The present study focuses on the issue of mediated learning as reflected in two conceptual systems: one associated with L. S. Vygotsky's notion of "psychological tools", the other associated with the notion of psychological activity, developed by A. N. Leontiev, P. I. Zinchenko and others. As a concrete test for these two conceptual systems the problem of a subject's discovery of and strategies for coping with contradictory information in a written text is chosen. It is argued that both psychological tools and psychological activity paradigms underestimated the complexity of a mediated learning situation and in particular overlooked the possibility that psychological tools would be used by subjects for the suppressing of cognitively dissonant (that is, contradictory) information.