Presentation Timing/Rate

[lisayen]

Hi,
I am considering using SuperLab to run an RSVP task.
The task involves presenting three words or three pictures on the screen for 100ms per item. With no delay between items. Following this subjects are asked to type in the words or names of pictures they have just been shown. I realise that I can use the RSVP option (but only for the words not the pictures).
I would like some additional information about how SuperLab controls the presentation of items when the screen refresh doesn't divide equally into the 100ms. Also, I note the Mac version (v 10.39+ I think) doesn't work with screen refreshes... so how is the timing of events controlled?
For example, previous presentation software (such as DMDX or Presentation) work with the screen refresh so that you know you are presenting for 111ms).
Please let me know if any of this enquiry is unclear.
Many thanks,
Lisa

[Hisham]

Hi Lisa,

> I would like some additional information about how SuperLab
> controls the presentation of items when the screen refresh
> doesn't divide equally into the 100ms.

SuperLab rounds up the duration to the next multiple of the refresh rate. In a future version, we're looking into having SuperLab express visual stimulus durations in multiples of refresh rates instead of milliseconds.

> Also, I note the Mac version (v 10.39+ I think) doesn't work with
> screen refreshes... so how is the timing of events controlled?

SuperLab does not synchronizes only on Mac OS 10.3.9. It synchronizes with the refresh rate on all Mac OS 10.4 versions.

Please let me know if you have any other questions.

Best regards,

Hisham.

[lisayen]

Dear Hisham,
Thanks for clarifying my queries.
Glad to hear SuperLab works with the refresh rate in Mac OS 10.4 versions.
I assume that the presentation duration on PC's also rounds up the requested presentation duration to the next multiple of the refresh rate (its possible we will end up running this experiment on PC's next year).
Specifying visual event durations in terms of ticks/refreshes might be a good option in the future, I mean it just makes it a little easier to understand how the timing is controlled. If not, just adding a help page (particularly in the RSVP section) would also make it clearer.
Cheers,
Lisa
=)

[Hisham]

Yes, the PC version also rounds up.