This study investigated the complexity of electroencephalogram (EEG) signals in response to visual stimuli by comparing the original versions of pleasant, unpleasant, and neutral images with their brightened counterparts. We used fractal dimension (FD), Approximate Entropy (ApEn), and Sample Entropy (SampEn) to quantify EEG signal complexity during image viewing. Our results showed that EEG signal complexity was consistently higher for the original images than for the brightened versions across the three image categories. This increase in complexity suggests that the original images were associated with richer neural dynamics under more natural luminance conditions. The findings indicate that brightness modulates EEG signal complexity and highlight the importance of considering luminance levels in studies of visual perception and emotional processing. These results provide useful insight into the influence of stimulus brightness on brain activity and may support the design of future neuropsychological studies and applications.
Pakniyat et al. (Tue,) studied this question.