The neural signatures of memory formation remain elusive. Converging evidence from recordings in the rodent hippocampus and neocortex indicates that memory traces may be "replayed" offline, facilitating memory formation. I will describe evidence of memory trace reactivation in the primate, and the rationale behind the use of ethologically-relevant stimuli in memory experiments. I will argue that behavioral and fMRI data support the assertion that macaques (and their brains) are specialized for perceiving and learning about social signals, such as facial identity and facial expressions. As such, the hunt for the neural signatures of memory formation may be best served by the use of these social signals.