A method for verifying a person's identity is of the general type which comprises storing a personal pattern of a pre-determined number of locations on a grid in association with personal identification data, and subsequently using the pattern in a verification process. According to the invention, the subsequent verification process comprises the steps of: (a) presenting to the person a challenge grid of locations occupied by a pseudo-random set of symbols, and challenging the person to identify a response set of symbols occupying locations in the challenge grid corresponding to the stored personal pattern; (b) receiving from the person the response set; (c) generating from the challenge grid and the stored pattern a verification set of symbols occupying locations in the challenge grid corresponding to the stored personal pattern; (d) comparing the response set of symbols with the verification set of symbols; and (e) verifying the identity of the person if the response set is the same as the verification set.