Effects of emotional decorative pictures on cognitive load as assessed by pupil dilation and EEG frequency band power

The present study examined the effects of decorative pictures (DP) on cognitive load during learning factual knowledge from texts assessed by physiological proxies, namely pupil dilation and the electroencephalogram (EEG) theta (4-6 Hz) and alpha (8-13 Hz) frequency band power at frontal and parietal electrodes, respectively. In a complete within-subjects design the presence of DP positioned beside learning texts and the emotional content of the DP (i.e., negative, neutral, and positive DP) were manipulated. For DP present, pupil dilation and the EEG alpha frequency band power indicated increased cognitive load, specifically for negative DP. Behavioral performance measures (i.e., learning times and learning outcomes) were not affected by the presence of DP. Subjective effort ratings were also not affected by DP, although specifically the negative DP were subjectively perceived as distracting. In sum, DP only moderately affected cognitive load allowing subjects to compensate.