The tingling sensation described in the study was, more often than not, associated with the amputated limb. The sensation was always stronger than any vague awareness of an intact limb. Henderson and Smyth hypothesized that the tingling presumably had an organic basis and depended upon impulses entering at a conscious level. The patient could elicit this tingling feeling by merely thinking about it, however in certain circumstances the sensations could be induced without his thoughts being directed to it.