Evidence is presented from both basic and applied EEG studies which validates the use of EEG methods as evaluators of advertising effectiveness. Despite variations in methodology and interpretation, there is considerable consensus on the ability of the EEG to reflect cognitive and attentive processes. Studies are also cited which have independently replicated our findings on the relationship of EEG to recall, frequency of ad exposure, and advertising content. New research data from our laboratory are presented on the relationships of brain response and respondents' ratings to purchase simulation. Cross-validation of advertising research methods is also discussed.