 What of microstimulation in the absence of a stimulus? Might we induce hallucinations as Penfield did in his patients? Rather than the work from the Newsome group that modulated ongoing perceptual processing, the issue here is to create an internal signal that mimics perception. Romo et al. (1998) demonstrated that monkeys can carry out sensory tasks via activation triggered by microstimulation. The monkeys’ task was to discriminate the frequency of two sequential “flutters” on their fingertips, that is, mechanical vibrations on the skin at specific frequencies. In an experimental trial, an initial sample flutter was presented for 500 ms and after a gap of 1-3 seconds, a second test flutter of either higher or lower frequency was presented. The animal reported whether the second test frequency was higher or lower than the sample.