Free Recall

Free-Recall is a psychological paradigm where the participant is shown a list of words and is then asked to recall the displayed words in any order immediately after being shown or after a period of delay.

The kind of Free-Recall Experiment that we wrote is the Immediate Free-Recall task. Our participant will view 10, 15, or 20 words and then be asked to recall as many words as possible from the list in 20, 30, or 40 seconds respectively. This experiment will show you how to use the Subroutine called FreeKey, as well as things like Label and Loop.

Below we will show you the best practices for coding an experiment like this one.

The Experiment

The best thing to do when coding a SMILE experiment is to break up the experiment into 3 different files: the experiment file with all the SMILE code, the config file with all the experimental variables, and the stimulus generation file.

The first thing we will look at is free_recall.py. In this file we need to import smile as well as execute the config.py and the gen_stim.py.

#freekey.py
from smile.common import *
from smile.freekey import FreeKey

#execute both the configuration file and the
#stimulus generation file
from config import *
from gen_stim import *

Inside config.py we setup any variables that will need to be used during the experiment as well as open any files that we might need for list generation or instructions for the participant.

#Names of the stimulus files
filenameL = "pools/living.txt"
filenameN = "pools/nonliving.txt"

#Open the files and combine them
L = open(filenameL)
N = open(filenameN)
stimList = L.read().split('\n')
stimList.append(N.read().split('\n'))

#Open the instructions file
instruct_text = open('freekey_instructions.rst', 'r').read()

#Define the Experimental Variables
ISI = 2
IBI = 2
STIMDUR = 2
PFI = 4
FONTSIZE = 40
RSTFONTSIZE = 30
RSTWIDTH = 900

MINFKDUR = 20

NUMBLOCKS = 6
NUMPERBLOCK = [10,15,20]

Next we can take a look into our list gen. Simply, we generate a list of dictionaries where study points to a list of words and duration points to the duration that the participants have to freely recall the words.

import random

#Shuffle the stimulus
random.shuffle(stimList)

blocks = []
#Loop NUMBLOCKS times
for i in range(NUMBLOCKS):
    tempList = []
    #For each block, loop either 10, 15, or 20 times
    #Counter balanced to have equal numbers of each
    for x in range(NUMPERBLOCK[i%len(NUMPERBLOCK)]):
        tempList.append(stimList.pop())
    #Create tempBlock
    tempBlock = {"study":tempList,
                 "duration":(MINFKDUR + 10*i%len(NUMPERBLOCK))}
    blocks.append(tempBlock)
#Shuffle the newly created list of blocks
random.shuffle(blocks)

Finally we can get to the fun stuff! We now can start programming our SMILE experiment. The comments in the following section of code explain why we do each part of the experiment.

#Initialize the Experiment
exp = Experiment()

#Show the instructions to the participant
RstDocument(text=instruct_text, base_font_size=RSTFONTSIZE, width=RSTWIDTH, height=exp.screen.height)
with UntilDone():
    #When a KeyPress is detected, the UntilDone
    #will cancel the RstDocument state
    KeyPress()
#Start the experiment Loop
with Loop(blocks) as block:
    Wait(IBI)
    with Loop(block.current['study']) as study:
        #Present the Fixation Cross
        Label(text="+", duration=ISI, font_size=FONTSIZE)
        #Present the study item
        Label(text=study.current, duration=STIMDUR, font_size=FONTSIZE)
    Wait(PFI)
    #Start FreeKey
    fk = FreeKey(Label(text="XXXXXXX", font_size=FONTSIZE), max_duration=block.current['duration'])
    #Log everything!
    Log(block,
        name="FreeKey",
        responses = fk.responses)
#Run the experiment
exp.run()

Analysis

When coding your experiment, you don’t have to worry about losing any data because all of it is saved out into .slog files anyway. The thing you do have to worry about is whether or not you want that data to be easily available or if you want to spend hours slogging through your data. We made it easy for you to pick which data you want saved out during the running of your experiment with use of the Log state.

