Slow delay between blocks in an emotional go/nogo task

tomchatwin

HI. I have created an emotional go/nogo task. It includes eight blocks each consisting of 30 trials. In each trial a picture is presented and the participant either produces or inhibits a response. After lots of work, I think the experiment is pretty much ready. However, there appears to be a long delay in between blocks and also between the general instructions and the first block. I am worried that this delay might cause the participant to keep pressing SPACEBAR meaning he/she misses the individual block instructions.

Any ideas what might be the problem?

Josh

Hi,

It sounds as if something at the start of your block requires processing power, causing the delay. At this point I can't tell if this is unavoidable for you, or if certain parts of your experiment could've been programmed more efficiently. What you could do in any case, is to present a screen at the end of each block, saying something along the lines of "Loading new block, don't press any button...". Alternatively, you could make sure that the instruction screens appear outside of your blocks, so that you know for sure that these will be presented without delay.

Cheers,

Josh

tomchatwin

Thanks Josh. Each block consists of 30 images of facial expressions of emotion. Could be file sizes of the pictures that are causing the delay? In any case, I will do as you suggested.

Daniel

Hi Tom,
Can you tell us which backend you are using for your experiment? Expyriment sometimes has this when it has to load a lot of resources like pictures for the experiment. Could you try psychopy as well and tell us if you notice a difference? You can change the backend by clicking on "Experiment" in the overview and then select it on the settings pane that appears.

tomchatwin

Thanks dschreij. I think I am running Expyriment. I will check when I'm home, try what you suggested and revert to the forum with the results. Your advice is very greatly appreciated. Best wishes, Tom

tomchatwin

Hi. I checked my experiment and notice that I was running Exypriment. I changed the backend to Psychopy but it didn't appear to make a difference. There is still a long delay between the introduction and the start of the first block (about 10 seconds) and also between blocks.

I also tried to fix the problem by changing the backend to Legacy. This has drastically improved the delay (from about 10 seconds to 1 or 2 seconds delay). It is not perfect as the delay might still cause a participant to press SPACEBAR more than once (thus skipping the first block instructions) but it is an improvement.

Furthermore, as I understand, Legacy sacrifices some accuracy in recording response times. I will investigate the effects of this sacrifice.