start_cogent is throwing error - 'cannot get active window'

I'm using Cogent toolbox (similar to psychtoolbox) for showing stimulus by opening a window.

I'm runing a sample code (given in the official site of Cogent: http://www.vislab.ucl.ac.uk/stroop_example_code.php) but each time i'm encountering an error:

*******
*ABORT* CogInput : Create : cannot get active window
*******


Error in start_cogent (line 125)
    hDevice = CogInput( 'Create', 'keyboard', cogent.keyboard.mode, cogent.keyboard.queuelength );

Error in test2 (line 6)
start_cogent;

System configuration: Matlab-R2020b and Windows-10

My analysis: start_cogent is trying to access system file CogInput and an error is throwing as it can't assign required resources. Can't access the CogInput, it's a mex code.

How to fix this issue?

[Amy Rapp]

@Joy Rakshit did you get an answer on this? I am also experiencing this issue.

[Milad Kassaie]

@Joy Rakshit @Amy Rapp Same issue here. I tried setting inputs to 'nonexclusive' in related matlab scripts (e.g. the cogent.keyboard.mode argument, and similar ones in config_keyboard, etc), hoping that it wouldn't have to look for active window but it didn't help. I'm on a multi-display-adaptor (Nvidia+Intel) Win10 machine, running R2018a.

[Shivam Kalhan]

Hi, I was getting the same issue when I used config_display, but the problem was solved for me when I used cgopen instead to set up my window.

[Fatemeh Fazlali]

Hi! I also have the same issue. Do you have any solutions?

[Joy Rakshit]

Hi all,

I couldn't solve the problem and I started using psychtoolbox.

Using psychtoolbox is easier than using cogent.

Answer 1

[Fatemeh Fazlali]

Hey! I used MATLAB 2016b version instead of 2021b and it works quite fine.