Does the Temporal P2 Wave in Event-Related Potentials Reflect the Process of Comparing Visual Information with a Working Memory Trace?

The aim of this work was to reveal the features of information processing in the brain at the early stages of perception in the context of solving a match–mismatch task for visual stimuli. For this purpose, visual stimuli—images (I) and their corresponding printed words (W)—were presented in the test as comparison pairs, each consisting of two sequentially presented stimuli. The participant had to compare these two stimuli with each other and give a motor response. In 50% of cases, the stimuli in the pair matched each other, while in 50% they mismatched. The results of tree tests—II, IW, WI—were analyzed. EEG was recorded in 31 leads in 84 healthy adult subjects during the tests. The results of event-related potential (ERP) analysis are reported here. It was shown that a new image presented in the comparison pair II caused an increase in the ERP P2 component, generated in posterior temporal leads P7 and P8, while stimulus repetition caused a decrease in P2 amplitude compared to the first image stimulus presentation in all tests. It is hypothesized that the observed increase in P2 reflects the processes occurring in neural networks when detecting a mismatch between the presented image and the object image stored in working memory.