A technician explains measurements whilst a scientist explains observations.

Motion and change

The most striking aspect of my experience, and the aspect of experience that is most at variance with school physics, is the way it contains motion and change. According to school physics only the present instant of no duration exists but my experience is full of whole sounds stretched over time and also contains movement.

My observation of motion and change shows that sounds can be extended through time for about a second at their location in experience but visual motions only extend 100 milliseconds or less at their location. The short duration of visual time extension is consistent with the rapid changes that can demand responses in the visual field such as catching, dodging, following moving patterns with many disparate parts etc. A detailed consideration of change shows it is conceivable that colour and other simple sensory qualia are the result of the different firing rates of neurons creating different 4D objects.

What is lacking in the descriptions below is any consideration of "becoming", that something that is outside time that gives life to time. 

The detailed observations of change are described below.


Sounds occur as whole entities extended in time. When I hear the "vrooom" of a passing car the sound occurs at the apparent location of the car and stretches into the apparent future in a similar way to how someone standing up stretches up into the vertical. When I hear the tick of a clock the experience is similar with the tick stretching into time at the fixed location of the clock. (The sound stretches into an apparent future because I seem to remain contemporaneous with the start of the sound as it progresses, up to a maximum length of perhaps a second).

If I hear the tick of a slow ticking clock the sound seems to just fade away when it has passed. This fading seems to be a mixture of attention to an absence of sound in my ears and the retrieval of a remembered sound.

If I hear a rapid succession of sounds such as music or speech there are successive 'phrases' of sound extended in time. If I attend to a phrase I can preserve about a second of sound and this fades away (the word "hot" in a song is easy to attend to but "anticipation" tends to fragment into "pation"). This process of attending breaks up music, for instance the phrase at the end of a line of verse may grab my attention, leaving the succeeding second or two of music faded into the background until another phrase grabs my attention. If I do not attend to any phrase in music then each succeeding phrase snaps the last out of experience.

Attending to sounds is similar to attending to spatial events, it involves highlighting an angular displacement in time relative to the "now" at the centre of experience of about a second and is disturbed when attention is grabbed by a succeeding event.

Bodily motion

If I shut my eyes and lightly touch two forefingers to my thumb in rapid succession I get a similar extension in time of the taps as I do in the case of sound. If I use two hands, each touching forefingers to thumb, I generate two time extended objects like two words.

If I close my eyes and make patterns by shaking my hands like a percussionist without a drum the patterns are also extended in time and can form objects up to about half a second to a second in length.

If I close my eyes and move two hands that are separated by about 10-30 cms upwards they seem to form a single moving entity that includes the gap.

Dance is a form of motion in which sound and motion act together creating time-extended forms of about 500ms, for instance the circular motion of the hips is an entity and this can create imaginary visual images so giving the impression of time extended vision so conjoining all the most prominent senses.

Visual Motion

Time extended sounds have an obvious character in which all the components of a word or a bar of a tune are present but extended in time at their location so they do not obscure each other. When I look at a moving leaf I can see it move but, unlike in the case of sound, I cannot say that I clearly have its previous positions as a time extended entity near its position on the tree.

The sight of moving objects can be accompanied by a distinct afterimage. For instance, if I move a finger at about quarter of a metre a second just in front of a dark surface (the surface being the object of focus) the finger is followed by a blurred, pink area with a stronger finger-like pink blur about two centimetres behind the finger. When the finger stops moving the blurry finger catches up with the original. The catch up time is consistent with the time taken to move two centimetres at about 0.25 m/s ie: around 80 milliseconds. I see the whole of the "catch up" as a single motion and this may be nearly the extent of the time extension of visual linear motions perpendicular to the radius of my experience. When I hear a clock tick of about a third of a second duration I cannot say that the visual motion of any object extends that far through time. This very short time extension of visual linear motion (<100ms) allows me to see visual motion but does not allow me to attend to it excessively: if a ball hits my hand my attention is close to the hand in experience, not in the past. I can also empathise with a visual movement, for instance I can imagine that the movement of a branch is like the movement of an arm. This empathy should really be called "bodily tracking" because it is especially marked when the body is actively interacting with the world, for example, in the case of a branch that swings across a path what I call visual movement is partly my planned avoidance of the branch hence visual movements can be part of a complex of movement that has a time extension related to the time extension of bodily motion.

