+xG'day,
I'm programming an experiment that is like a lottery task, with two different lotteries, a red one and a blue one. You simply click on a lottery to play. The chances of 'winning' on each lottery need to change across the task, as well as the probability of getting a big versus small win.
I thought about changing the probability of winning on each of the lotteries and the probabilities of getting a big versus small win by making a list for each lottery where a value is drawn, and based on that value trigger a win or loss, and through another list, trigger a big win or small win. Then I can set the itemprobabilities for those list items through values, and change those values at the start of each block.
While the task runs however, the itemprobabilities are not changing. When I debug, I can see that the values that I plug into the itemprobabilities have changed in block2, but the data shows the probability of a win or loss being triggered actually hasn't changed.
I've attached a simplified version of the script that has the same issue. Even though at the start of block2 I try to set the probability of a red win at .1 , and the probability of a blue win at .9, the data (monkey file also attached) shows that the chances of winning for red are .75, and for blue .25, which are the probabilities set at the start of the experiment. Similarly, the probabilities of a big versus small win are not being updated.
Any idea where I might be going wrong?
If you change the values responsible for the probabilities like this
<block Block2>
/ onblockbegin = [list.Acceptance_Red.resetselection(); list.Acceptance_Blue.resetselection()]
/ onblockbegin = [values.acceptchance_red = .1; values.rejectchance_red = .9; values.acceptchance_blue = .9; values.rejectchance_blue = .1]/ onblockbegin = [values.winbig_red = 0.2; values.winsmall_red = 0.8]
/ onblockbegin = [values.winbig_blue = 0.9; values.winsmall_blue = 0.1]/ trials = [1= StartTrial]
/ timeout = 60000
</block>
the lists won't pick that up unless you reset them after, i.e.
<block Block2>
/ onblockbegin = [list.Acceptance_Red.resetselection(); list.Acceptance_Blue.resetselection()]
/ onblockbegin = [values.acceptchance_red = .1; values.rejectchance_red = .9; values.acceptchance_blue = .9; values.rejectchance_blue = .1]
/ onblockbegin = [values.winbig_red = 0.2; values.winsmall_red = 0.8]
/ onblockbegin = [values.winbig_blue = 0.9; values.winsmall_blue = 0.1]
/ ontrialbegin = [
list.Acceptance_Blue.reset();
list.Acceptance_Red.reset();
list.Winnings_Blue.reset();
list.Winnings_Red.reset();
]/ trials = [1= StartTrial]
/ timeout = 60000
</block>
<expt>
/ blocks = [1 = sequence(Block1, Block2)]
</expt>
If you do that, you should see a marked change in the probabilities between the two blocks. Example data file attached, the trial counts in that are:
Block 1:
AcceptedBlue = 30
AcceptedRed = 80
NotAcceptedBlue = 89
NotAcceptedRed = 28
Winnings_Blue = 30
Winnings_Red = 80
Red Acceptance = 80/(80+28) = 0.74
Blue Acceptance = 30/(30+89) = 0.25
Block 2:
AcceptedBlue = 103
AcceptedRed = 15
NotAcceptedBlue = 8
NotAcceptedRed = 97
Winnings_Blue = 103
Winnings_Red = 15
Red Acceptance = 15/(15+97) = 0.13
Blue Acceptance= 103/(103+8) = 0.93