Dr. Tasha Stanton from the Neuroscience Research Australia group has been visiting the MIRAGE lab in Nottingham for the last 3 weeks. The aim of her visit was to learn how to use MIRAGE before taking one back to Australia with her. This picture was taken at the UCAS open day held at Nottingham yesterday (15/02/12) where she was demonstrating the illusions to prospective students and their families. The best way to learn how to use MIRAGE properly is to be thrown into a live public demo. She did brilliantly.
Tasha Stanton from the Neuroscience Research Australia at the University of Nottingham UCAS open day
Here is the much await third part of the story of the making of MIRAGE:
Recall that I had solved the problem of having a small cursor appear in the same place as the hand and have the cursor move about independently of it, but I had not solved the problem of the cursor looking nothing like a hand. There were several ways in which I could have addressed this issue and, after careful consideration, I went for the easy option. I took a picture of a passing Ph.D. student’s hand (Catherine Preston) and simply replaced the cursor with this picture. Now, I had a life-sized hand moving about in what appeared to be the same place as the subject’s real hand. It was not their real hand (and it only ever fooled one person) and I was stuck with a female hand, but it was a hand, nevertheless. This set up was used in a Transcranial Magnetic Stimulation (TMS) study investigating agency attribution (distinguishing between self generated action and action generated by other agents) and the right hemisphere (Preston and Newport 2008,published in SCAN).
Hand image used for this version of MIRAGE
The surrounding framework had also moved on, from box files and blu-tack to a homemade wooden structure. It would have cost me almost a thousand pounds to have a proper one built, but I didn’t have any research money, so I ignored all health and safety procedures and decided to build my own. I did most of this in secret, using the cover of students waiting noisily for a lecture in the corridor to drown out the noise of sawing and hammering. It was only after I nearly cut my own ear off with a power tool that I decided to tell anyone what I was up to, just in case I went missing for a few days and no-one thought to investigate the spreading pool of blood seeping out from under the lab door. Unfortunately, my woodworking skills were only as good as my Grade C O-level and the whole thing came tumbling down on a patient that Catherine was testing. At that stage, we decided to do things properly – and went to IKEA.
Next Time: IKEA, a boot, technological advancements and the first idea of what I might have inadvertently created.
This month’s illusion, the disappearing hand trick, is exactly what it says it is - an illusion that makes your hand disappear. It works on the principle that if we can be made to feel like a fake hand is belongs to our body or that our finger is reallystretchingusing multisensory integration (matching of vision and touch) then by using multisensory disintegration we can make our real limb seem to disappear.
Participants place both hands in MIRAGE so that they are hovering just above the tabletop. Blue bars then appear that gradually close in on the hands over about 25 seconds. The participant's only task at this point is to keep their hands within the blue bars.
Participant trying to avoid the blue bars.
What is actually happening here is that the images of the hands move very slowly inwards so that to keep their hands still the participant must move their hands ever so slowly outwards - so slowly that the don't know they are doing it (for full details on the experimental procedure see the supplementary material from the published article - Multisensory disintegration and the disappearing hand trick, Current Biology). After 25 seconds the hands are placed down on the tabletop and then the image of the right hand disappears along with the blue bars.
At this point the participant does not feel like their hand has actually disappeared, although all that they can see is the table where their hand used to be, but then they are asked to reach over with the left hand and touch their disappeared right hand.
We believe vision more than our body position sense (proprioception) so the the participant thinks their hand is where they last saw it, Because their hands are actually further away than they realise, when they reach to where they think their other hand is - it is no longer there and seems to have disappeared. It is this failure to touch the right hand with their left hand that is key to multisensory disintegration and the experience that the hand has actually gone.
The illusion is so effective that most people show some kind of stunned or amused reaction and some even pull their hands out to check they still have them both!
This video shows what the volunteer sees during the illusion.
This video shows a volunteer reaction to her disappeared hand. Note that her reaction is elicited at the moment that she reaches for her right hand but does not find it.
Well this is the first blog of 2012 and this year we hope to have another very productive year in the MIRAGE lab, finishing the arthritis grant sponsored by Dunhill medical trust, getting a new branch of the lab up and running in Malaysia as well as the day to day body/ action representation research.
Our quarterly illusion posts will continue with the Winter illusion (disappearing hand trick) in the next few days and of course the continuation of the "From Box Files to the British Science Festival" posts explaining how and why the MIRAGE began.
At the end of last east year Roger appeared on Health show talking about our arthritis research, if you missed it then however, you can still watch now thanks to Rockhopper.tv. Watch the video below or download your own copy from this link:
This week Dr. Roger Newport will be appearing onThe Health Showtalking about our arthritis project.
The Health Show is a new series that covers the latest advances in health related science and technology. This week they have a section on the MIRAGE technology and how we are using it to reduce pain in arthritis.
Roger demonstrating MIRAGE on The Health Show - BBC World
Image provided by Rockhopper.tv.
During the Show Roger will be demonstrating the technology as well as explaining what our research is all about and why we think it works. Our original findings published in Rheumatology (available free online) showed a dramatic reduction of pain in 85% of a sample of osteoarthritis sufferers. Since then we obtained a grant from the Dunhill Medical Trust(ongoing) to continue with the research.
