More wisdom from the CIA

There's another bit of information in the CIA's book Psychology of Intelligence Analysis that seems particularly relevant to information security. This concerns how much information people need to make good decisions. Here's what Chapter 5, "Do You Really Need More Information?" says about this:

Key findings from this research are:

• Once an experienced analyst has the minimum information necessary to make an informed judgment, obtaining additional information generally does not improve the accuracy of his or her estimates. Additional information does, however, lead the analyst to become more confident in the judgment, to the point of overconfidence.
• Experienced analysts have an imperfect understanding of what information they actually use in making judgments. They are unaware of the extent to which their judgments are determined by a few dominant factors, rather than by the systematic integration of all available information. Analysts actually use much less of the available information than they think they do.

So maybe it's the case that information security professionals don't need as much information as we might think they do to make informed decisions and that too much information can actually be harmful instead of beneficial when it comes to this. And if security professionals are really using only some of the available information to help them make these decisions, I'd be very interested to learn exactly what information they do use. Hundreds of marketing people probably would also.