Can't append str to lst after upgrading to OpenSesame v4

stoney

Hi mods,

Hopefully only a silly/quick question but I'm stumped - in some code that worked in v3, I split up sentences and iteratively append the words to an empty list called var.stimuli so that they are presented to participants one at a time (RSVP for EEG experiment; code snippet below). After upgrading OpenSesame to v4, I now get the error AttributeError: 'str' object has no attribute 'append'. I have confirmed that var.stimlui is a list and the word to append is a string, and it works to do this manually in the console, but for some reason returns the error when I run the inline script. Are lists and strings somehow handled differently in the new OpenSesame? The only clue is that when I print the word from the loop (w below), the output is e.g. the instead of 'the' (i.e. no quotes around it). Is that odd, even if it type() returns str?

Many thanks, Kate

# list to store words
var.stimuli = []

# function to split up sentences into words
def stim_prep(stims, trigger = "n"):
    stims = stims.split()
    for i, w in enumerate(stims):
        if(trigger == "y"):
            send = i + (var.cond + 1) * 10
        else:
            send = 0
        print(w)
        print(type(w))
        print(stimuli)
        print(type(stimuli))
        var.stimuli.append(w) # <--- error occurs here
        print(stimuli)
        word_canvas = canvas()
        word_canvas.text(w)
        word_canvas_list.append(word_canvas)
        var.pres_dur.append(pres_dur(w))
        var.trigger.append(send)
    return;

stoney

Update: It's something to do with using var.stimuli versus stimuli in the stim_prep function. If I use stimuli , it works fine, but then obviously it's not logged in the log file, which I would like. But it doesn't seem to recognise the pre-defined var.stimuli .

I've attached the whole experiment in case it's helpful. stim_prep is in the "settings" inline script and var.stimuli is defined in the RSVP/prepare inline script (I tried moving everything to the RSVP/prepare script and the same problem happened).

draft_rsvp_paradigm.zip

eduard

Hi Kate,

I think this has to do with this change in OS4: https://osdoc.cogsci.nl/4.0/notes/400/#important-backwards-incompatible-changes

So, a list is not stored as a list anymore. To still include it in the logger, you can explicitly add it to the logger.

Alternatively, it might work for you to not store the stimuli in a list but in a string, where each item is separated by the same character, so that during the analysis you can easily re-generate the list.

For example:

# during the experiment
a_list = ['these', 'are', 'my', 'stimuli']
a_string = '-'.join(a_list)
# during the analysis
a_string = read_from_logfile()
a_list = a_string.split('-')

Hope this helps,

Eduard

stoney

Hi Eduard,

Thanks very much for this, it makes a lot of sense and will work!

Best,

Kate