Variables in P300 recording: task type and electrode position

Purpose: To analyze the latency and amplitude of P300 responses obtained with electrodes positioned at Cz and Fz and in different tasks of infrequent stimulus identification in normal hearing individuals. Methods: Forty adults of both genders participated in the study. Three recordings with three different tasks were obtained for the identification of the infrequent stimulus; simultaneous recordings were obtained from Cz and Fz positions. Results: Cz position showed significantly greater amplitudes and lower latencies than Fz. Regarding the three tasks, only "pronouncing the word 'thin'" was different from "raising a finger", with lowest latencies for the verbal task. Regarding amplitude, significantly higher values were observed for "raising a finger", followed by "pronouncing the word 'thin'" and mental counting. Conclusion: Cz obtained the best values, highest amplitude and lowest latency. Lowest latencies were obtained for the task of "pronouncing the word 'thin'" and the highest amplitudes were obtained for "raising a finger".