The principles of classical and quantum holography are used to develop the theoretical basis for a non-phonemic method of detecting membership in secret social groups, such as cults, criminal gangs, drug cartels, and terrorist cells. Grounded in the basic sociological premise that every group develops a distinctive sociocultural order, the theory postulates that the primary features of a group's collective identity will be encoded, via a multilevel socio-psycho-physiological process, into the field of bio-emotional relations connecting group members. The principles of (...) classical holography (Gabor 1948) are used to describe how this information is recorded in the members' brains and communicated in interaction by a holographic-like process as a tacit signature of group affiliation —a constancy in group-related interactions. It is hypothesized that the identity signature is enfolded as a hologram in the energy spectra of vocal interactions among group members. The principles of quantum holography (Gabor 1946) are used to provide a description of the group's ongoing interactions as a dynamic process—a continuous, quantized series of snapshots (quantum holograms). Linked together, two forms of holography provide a model of how the group's collective identity evolves and is communicated over time to its members, as the group adapts to the ever-changing reality of its endogenous and exogenous circumstances. Using spectral analysis techniques, it should be possible to detect the group's identity signature in the recordings of relatively small samples of vocal interactions. In clandestine groups, the effort to remain hidden actually enhances the signal strength of the identity signature. It is predicted, therefore, that detection of unknown members can be achieved by using the spectral commonality identified in the analysis of recordings of vocal interactions among known members as a reference signature for comparison with those of the vocal spectra of suspected or potential members. (shrink)