ABSTRACTRhythmic groups of cyclical movements—action cycles—were identified during interactions between adults and children and young adults with profound mental handicap. The cycles were allocated to five categories according to rate, each action cycle clearly having its own communicative purpose. There was a striking regularity of rate within each performed set of action cycles, this being observed in the people with profound mental handicap as well as the adults, with the regularity more marked in the faster cycles. The people with profound mental handicap performed similar actions for apparently similar reasons at similar rates to their caregivers, giving strong indication of a biologically robust system of basic emotional communication which can quite literally be tapped into by caregivers. Comparisons of video records of interactions between mothers and their non‐handicapped babies (4‐8 weeks old) in Scotland and Nigeria yielding similar action cycles and rates to those seen in the interactions with people with profound mental handicap support this hypothesis.