Monkey-patching for more flexible randomisation in OpenSesame

alisdt

Hi,

I'm posting this for two contradictory purposes:

1. In case anyone finds it useful in the future
2. In case there is a better way to do this, so I don't do it again!

There is a table (Loop object) where the first 32 rows are experimental trials, and the next 96 are filler. We want to initially run 3 filler trials, then an experimental trial, then 2, 3 or 4 fillers before each remaining experimental trial. So if F represents filler and X experimental trial, the sequence will look something like this:

FFFXFFXFFXFFFFXFFFXFFFFX ....

My idea was to replace the run() method in the relevant Loop item, and use this to randomise the trials as we require. This method is an adapted version of the run() in the original code (module libopensesame.loop). My code to perform the replacement was:

https://gist.github.com/anonymous/66b01a1b3deb0db6dfcc
(I will also copy this code into a reply comment on this post, for posterity)

This was placed in the Prepare phase of an inline code item.

I'd be interested to know what other OpenSesame users (and the developers!) think of this.

Regards,

Alisdair

alisdt

# Replace run() for loop object with our own methods
import random
import openexp
import types

# Modified copy of original run() method
def new_MyLoop_run(self):
    self.set_item_onset()

    # generate cycle numbers (custom)
    # come up with an order of IDs from the table
    # First 32 are experiment, rest are filler
    # 2*11, 3*10, 4*10 plus 1*3 at start = 32 filler sequences
    n_filler_seq = [2]*11 + [3]*10 + [4]*10
    random.shuffle(n_filler_seq)
    n_filler_seq = [3] + n_filler_seq
    test_ids = range(0,32)
    filler_ids = range(32,128)
    l = []
    for n_filler in n_filler_seq:
        for _ in range(n_filler):
            l.append(filler_ids.pop(random.randrange(len(filler_ids))))
        l.append(test_ids.pop(random.randrange(len(test_ids))))

    # Create a keyboard to flush responses between cycles
    self._keyboard = openexp.keyboard.keyboard(self.experiment)

    # Make sure the item to run exists
    if self.item not in self.experiment.items:
        raise osexception( \
            u"Could not find item '%s', which is called by loop item '%s'" \
            % (self.item, self.name))

    # And run!
    _item = self.experiment.items[self.item]
    while len(l) > 0:
        cycle = l.pop(0)
        self.apply_cycle(cycle)
        self.experiment.set(u'repeat_cycle', 0)
        _item.prepare()
        _item.run()

test_obj = exp.items["MyLoop"]
test_obj.run = types.MethodType(new_MyLoop_run, test_obj)

sebastiaan

Thanks for sharing!