Fig. 1: Tablet interface.

a Screenshot of the object-sensation mapping task. By changing the positions of the cursors in the left and right rectangles, the participant could adjust four stimulation parameters. Touching the object (‘piece of toast’ in this example) generated stimulation trains in real-time. Participants manually touched the digital object or used an automated cursor by selecting the “start”/“pause” button in the top left corner, causing the bar to move across the object every 6.5 s. The toast image was made by Rainer Zenz and sourced from Commons.wikimedia.org (license: creativecommons.org/licenses/by-sa/3.0). No changes were made to the image. No changes were made to the image. b At the start of a trial, the four stimulation parameters (amplitude, frequency, biomimetic factor, drag) were randomly assigned to the A–D locations on the X- and Y-axes of the two rectangles. In addition, parameter values were randomly assigned to increase or decrease along the ten possible levels for each axis. Depending on where the participant touched the object, one of three stimulation electrodes (shown in different colors) was stimulated with the settings defined by the location of the cursors, evoking localized sensations on the palmar side of their right hand. c The exact locations of the evoked sensations by each stimulation electrode (shown in different colors on the hand images) were different for each participant, depending on the locations of the stimulation arrays in their somatosensory cortex. For more details on the exact implant locations for each participant, see Fig. 1 in ref. ²⁴. The remainder of the figure shows a schematic illustration of the stimulation parameters at their minimum (min.) and maximum (max.) levels: amplitude, frequency, biomimetic factor, and drag. Each parameter controlled the stimulation of three individual electrodes and could be changed across 10 levels, i.e., there were 10 unique values per parameter. d Replay task. When the participant touched the rectangle, a previously chosen set of stimulation parameters was replayed, evoking a sensation across the participants’ right hand. The participant was asked to indicate which object best matched the experienced sensation.