Psychologists who found leaning to the left makes the Eiffel Tower seem smaller and neuroscientists who registered brain activity in a dead salmon are among the winners of Ig Nobel prizes for the oddest discoveries.
The annual prizes are awarded by the satirical magazine Annals of Improbable Research in the United States as a whimsical counterpart to the Nobel prizes.
US researchers scooped an award at the gala ceremony at Harvard University for discovering that chimps can recognise other chimps by looking at snapshots of their backsides.
A Swedish researcher who solved the puzzle of why some people's hair turned green in a Swedish town also earned an Ig Nobel, Reuters reports.
The reason for the hair colouring was a combination of copper pipes and hot showers.
Other winners were a British/US team that came up with an equation to predict the shape of a ponytail.
The Ponytail Shape Equation takes into account the stiffness of the hair fibres on the head, the effects of gravity and the presence of the random curliness or waviness to model how a ponytail is likely to behave.
Research detecting meaningful brain activity in a dead salmon started as a joke, University of California researcher Craig Bennett said.
Before starting tests on people, scientists first check their equipment using such objects as a sphere filled with mineral oil, but decided to try out other items.
In the salmon test, the team showed photos to the dead fish and asked it to determine what emotion the person was feeling.
"By random chance and by simple noise, we saw small data points in the brain of the fish that were considered to be active," Mr Bennett said. "It was a false positive. It's not really there."
The often-quoted study exposed the perils of fMRI science, which can be prone to false signals, and underscored the need to do statistical corrections to safeguard against such silly findings.
The real Nobel Prize announcements will begin on 8 October.