Detection of Emotions Induced by Colors in Compare of Two Nonlinear Mapping of Heart Rate Variability Signal: Triangle and Parabolic Phase Space (TPSM, PPSM)

Abstract

Emotions in the word mean understanding, sensing and recognizing something with one’s senses. Emotions are relatively simple responses that the body presents to external or internal stimuli. As the individual’s mental and emotional state changes, the activity of the various parts of the body also changes and increases. This applies to all cultures. So emotion detection from biological signals especially heart rate variability (HRV) signal is considered in this article. The behavior of HRV in two nonlinear phase space have been evaluated and the extracted features of these two mapping have been used for emotion detection. Triangle and Parabolic Phase Space Mapping (TPSM and PPSM) are recently introduced methods which are able to indicate hidden aspects of HRV in response to different emotions. The Lead II of electrocardiogram signal was recorded from 32 female students while they were stimulated by four main psychology colors (blue, green, red, and yellow) to induce emotions which were labeled by SAM test. The results show that the mentioned colors caused emotions pleasure, joy, anger, and sadness, respectively. After rating the results by Kruskal–Wallis test, k-nearest neighbor classifier was used for emotion classification. The obtained accuracy after 10-fold cross validation was 90.91%. The hypotheses of being a relationship between colors and emotions without awareness of subjects have been proved. Furthermore, by studying the usefulness of TPSM and PPSM as new mapping of HRV, significant results have obtained which indicate the advantages of using them. So it is suggested to use and analyze the usage of these kinds of colors in different psychological situations and for biofeedback tests.