I question whether it is completely accurate to think of the philosophical meaning of consciousness as being switched-on or switched-off. It may be that, once consciousness is switched-on, it is then found in degrees in animals we deem conscious. In which case, consciousness is more like a switched-on rheostat, rather than a simple on–off switch. Christian de Quincey (2006) gives a list of what...

Scientists studying consciousness are attempting to identify correlations between measurements of consciousness and the physical world. Consciousness can only be measured through first-person reports, which raises problems about the accuracy of first-person reports, the possibility of non-reportable consciousness and the causal closure of the physical world. Many of these issues could be resolv...