Where do thoughts come from? Alva Noë provides a nice commentary here on an interesting paper by Melissa Ellamil et al. The paper reports on research into the origin of spontaneous thoughts.

The research used subjects trained in Mahasi Vipassana mindfulness techniques. They were asked to report the occurrence of thoughts during sessions when they were either left alone or provided with verbal stimuli. As well as reporting the occurrence of a thought, they were asked to categorise it as image, narrative, emotion or bodily sensation (seems a little restrictive to me – I can imagine having two at once or a thought that doesn’t fit any of the categories). At the same time brain activity was measured by fMRI scan.

Overall the study found many regions implicated in the generation of spontaneous thought; the researchers point to the hippocampus as a region of particular interest, but there were plenty of other areas involved. A common view is that when our attention is not actively engaged with tasks or challenges in the external world the brain operates the Default Mode Network (DMN); a set of neuronal areas which appear to produce detached thought (we touched on this a while ago); the new research complicates this picture somewhat or at least suggests that the DMN is not the unique source of spontaneous thoughts. Even when we’re disengaged from real events we may be engaged with the outside world via memory or in other ways.

Noë’s short commentary rightly points to the problem involved in using specially trained subjects. Normal subjects find it difficult to report their thoughts accurately; the Vipassana techniques provide practice in being aware of what’s going on in the mind, and this is meant to enhance the accuracy of the results. However, as Noë says, there’s no objective way to be sure that these reports are really more accurate. The trained subjects feel more confidence in their reports, but there’s no way to confirm that the confidence is justified. In fact we could go further and suggest that the special training they have undertaken may even make their experience particularly unrepresentative of most minds; it might be systematically changing their experience. These problems echo the methodological ones faced by early psychologists such as Wundt and Titchener with trained subjects. I suppose Ellamil et al might retort that mindfulness is unlikely to have changed the fundamental neural architecture of the brain and that their choice of subject most likely just provided greater consistency.

Where do ‘spontaneous’ thoughts come from? First we should be clear what we mean by a spontaneous thought. There are several kinds of thought we would probably want to exclude. Sometimes our thoughts are consciously directed; if for example we have set ourselves to solve a problem we may choose to follow a particular strategy or procedure. There are lots of different ways to do this, which I won’t attempt to explore in detail: we might hold different aspects of the problem in mind in sequence; if we’re making a plan we might work through imagined events; or we might even follow a formal procedure of some kind. We could argue that even in these cases what we usually control is the focus of attention, rather than the actual generation of thoughts, but it seems clear enough that this kind of thinking is not ‘spontaneous’ in the expected sense. It is interesting to note in passing that this ability to control our own thoughts implies an ability to divide our minds into controller and executor, or at least to quickly alternate those roles.

Also to be excluded are thoughts provoked directly by outside events. A match is struck in a dark theatre; everyone’s eyes saccade involuntarily to the point of light. Less automatically a whole variety of events can take hold of our attention and send our thoughts in a new direction. As well as purely external events, the sources in such cases might include interventions from non-mental parts of our own bodies; a pain in the foot, an empty stomach.

Third, we should exclude thoughts that are part of a coherent ongoing chain of conscious cogitation. These ‘normal’ thoughts are not being directed like our problem-solving efforts, but they follow a thread of relevance; by some connection one follows on from the next.

What we’re after then is thoughts that appear unbidden, unprompted, and with no perceivable connection with the thoughts that recently preceded them. Where do they come from? It could be that mere random neuronal noise sometimes generates new thoughts, but it seems unlikely to be a major contributor to me: such thoughts would be likely to resemble random nonsense and most of our spontaneous thought seem to make a little more sense than that.

We noticed above that when directing our thoughts we seem to be able to split ourselves into controller and controlled. As well as passing control up to a super-controller we sometimes pass it down, for example to the part of our mind that gets on with the details of driving along a route while the surface of our mind us engaged with other things. Clearly some part of our mind goes on thinking about which turnings to take; is it possible that one or more parts of our mind similarly goes on thinking about other topics but then at some trigger moment inserts a significant thought back into the main conscious stream? A ‘silent’ thinking part of us like this might be a permanent feature, a regular sub- or unconscious mind; or it might be that we occasionally drop threads of thought that descend out of the light of attention for a while but continue unheard before popping back up and terminating. We might perhaps have several such threads ruminating away in the background; ordinary conscious thought often seems rather multi-threaded. Perhaps we keep dreaming while awake and just don’t know it?

There’s a basic problem here in that our knowledge of these processes, and hence all our reports, rely on memory. We cannot report instantaneously; if we think a thought was spontaneous it’s because we don’t remember any relevant antecedents; but how can we exclude the possibility that we merely forgot them? I think this problem radically undermines our certainty about spontaneous thoughts. Things get worse when we remember the possibility that instead of two separate thought processes, we have one that alternates roles. Maybe when driving we do give conscious attention to all our decisions; but our mind switches back and forth between that and other matters that are more memorable; after the journey we find we have instantly forgotten all the boring stuff about navigating the route and are surprised that we seem to have done it thoughtlessly. Why should it not be the same with other thoughts? Perhaps we have a nagging worry about X which we keep spending a few moments’ thought on between episodes of more structured and memorable thought about something else; then everything but our final alarming conclusion about X gets forgotten and the conclusion seems to have popped out of nowhere.

We can’t, in short, be sure that we ever have any spontaneous thoughts: moreover, we can’t be sure that there are any subconscious thoughts. We can never tell the difference, from the inside, between a thought presented by our subconscious, and one we worked up entirely in intermittent and instantly-forgotten conscious mode. Perhaps whole areas of our thought never get connected to memory at all.

