Collecting keyboard respons during target presentation + shortly after target presentation

MarjoleinT

I have designed a task for OSWeb in which letters repeatedly appear at the left and right side of the screen, and when a target letter appears among the distractor letters, participants have to press 'space'. With a distractor letter, 'None' is the correct response. Presentation times are 300ms letter presentation and 450ms interletter, with a block including 30 trials with a distractor letter and 2 with a target letter.

I made it this way that there is a loop in which:

1. inter-letter sketchpad is presented (445ms),
2. letter sketchpad is presented (0ms) with either the target or non-target letter at either the left or right side of the screen (dependent on the how the variables are set for that specific trial),
3. keyboard response (295ms)
4. logger

I would like to collect the number of correct responses. However, as the letter presentation times are quite short for people to be able to press 'space', I would like to be able to also collect responses after the 295ms have passed, so when participants for example press space during the first 100ms of the next interstimulus sketchpad. I am struggling on how to implement this, and am not sure whether this is possible. Any suggestions would be really helpful!

eduard

Hi Marjolein,

Have you looked into Co-routines? They might provide the functionality that you need.

However, given that the response collection period extends over two trials (end of trial n, and start of trial n+1), it might be a bit tricky. In theory, you could use the same approach you have used for the letter sketchpad for all sketchpads, i.e. the inter-letter sketchpad. So basically, having a sketchpad open all the time. The tricky part is then to tease apart to which stimuli each of the responses belong. I don't think there is clear solution to that, instead it probably depends on your personal thoughts on which assumptions to make.

Regardless, every keyboard item has a variable: "response_keyboard_response" and i think also "response_time_keyboard_response". These variable you can use to paste together the total response times in your paradigm. For example, if the variable "response_letter_keyboard_response" on trial 1 has no value, but "response_interletter_keyboard_response" has one, you could add the second response time to the first to get the total response time.

Finally, a last thing to keep in mind. If the response is split over two trials, that will probably conflict with the prepare-run strategy of Opensesame. The experiment will still run, but the measured timings will be somewhat inaccurate.

Hope this helps somewhat.

Good luck,

Eduard