A method of quantitatively assessing the effectiveness of an audiovisual, visual or audio advertisement including the steps of: presenting the advertisement to a plurality of subjects, the advertisement having a sequence of audiovisual, visual and/or audio features which occur as a function of time obtaining, during presentation of the advertisement, EEG signals from the subjects from predetermined scalp sites thereof calculating SSVEP amplitudes and/or phase differences from EEG signals obtained from the predetermined scalp sites in order to obtain output signals which represent predetermined psychological states of each subject to the features as a function of time combining the output signals from the subjects to obtain pooled output signals and displaying the pooled output signals to thereby enable quantitative assessment of the subjects responses to the features of the advertisement in order to assess the effectiveness of the features of the advertisement.
