Fast asleep? Your unconscious is still listening
By Simon Makin
Some people swear that if they want to wake up at 6 am, they just bang their head on the pillow six times before going to sleep. Crazy? Maybe not. A study from 1999 shows that it all comes down to some nifty unconscious processing.
For three nights, a team at the University of Lubeck in Germany put 15 volunteers to bed at midnight. The team either told the participants they would wake them at 9 am and did, or told them they would wake them at 9 am, but actually woke them at 6 am, or said they would wake them at 6 am and did.
This last group had a measurable rise in the stress hormone adrenocorticotropin from 4.30 am, peaking around 6 am. People woken unexpectedly at 6 am had no such spike. The unconscious mind, the researchers concluded, can not only keep track
Don’t think: How your brain works things out all by itself
By Caroline Williams
Wouldn’t it be great if you could leave difficult decisions to your subconscious, secure in the knowledge that it would do a better job than conscious deliberation? Ap Dijksterhuis of Radboud University Nijmegen in the Netherlands proposed this counter-intuitive idea 12 years ago. No wonder it was instantly popular.
Dijksterhuis had found that volunteers asked to make a complex decision – such as choosing between different apartments based on a baffling array of specifications – made better choices after being distracted from the problem before deciding. He reasoned that this is because unconscious thought can move beyond the limited capacity of working memory, so it can process more information at once.
The idea has been influential, but it may be too good to be true. Many subsequent studies have failed to replicate Dijksterhuis’s results. And a recent analysis concluded that there is little reason to think the unconscious
We accurately weigh up a person’s character in 0.1 seconds
By Simon Makin
Ever felt love at first sight? Or an irrational distrust of a stranger on a bus? It could be because our unconscious is constantly making fast judgements. And they are often pretty accurate.
In the early 1990s Nalini Ambady and Robert Rosenthal, both then at Stanford University in California, asked volunteers to rate teachers on traits including competence, confidence and honesty after watching 2-, 5- or 10-second silent clips of their performance. The scores successfully predicted the teachers’ end of semester evaluations and 2-second judgements were as accurate as those given more time. Further experiments showed similar accuracy for judgements about sexuality, economic success and political affiliation. For anyone hoping to use this to their advantage, the bad news is that no one has worked out what to do to pass yourself off as a winner. It seems to be an overall body signal that is
How we know where our limbs are without thinking
By Anil Ananthaswamy
Thanks to unconscious processing, most of us instinctively know where our limbs are and what they are doing. This ability, called proprioception, results from a constant conversation between the body and brain. This adds up to an unerring sense of a unified, physical “me”.
This much-underrated ability is thought to be the result of the brain predicting the causes of the various sensory inputs it receives – from nerves and muscles inside the body, and from the senses detecting what’s going on outside the body. “What we become aware of is the brain’s ‘best guess’ of where the body ends and where the external environment begins,” says Arvid Guterstam of the Karolinska Institute in Stockholm, Sweden.
Break bad habits by hacking the autopilot in your brain
By Anil Ananthaswamy
So much of what we do in our day-to-day lives, whether it be driving, making coffee or touch-typing, happens without the need for conscious thought. Unlike many of the brain’s other unconscious talents, these are skills that have had to be learned before the brain can automate them. How it does this might provide a method for us to think our way out of bad habits.
Ann Graybiel of the Massachusetts Institute of Technology and her colleagues have shown that a region deep inside the brain called the striatum is key to habit forming. When you undertake an action, the prefrontal cortex, which is involved in planning complex tasks, communicates with the striatum, which sends the necessary signals to enact the movement. Over time, input from the prefrontal circuits fades, to be replaced by loops linking the striatum to the sensorimotor cortex. The loops, together with the memory
Your brain’s crystal ball helps you understand speech and fear
By Diana Kwon
Every moment, the brain takes in far more information than it can process on the fly. In order to make sense of it all, the brain constantly makes predictions that it tests by comparing incoming data against stored information. All without us noticing a thing.
Simply imagining the future is enough to set the brain in motion. Imaging studies have shown that when people expect a sound abstract or image to appear, the brain generates an anticipatory signal in the sensory cortices.
This ability to be one step ahead of the senses has an important role in helping us understand speech. “The brain is continuously predicting the sounds, words and meanings that people are trying to produce or communicate,” says Matt Davis at the MRC Cognition and Brain Sciences Unit in Cambridge, UK.