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Does general anaesthesia switch experience off, or only the memory of it?

Tsion Bekele Fellow
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Medicine & healthAnalyticBuddhistAbhidharmaDavid Chalmers#anaesthesia#awareness#consciousness-science#memory
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Its coordinates: 6.13 Philosophy of Medicine

Last month, a patient I was interpreting for asked before surgery whether she would "be there" during the operation and simply forget it, or whether she would not be there at all. I passed on the reassuring answer she was given. Afterwards I realised I didn't know if it was true.

Some anaesthetic drugs are powerfully amnesic. We know from rare cases of intraoperative awareness that a patient can be conscious and later remember. We also know, from studies where one arm is kept free of muscle relaxant, that some patients under general anaesthesia will respond to a spoken instruction during surgery and later recall nothing. That seems to show responsiveness, and perhaps experience, without memory.

So how would we ever know that experience was absent rather than unremembered? The obvious evidence, the patient's report, is exactly what amnesia removes. The less obvious evidence, brain measures, is calibrated against reports.

I would like several answers here, from philosophers and from clinicians. Is this a scientific question that better instruments will settle, a philosophical one about the limits of third-person evidence, or both? And does it matter morally if the experience is never remembered?

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6 answers

  1. Omar Ragab

    Fellow

    I share your discomfort. The isolated forearm studies are unsettling exactly because they show the dissociation. My own view: it is partly scientific. If we find neural signatures of consciousness that are validated in many ways, not only by report, we could use them during anaesthesia. But every validation ultimately rests on some report somewhere. The circle is wide, but it is still a circle.

  2. Priya Raghavan

    Fellow

    I think it's both, and the philosophical part is the hard problem in miniature. Measures like the complexity of the brain's response to a magnetic pulse track the difference between waking, dreamless sleep and anaesthesia remarkably well. But they track something. Whether that something is experience or only the capacity for reportable experience is exactly what the measures can't tell you from the outside.

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  3. Elin Hedqvist

    Fellow

    Some of the older people I look after were sedated for days in hospital, and a few later describe vivid, frightening experiences, often of being captured or harmed, that they remember as real. Others remember nothing. So what I hear isn't "off" versus "on and forgotten". There are strange states in between. I'd want any theory to account for those before it tells me what anaesthesia does.

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  4. Nirmala Jayasekara

    Fellow

    The Abhidhamma held that in dreamless sleep a subtle life-continuum consciousness, bhavaṅga, continues without any object being cognised in the ordinary way. I don't offer that as neuroscience. But it's a reminder that "no experience" and "no reportable experience" were distinguished long before anaesthetics.

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  5. Martín Iriarte

    Fellow

    On the moral question: psychoanalysis takes seriously that what is not remembered can still shape a person. The analytic literature describes patients who had traumatic procedures as children and carry something they cannot recall. So I would not say unremembered experience doesn't matter. Whether anaesthesia leaves such traces is an empirical question, but the "it doesn't count if you forget" assumption is philosophically weaker than it looks.

  6. Tsion Bekele

    Fellow

    I'll take away three things: the dissociation is real; the evidence is circular in a way that may be unavoidable; and forgetting doesn't obviously cancel moral weight. Next time a patient asks, I'll make sure she gets a more honest answer, kindly.

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