Investigating the Stream of Consciousness

Oliver Rashbrook-Cooper–British Academy Postdoctoral Fellow in Philosophy at the University of Oxford

There are a num­ber of dif­fer­ent ways in which we can fruit­fully study our streams of con­scious­ness. We might try to provide a detailed char­ac­ter­isa­tion of how con­scious exper­i­ence seems ‘from the inside’, and closely scru­tin­ize the phe­nomen­o­logy. We might try to uncov­er the struc­ture of con­scious­ness by focus­sing upon our tem­por­al acu­ity, and examin­ing when and how we are sub­ject to tem­por­al illu­sions. Or we might focus upon invest­ig­at­ing the neur­al mech­an­isms upon which con­scious exper­i­ence depends.

Sometimes, these dif­fer­ent approaches appear to yield con­tra­dict­ory res­ults. In par­tic­u­lar, the deliv­er­ances of intro­spec­tion some­times appear to be at odds with what is revealed both by cer­tain tem­por­al illu­sions and by research into neur­al mech­an­isms. When this occurs, what should we do? We can begin by con­sid­er­ing two fea­tures of how con­scious­ness phe­nomen­o­lo­gic­ally seems.

It is nat­ur­al to think of exper­i­ence as unfold­ing in step with its objects. Over a ten second inter­val, for instance, I might watch someone sprint 100 metres. If I watch this event, my exper­i­ence will unfold over a ten second inter­val. First I will hear the pis­tol fire, see the race begin, and so on, until I see the lead­er cross the fin­ish line. My exper­i­ence of the race has two fea­tures. Firstly, it seems to unfold in step with the race itself, secondly it seems to unfold smoothly — it seems as if I am con­tinu­ously aware of the race, rather than my aware­ness of it being frag­men­ted into dis­crete episodes.

Can this char­ac­ter­isa­tion of how things seem be recon­ciled with what we learn from oth­er ways of invest­ig­at­ing the stream of con­scious­ness? To answer this ques­tion we can con­sider two dif­fer­ent cases: the case of the col­our phi phe­nomen­on, and the case of dis­crete neur­al processing.

The col­our phi phe­nomen­on is a case in which the present­a­tion of two stat­ic stim­uli gives rise to an illus­ory exper­i­ence of motion. When two col­oured dots that are suf­fi­ciently close to one anoth­er are illu­min­ated suc­cess­ively in a suf­fi­ciently brief win­dow of time, one is left with the impres­sion that there is a single dot mov­ing from one loc­a­tion to the oth­er (examples can be found here and here)

This phe­nomen­on gen­er­ates a puzzle about wheth­er exper­i­ence really unfolds in step with its objects. In order for us to exper­i­ence appar­ent motion between the two loc­a­tions, we need to register the occur­rence of the second dot. This makes it seem as if the exper­i­ence of motion can only occur after the second dot has flashed, for without regis­ter­ing the second dot, we wouldn’t exper­i­ence motion at all. So it seems that, in this case, the exper­i­ence of motion doesn’t unfold in step with its appar­ent object at all. If this is right, then we have reas­on to doubt that exper­i­ence nor­mally unfolds in step with its objects, for if we can be wrong about this in the col­our phi case, per­haps we are wrong about it in all cases.

The second kind of case is the case of dis­crete neur­al pro­cessing. There is reas­on to think that the neur­al mech­an­isms under­pin­ning con­scious per­cep­tion are dis­crete (see, for example, VanRullen and Koch, 2003). This looks to be in ten­sion with the second fea­ture we noted earli­er – that our aware­ness of things appears to be con­tinu­ous. As in the case of col­our phi, it might be tempt­ing to think that this tells us that our impres­sion of how things seem ‘from the inside’ is mistaken.

However, when we con­sider how things really strike us phe­nomen­o­lo­gic­ally, it becomes clear that there is an altern­at­ive way to recon­cile these appar­ently con­tra­dict­ory res­ults. We can begin by not­ing that when we intro­spect, it isn’t pos­sible for us to focus our atten­tion upon con­scious exper­i­ence without focus­sing upon a tem­por­ally exten­ded por­tion of exper­i­ence – there is always a min­im­al inter­val upon which we are able to focus.

The claims that exper­i­ence seems to unfold in step with its objects and seems con­tinu­ous apply to these tem­por­ally exten­ded por­tions of exper­i­ence that we are able to focus upon when we intro­spect. If this is right, then we have a dif­fer­ent way of think­ing about the col­our phi case. On this approach, over an inter­val, we have an exper­i­ence of appar­ent motion that unfolds over the time it takes the two dots to flash. The phe­nomen­o­logy is, how­ever, neut­ral about what occurs over the sub-intervals of this experience.

The claim that this exper­i­ence unfolds over an exten­ded inter­val of time isn’t incon­sist­ent with what goes on in the col­our phi case. The appar­ent incon­sist­ency only arises if we think that the claim that exper­i­ence seems to unfold in step with its object applies to all of the sub-intervals of this exper­i­ence, no mat­ter how short (for devel­op­ment and dis­cus­sion of this point, see Hoerl (2013), Phillips (2014), and Rashbrook (2013a)).

Likewise, in the case of dis­crete neur­al pro­cessing, in order for the case to gen­er­ate a clash with how exper­i­ence appears ‘from the inside’, our char­ac­ter­isa­tion of how con­scious­ness seems must apply not only to some tem­por­ally exten­ded potions of con­scious­ness, but to all of them, no mat­ter how brief. Again, we might ques­tion wheth­er this is really how things seem.

While exper­i­ence doesn’t seem to be frag­men­ted into dis­crete epis­odes, this cer­tainly doesn’t mean that it seems to fill every inter­val for which we are con­scious, no mat­ter how brief (for dis­cus­sion, see Rashbrook, 2013b). As in the case of the col­our phi, per­haps our char­ac­ter­isa­tion of how things seem applies only to tem­por­ally exten­ded por­tions of exper­i­ence – so the deliv­er­ances of intro­spec­tion are simply neut­ral about wheth­er con­scious exper­i­ence fills every instant of the inter­val it occupies.

There is more than one way, then, to recon­cile the psy­cho­lo­gic­al and the phe­nomen­o­lo­gic­al strategies of enquir­ing about con­scious exper­i­ence. Rather than tak­ing non-phenomenological invest­ig­a­tion to reveal the phe­nomen­o­logy to be mis­lead­ing, per­haps we should take it as an invit­a­tion to think more care­fully about how things seem ‘from the inside’.



Hoerl, Christoph. 2013. ‘A Succession of Feelings, in and of Itself, is Not a Feeling of Succession’. Mind 122:373–417.

Phillips, Ian. 2014. The Temporal Structure of Experience. In Subjective Time: The Philosophy, Psychology, and Neurscience of Temporality, ed. Dan Lloyd and Valtteri Arstila, 139–159. MIT.

Rashbrook, Oliver. 2013a. An Appearance of Succession Requires a Succession of Appearances. Philosophy and Phenomenological Research 87:584–610.

Rashbrook, Oliver. 2013b. The con­tinu­ity of con­scious­ness. European Journal of Philosophy 21:611–640.

VanRullen, Rufin. and Koch, Christoph. 2003. Is per­cep­tion dis­crete or con­tinu­ous? Trends in Cognitive Sciences 7:207–13.