On the embodiment of unfeasible objects

Further to my last post detailing experiments relating embodiment of invisible and even third hands, here are some notes on my first ‘Clay hand Illusion’ experiments…

The ‘Rubber hand illusion’ shows it is possible to convince participants that a rubber hand is their own by placing it in front of them while stroking it in the same way as their hidden real hand. The use of self-made clay hands, or objects [see below] in place of the rubber hand raises several interesting possibilities for exploration, which move away from the embodiment of replica body parts, and towards the possible embodiment of modified body parts, or completely ‘unfeasible’ objects.tactile_object3.jpgThe clay allows for the gradual and immediate morphing of forms and for the participant to build a sensory connection with the object through its creation. As an artist [who has worked with clay] I feel a sense of deep connection with the objects I make, especially during making them. For example, I feel my face move and contort when I am trying to draw a face. I wonder if this is true of others? This is why for my first participants I am choosing those who work with clay.

In regard to the embodiment of ‘unfeasible’ objects, the possibility of such a thing has been loosely disproven in several studies [See ‘The Invisible Hand Illusion’]. Whereby a plank of wood and a spoon were substituted in place of the embodied hand. Therefore I am keen to explore this further. So far I have had encouraging results which build on the results from the first workshop session [See image below]. Is it easier to achieve a connection with self-made objects, rather than an irrelevant object, such as the plank of wood?
hands03In my first ‘beta’ study, I worked with a participant who is a maker and uses clay in their work. After making a good connection with their self-made clay hand, I asked if they could make a non-hand like an object, or a modification to the clay hand, for a further experiment. They immediately opted to make a roundish blob. Followed by a further iteration; a doughnut shape. They were able to make a strong feeling of connection with the blob and the Doughnut, though not as strong as to the hand, and the connection took longer to achieve. The connection was patchy, in parts, and mapped over the surface.

I found that the fingers could be mapped around the object by using a combination of synchronous tapping and swapping over the embodied finger with other digits, and the moving the already embodied finger over to a new location on the object. For example, the index finger feels fully connected to the clay object but, the ring finger does not. So I tap on the real ring finger and say I’m tapping on the index finger. They then seem to believe that this finger is now connected, when I return to the index finger – they now believe the finger next to the index finger is now newly connected to the clay. It’s not easy to explain! Mor on this later. The main part of the hand did not feel fully embodied.

It seemed like that with time, and combinations of synchronous and non-synchronous tapping, the hand could be mapped in two dimensions over the surface of the object.

I also found an interesting ‘compression’ in the perceived length of the fingers! When I tapped on the knuckle where the finger joins the hand, the participant thought this was the middle of their finger.

Working with the clay has an interesting effect of leaving traces of the tapping and stroking process so over time a textural surface is built up. When experimenting with the clay blob the participant made the following comment…

IMG_1640Unfeasible Object #1 Participant 1

 “I fully believe that’s my hand, but like there’s an obstacle, like you cant push past it…it feels like my hand is made out of this clay, but there is only so far you can push into it…it feels like a barrier”

The barrier seemed to be just under the surface of the clay. Perhaps this suggests a  surface-deep sensation of the perceived embodiment? Another interesting comment…

“Its like when I’m making something, I can feel my hand moulding something, and it feels like I’m on the opposite side of that”

The significance of this comment hit home when my supervisor picked up on the idea of ‘actions’ ie how we might hold an object, or how the object was made. Could embodiment of these objects be stronger if I considered them from the point of view of how they might be handled? This makes me think of ways in which the underside of the hand could be used in the illusion, rather than the back of the hand as is traditionally used. An upside down or inside out version of the Rubber hand Illusion? My experiment continues to evolve…

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Blind drawing of hand

Blind drawing of hand starting from the left and using a continuous line, before and after experiments.
before-afterCould this exercise be used as a measure of “proprioceptive drift” before and after ‘Rubber hand illusion’ type experiments? I will be exploring this idea soon with the research group at BEAM lab…

Clay hand drawings

Here are are a selection of drawn outlines of clay hands created by workshop participants aged 6 to 12 for the original clay hand experiment (see posts tagged rubber hand or clay hand) Participants of all ages were asked to create a hand and use it in place of a replica rubber hand, the idea was to test if a self-created hand was easier to connect with. The hands were then taken and worked on further, sometimes becoming more distorted and abstract.
hands03.jpg

Rubber hands ‘feel’ touch that eyes see

The first report on the Rubber Hand illusion. Published in Nature in 1998 by Matthew Botvinick, and Jonathan Cohen of the Department of Psychiatry, University of Pittsburgh…

“We report here an illusion in which tactile sensations are referred to an alien limb. The effect reveals a three-way interaction between vision, touch and proprioception, and may supply evidence concerning the basis of bodily self-identification.”

