London, March 9 (IANS): Wondered how great archer Arjuna hit the bird's eye with his arrow with such precision. Thanks to an in-built mechanism in the brain.

The human brain can select relevant objects from a flood of information and edit out what is irrelevant. It also knows which parts belong to a whole, said a research.

If, for example, we direct our attention to the doors of a house, the brain will preferentially process its windows, but not the neighbouring houses.

Psychologists from Goethe University Frankfurt have now discovered that this also happens when parts of the objects are merely maintained in our memory.

"These are essential skills of our brain, which are closely connected to intelligence and which are impaired in various psychiatric illnesses," said researcher Benjamin Peters.

In their study, Peters and colleagues examined "object-based attention", a well-known phenomenon in perception research.

This refers to the fact that we automatically extend our attention to the whole object when we attend only part of an object.

In the experiment the subjects were asked to direct their attention alternately to one of four screen positions, which formed the ends of each of two artificial objects.

The subjects were able to shift their attention more quickly between two positions that belonged to the same object than between those that were part of different objects.

It was discovered that this effect also occurred when the subjects envisaged these positions only in short-term memory.

Using magnetic resonance imaging, they initially found increased activity at those positions in the cerebral cortex where the currently focused position was represented.

However, this increased activity also extended to the areas in the brain that represent the relevant associated position of the same object, despite the fact that the subject was not concentrating on it.

"It is remarkable that this effect was observed in regions of the brain that are normally involved in perception, despite the fact that here, objects and positions were only maintained in memory," said Peters.