how to vary presentation times based on responses?


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Robert Balas
Robert Balas
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Hi,


I have this issue. I need to vary presentation time within a trial based on the accuracy of participant's responses. The thing is that I need to find a perceptual threshold for each individual participant. So within this trial:


<trial thresh_setup>


/ stimulustimes = [1 = fixation; 1001 = mask1; 1302 = noreplace(CS_neg, non_words); 1903 = mask2; 2204 = rect, Q_word, P_nonword]


/ validresponse = ("q", "p")


/ correctresponse = ("q")


</trial>


I am starting with 600 ms presentation of 'CS_neg' or 'non_words'. If a participant correctly answers, I need to reduce the presentation time by 50ms. And this reduction by 50ms should follow until participants cannot give a correct answer at the specific presentation duration, which would approximate their individual perceptual thresholds.



Can you give me any hints how to do that?



All the best,


Robert


Dave
Dave
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You need to use the <trial> element's setstimulustime(), insertstimulustime() and resetstimulusframes() functions to do this.


Robert Balas
Robert Balas
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Thanks, Dave! Helpful as always


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