The effects of immediate and short-term retest on the latencies and amplitudes of the auditory event-related potentials in healthy adults

Objective: To evaluate the immediate and short-term effects of repeated within session trials on N1, P2, N2 and P3 latencies and P2, N2 and P3 amplitudes in healthy adults. Materials and methods: ERPs were elicited by the auditory oddball paradigm and recorded over Fz, Cz and Pz in 18 healthy adults over two sessions, one to three days apart, and two within session trials with one to three minutes trial-retrial interval. The ERPs' latencies and amplitudes were blindly calculated and were analyzed by Analysis of Variance (ANOVA) with repeated measures. Results: Significant decreases of N2 amplitude at Fz, P3 amplitude at Cz and P3 latency at Pz were recorded in the second-compared to the first within session trial (p = 0.034, 0.041, 0.046, respectively). There were no significant inter-session differences regarding N1, P2, N2 and P3 latencies or amplitudes. There was no significant interaction between session and trial. A statistically significant difference was found between the first session's mental count errors (p = 0.039) but there were no significant differences between the second session's trials (p = 0.581) or between sessions (p = 0.328). Conclusions: N1, P2, N2 and P3 latencies and amplitudes are stable at short-term intervals of one to three days, but one to three minutes' retrial interval may affect P3 latency and N2 and P3 amplitudes. We suggest that when primary novelty-induced cognitive processes are evaluated, single trial sessions or more than three-minute inter-trials interval should be employed in order to mitigate habituation.