Python Tutorial: Level 3 Exercises

Table of Contents

Experiment structure exercises
Import exercises
Directory exercises

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Experiment structure exercises

We want to find out how long it takes people to see faces in common objects. We will present 10 images, one image per trial, in a randomized order. Each image will appear for 1 second in the center of the screen, at a size of 200x200 pixels. Each trial will start with a 1-second fixation cross, and end with a "wait for next image" text. There will be 2 blocks of trials, with 10 trials each.

On the lines denoted with an asterix *, write in the correct python code:

#=====================
#IMPORT MODULES
#=====================
#-import numpy and/or numpy functions *
#-import psychopy functions
#-import file save functions
#-(import other functions as necessary: os...)

#=====================
#PATH SETTINGS
#=====================
#-define the main directory where you will keep all of your experiment files
#-define the directory where you will save your data
#-if you will be presenting images, define the image directory
#-check that these directories exist

#=====================
#COLLECT PARTICIPANT INFO
#=====================
#-create a dialogue box that will collect current participant number, age, gender, handedness
#get date and time
#-create a unique filename for the data

#=====================
#STIMULUS AND TRIAL SETTINGS
#=====================
#-number of trials and blocks *
#-stimulus names (and stimulus extensions, if images) *
#-stimulus properties like size, orientation, location, duration *
#-start message text *

#=====================
#PREPARE CONDITION LISTS
#=====================
#-check if files to be used during the experiment (e.g., images) exist
#-create counterbalanced list of all conditions *

#=====================
#PREPARE DATA COLLECTION LISTS
#=====================
#-create an empty list for correct responses (e.g., "on this trial, a response of X is correct") *
#-create an empty list for participant responses (e.g., "on this trial, response was a X") *
#-create an empty list for response accuracy collection (e.g., "was participant correct?") *
#-create an empty list for response time collection *
#-create an empty list for recording the order of stimulus identities *
#-create an empty list for recording the order of stimulus properties *

#=====================
#CREATION OF WINDOW AND STIMULI
#=====================
#-define the monitor settings using psychopy functions
#-define the window (size, color, units, fullscreen mode) using psychopy functions
#-define experiment start text unsing psychopy functions
#-define block (start)/end text using psychopy functions
#-define stimuli using psychopy functions
#-create response time clock
#-make mouse pointer invisible

#=====================
#START EXPERIMENT
#=====================
#-present start message text
#-allow participant to begin experiment with button press

#=====================
#BLOCK SEQUENCE
#=====================
#-for loop for nBlocks *
    #-present block start message
    #-randomize order of trials here *
    #-reset response time clock here
    
    #=====================
    #TRIAL SEQUENCE
    #=====================    
    #-for loop for nTrials *
        #-set stimuli and stimulus properties for the current trial
        #-empty keypresses
        
        #=====================
        #START TRIAL
        #=====================   
        #-draw stimulus
        #-flip window
        #-wait time (stimulus duration)
        #-draw stimulus
        #-...
        
        #-collect subject response for that trial
        #-collect subject response time for that trial
        #-collect accuracy for that trial
        
#======================
# END OF EXPERIMENT
#======================        
#-write data to a file
#-close window
#-quit experiment

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Import exercises

1. Fill in the "Import Modules" section of the experiment structure:

#=====================
#IMPORT MODULES
#=====================
#-import numpy and/or numpy functions
#-import psychopy functions
#-import file save functions
#-(import other functions as necessary: os...)

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Directory exercises

1. Automate the creation of the list of images ("pics"). Do not write them all out manually.
2. Automate the task of finding out whether each image (as listed in "pics") exists in the "images" directory. Use a for loop and if statements to print "cat1.jpg was found!", "cat2.jpg was found!"... etc. Raise an exception if an image does not exist.
3. Fill in the following sections of the experiment structure:

#=====================
#PATH SETTINGS
#=====================
#-define the main directory where you will keep all of your experiment files
#-define the directory where you will save your data
#-if you will be presenting images, define the image directory
#-check that these directories exist

#=====================
#PREPARE CONDITION LISTS
#=====================
#-check if files to be used during the experiment (e.g., images) exist

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