Event-Related Brain Potentials when Comparing Visual Stimuli – Words and Pictures

The goal of this paper was studying neurophysiological processes in the brain during presentation of visual stimuli (printed words and pictures). 84 participants took part in the investigation. The article presents the results of the analysis of event related potentials (ERP) in a three-stimulus visual test. In the time interval 80-280 ms after the second stimulus, ERP components were recorded: N1O in the occipital area, and N1T and P2 in the posterior temporal lobes. The N1O, N1T, P2 waves in response to the second word-stimulus differed in amplitude and latency from the waves in response of the image-stimulus. No difference in ERP in the posterior temporal and occipital components N1O, N1T, P2 between match and mismatch conditions in words comparison was found. We infer that the operation of comparing two words is not reflected all measured ERP waves. In response to the second picture-stimulus the amplitude of the occipital and posterior temporal components N1O, N1T was greater when the stimuli matched the first stimulus. We conclude that the recorded difference wave indicates facilitation operation during the perception when the predicted signal matches the actual input signal. In summary, the modulation of the posterior temporal P2 wave in response to the second mismatched picture-stimulus in the pairs is caused by two hypothetical psychological operations: physical repetition of the stimulus, and mismatch with the image in the working memory.