A pressure algometer comprises a tip for applying pressure to a point of the patient's body, a pressure transducer for sensing the intensity of the pressure applied to the patient's body and for producing a pressure intensity representative signal, and first and second elongate, laterally adjacent display units. A ramp signal is generated to drive the first elongate display unit and displace a first visual signal in a given direction along that first display unit at a predetermined speed. In response to the pressure intensity representative signal increasing in amplitude, a second visual signal is displaced in the given direction along the second display unit. In operation, the rate of intensification of the pressure applied to the point of the patient's body is adjusted to follow, with the second visual signal, the first visual signal displacing in the given direction along the first display unit whereby the rate of intensification of the pressure is controlled by the speed of displacement of the first visual signal along the first elongate display unit.