An Advanced Data Augmentation Scheme on Limited EEG Signals for Human Emotion Recognition

EEG signals are the modality that is widely used to recognize human emotions. However, the limited data on EEG signals remains challenging because of the small recording participants, the need for an expert to interpret EEG signals, and the expensive cost of tools to record EEG signals. This research proposed the data augmentation schemes on the EEG datasets to overcome the limited available data problem. Augmenting the data will help the generalizability of the emotion recognition model. The EEG signals on the DEAP and SEED datasets are transformed into image samples using a recurrence plot and spectrogram. Then, the artificial recurrence plot and the artificial spectrogram samples are generated using Pix2pix. This research used these artificial samples to conduct the data augmentation process. LeNet5, ResNet50, MobileNet, and DenseNet121 are used to conduct the classification. The best four data augmentation schemes are as follows: Appending 20,000 artificial recurrence plot samples to DEAP and SEED training datasets, appending 20,000 artificial spectrogram samples to the DEAP training dataset, and appending 15,000 artificial spectrogram samples to the SEED training dataset. The kappa coefficient for each classification model based on the best data augmentation schemes is computed. It is found that among the compared classifiers, LeNet5 achieved the best accuracy in both SEED (98.58%) and DEAP (86.12%) datasets when spectrogram was used. Therefore, LeNet5 trained on the spectrogram samples is a reliable and robust classification model. This finding implies that the use of spectrogram is more promising than the recurrence plot in human emotion recognition.