That eerie feeling you get upon entering an abandoned building has little to do with what is called the sixth sense.
The feeling is your brain's ability to recognise visual stimulants without you realizing it.
New research suggests that this phenomenon of "knowing without knowing" can often be mistaken for psychic ability or supernatural intuition.
"We have provided direct behavioural evidence that observers can regularly detect when a change has occurred without necessarily being able to identify what has changed," said lead researcher Piers Howe of the Melbourne school of psychological sciences at the University of Melbourne.
The researchers presented participants with pairs of colour photographs of the same person's face.
In some cases, the two photographs were identical.
In others, there were minor but significant differences (such as in person's hairstyle).
Each photograph was seen for one and a half seconds, with a one-second break between the images.
The subjects were then asked to determine whether or not a change had occurred and, if it had, to correctly identify the change from a list of possible options.
"We found that this ability to detect unidentified changes is not unique to images containing faces," said Howe.
Humans pick up subconscious visual cues from their environment and assimilate it into their knowledge without realising it, said the study published in the journal PLoS-ONE.
"We were able to show how this process worked and debunk the claim that this was due a quasi-magical ability such as the sixth sense," Howe said.
The point is that people can sometimes get the strong impression that they can sense changes that they cannot see, he added.
"What the research showed was that while this sensing ability is indeed real, it has nothing to do with a sixth sense and can be explained in terms of known visual processes," the study said.
