Millisecond Forums

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ryb34 - 9/8/2021

Hi,

My experiment involves the use of stimulus presentation at a single frame on a 60hz monitor. For most computers it seems to be working fine, but my i9 MacBook Pro seems to be struggling with it. For instance, yesterday I was getting a reading (display.refreshrate) of 85 when I was connected to an external monitor through VGA (USB-C to VGA, specifically). Today, when not connected to an external monitor, the reading from display.refreshrate is 59 (despite all other indicators of the laptop pointing to the native 60hz). It doesn't, however, appear to be a Mac-specific issue, as an older MacBook Pro runs the experiment fine. Not really even sure where to begin or if I'm missing something obvious.

Thanks in advance.

Not sure I understand what the problem is supposed to be. Can you clarify?

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Dave - 9/8/2021

+x

 

ryb34 - 9/8/2021

Hi,

My experiment involves the use of stimulus presentation at a single frame on a 60hz monitor. For most computers it seems to be working fine, but my i9 MacBook Pro seems to be struggling with it. For instance, yesterday I was getting a reading (display.refreshrate) of 85 when I was connected to an external monitor through VGA (USB-C to VGA, specifically). Today, when not connected to an external monitor, the reading from display.refreshrate is 59 (despite all other indicators of the laptop pointing to the native 60hz). It doesn't, however, appear to be a Mac-specific issue, as an older MacBook Pro runs the experiment fine. Not really even sure where to begin or if I'm missing something obvious.

Thanks in advance.

Not sure I understand what the problem is supposed to be. Can you clarify?

Sure. The experiment I'm using presents images of faces for a backward masking procedure. That is, a Target (face) is presented for 1 frame on a 60 hertz monitor (16.67 milliseconds) followed immediately by a Mask (face) for 9 frames (~150 milliseconds). As the code we're using is relying on the use of a user-specified timing parameter for the frames at which the target/mask are presented, the experiment timing is directly tied to the refresh rate of the monitor we're using. So, when I use the experiment on most other computers, we get a refresh rate reading from the output file of the code of 60hz which makes the target presentation 16.67 milliseconds. When the refresh rate differs (e.g., 59 on my i9 MacBook Pro), so too does the target stimulus presentation interval (since it's directly tied to the "1" input into the timing parameter). I hope I've explained it better, but happy to try again if not. Thanks for your patience.

To be clear, the output file from the experiment is telling me my refresh rate is something different (e.g., 59 when not plugged into an external display, 85 when plugged in to an external display) than what my hardware is supposed to produce and what other diagnostic tools tell me I'm getting (60). It strikes me as maybe a compatibility issue, but I'm really not sure.