This most touching study was published in 2015:
“Illusory Sense of Human Touch From a Warm and Soft Artificial Hand,” John-John Cabibihan, Deepak Joshi, Yeshwin Mysore Srinivasa, Mark Aaron Chan, and Arrchana Muruganantham, IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 23, no. 3, 2015, pp. 517-527. The authors, at Qatar University, Graphic Era University, India, National University of Singapore, and GE Global Research, Munich, Germany, report:
“Results showed that an artificial hand with skeletal structure is as soft as a human hand. Lastly, the participants’ arms were touched with human and artificial hands, but they were prevented from seeing the hand that touched them. Receiver operating characteristic curve analysis suggests that a warm and soft artificial hand can create an illusion that the touch is from a human hand.”