As Noreika points out, “consciousness” defined by the status of phenomenal content is something very different from a conscious state, as this connotation of consciousness can only be investigated in human subjects. The reason for this is that the distinguishing criterion is the degree of subjective awareness of a cognitive content, and this variable can only be assessed through verbal report. It is simply not possible to know whether a monkey trained to press a lever to signal that it has recognized a particular pattern has the subjective experience that we equate with conscious perception. The monkey brain has the same mechanisms as humans for the allocation of attention, the selection of objects for perception, and the routing of experiences to the different storage modes (working memory, procedural and episodic memory). Thus it is very likely that monkeys are aware of their perceptions in a similar way to us, and that the distinction between conscious and non-conscious processing holds for them as well—but we have no way of knowing. Conditioned lever presses in response to stimuli do not require conscious perception of the stimuli, just as stopping at a red light while being engaged in a conversation does not require conscious recollection of having perceived the light. It is for this reason that the criterion for conscious processing is the reportability of the perceived stimulus, and hence this aspect of consciousness can only be studied in humans.
Attempts to identify the differences between the neuronal processes that accompany non-conscious and conscious processing, respectively, are of course interesting in their own right. The expectation is that they will provide answers to the question of why certain processes are reportable and have access to working and episodic memory while others are excluded, or the question of why certain forms of reasoning and decision-making require conscious deliberations while others do not. However, as pointed out so stringently by Noreika, these attempts fall short of identifying the NCC proper, and at best cover some aspects of conscious processing while being fraught with problems. The most difficult problems are related to the distinction between the processes that are essential for subjective awareness and reportability and those that are the consequence of having become aware of something or that simply provide favourable conditions for becoming aware, such as the allocation of attention or the saliency of stimuli. So far the only neuronal signatures distinguishing between reportable and non-reportable processes have been found to be transitory, lasting at most a few hundred milliseconds. Noreika argues rightly that this disqualifies these events as NCCs because the stream of consciousness is continuous and the awareness of contents can persist for quite some time.