The show will be aired on BBC World this Saturday at 10:10 and 20:10 GMT and again on Sunday at 07:10 and 23:10.
Not just arthritis: The MIRAGE was originally developed to investigate action and body representations of which pain is only one aspect (to learn more about how the MIRAGE was developed see our ongoing blog series - From Box Files to the British Science Festival). The MIRAGE allows us to create various weird and interesting bodily illusions that are not only fun, but can help tell us about how our brain represents and controls our body. You can find out about the different illusions we use from our quarterly illusion blog posts. The next (Winter) illusion - coming soon - will be the Disappearing Hand Trick, which was used for the latest MIRAGE publication (Current Biology) investigating body awareness.
Here is Part 2 of the series on how and why the MIRAGE was developed
If you remember, I was trying to make adaptation to visual shifts (like when wearing prism goggles) more flexible. To do this, I hacked into some motion tracking software (this tracked a sensor on the hand as it moved through space) so that I could read and change the x, y and z coordinates of the cursor on a moment-by-moment basis. This created a system whereby the cursor could either track the location of a subject’s hand, or could be manipulated to move independently of it. Once I could do this, I could show a cursor (a big black dot) to the subject as a representation of their hand location. When I first tried this I glued a projection screen that I found in my loft onto the top of a box, and hung a projector from the ceiling so it shone down onto the screen. The subject’s hand was inside the box with the motion tracking sensor on so wherever the hand moved inside the box, a black dot followed it around on top of the box. This, I suppose, was Mark 1, but I didn’t like it for two reasons: firstly a cursor is not a great representation for the hand and secondly, the projected cursor was not in the right spatial location as it was always above the hand. This was a problem for some people, especially patients with brain damage, as they would always lift their hand up to try to match it to the cursor location above.
Mark 2 was made out of box files, a stolen mirror and some drafting paper (a bit like greaseproof baking paper) and was designed to solve the second of these problems. The projector shone down from the ceiling onto the paper and, because it was a little bit see through, the image of the cursor could be seen on the underside of the paper as well. A big mirror, rescued from a skip, rested precariously on box files so that it lay horizontally exactly half way between the paper and the table. Now, when the subject looked down into the mirror, they could see a reflection of the cursor (above) so that it appeared to be at the same level as their hidden hand on the table (below the mirror). So the cursor was now in the right place, but it still looked like a cursor, not a hand.
This post begins a series written by Dr. Roger Newport about how and why the MIRAGE system was developed.
I am often asked how MIRAGE came about, how I thought of it and how I designed it. The truth is that it all came about by chance - I was actually designing something else. About 10 years ago I was experimenting with prism goggles. Prism goggles shift everything you see over to one side so that when you point at something, you miss it. After a while your brain gets used to the visual shift and you learn to point accurately again, but when you take the goggles off you overcompensate and miss to the other side (because your brain has adapted to the visual shift). While this is very interesting as it helps us to understand how the brain learns and adapts to new tasks, I felt that the fixed visual shift of prism goggles was too simple and that it would be more interesting if we could create a situation where the brain has to learn something more dynamic and flexible. At the same time, I was also messing about with mirrors. You can try this one at home: Fix a mirror upright on a table (I actually had a big mirror wedged vertically between two tables), then put one hand either side and look into the right side of the mirror so that you can see a reflection of your right hand where your left hand should be. Now repeatedly point backwards and forwards (towards and away from your body) either side of the mirror with both hands between two (or more) fixed points while looking at your ‘left’ hand. After about 40 reaches, stop with your hands at the furthest point and peer round the left side of the mirror to see where your left hand really is. You will probably find that it has drifted off either away from the mirror or towards it without you noticing. Sometimes it can drift more than 20 cm and you still won’t notice.
Participant reaching to targets either side of an upright mirror. Instead of seeing the real left hand only a mirror reflection of the right hand (appears like the real left hand) can be seen.
How does this work (assuming it has if you’ve just tried it)? When you look in the right side of the mirror, what you see as your ‘left’ hand is obviously actually just the reflection of your right hand. However, because it happens to be in the right place at the right time, your brain will treat it as if it was your real left hand. Your ‘left’ hand won’t be very accurate at pointing to the targets because what you’re actually seeing is a reflection of the right hand (that you’re not looking at!), so it will appear to miss the target by a small amount each time. Your brain will try to correct for the error of your ‘left’ hand but can’t because it is actually your right hand, and so over the course of many reaches these small corrections all add up and you find that your real left hand has drifted off significantly to the left or right without you noticing. The direction the left hand drifts will depend on which way the right hand missed on the first reach. Here is a series of videos that demonstrate what I mean.
Set-Up as the participant sees it. Note that the 'left' hand appears to be pretty accurate throughout.
This video you shows what the hands are actually doing and you can see the left hand starting to drift off to one side.
In the final video you can see that the participant almost hits the mirror and even changes hand posture without noticing, demonstrating the illusory power of seeing a hand in the right place at the right time doing approximately the right thing.
Next time: How these seemingly unconnected ideas began to fuse into what eventually turned into MIRAGE.