“It has been proposed that the body is distinguished from other objects as belonging to the self by its participation in specific forms of intermodal perceptual correlation7,8. Subjects in our first experiment who referred their tactile sensations to the rubber hand also consistently reported, in both sections of the questionnaire, experiencing the rubber hand as belonging to themselves. Indeed, eight of ten subjects spontaneously employed terms of ownership in their free-report descriptions, for example: “I found myself looking at the dummy hand thinking it was actually my own.”

https://www.ncbi.nlm.nih.gov/pubmed/9486643

 

 

 

 

Rubber-hand illusion experiment

As part of my research into perceptual illusions, I looked into The ‘Rubber Hand Experiment’. This is a classic low tech experiment that can help us “understand how sight, touch and “proprioception” the sense of body position, combine to create a convincing feeling of body ownership, one of the foundations of self-consciousness  (Nature 1998, vol 391, p 756 )”. Recent studies have gone on to experimentally induct of out of body experiences or create body swap illusions. See the work of Henrik Ehrsson and Olaf Blanke. [see link http://www.eurekalert.org/pub_releases/2007-08/ucl-foe081407.php ] I invited some psychologists to the studio [including Lizzi Lewis of BEAM Lab and Paul Sermon] who I have expertise in this area, they brought presentations and some kit to do the rubber-hand experiment, most importantly a realistic rubber-hand [which I since discovered is not really needed] with Head Mounted Displays, and a DV camera we had everything we needed to experimentally induct an out of body experience!


I was amazed at how well the rubber hand illusion worked. In this experiment, the fingers of the rubber hand are stroked synchronously with the real hand [hidden from view]. You see the rubber hand in place of your own.  It took a long time for me but as the illusion kicked in I began to feel a strong connection with the fake rubber-hand. I felt the unnerving sensation that the rubber hand was in fact, my own hand, and always had been. It felt that at any moment I could start to move the hand. It started to feel heavy, and this made my arm start to ache.

To be honest, before I tried this I was slightly sceptical of this experiment, I was not convinced that the effect could be strong, total, or convincing’. For me there were several stages; a weirdness at the beginning, where I thought nothing more was going to happen; this then increases as your real hand starts to feel very odd. Then there is a drifting and an odd numbness as you begin to connect with the rubber-hand, this connection then becomes strong, and even remains if visual contact is broken with the hand briefly.

I had an idea to try a wooden hand, and this worked surprisingly well. It made me feel as if my hand was shiny hard and smooth. This left me wanting to push this experiment further; What happened if you swapped the hand for a modified hand during the experiment, used fewer fingers or increasingly abstracted the hand progressively? Or used a hand with just 3 fingers or a beast hand with hair and claws? Lizzi Lewis brought a set of other hands made with rubber gloves and with different textures which she uses as part of her research.

attempting the handshake illusion using HMDs and a DV camera.

 

Basic set up for out of body experience Henrik Ehrsson and Olaf Blanke. [see link http://www.eurekalert.org/pub_releases/2007-08/ucl-foe081407.php
We Also experimented with some HMDs. Attempting the ‘hand-shake illusion’ which feels like you have swapped hands with the other person or that you have lost control of your own hand. We also tried the set up as illustrated above. Like the rubber-hand it seemed, there were progressive stages where so-called ‘ownership’ shifts to the virtual body. In our experiment, we really only entered a mild sensation of ‘weirdness’. From here we could not quite get to a total shift of body location in a strong sense, but with better HMDs and more space, I am sure it would have been more effective.

Given my scepticism about the rubber-hand experiment, I am now convinced that the Body swap illusion could create a very strong sensation of being removed from one’s own body or simulate the effect of an out of body experience. Next time to do this experiment effectively, we need more space and time to set up with less visual distractions in the space.

 

 

Clay hand experiment #1

Working again with Lizzi Lewis of BEAM Lab and Manchester Science Museum we developed a workshop based on the ‘Rubber Hand Experiment’. As we had to work with a large number of people and we didn’t have funding to get loads of rubber hands. So we made the hands in the workshop with clay and used gloves full of different materials, sand, gel, lentils, etc. This had some interesting outcomes, that warranted further research…

clay_hands

Clay hands

As you can see the hands were diverse in form, for the illusion to be effective the hand does not need to be true to life necessarily. Some hands were made purposefully alien for experiments and seemed to work effectively. I wondered if participants are more likely to connect with a hand that they made themselves?

Additionally, we found that you can also remove a finger of the clay hand while maintaining the tactile stimulation routine, and move it away from the hand and reposition it! With clay it is also possible to try squashing and reshaping the hand, making holes in the hand. Rejoining parts of the hand into different places.