Fig 3. Two different perspectives on the evolution of self-awareness.

In the traditional binary model (A), species showing MSR possess a self-concept, whereas all other species do not. The gradualist view (B), in contrast, assigns the highest level of self-awareness to hominids, who spontaneously explore and play with their reflection and care about their appearance, and assigns intermediate or lower levels to other species, but no zero level because all animals need a self-concept. Reactions to mirrors range from permanent confusion about one's reflection to a certain level of understanding of how mirrors operate (e.g., using them as tools) and only brief or no confusion between one's reflection and a stranger. Some species, such as macaques and perhaps cleaner fish, seem to possess this intermediate level and can therefore, with the aid of training and/or multimodal stimulation, be "lifted" (arrow) to a level of mirror understanding closer to MSR. MSR, mirror self-recognition.