Here is your first WPA! Today we are going to run a s ample script from a risky choice Experiment. To get the script and the stimuli list go here and download the file ‘LotteryRTE2V1.iqx’ as well as the contents of folder ‘week1’.
The first thing we’ll do is try participating in the Experiment yourself, so you can see how it works. Once you have downloaded the file, open it in Inquisit. To run it, just press the Green Arrow at the top. You’ll be prompted to enter a participant number before the experiment begins.
If you need to exist the experiment press ctrl + e
The number of trials is defined at the block level. Lets change the number of test trials from 10 to 5. Find the element <block testlt> and change it as follows:
Example Code
<block testlt>
/trials = [1-10=noreplace(testlt)]
/bgstim = (leftresp, rightresp)
/preinstructions = (lotterytest)
</block>
We now have more stimuli than we do trials. What do you think will happen when we run the code again?
Currently there are separate practise stimuli and test stimuli. Let’s make some of the stimuli the same. The practise stimuli are defined by the <item rpraclt> element. Let’s change the images used for these items to match the first 4 stimuli in the test items.
Example Code
<item rpraclt>
/1 = "lt1.png"
/2 = "lt2.png"
/3 = "lt3.png"
/4 = "lt4.png"
</item>
Currently participants use the a and l keys to respond to indicate their preferences. We can change these by changing the /validresponse attribute of the <trial> element.
For example, we could change them to s and k for the test trials by altering <trial testlt> as follows:
Example Code
<trial testlt>
/stimulustimes = [0=Ready; 600=testlt]
/iscorrectresponse = [trial.testlt.latency>300 &&trial.testlt.latency<20000 && (trial.testlt.response == 30 || trial.testlt.response == 38)]
/validresponse = ("s", "k")
/errormessage = true(speed, 2000)
/pretrialpause = values.tpause
/posttrialpause = values.ppause
</trial>
Unfortunately, this will only change the responses for the test trials. Do the same for the practise trials. Also see if you can work out how to make the instructions displayed at the bottom of the page during a trial match the new response keys.
There are a lot of Instructions on that first page. Let’s try to change them. Instructions are defined in two ways in this script. The first Instruction page is called as a text element called startpage. If you find this page in your script then you can change the instructions in " " to whatever you want.
Example Code <text startpage>
/items= ("That was a lot of instructions, this is better")
/ hjustify=left
/ valign=center
/ size =(90%,90%)
/ fontstyle=("Arial", 2.5%)
</text>
The other Instruction pages are defined as specific page elements. They have the tag <page XXXX.> See if you can find them and alter these other instructions.
Try playing around with other elements of the code. Or try out another experiment from the Millisecond test Library. You can also have a look at the data file.