Clay hand/unfeasible object Experiment

Recent studies based on the Rubber Han­­d Illusion (RHI see original experiment) have shown it is possible to convince participants that a replica stone hand, or even an empty space, is their own, by placing it in front of them while stroking it simultaneously with their hidden real hand. However, attempting the illusion with an entirely ‘unfeasible object’ such as a plank of wood have proved less successful [see this link for more information on variants of the illusion].

This clay hand experiment uses clay in place of the rubber hand to test the possibilities of this illusion, distorting and manipulating the clay beyond the form of a hand into ‘unfeasible objects’. Exploring the real-time effects of perceptual plasticity. Here is some documentation of the first experiment recorded for IPA analysis.

examples of variations of hand created for the original experiment. Museum of Science and industry event

Outline of the experiment:
1/ Create a blind drawing of hand before the experiment.
2/ Create clay hand or objects for illusion experiment.
3/ Generate illusion through tapping of hands and objects and introspective interview throughout this process.
4/ Measurement of ‘Proprioceptive Drift’ after each experiment
5/ Blind drawing of hand after each experiment.
6/ Self-report questionnaire (see below).

The Self report questionnaire

10 questions based on the original questions used in the early RHI experiments (Botvinick and Cohen, 1998). These Questions are rated on a ‘Likert scale’ ranging from strongly agree (+3) to Strongly Disagree (-3)

  1. It seemed as if I were feeling the touch in the location where I saw the clay hand object being touched.
  2. It seemed as though the touch I felt was caused by the touch to the clay hand / object.
  3. I felt as if the clay hand/object was my hand.
  4. It felt as if my hand were drifting towards the clay hand/object.
  5. It seemed as if I had more than one right hand.
  6. It seemed as if the touch I was feeling came from somewhere between my own hand and the clay hand/object.
  7. It felt as if my hand was turning into the same material as the clay hand.
  8. It appeared as if the clay hand/object was drifting towards my hand.
  9. I felt I had some agency over the clay hand/object.

Introspective Interview

The open-ended interview is designed to enable the prompt the participant and give them space to explore and express the unusual sensations they might experience. These are based on questions developed in previous more recent studies with the RHI  (Lewis E., 2018)  The prompts include:

Do you have any unusual sensations, and can you describe them?
How do you feel about the rubber hand at the moment?
How do you feel about your real hand at the moment?
How intense is this sensation?
How comfortable do you find this sensation?
Have these feelings changed over time?
Compared to the synchronous stroking how does the asynchronous stroking feel?
What does this feeling mean in terms of how you feel about yourself in general?

Drawings of the ‘unfeasible’ objects can be seen here

Further links to previous experiments…
Experiment 1, Participant 1 [the unfeasible object…]

Links to my blog posts on previous experiments with clay and hands.