The limitations on human information processing, in the broad sense, create opportunities to confuse, deceive, to pass off and so on. These opportunities have led to infringements and, in turn, to laws to regulate and control. The courts in their turn have had to interpret and administer the laws. Judges and regulators could and did use their own judgment, based on mental models of what other people might perceive, in judging whether substantive infringement had occurred. Given the tremendous developments in cognitive theory and methodology over the last 50 years it is no longer reasonable to make such judgments in the absence of data about what actually happens in the relevant marketplace.
Confusion is no longer something to be speculated or opined about by judges.
Instead it must be demonstrated. Modern techniques and statistical models make it possible to obtain quantitative data about the degree of similarity and confusability of two marks or names in the laboratory. As these techniques become validated in the field the use of preliminary laboratory measurement will grow and the difficulty of field work diminish. The techniques of the behavioral laboratory and the very specific demands of the law for demonstration of hitherto ill-defined and hypothetical behaviors have produced a new kind of field experiment drawn from the laboratory to answer questions relevant to the law. The courts, and the law, will inevitably follow, albeit with some delay, the new human cognitive sciences.