This study examined how dynamic visual backgrounds affect brain activity during a working memory task. Sixteen healthy adults performed a 2-back task while viewing either a stereoscopic dynamic scene containing depth cues and lateral motion (background-on) or a static background (background-off). EEG was recorded from the frontal pole sites (Fp1/Fp2). In the linear analysis, power spectral density (PSD) was estimated, but no clear differences between the two background conditions were observed in any frequency band. In contrast, the nonlinear analysis, which was based on Hilbert-derived amplitude envelopes, showed that the difference measures of Permutation Entropy, Sample Entropy, and Lempel–Ziv Complexity exhibited small, localized increases in complexity under the background-on condition, predominantly within the high-gamma range (101–130 Hz). The effect sizes were small, and the temporal and spectral patterns were not consistent across participants. These findings indicate that dynamic visual backgrounds exert little influence on frontal EEG amplitude but may induce subtle changes in the temporal complexity of the signal.