Cognition is a crucial problem that affects human performance and subjective experiences in the given environment. However, the cognition problem will be different if we consider it in a symmetrical reality environment. Though researchers have studied the cognition problem for many years, there are still many different points within a symmetrical reality environment. In this paper, we discuss the cognition problem from some perspectives, i.e., attention, perception, pattern recognition, and communication. We show how the symmetrical reality system can change the traditional attention mechanism, the perception process, the recognition and the communication between different agents. Finally, we introduce the application of symmetrical cognition to expand the current cognition research and give some useful suggestions for studying the cognition problem.