Working with concrete states of mind confronts the analyst with major countertransference problems: faced with the emptiness of the patient's psychic functioning, the analyst is threatened with the deadening of his own psychic capacities and the crumbling of the analytic process.

This paper examines two cases of children who presented in very different ways, one featuring deep-rooted depression and empty behaviour, the other featuring mastery and destructive omnipotence. It proposes a specific technique to enable the reconstruction of representational functioning through play. In the context of the transference/countertransference relationship and the analytic process, the introduction of a game of imaginary hide and seek, whose rules are defined and analysed, may represent an instrument of choice for opening up an undeveloped psychic space in these pathologies.