[solved] how to use one interval screen with several durations

pshahim

Hello everyone,

We're trying to program a reaction time task for our thesis. Our task is very simple, a dot is being showed and the participant has to press the spacebar as quick as possible. However we're facing a problem. We want the interval between the dots being showed randomly to range from 2.2 seconds to 3 seconds and each dot is being presented untill a keypress response. We're not sure how to do this. Can we make one intervalscreen which can be presented with different durations ranging from 2.2 seconds to 3 seconds or do we have to make several intervalscreens?

Edwin

Hi,

Two options:

Fixed delay amounts

Add a new variable to your loop, e.g. called "delay". Refer to this variable for the duration of your sketchpad, using square brackets: [delay].

Random delay

There is a plug-in built into OpenSesame to do precisely this. It's called the advanced_delay. Your experiment could look as follows:

# start of your experiment
- loop (for the trial blocks)
    - sequence (for a single trial)
        - blank sketchpad (duration of 0)
        - advanced delay (see below for details)
        - sketchpad showing a dot (duration of 0)
        - keyboard_response

Now for the advanced delay: it requires two values: the average delay, and the jitter. Furthermore, you have to indicate the type of jitter. In you case, you want values to occur equally between 2.2 and 3 seconds, so set the jitter mode to uniform. The average duration should be 2600 ms, and the jitter should be 400 ms. This gives you values between 2600-400 ms (= 2.2 seconds) and 2600+400 ms (= 3 seconds).

Good luck!

pshahim

Hi Edwin,

We used your first option. Thank you very much.