Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!princeton!mind!harnad From: harnad@mind.UUCP (Stevan Harnad) Newsgroups: comp.ai,comp.cog-eng Subject: Re: Searle, Turing, Symbols, Categories Message-ID: <394@mind.UUCP> Date: Sat, 29-Nov-86 01:52:21 EST Article-I.D.: mind.394 Posted: Sat Nov 29 01:52:21 1986 Date-Received: Sat, 29-Nov-86 20:57:30 EST References: <158@mind.UUCP> <150@cwrudg.UUCP> <160@mind.UUCP> <2495@utai.UUCP> <7158@boring.mcvax.UUCP> Organization: Cognitive Science, Princeton University Lines: 104 Keywords: appetite, consciousness, self-model, illusion Summary: Subliminal perception, dreams, unheard sounds and the Total Turing Test Xref: mnetor comp.ai:76 comp.cog-eng:20 Peter O. Mikes at S-1 Project, LLNL wrote: > An example of ["unexperienced experience"] is subliminal perception. > Similar case is perception of outside world during > dream, which can be recalled under hypnosis. Perception > is not same as experience, and sensation is an ambiguous word. Subliminal perception can hardly serve as a clarifying example since its own existence and nature is anything but clearly established. (See D. Holender (1986) "Semantic activation without conscious identification," Behavioral and Brain Sciences 9: 1 - 66.) If subliminal perception exists, the question is whether it is just a case of dim or weak awareness, quickly forgotten, or the unconscious registration of information. If it is the former, then it is merely a case of a weak and subsequently forgotten conscious experience. If it is the latter, then it is a case of unconscious processing -- one of many, for most processes is unconscious (and studying them is the theoretical burden of cognitive science). Dreaming is a similar case. It is generally agreed (from studies in which subjects are awakened during dreams) that subjects are conscious during their dreams, although they remain asleep. This state is called "paradoxical sleep," because the EEG shows signs of active, waking activity even though the subject's eyes are closed and he continues to sleep. Easily awakened in that stage of sleep, the subject can report the contents of his dream, and indicates that he has been consciously undergoing the experience, like a vivid day-dream or a hallucination. If the subject is not awakened, however, the dream is usually forgotten, and difficult if not impossible to recall. (As usual, recognition memory is stronger than recall, so sometimes cues will be recognized as having occurred in a forgotten dream.) None of this bears on the issue of consciousness, since the consciousness during dreams is relatively unproblematic, and the only other phenomenon involved is simply the forgetting of an experience. A third hypothetical possibility is slightly more interesting, but, unfortunately, virtually untestable: Can there be unconscious registration of information at time T, and then, at a later time, T1, conscious recall of that information AS IF it had been experienced consciously at T? This is a theoretical possibility. It would still not make the event at T a conscious experience, but it would mean that input information can be put on "hold" in such a way as to be retrospectively experienced at a later time. The later experience would still be a kind of illusion, in that the original event was NOT actually experienced at T, as it appears to have been upon reflection. The nervous system is probably playing many temporal (and causal) tricks like that within very short time intervals; the question only becomes dramatic when longer intervals (minutes, hours, days) are interposed between T and T1. None of these issues are merely definitional ones. It is true that "perception" and "sensation" are ambiguous, but, fortunately, "experience" seems to be less so. So one may want to separate sensations and perceptions into the conscious and unconscious ones. The conscious ones are the ones that we were consciously aware of -- i.e., that we experienced -- when they occurred in real time. The unconscious ones simply registered information in our brains at their moment of real-time occurrence (without being experienced), and the awareness, if any, came only later. > suggest that we follow the example of acoustics, which solved the > 'riddle' of falling tree by defining 'sound' as physical effect > (density wave) and noise as 'unwanted sound' - so that The tree > which falls in deserted place makes sound but does not make noise. > Accordingly, perception can be unconcious but experience can't. Based on the account you give, acoustics solved no problem. It merely missed the point. Again, the issue is not a definitional one. When a tree falls, all you have is acoustic events. If an organism is nearby, you have acoustic events and auditory events (i.e., physiological events in its nervous system). If the organism is conscious, it hears a sound. But, unless you are that organism, you can't know for sure about that. This is called the mind/body problem. "Noise" and "unwanted sound" has absolutely nothing to do with it. > mind and consciousness (or something like that) should be a universal > quantity, which could be applied to machine, computers... > Since we know that there is no sharp division between living and > nonliving, we should be able to apply the measure to everything We should indeed be able to apply the concept conscious/nonconscious to everything, just as we can apply the concept living/nonliving. The question, however, remains: What is and what isn't conscious? And how are we to know it? Here are some commonsense things to keep in mind. I know of only one case of a conscious entity directly and with certainty: My own. I infer that other organisms that behave more or less the way I would are also conscious, although of course I can't be sure. I also infer that a stone is not conscious, although of course I can't be sure about that either. The problem is finding a basis for making the inference in intermediate cases. Certainty will not be possible in any case but my own. I have argued that the Total Turing Test is a reasonable empirical criterion for cognitive science and a reasonable intuitive criterion for the rest of us. Moreover, it has the virtue of corresponding to the subjectively compelling criterion we're already using daily in the case of all other minds but our own. -- Stevan Harnad (609) - 921 7771 {allegra, bellcore, seismo, rutgers, packard} !princeton!mind!harnad harnad%mind@princeton.csnet