Scalp distribution of the difference in cortical potentials elicited by familiar versus novel auditory tones. A cluster-based permutation test was used to assess statistical significance while correcting for multiple comparisons, with a two-sided test at a false alarm rate of 0.05. Black asterisks (*) mark positive clusters where responses to deviant tones were significantly greater than those to standard tones, while red asterisks (*) denote negative clusters indicating the opposite pattern.