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Thread: Sirius Manual (U2) Mode Expand vs Focus Problem?

  1. #11

    Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    Mark,

    Just my opinion but even with dual-lights I would avoid using the Proteus manual expand mode if you are really trying to entrain to a specific freq. I'd just use the normal lightframe mode; not as entertaining, but probably a bit better for entraining.

    Ya, it will be interesting to see some of Craig's EEG findings. I might dust off my old Thoughtstream unit and see if I can see any significant differences myself.

    Cheers,
    TomC

  2. #12

    Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    Greetings!

    The 'focus vs expand' frequency issue is not a 'bug' but rather a design decision--we definitely spent some time mulling over whether to double the frequency in 'expand' mode vs. 'focus', and decided on the present approach because light entering one closed eye actually stimulates both hemispheres, though more strongly in the contralateral hemisphere. So, 10 hz alternating left/right (5 hz each side) still does produce 10 Hz stimulation, with some phase shifts due to cortical propagation delays, etc.

    It is possible under controlled circumstances to affect only the contralateral hemisphere by stimulating only the 'hemifield'--a region in the far left or right of the visual field (this only works with eyes open, due to the diffusing nature of the closed eyelids). Dr. Tom Budzynski had a prototype hemifield system built for him in the mid to late 1980s and gathered a fair amount of data using a 21 channel Lexicore EEG. He found that it was possible to stimulate left and right visual cortices to different frequencies but only for brief periods; he told me that after some seconds they would 'snap back' to a share frequency after that. He also told me that it was very difficult to carry this out if the two stimulation frequencies were more than two or three hz apart, which is why we decided not to pursue this line of research back in the late 80s.

    There are some supposed 'hemifield' stimulation glasses on the market today, but despite the neat concept, they most likely do not work as advertised (again, you need to have your eyes open and be staring straight ahead in order to achieve hemifield stimulation/activation of the visual cortex).

    Hope this helps!

    --Robert

  3. #13

    Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    Quote Originally Posted by Robert Austin View Post
    Greetings!

    The 'focus vs expand' frequency issue is not a 'bug' but rather a design decision--we definitely spent some time mulling over whether to double the frequency in 'expand' mode vs. 'focus', and decided on the present approach because light entering one closed eye actually stimulates both hemispheres, though more strongly in the contralateral hemisphere. So, 10 hz alternating left/right (5 hz each side) still does produce 10 Hz stimulation, with some phase shifts due to cortical propagation delays, etc.

    Robert,

    Thanks for your thoughtful reply. I agree with everthing you've said (well the bits that I can understand anyway).

    I understand your statement that if each eye is getting 5hz alternating (180 deg out of phase) then the net result is 10hz. I do this when I make a NP2 session and want something a little more entertaining than single flashes but without affecting the entrainment frequency.

    The problem with the Sirius/Proteus user expand feature is 10hz produces 10hz (not 5hz) on each eye and alternates (180 deg phase shift) so by your logic, this results in a 20hz net effect.

    I might be misunderstanding your point(s) so maybe you could help clarify this for me. Many thanks.

    Cheers,
    TomC

  4. Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    An interesting post from Robert Austin.

    I notice that between 20 and 30hz, I can't really percieve any visual difference between normal and expand mode with my Procyon ( although I can hear it) . It seems at that speed I only seem to visually process the red flash.

  5. #15

    Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    Gents,

    I think the main question which has emerged from this thread is, how to handle the 'expand' frequencies as related to 'focus'? There are two options:

    1. Set the 'expand' frequency to the same as 'focus', so that at 10 Hz 'focus', this alternates left/right at half the 'focus frequency, per side (that is, 5 Hz each left/right, out of phase)

    2. Set the 'focus' frequency such that the left eye receives 10 Hz, and the right eye 10 Hz, when 'focus' is set to 10 Hz.

    We've played with both approaches over the years, and I'm personally still not sure which may be most useful to you, our users.

    How about we set up a poll, and you can all vote on it? It's possible that this could become a programmable option in the future, at least for the Proteus. As I recall we don't have much if any memory left in the Sirius to add an 'either 1 or 2' option, but it is inevitable that we eventually update the Sirius with a new model, and this could have some flash memory (like the Proteus and Procyon) to store your favorite option.

    Should we set up a poll, then?

    -Robert

  6. #16
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    Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    My two cents worth - don't worry about it or do away with the expand feature completely. With monocolor glasses I find it annoying, and with bicolor glasses I don't find it particularly interesting.

    As the entrainment virtue of either frequency strategy is so subject to debate, treat it as a novelty and either use it or don't.

    Cheers,
    Craig

  7. #17

    Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    Robert,

    I'd never say no to a good poll but I'm not sure it's necessary. I think that you will end up with a huge wish-list that will be impossible to do. To be honest, I know that many things on my wish list are 'nice to haves' as opposed to 'need to haves'.

    I'd say that the simplest approach would be just to modify the current Usr Expand visual to honour the Focus entrainment frequency as you've described in point (1.). I'd guess this would be a fairly straightforward update for the Proteus and maybe a flash option for the Sirius (or something to add to a new updated Sirius), without any additional memory requirements.

    I know it's pretty hard, or impossible, to satisfy all user requests. For example, unlike Craig I like expand (alternating freq's) down to as low as 2hz (1hz for each eye alternating), even with moncolour glasses (separate left/right channels).

    So maybe the best thing is to do as Craig says and just get rid of the Expand feature in the Usr mode on both the Proteus and Sirius machines (or at least the new Sirius units) and just retain the Usr Focus feature. At least then the Usr mode (focus only) will be honouring the entrainment frequency selected. This would also be a nice, simple update option for a Procyon Usr model as well (hint-hint).

    As far as in-built sessions go, I don't think that it is necessary to modify any Proteus or Procyon sessions since a user can use the editor to modify them if they so wish.

    However, on the Siruis in-built sessions I really think that the the Expand mode used in all sessions should be modified so that in the Expand part of each session it halves the current visual right/left frequency (but not the audio freq, they're fine as is) and hence honours each session's freq's.

    If you could make a flash update on the Sirius to allow these modified sessions to be updated (and/or the old ones to be returned) that would be great. Another simpler approach would be to modify all the Sirius sessions sectors to Focus only. However, I think that most would find this a bit too boring.

    Anyway, just my $0.02 worth.

    Cheers,
    TomC
    Last edited by TomC; 03-22-2009 at 12:14 AM.

  8. Default Re: Sirius Manual (U2) Mode Expand vs Focus Problem?

    I like the expand feature. I find on my Proteus a much richer visual experience particularly in the Alpha range.

    The issue over display target frequency is certainly complicated by the way the various glasses display it: each eye flasing alternately is certainly a differnt experience to having two colours flash alternately in unison in both eyes. I don't know how many people use manual mode much , I certainly use it.

    I'm in favor , as there is no general agrrement on the neurological effects of expand mode to just leave the displays the way they are and keep in mund that it is an `experimental ' mode.

    Perhaps someone with an EEG could do some experimentation and find out if with the two differnt kinds of glasses , that brainwave frequencies are actually enhanced at double the frequency in expand mode.

    Mark

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