Relevant and irrelevant information are determined through discerning the qualities of such information and judging them under a specific scope. This type of cognitive activity is possible through logical reasoning which, according to Albrecht inBrain Building,can be an acquired skill that is taught and learned; this means that logical reasoning is not a genetic virtue, but a result of molding our thinking processes.
In order to acquire logical thinking, the basic skill that is taught from a very early academic level is sequential training. Sequencing consists on "if/then" scenarios, on organized thinking, and on cause/effect strategies. The act of discerning and critically determining the value or importance of information comes as a result of a learned ability to understand the the difference between what is relevant and what is irrelevant; this is what the if/then thinking is all about.
To be able to develop logical reasoning skills, there has to be a tendency to observe traits and qualities, as well as to think flexibly about opposing traits and qualities: if there is good, then there is bad; if there is effectiveness, then there must be ineffectiveness. Again, practicing "if/then" scenarios is the best way to sequentially understand the traits of relevant and irrelevant information.