Relevant data from the Free-Recall task would be the responses from each FreeKey state. In the Log that we used in the experiment above, we log everything in each block of the experiment, i.e. the stimulus and the duration that they are allowed to respond in, and the responses from FreeKey.

If you would like to grab your data from the .slog files to analyze your data in python, you need to use the log2dl(). This function will read in all of the .slog files with the same base name, and convert them into one long list of dictionaries. Below is a the few lines of code you would use to get at all of the data from three imaginary participants, named as s000, s001, and s002.

from smile.log as lg
#define subject pool
subjects = ["s000/","s001/","s002/"]
dic_list = []
for sbj in subjects:
    #get at all the different subjects
    dic_list.append(lg.log2dl(log_filename="data/" + sbj + "Log_FreeKey"))
#print out all of the study times in the first study block for
#participant one, block one
print dic_list[0]['study_times']

You can also translate all of the .slog files into .csv files easily by running the command log2csv() for each participant. An example of this is located below.

from smile.log as lg
#define subject pool
subjects = ["s000/","s001/","s002/"]
for sbj in subjects:
    #Get at all the subjects data, naming the csv appropriately.
    lg.log2csv(log_filename="data/" + sbj + "Log_FreeKey", csv_filename=sbj + "_FreeKey")

free_recall.py in Full

#freekey.py
from smile.common import *
from smile.freekey import FreeKey

#execute both the configuration file and the
#stimulus generation file
from config import *
from gen_stim import *

#Initialize the Experiment
exp = Experiment()

#Show the instructions to the participant
RstDocument(text=instruct_text, base_font_size=RSTFONTSIZE, width=RSTWIDTH, height=exp.screen.height)
with UntilDone():
    #When a KeyPress is detected, the UntilDone
    #will cancel the RstDocument state
    KeyPress()
#Start the experiment Loop
with Loop(blocks) as block:
    Wait(IBI)
    with Loop(block.current['study']) as study:
        #Present the Fixation Cross
        Label(text="+", duration=ISI, font_size=FONTSIZE)
        #Present the study item
        Label(text=study.current, duration=STIMDUR, font_size=FONTSIZE)
    Wait(PFI)
    #Start FreeKey
    fk = FreeKey(Label(text="XXXXXXX", font_size=FONTSIZE), max_duration=block.current['duration'])
    #Log everything!
    Log(block,
        name="FreeKey",
        responses = fk.responses)
#Run the experiment
exp.run()

config.py in Full

#Names of the stimulus files
filenameL = "pools/living.txt"
filenameN = "pools/nonliving.txt"

#Open the files and combine them
L = open(filenameL)
N = open(filenameN)
stimList = L.read().split('\n')
stimList.append(N.read().split('\n'))

#Open the instructions file
instruct_text = open('freekey_instructions.rst', 'r').read()

#Define the Experimental Variables
ISI = 2
IBI = 2
STIMDUR = 2
PFI = 4
FONTSIZE = 40
RSTFONTSIZE = 30
RSTWIDTH = 900

MINFKDUR = 20

NUMBLOCKS = 6
NUMPERBLOCK = [10,15,20]

gen_stim.py in Full

import random

#Shuffle the stimulus
random.shuffle(stimList)

blocks = []
#Loop NUMBLOCKS times
for i in range(NUMBLOCKS):
    tempList = []
    #For each block, loop either 10, 15, or 20 times
    #Counter balanced to have equal numbers of each
    for x in range(NUMPERBLOCK[i%len(NUMPERBLOCK)]):
        tempList.append(stimList.pop())
    #Create tempBlock
    tempBlock = {"study":tempList,
                 "duration":(MINFKDUR + 10*i%len(NUMPERBLOCK))}
    blocks.append(tempBlock)
#Shuffle the newly created list of blocks
random.shuffle(blocks)

CITATION

Murdock, Bennet B. (1962), "The serial position effect of free recall", Journal of Experimental Psychology 64 (5): 482–488

Waugh, Nancy C. (1961), "Free versus serial recall", Journal of Experimental Psychology 62 (5): 496–502