Randomise trial timings

jacklee-w — Mon, 31 Jul 2017 10:54:03 GMT

Hi all,

Just a little thing - I have a reading task on the go with intermittent probes and want to randomise the time it takes for them to appear.

The part of the script concerned is:

<trial readingtrialHAT>
/ ontrialend = [if (trial.readingtrialHAT.response==205 && values.pagenumber < values.npages) values.pagenumber +=1;
if (trial.readingtrialHAT.response==203 && values.pagenumber > 1) values.pagenumber -= 1;]
/ ontrialend = [values.timeuntilprobe -= trial.readingtrialHAT.latency]
/ stimulusframes = [1=pagetext]
/ validresponse = (203, 205, 57)
/ timeout = values.timeuntilprobe
/ branch = [if (trial.readingtrialHAT.response == 0) trial.HATtrial else trial.readingtrialHAT]
</trial>

<trial HATtrial>
/ ontrialend = [values.probenumber += 1;
values.timeuntilprobe = values.probeinterval]
/ stimulusframes = [1=clearscreen, probepromptHAT; 2=picture.hat]
/ correctresponse = ("y", "n")
/ validresponse = ("y", "n")
/ branch = [trial.readingtrialHAT]
</trial>

<values>
/ npages = 20
/ pagenumber = 1
/ probeinterval = 10000
/ timeuntilprobe = values.probeinterval
/ nprobes = 8
/ probenumber = 0
/ completed = 0
</values>

I thought changing '10000' in /probeinterval to replace(30000,40000,50000,60000) would do the trick- which is the effect I want- but it seems to just select the last value and use it consistently.

Any ideas as to what I'm missing?

Thanks!

RE: Randomise trial timings

Dave — Mon, 31 Jul 2017 10:54:03 GMT

[quote]

[b]jacklee-w - Monday, July 31, 2017[/b]

[/quote]

The proper way to do this is to sample the intervals from a <list>:

<values>
/ npages = 20
/ pagenumber = 1
/ timeuntilprobe = 0
/ nprobes = 8
/ probenumber = 0
</values>

<list probeintervals>
/ items = (30000,40000,50000,60000)
/ replace = true
</list>

<block myblock>
/ onblockbegin = [
    values.timeuntilprobe = list.probeintervals.nextvalue
]
/ stop = [values.probenumber == values.nprobes]
/ trials = [1=readingtrial]
</block>

<trial readingtrial>
/ ontrialend = [if (trial.readingtrial.response==205 && values.pagenumber < values.npages) values.pagenumber +=1;
    if (trial.readingtrial.response==203 && values.pagenumber > 1) values.pagenumber -= 1;]
/ ontrialend = [values.timeuntilprobe -= trial.readingtrial.latency]
/ stimulusframes = [1=pagetext]
/ validresponse = (203, 205)
/ timeout = values.timeuntilprobe
/ branch = [if (trial.readingtrial.response == 0) openended.probetrial else trial.readingtrial]
</trial>

<openended probetrial>
/ ontrialend = [values.probenumber += 1;
    values.timeuntilprobe = list.probeintervals.nextvalue]
/ stimulusframes = [1=clearscreen, probeprompt]
/ branch = [trial.readingtrial]
</openended>

<text pagetext>
/ items = pageitems
/ erase = false
/ size = (90%, 90%)
/ select = values.pagenumber
</text>

<item pageitems>
/ 1 = "Page 01 Text..."
/ 2 = "Page 02 Text..."
/ 3 = "Page 03 Text..."
/ 4 = "Page 04 Text..."
/ 5 = "Page 05 Text..."
/ 6 = "Page 06 Text..."
/ 7 = "Page 07 Text..."
/ 8 = "Page 08 Text..."
/ 9 = "Page 09 Text..."
/ 10 = "Page 10 Text..."
/ 11 = "Page 11 Text..."
/ 12 = "Page 12 Text..."
/ 13 = "Page 13 Text..."
/ 14 = "Page 14 Text..."
/ 15 = "Page 15 Text..."
/ 16 = "Page 16 Text..."
/ 17 = "Page 17 Text..."
/ 18 = "Page 18 Text..."
/ 19 = "Page 19 Text..."
/ 20 = "Page 20 Text..."
</item>

<text probeprompt>
/ items = ("What are you thinking about right now?")
/ position = (50%, 10%)
</text>

Millisecond Forums » Millisecond Forums » Inquisit 5 » Randomise trial timings

Randomise trial timings

RE: Randomise trial timings