Changes in Brain Activity During the Observation of TV Commercials by Using EEG, GSR and HR Measurements

Abstract

In this study we were interested to analyse the brain activity occurring during the "naturalistic" observation of commercial ads intermingled in a random order within a documentary. In order to measure both the brain activity and the emotional engage of the 15 healthy subjects investigated, we used simultaneous EEG, Galvanic Skin Response (GSR), Heart Rate (HR) recordings during the whole experiment. We would like to link significant variation of EEG, GSR, HR and Heart Rate Variability (HRV) measurements with the memory and pleasantness of the stimuli presented, as resulted successively from the subject's verbal interview. In order to do that, different indexes were employed to summarize the cerebral and autonomic measurements performed. Such indexes were used in the statistical analysis, performed with the use of Analysis of Variance (ANOVA) and z-score transformation of the estimated cortical activity by solving the associated EEG inverse problem. The results are summarized as follows: (1) in the population analyzed, the cortical activity in the theta band elicited during the observation of the TV commercials that were remembered is higher and localized in the left frontal brain areas when compared to the activity elicited during the vision of the TV commercials that were forgotten (p< 0.048). Same increase in the theta activity occurred during the observation of commercials that were judgment pleasant when compared with the other (p < 0.042). Differences in cortical activity were also observed for the gamma activity, bilaterally in frontal and prefrontal areas. (2) the HR and HRV activity elicited during the observation of the TV commercials that were remembered or judged pleasant is higher than the same activity during the observation of commercials that will be forgotten (p < 0.001 and p < 0.048, respectively for HR and HRV) or were judged unpleasant (p < 0.042 and p < 0.04, respectively for HR and HRV). No statistical differences between the level of the GSR values were observed across the experimental conditions. In conclusion, the TV commercials proposed to the population analyzed have increased the HR values and the cerebral activity mainly in the theta band in the left hemisphere when they will be memorized and judged pleasant. Further research with an extended set of subjects will be necessary to further validate the observations reported in this paper. However, these conclusions seems reasonable and well inserted in the already existing literature on this topic related to the HERA model.

O Uso de Biomarcadores em Pesquisas de Marketing

“…Além da apresentação detalhada dos métodos de coleta e análise, importantes para a replicação do estudo, e de corroborar outros trabalhos que já haviam evidenciado a relação das respostas autonômicas com emoções, os autores desse estudo tornaram pública sua base de dados com 30 sujeitos que avaliaram 40 clipes, conclamando os pesquisadores na busca por métodos e algoritmos que expliquem a relação entre as valências dos videoclipes e as emoções resultantes (Koelstra, Soleymani, Yazdani, & Nijholt, 2012). Em outro estudo, EEG, condutância da pele e da frequência cardíaca foram as medidas utilizadas para aferir a resposta neural decorrente do ato de assistir à televisão naturalmente, em 15 sujeitos, tendo-se evidenciado variações específicas nessas medidas, conforme o conteúdo a que assistiram e com o ato de se lembrar do mesmo ou não (Vecchiato et al, 2010).…”

“…Podem ser úteis em estudos que aprofundem relações de processamento de informação cerebral como a reação autonômica frente a imagens, sons, filmes, material publicitário, dentre outros, que objetivem explorar variáveis dependentes, como interesse, preferência e tipos de memória (Vecchiato et al, 2010). Variações de gênero nesse contexto podem ser interessantes em estudos futuros .…”

The added value of the electrical neuroimaging for the evaluation of marketing stimuli

“…In fact, from literature we know that signs of this cognitive activity can be found within the theta and the range of frequencies of the beta band [7]. Hence, in order to properly extract the variable of interest for the evaluation of the observed ads we first filtered the collected EEG signals in the theta and beta bands, as already described in a previous paper [8].…”

“…In addition, in order to summarize the properties of the cerebral activation for the analyzed ad, we also use a couple of indexes that were defined in a previous paper called Memorization Index (MI) and the Attention Index (AI) [8]. Such indexes are linked to the episodic memorization and attention posed to the ad by the experimental population, and they have been previously validated by using a correlation analysis with the answers the subjects gave during the interview.…”

From the Analysis of the Brain Images to the Study of Brain Networks Using Functional Connectivity and Multimodal Brain Signals

“…As a further example of the multimodal integration of data, Vecchiato et al (2010) present the use of different data from the central and autonomic nervous systems in relation to the assessment of cognitive and emotional activities during the observation of TV commercials. Such assessment was done by using EEG, heart rate, and galvanic skin responses.…”