Fig. 7. (A) The voltage distribution (peak-to-peak amplitude of the LEOD) on the skin, measured in the presence (red squares) and absence (blue squares) of a metal cube. Each symbol represents the average of ten LEODs. The abscissa shows the plane where the voltages were measured along the fish at the left and right side of the mouth, with 0 indicating the position of the mouth. Note the relatively stable voltage distribution in the range from –15 to +15 mm (the arrows indicate the distortions caused by the nostrils). (B) The resulting voltage difference caused by the presence of the metal cube. (C) The modulation of the voltage due to the presence of the object. (D) Normalised modulation (maximum set to 1), which was used to calculate the slope of the electric images. In B and C, values are means ± s.d. (N=10).