Abstract
Most brain-based measures of the electroencephalogram (EEG) are used in highly controlled lab environments and only focus on narrow mental states (e.g., working memory load). However, we assume that outside the lab complex multidimensional mental states are evoked. This could potentially create interference between EEG signatures used for identification of specific mental states. In this study, we aimed to investigate more realistic conditions and therefore induced a combination of working memory load and affective valence to reveal potential interferences in EEG measures. To induce changes in working memory load and affective valence, we used a paradigm which combines an N-back task (for working memory load manipulation) with a standard method to induce affect (affective pictures taken from the International Affective Picture System (IAPS) database). Subjective ratings showed that the experimental task was successful in inducing working memory load as well as affective valence. Additionally, performance measures were analyzed and it was found that behavioral performance decreased with increasing workload as well as negative valence, showing that affective valence can have an effect on cognitive processing. These findings are supported by changes in frontal theta and parietal alpha power, parameters used for measuring of working memory load in the EEG. However, these EEG measures are influenced by the negative valence condition as well and thereby show that detection of working memory load is sensitive to affective contexts. Unexpectedly, we did not find any effects for EEG measures typically used for affective valence detection (Frontal Alpha Asymmetry (FAA)). Therefore we assume that the FAA measure might not be usable if cognitive workload is induced simultaneously. We conclude that future studies should account for potential context-specifity of EEG measures.
Highlights
Investigating Complex User States with the ElectroencephalogramIn recent years, there has been increased interest to use the electroencephalogram (EEG) in the context of human-machine interaction (Frey et al, 2013)
In this article we systematically investigate the relation between two types of mental states that are widely used in the context of humanmachine interaction, namely working memory load (e.g., Spüler et al, 2016) and affective valence (e.g., De Smedt and Menschaert, 2012), to study the interaction of the brain responses typically associated to these mental states
A Post hoc test using the Šidák correction revealed that the negative valence condition resulted in an increase of subjective working memory load when compared to the positive valence condition (p < 0.001) as well as the neutral valence condition (p < 0.02)
Summary
Investigating Complex User States with the ElectroencephalogramIn recent years, there has been increased interest to use the electroencephalogram (EEG) in the context of human-machine interaction (Frey et al, 2013). Most studies using the EEG to measure mental states focus on very specific states like working memory (Klimesch, 1999) or affective valence (Ahern and Schwartz, 1985), which are investigated in well controlled lab environments. It is necessary to systematically investigate the relationship between different mental states and the different EEG measures that are widely used in neuroscientific studies, to investigate if such measures can be used outside the lab. In this article we systematically investigate the relation between two types of mental states that are widely used in the context of humanmachine interaction, namely working memory load (e.g., Spüler et al, 2016) and affective valence (e.g., De Smedt and Menschaert, 2012), to study the interaction of the brain responses typically associated to these mental states
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