On the use of EEG or MEG brain imaging tools in neuromarketing research

Abstract

Here we present an overview of some published papers of interest for the marketing research employing electroencephalogram (EEG) and magnetoencephalogram (MEG) methods. The interest for these methodologies relies in their high-temporal resolution as opposed to the investigation of such problem with the functional Magnetic Resonance Imaging (fMRI) methodology, also largely used in the marketing research. In addition, EEG and MEG technologies have greatly improved their spatial resolution in the last decades with the introduction of advanced signal processing methodologies. By presenting data gathered through MEG and high resolution EEG we will show which kind of information it is possible to gather with these methodologies while the persons are watching marketing relevant stimuli. Such information will be related to the memorization and pleasantness related to such stimuli. We noted that temporal and frequency patterns of brain signals are able to provide possible descriptors conveying information about the cognitive and emotional processes in subjects observing commercial advertisements. These information could be unobtainable through common tools used in standard marketing research. We also show an example of how an EEG methodology could be used to analyze cultural differences between fruition of video commercials of carbonated beverages in Western and Eastern countries.

Figure 1

Cortical activations associated to the decisions of an experimental subject. Predictable choices (P) are the ones related to familiar items which have been often bought or used in the past, compared with the unpredictable ones (U). Label letters indicate the different stages of the trial, namely, working memory, memory recall, semantic analysis, integration, binding, vocalization, judgement, as the legend indicates as well. Cortical maps present the brain areas activated (blue: lower activity; red: higher activity) during the different decision stages in the frequency range from 30 to 40 Hz. Activations over the left prefrontal cortices are genderrelated, as the bidimensional map shows (high perspective, nose up), reproduced with permission from [11].

Figure 2

Figure presents the results of statistical comparisons of RMB and FRG groups in the theta and alpha frequency ranges (a), and in the beta and gamma bands (b). In particular, the picture is composed by three rows: the first one shows the brain from a frontal perspective, the second one is related to a medial-sagittal perspective, while the third one presents statistically significant images associated to the left and right lateral vision. Statistically significant increases of PSD values for the RMB group are represented as black spots on the average cortical model, reproduced with permission from [25].

Figure 3

Figure presents four cortical z-score maps, in the four frequency bands employed. The average cortical model is seen from a frontal perspective. Colour bar represents cortical areas in which increased statistically significant activity occurs in the RMB group when compared to the FRG group in red, while blue is used otherwise (P < 0.05 Bonferroni corrected). Grey colour is used to map cortical areas where there are no significant differences between the cortical activity in the RMB and FRG groups (a). (b) refers to the statistical comparison LIKE versus DISLIKE with the same conventions of (a), reproduced with permission from [26].

Figure 4

(a) The two scalp maps in figure represent the Z score distribution for the theta (left) and alpha band (right) in the population analyzed. Z values are mapped onto a realistic scalp model, seen from a frontal perspective. Colorbar codes scalp areas in which the LIKE spectral activity is greater than the DISLIKE (red) and regions in which the DISLIKE spectral activity is greater than the LIKE (blue). Grey indicates regions with no difference between the two experimental conditions, reproduced with permission from [42]. (b) Electroencephalography trace of emotional response. In version 1, only the model's face was presented; conversely, in version 2, the viewers saw her face from a slightly different angle (for 2.5 s), and then she made a particular manual gesture (for 1.5 s), reproduced with permission from [43].

Figure 5

Representation of the filtered and smoothed GFP related to the frontal electrodes in the lower alpha band for the analyzed Italian subjects during the observation of the TV commercial advertising a carbonated beverage. On the x-axis, there is the time duration of the spot; on the y-axis there is the z-score smoothed values of the GFP considered. Film segments are showed when increase of cerebral activity occurred.

Figure 6

Representation of the filtered and smoothed GFP related to the frontal electrodes in the lower alpha band for the analyzed Chinese subjects during the observation of the TV commercial advertising a carbonated beverage. On the x-axis, there is the time duration of the spot; on the y-axis there is the z-score smoothed values of the GFP considered. Film segments are showed when increase of cerebral activity occurred.