Millisecond Forums

Hi all,
I've been browsing the forum but I still haven't found a solution for several little problems I am experiencing. I hope somebody will be able to help me out.

First, I'd like to direct participants to either a block or another one as a function of their choice. They start by doing task 1 then task 2 and then, I'd like them to decide between 1 and 2 to further do it again as a function of their choice. So far I've tried to implement:

<trial choice>
/ stimulusframes = [1=choice]
/ validresponse = ("1", "2")
/ responsetrial = ("k", task1)
/ responsetrial = ("d", task2)
</trial>

<slider choice>
/ caption = "Please indicate the task you would like for Stage 3
"
/ labels = (
    "task1", "task2")
/ range = (1, 2)
/ slidersize = (60%, 5%)
/ showtooltips = false
</slider>

But this simply doesnt work. Also, I don't really know what to indicate in the design of the task. So far, it was

<block task>
/ trials = [1-2=instructions; 3-5=task1; 6=instructions; 7-9=task2; 10=choice
</block>

But then I don't know what to write as the 11th step is depending on the choice. Is there a way to specify that it'll be either Task 1 or Task 2 here ?

The second question I have is regarding the number of trials. In the example provided I can modify the number of trials by putting 3-5=task1 or 3-555=task1. I'd like to know if there is a way to restrict the length of a block to a fixed amount of time instead of using a specified number of trials. For example, I'd like them to fill as many items as they can in 2mn and then to switch to task 2. Is there a way to do that ?

The final question I had was to know how to display a performance feedback on both tasks. Ideally, this would just present the sum of good answers (or an average percent) after each answer on task 1 and then the same on task 2 but this may be too complicated.

Thanks for your help,
Regards,
Vincent.