The importance of emotions in advertising has been well established (Binet and Field 2009). Electroencephalography (EEG) has proven to be an excellent technique for measuring emotional motivation at a non-conscious level in frontal asymmetry signals (Davidson et al. 1990; Coan and Allen 2004; Harmon-Jones, Gable and Peterson 2010). Evoked potentials have also been used to assess response to brands and brand attributes. While there are limitations to EEG in terms of understanding the precise brain regions that are active, the signals have a higher temporal resolution than functional MRI and allow marketers to understand the onset of a brain response with a few hundred milliseconds of precision (Niedermeyer and da Silva 2004).
Marketing researchers have turned to EEG to measure emotions as they have become increasingly sceptical of measuring the emotional impact of TV commercials on consumers based solely on their verbal responses, which do not provide an effective measure of subconscious responses to such stimuli, and are difficult to measure with self-reports alone, due to their complexity and a greater likelihood of eliciting socially acceptable responses. In addition, there are many aspects beyond the consumer’s control that are difficult to record with surveys or self-reports.
Ohme et al. (2010) used electroencephalography (EEG) to measure prefrontal cortex responses to three Sony TV commercials and found dominant left prefrontal cortex reactions, indicating attraction to one of the advertisements tested. They concluded that measurements of frontal asymmetry may be a valid resource for studying the emotional potential of commercials.
Functional magnetic resonance imaging has also been used to measure emotional responses. Morris et al. (2008) investigated which brain regions produced emotional responses to five television commercials, consistent with the PAD (pleasure, arousal and dominance) paradigm of emotional measurement. They found significant differences in bilateral activations in the inferior frontal gyrus and medial temporal gyrus associated with the difference in the pleasure dimension, and activations in the right superior temporal gyrus and right middle frontal gyrus associated with the difference in the arousal dimension.
Research on prefrontal responses to emotion and motivation has postulated the existence of two general motivational systems that organise behaviour: one linked to a possible desirable outcome and the other associated with a possible aversive outcome.
Based on empirical EEG evidence, Davidson, Schwartz, Saron, Bennett and Goleman (1979) proposed a model linking frontal asymmetry with emotional states. They proposed that the left prefrontal cortex (PFC) would be involved in a system that facilitates approach behaviour to pleasant stimuli, while the right PFC would be involved in a system that facilitates withdrawal behaviour from aversive stimuli.
Such a model assumes that processing related to emotional valence itself is not lateralised in the CPF. Rather, emotional lateralisation would be associated with the fact that emotions contain components of approach or withdrawal. Therefore, emotion will be associated with a right or left asymmetry depending on the degree to which it is accompanied by approach or withdrawal behaviour.
Davidson, Marshall, Tomarken, and Henriques (2000) hypothesised that the approach and disengagement systems would be associated with pre-goal emotions, i.e., emotions that are normally generated when attempting to achieve a goal. For example, the approach system would be associated with enthusiasm, but not with satisfaction, which would be considered a post-goal emotion.
Different contexts can provide information about the function of an emotion. Some authors have also emphasised the importance of function in context for understanding emotions. To date, numerous independent studies have examined the relationship between emotion or emotion-related constructs and asymmetries in EEG activity in the frontal cortex.
The study by Ohme et al. (2010) showed that Davidson’s emotional frontal asymmetry model can be applied to analyse emotional responses to TV commercials and can even be validated with electromyographic (EMG) measurements of facial muscle responses to positive or negative emotional expressions.
Despite the limitations that the paradigm of asymmetry of some encephalic functions, whether frontal or other brain regions, may have, it is such a quantity and quality of empirical evidence that supports Davidson’s explanation of frontal asymmetry, such is the quantity and quality of empirical evidence supporting Davidson’s explanation of frontal asymmetry that measuring EEG activity to market stimuli in general and not just television commercials can be a versatile tool for understanding the brain’s reactions to any stimulus in terms of cognitive and affective processes related to brands, products, commercial campaigns and advertisements, not only on television but also in the digital media that predominate today.
In summary, the use of EEG in neuromarketing has significantly enriched the market research portfolio and can continue to help marketers to more deeply analyse the emotional impacts on the temporal sequences of advertising spots whether on television, YouTube or any other digital audiovisual medium. It has become commonplace for companies offering neuromarketing research services to use EEG in combination with other neurophysiological measurement techniques such as EMG, electrodermal, cardiac, respiratory and eye-tracking responses, in addition to validation with traditional self-report methods, as well as reaction time measures and behavioural indices.
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