London, Mar 17 (IANS): The strength of alpha brain waves reveals if you are about to make a biased decision, says a new study.

According to the researchers, biases in sensory perception can arise from both experimental manipulations and personal trait-like features.

Everyone has bias, and neuroscientists can see what happens inside your brain as you succumb to it. The clue comes from alpha brain waves -- a pattern of activity when the neurons in the front of your brain fire in rhythm together, they said.

Alpha brain waves pop up when people make decisions, but it remains unclear what their role is.

For the findings, published in the journal JNeurosci, the researchers Laetitia Grabot and Christoph Kayser from the Bielefeld University in Germany, used electroencephalography to monitor the brain activity of adults while they made a decision.

According to the study, the participants saw a picture and heard a sound milliseconds apart and then decided which one came first.

Prior to the experiment, the researchers determined if the participants possessed a bias for choosing the picture or sound.

Before the first stimulus appeared, the strength of the alpha waves revealed how the participants would decide, the researchers said.

The study revealed that weaker alpha waves meant resisting the bias; stronger alpha waves indicated succumbing to the bias.

"These results also hold after temporal recalibration and are specific to the alpha band, suggesting that alpha band activity reflects, directly or indirectly, processes that help to overcome an individual's momentary bias in perception," the researchers wrote/

"We propose that combined with established roles of parietal alpha in the encoding of sensory information frontal alpha reflects complementary mechanisms influencing perceptual decisions," the researchers added.