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# Response time

Hi!

Sorry if I've missed this somewhere, but how is average_response_time calculated? I have a task with multiple trials in which participant listen to a stimulus and see images before choosing a matching image.

Are the average response times calculated as the ms from the onset of the trial? If I wanted to work out the onset of the audio how could I do that? In other words, I want to know how long after the audio they responded. I'd also like to know how long in total each trial was. This way I can compare trials with differing lengths of audio. Is this possible? I extracted all variables but couldn't see a timestamp for start of trial or audio, or end of trial.

Sophie

• Hi Sophie,

> Sorry if I've missed this somewhere, but how is average_response_time calculated?

The average response time is simply the average of all response times (since resetting the feedback variables). So I'm guessing that what you're really asking is how response times are calculated (?). This depends on the item, but in most cases the response time would be the difference between the moment that the item is executed and the moment that the participant responds. The start of the item serves as a t0, in other words.

> Are the average response times calculated as the ms from the onset of the trial?

So, no, not unless the response item is the first item of the trial (which it usually isn't).

> In other words, I want to know how long after the audio they responded

This depends on how you've structured your trial sequence. In the simplest case, the audio will be played by a non-blocking sampler (i.e. with a 0 ms duration) followed by a keyboard_response. In this simple case, the response time is relative to the onset of the audio. But in more complex cases it may not be.

> I'd also like to know how long in total each trial was. This way I can compare trials with differing lengths of audio. Is this possible? I extracted all variables but couldn't see a timestamp for start of trial or audio, or end of trial.

Most items maintain a time_[item name] variable that corresponds to when the item was executed. So if you have, say, a sketchpad at the start and at the end of the trial, then you can take the difference between those two timestamps as the trial duration.

Hope this clears things up!

Cheers!

Sebastiaan