Successively flashing lights

If two lights separated by about two centimetres at a metre distant from my eyes are flashed in succession they can appear as a single light that moves between the positions of the two lights. (Known as the Phi Effect). This effect occurs if the interval between flashes is less than about half a second. Some authors have proposed that the effect does not "really" happen but recent experiments have shown that the imaginary path of the lights is traced out on the visual cortex. The brain models the movement. The switch over from two flashing lights to one moving light occurs at about half a second interval between flashes and this suggests that my experience is about a half second behind the events in the world. A half second because, to construct a smooth motion the brain must already have recorded the time of the second flash.

It would be interesting to investigate the time course of the cortical modelling of the moving light in relation to actual timings of events - is the cortex a half second behind events or does it patch in the connection between the lights after the second light has flashed? If it is the latter where does the linear timing of the lights in experience originate? Current data suggests it is the former, the cortex is indeed a half second behind and only produces activity that is part of experience during the P3 phase of event related potentials (after perhaps 400 ms).

How far do I extend in time?

I can only attend to events of up to about 1 second in duration in the case of sound and of almost imperceptible duration in the case of visual movement. Events may well be pre-packaged, my brain generating objects in my experience that are up to 1 second long. It is impossible to tell how long the black background of experience in a dark room with eyes closed extends, perhaps it is being refreshed continuously.

What I call the "present" is most probably a set of events delayed by 0.5 seconds, furthermore, the centre point of my experience, the "now" may be even further behind the present being physically displaced in the past. Such a displacement would be consistent with an experience that contains time extended objects such as sounds that are directed into the future.

Change and change blindness

Events appear to occur fully formed within my experience. Words seem to have been processed elsewhere and offered up as neat, time extended objects. The change that I have in my experience is the appearance of new events that extend into the apparent future. It may be that my experience is a limited spatio-temporal sphere that is being stoked with events from my brain or it may be that experience is continually moving into new stretches of time, again filled with events from the non-conscious parts of my brain.

In fact I do not even usually process the content of experience:

This video is copyright Richard Wiseman, all rights reserved. This video may not be used or re-created for any commercial purpose without permission, and may not be altered or edited for any purpose without permission.

"Change blindness" raises many interesting issues.

It demonstrates the essentially passive nature of experience. Experience itself does not process its content - processing is done elsewhere. This should surprise no-one because experience is a time extended form that contains the results of processes, not the processes themselves.

It reinforces the fact that the area outside of the centre of attention (around 5 degrees either side of the centre of vision in the case of sight) is present in low definition. For instance, a picture on my wall that is 20 degrees to the left of the centre of my attention is just a grey green smudge.

It shows that the 0.5 seconds or so required to fully attend to and model a new event at a different location in experience is close to or exceeds the time extension of experience so that by the time a new scene is acquired the old scene has gone.

It suggests that objects are mounted in experience as four dimensional entities. For instance, if a change is a continuous motion then there is a motion in experience that is present as a time extended motion. In the case of vision, if there is a gap, or interstimulus interval, between changes of more than about 100 ms (see Rensink et al (2000) a change indicator such as surprise is needed for the change to be registered in experience. Change blindness occurs when such an indicator is not placed in experience after an interstimulus interval. Without an indicator events that are separated by more than the time extension of a sensory modality do not contrast with each other in experience.

Auditory change blindness occurs after a 500 ms interstimulus interval, as would be expected from the longer possible time extension of auditory events and also occurs in contiguous events where the events are separate auditory objects. (ie: there is no change blindness to "aaaaeee" where that is a single contiguous sound with "aaaa" changing continuously to "eee" but there can be change blindness to separate sounds see Pavani and Turatto (2008)).

Change blindness shows that if events change within an object within experience, such as within a single short word or during a continuous motion they are perceptually "known" but the nature of "known" deserves further exploration. If events change outside of the time extension of experience (<100ms for vision, <~500ms for sound and tactile sensation) or create new objects then an indicator such as surprise is required to register the change. This suggests that being "known" is a property of being part of a time extended object in experience. The long time extension of auditory objects explains why knowledge and language are often confused.

