Image remains visible at 1ms presentation time

[JoAnn Silkes]

So far as I understand it, it's not possible to get as fast as a 1 ms 
presentation rate due to the limitations of the refresh rate of the 
computer monitor. With a 100 Hz refresh rate, the quickest presentation 
that you can achieve is 10 ms; you would need a 1000 Hz refresh rate for a 
1 ms presentation, which I don't think exists. I've also found that, 
depending on the computer I'm using, sometimes asking EPrime to present 
something for just a single frame (i.e., 10 ms when the refresh rate is 100 
Hz), the processor can't quite keep up and it ends up dropping frames, so 
the minimum I can really do is two frames (in this example, 20 ms). My 
guess is that you've got a mismatch between refresh rate and requested 
exposure duration, and that's throwing everything off.

Another thing to think about is whether you're using masking, or just 
relying on the rapid presentation rate. Perception of extraordinarily brief 
presentations is still likely, especially for images, if you don't have 
adequate masks present.

Good luck figuring it out.

JoAnn.


On Wednesday, October 1, 2014 11:39:17 PM UTC-7, Tan Li wrote:
>
> Hi!
>
> I'm starting out with E-prime and using it for a psychology experiment, 
> where I'm employing a image prime. Even when I change the duration of 
> presentation of the image to 1 ms, I can still see the image flash during 
> the run rather than appearing "invisible". Another study took <14 ms for 
> the primes to appear invisible.   
>  
> On DataAid, there is no ActionDelay for the image. DurationError is -1, 
> and OnsetDelay ranges from 0-1 ms. Each image is about 240KB.
>
> Would anyone have any idea what's happening? I haven't been able to find 
> an answer in the database... 
>
> Any reply is much appreciated!  
>

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