luxury cars could be solved by running them over with an armoured tank".

While the public safety prize went to John Senders from the University of Toronto for a series of experiments studying the effects of a highway driver being repeatedly blinded by a flapping visor.

Awards were also presented to researchers who found red-footed tortoises don't yawn contagiously, the ideal density needed to create an airborne wasabi fire alarm, and that the best way to procrastinate is to work on something else.

Previous Australian winners include Nic Svenson and Piers Barnes from CSIRO for calculating the number of group photos you need to take to ensure no-one has their eyes closed; ABC Science's Dr Karl Kruszelnicki for working out the composition of belly button lint; and the University of Adelaide's Dr Mike Tyler for smelling and cataloguing the odour of 131 stressed frogs.