Eye-Tracking with Python and Pylink

ISBN-13: 9783030826345 / Angielski / Twarda / 2021 / 265 str.

Zhiguo Wang

Spis treści

Preface 5

Chapter 1 A gentle introduction to Python 7

Install Python 7

Python modules 8

Python shell 9

Script editors 11

Data types 12

Numbers 12

Strings 12

List 14

Tuple 15

Sets 16

Dictionary 16

Booleans 17

Operators 17

Data type conversion 18

Control flow 19

if statement 19

for statement 20

while statement 21

More on looping 22

List comprehension 22

Functions 23

Output 25

Output formatting 25

Files 26

Modules 28

Choose a library to create your “video games” 29

Where to go from here 29

Chapter 2 Building experiments with PsychoPy 31

Install PsychoPy 31

PsychoPy Coder 32

1

Open a window 34

Screen units 34

Monitor 36

Window types 37

Gamma 37

Vertical blanking 38

Call on flip 39

Screen capture 39

Visual stimuli 40

Shapes 40

GratingStim 42

TextStim 43

Font and font files 44

Right-to-left text 44

Wrap width 45

Non-ASCII characters 45

Aperture 45

Mouse and keyboard 47

Mouse 47

Keyboard 48

Register keyboard events with the event module 49

Register keyboard events with the ioHub module 49

Register keyboard events with PsychHID 50

Trial control 51

A real example: Simon effect 54

Chapter 3 Building experiments with Pygame 59

Install Pygame 60

Display 61

Events 63

Draw 65

Text 66

Image and sound 68

A real example: Posner cueing task 69

Chapter 4 Getting to know Pylink 76

A brief introduction to eye-tracking 76

Install Pylink 78

An overview of an eye-tracking experiment 78

Connect to the tracker 80

Open a camera setup / calibration screen 81

2

Configure the tracker 81

Open an EDF file 82

Calibration 82

Data recording 82

Retrieve the EDF data file 83

Disconnect from the tracker 83

A real example: Free viewing 83

Calibration graphics 86

Idle mode 86

EyeLink Host commands 86

Preamble text in EDF 87

Record status message 87

Drift-check/drift-correction 87

Logging messages 88

Chapter 5 Preparing scripts for analysis and visualization in Data Viewer 90

Trial segmentation 91

Trial variables 93

Interest Areas 95

Background graphics 97

Size of the screen 97

Image 97

Video 98

Simple drawing 99

Draw list file 101

Target position 102

Examples in PsychoPy 102

The Stroop task 102

Custom graphics for calibration 106

The DISPLAY_COORDS message 107

The TRIALID and TRIAL_RESULT messages 107

Record status message 107

Background graphics: the IMGLOAD message 107

Trial variables messages 107

Messages marking critical trial events 108

Video playback 108

Pursuit task 113

Chapter 6 Retrieving gaze data over the link 119

Samples and events 119

Retrieving sample data 121

3

Commands for sample retrieval 121

Example in PsychoPy: Gaze-contingent window 124

Retrieving eye events 127

Commands for event retrieval 127

Example in PsychoPy: Fixation trigger 133

Recording playback 136

Chapter 7 Advanced Pylink Functions 141

Drawing to the Host PC 141

Option 1: Using the draw commands 141

Option 2: Sending images to the Host 142

Option 3: The bitmapBackdrop command 143

Send TTL via the Host PC 145

Broadcasting 148

Calibration and custom CoreGraphics 151

Chapter 8 Data analysis and visualization in Python 163

EyeLink EDF data file 163

Samples 163

Events 164

Other useful information in the EDF data file 165

EDF2ASC Converter 166

Extract data from the ASC files 169

Parse the ASC file with the string function split() 169

Parse ASC files with regular expressions 174

Data visualization 176

Gaze trace plots 177

Heat maps 180

Scan path 183

Interest area-based visualization 183

Chapter 9 Miscellaneous 185

Predefined constants in Pylink 185

Frequently used EyeLink Host commands 185

References 187

O autorze

Dr. Zhiguo Wang is a research professor at Zhejiang University. He received his Ph.D. from the Graduate University of Chinese Academy of Sciences and had his post-doctoral training at Vrije Universiteit (the Netherlands) and Macquarie University (Australia). He was a senior scientist at SR Research Ltd. (Canada) before joining the Center for Psychological Sciences at Zhejiang University.

Dr. Zhiguo Wang was a recipient of the prestigious Australian Research Council Discovery Early Career Researcher Award. His current research work focuses on issues in engineering psychology, but he is also interested in research topics in vision, eye movements, visual working memory, spatial attention, and developmental disorders

Blurb

Several Python programming books feature tools designed for experimental psychologists. What sets this book apart is its focus on eye-tracking.

Eye-tracking is a widely used research technique in psychology and neuroscience labs. Research grade eye-trackers are typically faster, more accurate, and of course, more expensive than the ones seen in consumer goods or usability labs. Not surprisingly, a successful eye-tracking study usually requires sophisticated computer programming. Easy syntax and flexibility make Python a perfect choice for this task, especially for psychology researchers with little or no computer programming experience.

This book offers detailed coverage of the Pylink library, a Python interface for the gold standard EyeLink ® eye-trackers, with many step-by-step example scripts. This book is a useful reference for eye-tracking researchers, but you can also use it as a textbook for graduate-level programming courses.