![]() ![]() For running an experiment it’s usually best to use something like ‘cm’ or ‘deg’ so that the stimulus is a fixed size irrespective of the monitor/window. For conducting demos, the two normalised units (‘norm’ and ‘height’) are often handy because the stimulus scales naturally with the window size. Your choice of unit depends on the circumstances. In PsychoPy, after providing information about your monitor, via the Monitor Center, you can simply specify your stimulus in the unit of your choice and allow PsychoPy to calculate the appropriate pixel size for you. In most other systems you provide the stimuli at a fixed size and location in pixels, or percentage of the screen, and then have to calculate how many cm or degrees of visual angle that was. 2.2 Units for the window and stimuli One of the key advantages of PsychoPy over many other experiment-building software packages is that stimuli can be described in a wide variety of real-world, device-independent units. The two additional tables in the Calibration box of the Monitor Center provide conversion from DKL and LMS colour spaces to RGB. 3 PsychoPy - Psychology software for Python, Release 1.84.2 Note that, if you don’t have a photometer to hand then there is a method for determining the necessary gamma value psychophysically included in PsychoPy (see gammaMotionNull and gammaMotionAnalysis in the demos menu). To run a calibration, connect the PR650 via the serial port and, immediately after turning it on press the Find PR650 button in the Monitor Center. Alternatively this can be added manually into the grid to the right of the Monitor Center. If you have a Spectrascan PR650 (other devices will hopefully be added) you can perform an automated calibration in which PsychoPy will measure the necessary gamma value to be applied to your monitor. Your choice of units determines the information you need to provide: Units ‘norm’ (normalised to width/height) ‘pix’ (pixels) ‘cm’ (centimeters on the screen) ‘deg’ (degrees of visual angle) Requires n/a Screen width in pixels Screen width in pixels and screen width in cm Screen width (pixels), screen width (cm) and distance (cm) 2.1.2 Calibrating your monitor PsychoPy can also store and use information about the gamma correction required for your monitor. In order for this to be possible you need to inform PsychoPy of some characteristics of your monitor. 2.1.1 Real world units One of the particular features of PsychoPy is that you can specify the size and location of stimuli in units that are independent of your particular setup, such as degrees of visual angle (see Units for the window and stimuli). e.g.: from psychopy import visual win = visual.Window(, mon='SonyG500') Of course, the name of the monitor in the script needs to match perfectly the name given in the Monitor Center. For experiments created as scripts you can retrieve the information when creating the Window by simply naming the monitor that you created in Monitor Center. For experiments written in the Builder view, you can then import this information by simply specifying the name of the monitor that you wish to use in the Experiment settings dialog. Information is inserted in the Monitor Center (Tools menu), which allows you to store information about multiple monitors and keep track of multiple calibrations for the same monitor. ![]() 2.1 Monitor Center PsychoPy provides a simple and intuitive way for you to calibrate your monitor and provide other information about it and then import that information into your experiment. About PsychoPy CHAPTER TWO GENERAL ISSUES These are issues that users should be aware of, whether they are using Builder or Coder views. 1 PsychoPy - Psychology software for Python, Release 1.84.2 2 Chapter 1. Citing these papers gives the reviewer/reader of your study information about how the system works, it also attributes some credit for its original creation, and it means provides a way to justify the continued development of the package. Peirce JW (2009) Generating stimuli for neuroscience using PsychoPy. ![]() Peirce, JW (2007) PsychoPy - Psychophysics software in Python. ![]() for teaching) 259 13 For Developers 261 14 PsychoPy Experiment file format (.psyexp) 275 Python Module Index 279 Index 281 i ii CHAPTER ONE ABOUT PSYCHOPY 1.1 Citing PsychoPy If you use this software, please cite one of the papers that describe it. PsychoPy - Psychology software for Python Release 1.84.2 Jonathan Peirce CONTENTS 1 About PsychoPy 1 2 General issues 3 3 Installation 29 4 Manual install 31 5 Getting Started 35 6 Builder 41 7 Coder 69 8 Reference Manual (API) 83 9 Troubleshooting 241 10 Recipes (“How-to”s) 245 11 Frequently Asked Questions (FAQs) 257 12 Resources (e.g. ![]()
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