|
|
Post by ottuba on Dec 1, 2020 17:08:50 GMT
I was wondering how the number of trials in the training and testing blocks were set for the following two experiments in the library:
- Visual search task -> no training block but 50 trials in the testing block. Is there a reason for the specific number 50? What is the reason for there being no training block here? How much can you change those numbers without messing up the validity? - Go/No-go task -> training block where you have to get 20 trials right in a row (!), testing block with 40 trials. Can you decrease the number of training trials without worry, e.g. to 10, so participants don't potentially get frustrated and quit? How was the number 40 chosen here for the testing block?
Feel free to also just point me to literature/studies -- I have done an initial search and found some general conclusions on online cognitive tests, but they weren't of that much help in regards to this.
Thanks in advance!
|
|
|
|
Post by matia on Dec 2, 2020 9:13:26 GMT
Dear ottuba, www.psytoolkit.org/experiment-library/search.zip is the link for downloading the experiment (there is a code in it also). When looking at the code, you define the number of trials when defining a block. You are free to have anywhere between 1 and many more trials per block. Should you want to include a training block, ofcourse, you must define trials and then state that training block (that consists of a no. of trials you deem enough) precedes the test block. I cannot answer why there are 40 trials or 50 trials or any number of trials. I suppose it depends on many factors, but mainly on the effect size in question, no. of participants available, no. of stimuli used and so on. Hope this helps, best,Matia Matia |
|
|
|
Post by ottuba on Dec 2, 2020 15:36:15 GMT
Dear ottuba, www.psytoolkit.org/experiment-library/search.zip is the link for downloading the experiment (there is a code in it also). When looking at the code, you define the number of trials when defining a block. You are free to have anywhere between 1 and many more trials per block. Should you want to include a training block, ofcourse, you must define trials and then state that training block (that consists of a no. of trials you deem enough) precedes the test block. I cannot answer why there are 40 trials or 50 trials or any number of trials. I suppose it depends on many factors, but mainly on the effect size in question, no. of participants available, no. of stimuli used and so on. Hope this helps, best,Matia Matia Hi Matia,
thanks for your answer! I'm aware of the possibility to change the numbers (and have also set up everything already), I was mostly wondering about the theoretical framework behind them because I'm about to start data collection and have been considering to make a few small adaptations.
I will try to do some more literature search myself and will also send the admin a direct email. Thanks again.
Best, Adani
|
|
|
|
Post by matia on Dec 3, 2020 8:59:48 GMT
Dear Adani,
sorry, once I've sent a response I saw that you didn't ask to change the number of trials but how to know in advance how many do you need. I am also having trouble deciding on the number of trials since the literature on the number of observations for within subjects design is not as straight forward as is the literature on between subjects design (see Jacob Cohen - Statistical Power Analysis for the Behavioral Sciences).
Maybe this can be a good starting point with links to other materials instructing you how to to determine the no. of stimuli (https://stats.stackexchange.com/questions/59235/repeated-measures-within-factors-settings-for-gpower-power-calculation)
Best, Matia
|
|
|
|
Post by ottuba on Dec 4, 2020 15:32:59 GMT
Dear Adani, sorry, once I've sent a response I saw that you didn't ask to change the number of trials but how to know in advance how many do you need. I am also having trouble deciding on the number of trials since the literature on the number of observations for within subjects design is not as straight forward as is the literature on between subjects design (see Jacob Cohen - Statistical Power Analysis for the Behavioral Sciences). Maybe this can be a good starting point with links to other materials instructing you how to to determine the no. of stimuli (https://stats.stackexchange.com/questions/59235/repeated-measures-within-factors-settings-for-gpower-power-calculation) Best, Matia No worries! Thanks for the tip and link, that's very helpful, I'll have a look at that 
Have a good weekend, Adani
|
|
