Physiological evaluation on emotional change induced by imagination

In this study, emotional changes were induced by four imaginations--pleasantness, unpleasantness, arousal, and relaxation. They were induced using situations or pictures, as stimuli for imagination, selected on the basis of subjective evaluation and were examined by analyses of the physiological signals of the central and autonomic nervous systems whether the intended emotions were appropriately achieved, and whether these emotional changes could be distinguished from the analysis of physiological signals. While participants were asked to recall each situation (for experiment 1--free recall) or picture (experiment 2--forced recall) of the four imaginations, Electroencephalogram (EEG) in the area of Fz and Cz, Electrocardiogram (ECG), Galvanic Skin Response (GSR), Skin Temperature (SKT), and Respiration (RSP) were measured. The analysis of the EEG revealed that three emotional states were classified by values of alpha/(alpha + beta) and beta/(alpha + beta) and the autonomic nervous system responses, particularly the average interval of R-R and RSP. The results suggest that the values of alpha/(alpha + beta) or beta/(alpha + beta) in the areas of Fz and Cz and the average interval of R-R and/or RSP can be reliable parameters to measure some of the emotional states.