The Illusions

Finger Stretching

One of our favourite illusions which makes it look and feel as though your finger is getting longer. In this illusion, we pull gently on the end of your finger while making your finger look longer. Because you can see your finger getting longer at exactly the same time as feeling the pull your brain automatically puts that information together and tries to make sense of it by coming to the conclusion that your finger must actually be getting longer. It feels, in the words of 90% of people, ‘weird’.

This was one of our first illusions  and it was during one of our public engagement events that Catherine (see Lab Members) noticed that it could change how people felt pain. You can read more about this discovery on our publications page and on Kristy’s research page.

Used in: Pulling the finger off disrupts agency, embodiment and peripersonal space (2010); Analgesic effects of multisensory illusions in osteoarthritis (2011); How long is your arm? Using multisensory illusions to modify body image from the third person perspective (2012).

The Disappearing Hand Trick

Another favourite and one that really blows people away. With this illusion we can make it feel as though your hand has suddenly gone missing. Nobody seems to know where their hand has gone and it frequently gets denounced as witchcraft. There is no ‘magic’ trickery here, though; the disappearing hand is caused purely by the way your brain puts together sensory information about what it can see, feel and touch.

This illusion won Best Illusion of the Year in 2012. It is our favourite public engagement demonstration, but we also use a variation of it in our research because it can help us to understand how the brain knows where your body parts are.

Used in: Multisensory disintegration and the disappearing hand trick (2011); Untangling visual and proprioceptive contributions to hand localisation over time (2015).

The Invisible Hand Trick

We discovered this one in 2011 while messing around with the  Disappearing Hand Trick. It demonstrates how we can make your brain feel like it knows where your hand is even when it appears invisible. We have never published this illusion and only use it for fun at public engagement events.

The Supernumerary Limb Illusion

We came up with the idea for this one on a train on the way to Edinburgh for a conference in 2009. What, we thought, would happen if you suddenly found yourself with two right hands. How would you know which one was yours? Would you think you had two?

Used in: Fake hands in action: embodiment and control of supernumerary limbs (2010); Disownership and Disembodiment of the real limb without visuo-proprioceptive mismatch (2011); Evidence for dissociable representations for body image and body schema from a patient with visual neglect (2011); Differential effects of perceived hand location on the disruption of embodiment by apparent physical encroachment of the limb (2011).

Hand Switching

Here is a video of some hand switching fun. This is actually the first illusion that we got MIRAGE to do (c. 2008), but we have not yet used it for any research purposes. As you can see from the video, we place a small piece of cloth in one hand and then repeatedly switch the hands around. The impression you get is that the cloth is moving, rather than the hands, because the hands are the right shape and in the right place at the right time so the brain automatically assumes they are the left and right hands are on the left and right respectively, even when they are not.

More to follow, including:

The Tingling Skin Illusion. Used in: Increased somatic sensations are associated with reduced limb ownership (2015). 

The Nose Job