Sameness and difference

The discussion of change blindness suggested that change is evident within time extended objects in experience but not necessarily evident between such objects. Change is evident in a single, short word that changes pitch but if several words happen concurrently and also successively changes to entire words may go unnoticed. If a table cloth continuously changes colour this will be evident in experience as the nature of the cloth but if the cloth goes out of experience then returns as a cloth of a different colour this could easily be missed, especially if there is no surprise indicator within experience to mark the change. Difference or change is a property of a single time extended object and where it occurs outside of a single object change is only known if it is labelled within experience by the presence of a new, surprise or change indicator.

Sameness, such as the sameness of the black-grey background when relaxing in the dark with eyes closed, is also a property of objects in experience. If I observe a green area on a white sheet it is a particular green because it remains green. Objects that are of short duration, such as during a very brief opening of the eyelids, have colour but the colour is ill defined. On a brief entry into experience an object may be green but on longer exposure it becomes dark green or light green etc. This failure to display clear colours on objects in experience that have a short duration may be due to nothing more than a failure to load the correct colour into experience or it may be the result of some more fundamental graininess in experience itself. It is not just colours that are vague during short exposures in experience, forms are also indistinct.

Minimum duration of experience - persistence

I can open and close my eyes extremely quickly, certainly in under a quarter of a second. If I close my eyes then rapidly open and close my eyes again whilst looking at a scene the scene persists after my eyes have closed. The scene exists for about a half second, a considerable proportion of this time being after my eyes have closed. If I simply close my eyes whilst looking at a scene it also persists. If I move my head past a scene and close my eyes as it passes it remains in its correct location for about .5 secs. This suggests that the internal scene is part of a coordinate system in which the position of my body is kept in the correct relation to the position of visual scenes.

The nature of sensory qualia

If I hear a pure sound it consists of a certain pitch, intensity and duration. The pitch of the sound is evident throughout its duration. If the sound is divided into short durations of the same pitch there is a minimum duration of about 30-50 ms where the pitch can still be discerned but below which the pitch is lost to be replaced by a click at high intensities. It is possible that this effect is solely due to harmonics generated by a sudden square wave of sound but even in my dreams and imagination there are no sounds of ultra short duration. It is probable that a note a sixteenth of a second long (about 60 ms) can have pitch but that a note 30ms long loses this attribute.

So to recap, the fact that sounds of less than about 20Hz tend break into a succession of clicks suggests that hearing is composed of pulse trains with a minimum duration of about 30ms. Each pulse train may be composed of many pulses but in my experience they are heard as a whole note. The pulse trains (notes) are four dimensional objects that constitute a unit of auditory experience.

A minimum duration of sensory qualia also seems to occur in visual qualia, as noted above.

If there is truly a minimum duration for sensory qualia of about 30ms then different pitches of sound can be construed as packets with a given pulse frequency. The note 'C' may indeed be 256, 512 or 1024 pulses per second etc. (or similar) in a 25ms packet. The packets abut continuously in a time extended sound of 0.5 secs.

This idea of qualia as 'pulse packets' can also be applied to vision. Suppose visual experience consists of objects with a time extension of about 30-80 ms and these visual objects can consist of 30 or 20 pulses of whatever makes up the groundform or substance of experience. It is then conceivable that "blue" is a time extended object that has 20 pulses and green has 30 pulses. If qualia are due to fairly high frequency pulse trains of short duration in experience then qualia might correlate with a simple physical phenomenon such as the rate of firing of a neuron. At first sight this might suggest possible tests of the relationships between stimulus frequencies, movement and experience but these are likely to be confounded if the non-conscious part of the brain delivers colour as pre-formed pixels within what appears as a moving object.

Rensink RA, O'Regan JK, and Clark JJ (2000). On the Failure to Detect Changes in Scenes Across Brief Interruptions. Visual Cognition,7:127-145. (pdf file) http://www.psych.ubc.ca/~rensink/flicker/abs.00.3a.html

Pavani, F and Turatto, M. (2008) Change perception in complex auditory scenes. Perception & Psychophysics 2008, 70 (4), 619-629 doi: 10.3758/PP.70.4.619 http://www.app.psychonomic-journals.org/content/70/4/619.full.pdf

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