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Neural correlates of cross-modal affective priming
MRHÁLEK, Tomáš
This dissertation aims to investigate the correlations of visual evoked potentials during the experimental process of serial passive affective priming. The aim of this dissertation is to identify partial processes of affective perception, which are influenced by relations to previous affective priming stimulation. The research is designed as a laboratory EEG experiment, which uses affective priming techniques, particularly its sequential passive multimodal (auditory-visual) variation. The research experimentally manipulates emotional characteristics of stimuli that are constructed on the basis of the dimensional theory. As a starting dimension, arousal was chosen that is equivalent to psychic activation connected to reactions to stimuli. The study was carried out in the PF JČU neurological laboratory using a 64 channel EEG Biosemi Active II. Probands was selected from the JČU students, whose brain electrical activity was measured during an exposure to affective stimuli from international emotional elicitation databases. Records from 29 people were used. The independent variable used was the variation of priming and arousal characteristics of the priming stimulus from the affective melodies database (Eerola &Vuoskoski, 2010) and the arousal characteristics of a visual stimuli (Marchewka et al., 2014). Visual perception is the most explored ERP process, therefore the differences between the results of this dissertation study and comparative studies can be the basis for interpreting the mechanism of contextual affective transmission. Time progress and activation reactions are modulated based on experimental conditions and the dependent variables are the differences of latency and amplitude of individual components of evoked potentials, which represent partial psychological processes. The use of sound as priming stimulus together with a high interstimulus interval decreases the conflict between perceptual processes in selective attention. The differences in processes of visual perception according to affective arousal characteristics of stimuli suggest a parietally increased early posterior negativity (EPN) and late positive potentials (LPP) of high-arousal stimuli in comparison to low-arousal stimuli. Signs of EPN manifest as indicators for prioritization of attention in comparison with actively motivating stimuli. The priming effect manifested in P1 and N1 components occipitoparietally and in N2 centroparietally, which suggest stronger negativity of EPN in the case of previous priming. LPP increase for the priming condition was there only for high-arousal stimuli. The cause for higher activation for priming conditions in P1 and N1 is unknown, it is a case of premature latency for possible explanation using the evaluation mechanism. The results showcase the influence of conflict between processes of attention or the alternative interpretations of affective priming based on the influence of context on the formation of evaluative conclusions. The priming effects in LPP show a lower later parietal activation of primed stimuli which can be connected to their previous increased activation as a part of early and medium latency component.
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