Barlow (1992) has identified a crucial prerequisite for self-consciousness. I concur with most of his commentary adding only a few elaborations.
2. What happens to the capacity for language and self-consciousness once it is established? Several sources of evidence indicate that it becomes autonomous. While it may depend on social interaction in young children, it can persist in the absence of social context in adults. The Robinson Crusoe who finds himself on an island, entire of itself, remains conscious. He knows who he is and can still think and plan. Closer to home, people who become deaf after acquiring speech continue to use the internal analogue of spoken language in their own thought, sometimes for 60 or more years after the possibility of learning and using auditory speech is closed off. Social interaction is necessary to establish the full power of both speech and the planning mechanism, but once established they can run autonomously.
3. The influences of others come into the individual through the sensory channels. Those influences remain distinct from internally held plans even if information from outside dominates the process of establishing plans. Normally the creation and execution of plans occurs in a social context, but it remains possible in an isolated human. Society provides us with many powerful tools and influences, but the final planning process remains an internal one, and fails in the absence of the appropriate brain machinery.
Barlow, Horace (1992) The Social Role of Consciousness: Commentary on Bridgeman on Consciousness. PSYCOLOQUY 3(19) consciousness.4