Robustness of functional connectivity metrics for EEG-based personal identification over task-induced intra-class and inter-class variations

•Scalp EEG may represent unique fingerprint of individual neural activity.•The impact of different estimates of functional connectivity was assessed.•Connectivity fingerprints were analyzed across different tasks.•Different metrics have shown different sensitivity to detect subject-specific patterns.•Frequency content and spurious connections may play a role to define EEG fingerprints.