Instinctive decisions can be more reliable than decisions made after conscious thought.

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SYDNEY: Instinctive snap decisions can be more reliable than decisions made after conscious thought, according to British scientists.

In a study published this week in the journal Current Biology, participants were more likely to choose the correct answer in certain situations when they were given very little time to think, compared with when they were given time to engage their conscious brains.

"This finding seems counter-intuitive," said co-author Li Zhaoping of University College London. "You would expect people to make more accurate decisions when given the time to look properly. Instead they performed better when given almost no time to think. The conscious, or 'top-level' function of the brain, when active, vetoes our initial subconscious decision - even when it is correct.

"Falling back on our inbuilt, involuntary subconscious processes for certain tasks is actually more effective than using our higher-level cognitive functions."

Participants were asked to identify which side of a computer screen held a single reversed symbol in a pattern of 650 identical objects. The subjects were given between zero and 1.5 seconds after their eyes landed on the mismatched symbol to make up their minds.

Given only a fraction of a second to scrutinise the target, subjects were correct 95 per cent of the time. But when allowed more than a second to scrutinise the image, accuracy dropped to only 70 per cent. Given more than four seconds to decide, accuracy recovered.

According to the researchers, the instinctive decisions were more likely to be correct because the subconscious brain recognises a rotated version of the same object as different from the original, whereas the conscious brain sees the two objects as identical - for the conscious brain, an apple is still an apple whether rotated or not.

So while the lower-level cognitive process spots the rotated image as the odd one out, the higher-level function overrides that decision and dismisses the rotated object because it is the same as all the other symbols.

The team controlled the time allotted to each individual's search for their target by tracking eye movements. The visual display screen was switched off at various time intervals either before or after a subject's eyes landed on the target.

When the on-screen image was hidden immediately after the subject's eyes had landed on the target, the subject often believed they were just guessing the location of the odd one out. They were unaware that their gazes had shifted to the target just before the image was hidden and their instinctive answers weren't guesswork at all.

According to Zhaoping, "Our eye movements are often involuntary. What seems like a random darting of the eye is often an essential subconscious scanning technique that allows us to pick out unique and distinctive features in a crowd - such as colour or orientation.

"Soon after our eyes have fixed on a target, the conscious or top-down part of cognition engages and examines whether the candidate really is the target or not. If the target is not distinctive enough in the 'eyes' of the conscious, failure of identification can occur."