"ISI" IN BUILDER

[Elisa PC]

Hello there.

I´m new in psychopy, I need help for how to set up a interval inter trails, and interval inter stimuli in my experiment where I have three stimuli with different duration in each trial. How can I do it?? I would like to know how to use the static screen period, I have already checked the link of help (http://www.psychopy.org/builder/components/static.html) but I couldn´t understand it. Is there any other way to do that?

I would appreciate any help.

Eli 

[Michael MacAskill]

Dear Eli,

Just lay out your stimuli as required along the time line. Any point at which none of those stimuli is actually being displayed is by definition an inter-stimulus interval. You don't need to do anything explicit to create such a period: it is simply the absence of other stimuli.

If the start/stop times will vary from trial to trial (because they are set by variables), you can enter representative values in the "expected start" and "expected stop" fields so that you get an impression of when the stimuli will occur and the gaps in between them (this is just for cosmetic purposes within Builder).

You don't need to use the Static Screen Period here: it is for other technical purposes.

An inter trial interval can either be a non-stimulus period at the end of your routine, or you can insert a separate routine just for that purpose.

Regards,

Michael

--
Michael R. MacAskill, PhD 66 Stewart St
Research Director, Christchurch 8011
New Zealand Brain Research Institute NEW ZEALAND

Research Fellow, michael....@nzbri.org
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University of Otago, Christchurch http://www.nzbri.org/macaskill

[Elisa PC]

Hi Michael,
Thank you very much for answering. I think I have a doubt about how to put the begining of the stimuli for condition, not exactly for time, because I try to test time stimation in a task with three tones of different duration. For example 600- 1200-850 ms. And I would know how I can set the stimuli one after another, but in every trial the tones change randomly. Could you help me??

Thanks.
Eli

[Michael MacAskill]

Hi Eli,

Could you give a very precise description of the sequence of what you want to occur on each trial?

i.e. include descriptions of the stimuli, the conditions, and also when and how subjects need to give responses, as well as when inter-stimulus and inter-trial intervals occur.

Regards,

Michael

[Elisa PC]

In each trial I will display three tones differents, after that the subjects have to answer which was the tone by asking them, they have to play the duration of the stimuli by keep pressing a key. I would like to define a inter- stimulus and inter-trals interval with a specific time, and set the tone for start condition one ater one.

I leave an Excel with the example of the stimulus list with the tones and the question (in the question case, the nomenclature is: Preg.nb1= asking 3rd tone: Preg.nb2= asking for 2nd; Preg.nb3=asking for 1st one)

Regards!!

Eli