In this study, cortical brain activity during a pattern matching task (PMT) was measured by employing electroencephalography (EEG). The EEG data were recorded from 128 scalp locations during a pattern-matching task and in rest conditions (eyes open and eyes closed). Spectral Analysis of EEG frequency bands reflected a significant (p<0.025) difference between baseline and PMT task. The EEG activity in slow waves (delta: 0.5 to 3 Hz and theta: 4 to 7 Hz) was high during PMT in frontal regions, while EEG activity in fast waves (Beta: 14 to 20 Hz and Gamma: 21 to 30 Hz) was reduced in parietal and occipital regions as compared to the frontal region. The changes in EEG medium waves (alpha: 8 to 13 Hz) was high in frontal, central, and temporal regions, while depressed in parietal, parieto-occipital and occipital regions. The results show high cortical activations in different brain regions during solving pattern-matching task as compared to baseline resting conditions. The study has implications for thinking and decision-making situation, such as object recognition, visual comparison, and consumer choice. © 2022 IEEE.