That does suggest that using fMRI was a good idea; if the problem is insoluble in first-person terms maybe we have to address it on a third-person basis. It’s likely that we might pick up some neuronal indications of switching if thought really alternated the way I’ve suggested. Likely but not guaranteed; after all a novel manages to switch back and forth between topics and points of view without moving to different pages. One thing is definitely clear; when Noë pointed out that this is more difficult than it may appear he was absolutely right.


  1. 1. Sci says:

    “In fact we could go further and suggest that the special training they have undertaken may even make their experience particularly unrepresentative of most minds; it might be systematically changing their experience.”

    Isn’t this issue of special conditions applicable to the entirety of psychology though? The field seems to consist of odd experimental situations divorced from actual life, and/or an extension of simple cases assumed to extend into more complex situations.

    Perhaps this is why the field has had so many failed replications coming to light?

  2. 2. Peter says:

    I can’t really disagree. It’s also notoriously the case that most psychology research is based on American undergraduates (because they’re there). Still, there are differences of degree.

  3. 3. Hunt says:

    The idea that there is conscious and subconscious thinking is really interesting. There are certainly times when a “spontaneous” thought comes to me that must be related to my conscious stream of thought, yet I can’t recall any conscious logical connection. What generates these thoughts and why are the processes that do so subconscious? In effect, what are thoughts made of, and can we call their building blocks ‘thoughts’ and if so what determines when a thought is conscious or not? It seems to me there are two possibilities:

    1. All processes of the mind are basically the same kind. We can call them all “thoughts” and they each have an attribute ‘conscious’ which is either true or false. Something determines whether the conscious attributes is set true or false, or when it is toggled on and off. You might picture the mental process as a boiling pot of water and only the water that splashes above a certain line are conscious thoughts.

    2. Thoughts are build on top of other, more finely grained mental processes, which are not ‘thoughts’ as we know them. All thought is conscious, all other more fundamental processes are subconscious.

  4. 4. Hunt says:

    And of course, the Homunculus is always lurking. There are thoughts and “the thinker”. By choosing either the attribute model (‘conscious’ is either true or false) or the idea that thoughts simply are always ‘conscious’ (whatever that is) nails things down at least a little. I don’t see it as revealing anything about the mystery of consciousness, though. The argument still comes down to “conscious thought are conscious”, which isn’t very helpful.

  5. 5. Arnold Trehub says:


    According to the retinoid theory of consciousness, subconscious thoughts are neuronal events (activations) in the sensory and cognitive mechanisms of the brain. These subconscious neuronal activations do not become part of the conscious stream until they are projected into the plenum of egocentric retinoid space, a response lag of ~ 500 milliseconds.

  6. 6. John Davey says:


    “The argument still comes down to “conscious thought are conscious”, which isn’t very helpful.”

    They are as helpful as comments like “time is time” or “space is space” or any other ‘is’ question involving an irreducible. Do you attach the same doubt to ‘time’ or ‘space’ or are you confident of delivering a non-tautological definition ?

  7. 7. Hunt says:

    I don’t see any of those things as necessarily irreducible, especially consciousness. “Consciousness just is consciousness” sounds like something Deepak Chopra would say. 🙂

  8. 8. Sci says:

    @ Hunt – ‘“Consciousness just is consciousness” sounds like something Deepak Chopra would say.’

    Actually Sam Harris who came pretty close to saying that:


    ‘To say “Everything came out of nothing” is to assert a brute fact that defies our most basic intuitions of cause and effect—a miracle, in other words.

    Likewise, the idea that consciousness is identical to (or emerged from) unconscious physical events is, I would argue, impossible to properly conceive—which is to say that we can think we are thinking it, but we are mistaken.’

  9. 9. john davey says:


    “I don’t see any of those things as necessarily irreducible”

    OK. Reduce away !

    Let’s start with time.


  10. 10. john davey says:


    .. just a short definition of time will do and why you think the definition contains no tautologies.


  11. 11. john davey says:


    “‘To say “Everything came out of nothing” is to assert a brute fact that defies our most basic intuitions of cause and effect—a miracle, in other words.”

    I think he’s getting into a mistake which a lot of people do with physics – confuse empty space (space is definitely “something”) with a nullity. Something of out a nullity is unintuitive : something out of empty space less so. But as a definition of a nullity may simply be something out of which causes may not originate, that might be a bit on the circular side


  12. 12. Sci says:

    @ John Davey: Heh I don’t want to go too far afield here and get into the creation of the universe…I was just pointing out that a New Atheist, someone we’d consider far afield from Chopra’s views, points out that consciousness *seems* irreducible.

    I figure we’re too early in our examination of reality to worry about “isms”. We have stuff we can cut up and break down, let’s just keep doing that for awhile and see what we get.

  13. 13. Sci says:

    Regarding fMRIs ->

    Software faults raise questions about the validity of brain studies.


    ‘In other words, while they’re likely to be cautions when determining whether a given voxel is showing activity, the cluster identification algorithms frequently assign activity to a region when none is likely to be present. How frequently? Up to 70 percent of the time, depending on the algorithm and parameters used.’

    ‘Is this really as bad as it sounds? The authors certainly think so. “This calls into question the validity of countless published fMRI studies based on parametric clusterwise inference.” It’s not clear how many of those there are, but they’re likely to be a notable fraction of the total number of studies that use fMRI, which the authors estimate at 40,000.’

  14. 14. Sci says:

    Relating to my first comment, more on the failing of psychology as a discipline:

    Spot the WEIRDo


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