The modulation effect of art painting content on saccade evoked perceptual processes: A high-density EEG study

Art perception involves complex neural mechanisms, with specific responses tied to the elements and content of paintings. The process of artistic appreciation involves processes at difference time scale; early perception of content within few hundred milliseconds followed by style recognition that leads to a later, contemplative stage after a few seconds. This study investigates group-level power differences in the earliest stage of EEG activity during the perception of four distinct categories of paintings: Faces, Geometry, Townscapes and People. Participants of the experiment were presented with a series of Abstract and Figurative paintings in random order. To simulate natural viewing conditions, each painting was displayed for 8 seconds, followed by a 4-second blank screen for a key-press response (“like” or “dislike”) and a 1-second cue. Eye movements were registered with a Tobii Pro Fusion eye-tracking device. Brain activity was recorded using a 128-channel Biosemi ActiveTwo EEG system at a sampling rate of 2048 Hz. After pre-processing (high-pass filtering at 1 Hz, low-pass filtering at 40 Hz and down-sampling to 512 Hz), we performed Independent Component Analysis (ICA) to isolate neural and non-neural sources of activity. One of the ICA components showed distinct saccade-related lambda waves, i.e. transient potential peaks appearing ~100 ms after saccade onsets, which allowed us to identify individual saccades and visual responses in freeviewing settings, and consequently perform single-trial analysis. The 8-second EEG data window of painting viewing were segmented into lambda-peak centred epochs (-150 ms to 150 ms), resulting in 400–550 epochs per content category. Power spectral density was computed in the alpha and beta frequency bands using the FieldTrip EEG Toolbox, then the relative power differences were calculated between the painting categories (e.g. Faces vs. Geometry, Faces vs. Townscapes). The preliminary results indicate different topography of activations, mainly in the alpha band, distinguishing geometry/townscapes and faces/people contents. It also demonstrates the utility of this lambda peak-based epoching and analysis method in situations where eye-tracking data and saccade information are unavailable. This study confirmed that content modulates early saccade-evoked perceptual processes and the results contribute to the better understanding of the neural mechanisms related to art perception.