A retrospective editing of consciousness

A new study has found that conscious experience can be altered retrospectively, so that experience of visual information can be changed almost half a second later by manipulating where our attention is drawn.

The research, led by cognitive scientist Claire Sergent, involved asking people to stare at a centre point of a screen with two empty circles either side.

At some point, one of the two circles would fill with randomly oriented stripes for just 50ms (one twentieth of a second) and afterwards the participants were asked to say which direction the stripes were pointing in.

Crucially however, each time this happened, one of the two circles would dim either before or after the stripes appeared.

This would happen at different times – from 400ms before the stripes appeared, up to 400ms after the stripes appeared, and the dimmed circle might appear on the matching side to the stripes or on the opposite side.

Dimming one of the circles grabs your attention. It makes you instantly focus more on whichever side of space it happens.

For example, if the left-hand circle dims, it grabs your attention, and if the stripes then appear on the left, you’re more likely to make a correct judgement about which direction they’re pointing because you’re already focused on this area. But if the stripes subsequently appear on the other side, you’re distracted and you do worse.

The key discovery from this experiment was that this also happens if the dimmed circle appears after the stripes. Up to 400ms seconds after.

In other words, you perceive the original visual details that would otherwise have escaped consciousness if your attention is drawn to the area after the picture disappears. It’s like a retrospective editing of consciousness by post-event attention.

This suggests that consciousness isn’t ‘filtered’ sensory information, but an active ‘conclusion’ drawn from information distributed across senses, space and time.

Link to locked scientific study.
Link to open-access commentary from same journal.

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Anesthesia as a consciousness scalpel

I’ve just written a piece for the Discover Magazine blog The Crux about a new study that used anaesthetics to “put people under” and test the limits of their conscious mind even after they’d stopped responding to the outside world.

Doing psychology experiments on people undergoing anaesthesia is not a new idea but it has always been done on people who volunteered due to undergoing genuine surgery. But this was the first study to put volunteers under anaesthesia solely as part of an experiment.

In this case, the experiment tested whether people had conscious experiences despite being unable to respond to outside stimuli – the medical definition of being unconscious.

It turns out the conscious mind keeps working way past the point where people are medically defined as unconscious.

In addition to the standard surgical way of checking unconsciousness, participants were also regularly asked to open their eyes to check when they stopped and started responding. Afterwards, each participant was questioned about their memories of the anesthesia session to see if they had conscious experiences even when seeming to be comatose. These included simple thoughts or perceptual experiences like flashes of light, to more complex experiences such as seeing or hearing the researchers, or having dream-like, out-of-body hallucinations.

It turns out that despite being rated as unresponsive and, therefore, by the current medical definition, unconscious, participants reported conscious experiences in about 60% of the sessions. This does not mean that everyone was “awake” as we normally understand it, as the extent to which the experiences reflected the reality of what was going on around the person varied, but the volunteers were clearly having conscious experiences.

Excitingly, the researchers suggest that experimental anaesthesia could be used as a ‘dimmer switch’ for the mind to find the point where no further conscious experience takes place.

Doing these studies while studying brain activity could help us understand which brain circuits are needed for the cross-over into consciousness.

More at the link below.

Link to ‘Anesthesia May Leave Patients Conscious—and Finally Show Consciousness in the Brain’.

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The quest to understand consciousness: Antonio Damasio on TED.com

Every morning we wake up and regain consciousness — that is a marvelous fact — but what exactly is it that we regain? Neuroscientist Antonio Damasio uses this simple question to give us a glimpse into how our brains create our sense of self. (Recorded at TED2011, March 2011, in Long Beach, California. Duration: 18:43)

Watch Antonio Damasio’s talk on TED.com, where you can download it, rate it, comment on it and find other talks and performances from our archive of 1,000+ TEDTalks.

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