Fig. 12. (A) Schematic of the set-up and method to determine the amplitude of the novelty response. A dipole object of variable resistance was suddenly switched from a high to a low resistance or vice versa. The EOD frequency was monitored in response to the switch (see arrow). Several trials with identical switches and identical positioning of the dipole objects were normalised (normalised ) by subtracting the mean frequency and dividing by the variation of the 20 EODs prior to a switch. Note that negative values in the normalised data correspond to an acceleration of EOD frequency and that this measure is transformed to positive values in B. (B) Mean response magnitude (determined in four fish, based on 64 switches at each position) for a switch occurring at the indicated positions along the fish at a distance of 3 mm from the skin. Note that the response was maximal for a dipole positioned at the tip of the Schnauzenorgan. NS, not significant.