Detecting the presence of a finger in proximity of a screen that generates detection signals in the horizontal direction and vertical direction includes sampling the detection signals and generating raw-data vectors X and Y. The raw data have a maximum for elements of the vector that define the position of the finger on the screen in the directions X and Y, respectively. The vectors X and Y are divided into subsets defined as “macro-areas” and cumulative values computed of each macro-area by adding together all the elements of the vector X and of the vector Y that belong to the macro-area. The maximum values are selected from among horizontal cumulative values and vertical cumulative values. A value identifying the macro-area selected on the basis of the maximum values is supplied, or no value supplied in the presence of elements of disturbance in the proximity of the screen.