On which side lies the truth? It's on the left, according to a 1993 study published in the journal Neuropsychologia. The left ear, this study says, is better than the right ear at discerning truth.

Slightly better. In most people. Some of the time.

The report is called Hemispheric Asymmetry for the Auditory Recognition of True and False Statements. Franco Fabbro and his team at the University of Trieste conducted an experiment. Twenty-four men and 24 women each donned headphones, and then (presumably) followed these instructions:

"In the headphones you will hear phrases pronounced by four people you don't know. There are two types of phrase - 'This is a pleasant photo' and 'This is an unpleasant photo'. While they pronounced these phrases they were looking at photographs which they had previously judged to be pleasant or unpleasant. Sometimes they are telling the truth. Sometimes they are lying. After hearing a phrase you have to decide whether you think the speakers are telling the truth or a lie."

The effect is subtle. According to the data, the left-ear truth detector is not especially good at recognising women's lies. It works, to the extent it works, only when a man does the lying. Even then, it correctly recognises only 63% of the true statements as being true.

Fabbro and his colleagues were intrigued by the two cerebral hemispheres. One is thought to be more skilled than the other at handling emotions. "Most people undergo an increase in emotional stress when telling a lie," the study says. The theory, too, is subtle. Fabbro and his colleagues phrase it this way: "Since in human cultures lying prevailingly occurs at the verbal level, it is reasonable to expect a stronger tendency to consider false that kind of information which is transmitted and processed through verbal systems. By the same token, it is reasonable to expect a stronger tendency to consider true the information which is processed by non-verbal systems."

A different experiment, conducted more than a decade earlier at McGill University in Montreal, Canada, looked for something less subtle. And found it.

Walter W Surwillo told all in his study called Ear Asymmetry in Telephone-Listening Behavior, which was published in the journal Cortex. He, too, was curious about the powers of the left ear versus the right. Surwillo surveyed people whose jobs involve a lot of telephoning, and also people whose jobs don't. His question: which ear do they prefer for listening on a telephone?

The results: "Listening with the left ear was associated with heavy use of the telephone. The most frequently given reason for listening with the left ear was that it freed the right hand for writing and dialling. This preference would appear to be motivated by convenience for although either ear is available for listening, it is easier to hold the receiver to the left than the right ear while grasping it in the left hand."

(Thanks to Rich Palmer for bringing the Fabbro study to my attention.)

· Marc Abrahams is editor of the bimonthly magazine Annals of Improbable Research (www.improbable.com) and organiser of the Ig Nobel Prize