Halliday & Matthiessen (1999: 609):
Edelman's interpretation of higher-order consciousness referred to above suggests that this form of consciousness (unlike primary consciousness) is constituted in language. Language is a socio-semiotic system, so it follows that higher-order consciousness is constituted socio-semiotically; and since socio-semiotic systems are collective, it follows that higher-order consciousness must also be collective.
Collective consciousness is an attribute of human social groups — the members of a given culture. But we need to distinguish between the consciousness of a social group and the consciousness of a species, whose collective construal of experience is codified in the structure of the brain. All human populations have the same brain, and to that extent all construe experience in the same way. But humans live in social groups, and their local environments vary one from the other; to that extent, different groups construe experience in different ways.
The significance of this for us is that language is the resource for both: both what is common to the species as a whole, and what is specific to the given culture. In the way these two components are construed in the grammar, we cannot tell them apart. But it is the role of language in the construction of experience as meaning — as shared activity and collaboratively constructed resource — that gives substance to the concept of collective consciousness as an attribute of the human condition.