Method for reducing the dimensionality of data which comprises at least the following stages: (i) a learning stage (10) for generating an output map from data relating to the input space, which is made up of nodes, by forming a structure with a size smaller than the input and by updating the values of the input vectors associated with these nodes; and (ii) an execution stage (20a,20b) which is intended to use said output map and in turn comprises two different stages: (a) reducing the size (20a) by representing an input data item using the coordinates of the output vector of the node which represents it; (b) reconstruction (20b) which involves reconstructing an input data item from the reduced set of coordinates which represents it and from the map of output nodes generated in the learning stage (10).