The immediacy of current awareness or sentience runs up against a paradox of time: that the present is a moving knife-edge with no duration and therefore no content. Even the simplest stimuli and the most direct neural events require time to be coded. The psychological present must therefore extend into the past. Our feeling of rich awareness escapes the paradox by using a working memor. The contrast between the properties of this memory and the long-term episodic memory creates the contrast between immediate and reflective consciousness. Conscious experience and memory are inextricably intertwined from start to finish. Experience requires memory and is made meaningful by other memory. And different aspects of consciousness are supported by different kinds of memory with distinct neurological organizations.
1.1 It seems almost self-evident that current experience is meaningful, and our introspection supports a differentiation between immediate conscious experience and reflective consciousness (awareness of events that have occurred in the past). These are two quite distinct processes that are lumped under the same word in everyday terminology. The issue of differentiation arose in the context of a hypothetical "perfect" general anesthetic, one that paralyzes the patient during an operation and erases any memory of the event but does not reduce pain. Reidbord (1992) would prefer an agent that erases pain from current as well as remembered experience, and it is hard to disagree.
1.2 Given the goal of finding an anesthetic agent that prevents both suffering and the memory of suffering, the problem is to find an agent that does both. How do I decide that a candidate anesthetic prevents current suffering as well as the memory of suffering? The shocking answer is that I'LL NEVER KNOW! There are only two paths by which an experience during surgery (or at any other time) could become known: by direct experience, or by the reports of others on one's responses during an experience. In the anesthetic case, neither path is effective. Erasure of episodic memory prevents me from being able to report any pain after the operation. Paralysis prevents me from expressing pain to the surgeon, either orally or by behavioral avoidance responses. So neither the patient nor those observing the patient can tell whether pain has been experienced during the operation. There are some measures from which we might infer pain (autonomic responses, shock, EEG desynchronization etc.), but these are indirect and do not speak to experience. The anesthetic might well prevent autonomic as well as muscular responses to the painful stimuli. If we were mistaken in interpreting these measures, we would have no way of checking them.
1.3 For all we know, all presently used general anesthetics may work in this way, by combining paralysis with amnesia. Given Reidbord's choice, I'll choose a local anesthetic every time. With both memory and reflexes intact I'll know at the time and remember afterward what happened, but as an observer rather than an experiencer. And I'll know that I was not in pain during the operation.
2.1 Reidbord's commentary puts into relief a persistent issue in the interpretation of consciousness. The immediacy of current awareness or sentience runs up against a paradox of time: that the present is a moving knife-edge with no duration and therefore no content. Even the simplest stimuli and the most direct neural events require time to be coded. The psychological present must therefore extend into the past. Our feeling of rich awareness escapes the paradox by using a working memory, a buffer which holds a few seconds or minutes worth of the immediate past in a limited-capacity but easily accessed mechanism. The contrast between the properties of this memory and the long-term episodic memory creates the contrast between immediate and reflective consciousness.
2.2 The value of this two-mode memory and its concomitant two modes of conscious awareness is made plain in some kinds of amnestic patients who have lost the ability to form new episodic memories (anterograde amnesia) but retain working memory. Ideas can be held in present awareness, but only if no distractions occur. Even a momentary digression results in permanent loss of the original awareness and things start over. Brenda Milner's patient H. M. explains it in this way: "You see, at this moment everything looks clear to me, but what happened just before? That's what worries me. It's like waking from a dream. I just don't remember" (Milner, 1970, p. 37). H. M. had bilateral lesions of the hippocampus, with some amygdala damage as well. Patients with prefrontal lesions have a different sort of loss -- they seem to have a memory, but it doesn't connect up with plans. These patients can feel pain and remember it, but it doesn't bother them in the way that it bothers normal people. The sensory aspects of pain seem intact, but the link with emotion, motivation, and from there to the planning of future behavior (Bridgeman, 1992) is interrupted.
2.3 The conclusion is that conscious experience and memory are inextricably intertwined from start to finish. Experience requires memory and is made meaningful by other memory. And different aspects of consciousness are supported by different kinds of memory with distinct neurological organizations.
Bridgeman, B. (1992). On the evolution of consciousness and language. PSYCOLOQUY 3(15) consciousness.1.
Milner, B. (1970) Memory and the temporal regions of the brain. In K. H. Pribram & D. E. Broadbent (Eds.), Biology of Memory. New York: Academic Press.
Reidbord, Steven (1992) Would You Choose Unremembered Pain? Commentary on Bridgeman on Consciousness. PSYCOLOQUY 3(41) consciousness.22