Attention is the concentration of consciousness in some phenomenon, achieving the exclusion of other stimuli. It constitutes the means by which we actively process a limited quantity of information from the enormous amount of data available through our senses, our stored memories and other cognitive processes (De Weerd, 2003). Attention involves both automatic and controlled processes. Digit-span tasks (both forwards and backwards) allow to measure attentional mechanisms and the amplitude of the capacity to retain information units.