Posner Taks

SuperLab SuperLab 4 Support
1

hello, I am currently programming a Posner task that involves a words appearing in one of two boxes followed by dots in either box. I have this bit working and have the words and dots appearing at random in either the left or right box.

But

I need the dots to appear in the same box that the word appeared on 2/3 of the trials and on one third of them i need the dots to appear in the opposite box to where the word appeared…is there any way to do this?

Thanks Im really stuck with this part.

2

This can probably be done by using trial variables of type Location (which I’m guessing that you already are using) and adjusting the number of levels in it. For example, suppose that your two boxes happen to be at positions

INDENT
(0,200)

for the left and right boxes respectively. Normally, you would have just two levels in your trial variable. To have the dots appear 2/3 of the trials in one and 1/3 in the other, you can duplicate one of the levels so that you have

INDENT
(0,-200)
(0,200)

This will cause trials to appear on the left 2/3 of the time.

I hope that I answered the right question!

3

Thanks this is helpful,

although I need a word to appear in the box follwed by dots a moment later on 2/3 of the trials and then on one thirs i need the word to appear in one box and the dots to appear in the opposite…so teh position of the dots are contingeint on teh poition of teh words is there any way of doing this so this? Im confued!

Thanks again

4

Alas, it doesn’t seem possible to do this right now.

There is a way where you can setup up three trials that will present the list items, with two of these trials presenting on one side, and 1 trial presenting on the other side (this approach would not use trial variables). In other words, you will be presenting in total three times the number of trials that you originally intended, randomized. Then, you can would use a macro to exit the block after one third of the trials have been presented.

Due to randomization being done at the trial level (vs. the position itself being randomized), the disadvantage of this method is that you will not be able to guarantee that each participant has seen stimuli on one side exactly 2/3 of the time.