A clinical test of visual crowding — CriticalSpacing.m is our MATLAB program that uses any font to measure acuity and critical spacing. It allows testing with single or repeated targets. With single targets, it can test at any eccentricity, using brief presentation. It works under Mac OS X, Windows, and Linux. You can download it from GitHub: https://github.com/denispelli/CriticalSpacing/. We hope this will encourage more investigators to measure the critical spacing of crowding. Publications of research using CriticalSpacing.m should cite:
uncrowded-span model of reading rate — Pelli
et al. (2007) describe a model of reading rate. Levi et al. (2007)
apply it to reading by amblyopes. Here we provide a MATLAB program
that fits the model to human data (e.g. Chung et al., 1998) and plots
a figure. The program is pure MATLAB, compatible
with MATLAB 7 on any computer. (Tested only under Mac OS X.) [Download]
Chung, S. T. L., Mansfield, J. S.,
Legge, G. E. (1998). Psychophysics of reading. XVIII. The effect of
print size on reading speed in normal peripheral vision.Vision
Research, 38, 2949–2962.
Pelli, D. G., Tillman, K. A., Freeman, J., Su, M., Berger, T. D., & Majaj, N. J. (2007) Crowding and eccentricity determine reading rate.Journal of Vision, 7(2):20, 1-36, doi: 10.1167/7.2.20 http://journalofvision.org/7/2/20/
Toolbox — A free software package for vision research. Its routines
provide an efficient interface between a high-level interpreted language
(Matlab) and the display hardware on Macintosh and Windows computers. It
also provides interfaces for timing, sound, and keyboard. The number
of Psychtoolbox installations (with unique internet addresses) was 4,598
in December 2007. (See the overview for
the current count.) Of these, 1634 are running under Mac OSX, 2958 under
Windows and 6 under Linux. (We estimate that a further several hundred
computers are still running the Mac OS 9 version of the Psychtoolbox.)
The Psychtoolbox forum averages
more than 3 messages a day. We know of 126 grant-supported
projects that use it. And 404 papers cite it.
(With David Brainard, Allen Ingling, and Mario Kleiner.)
Quest — A
free software package for threshold estimation. It will run on any computer
with MATLAB 5 or better. It is distributed both on its own and as part
of the Psychophysics Toolbox (above). It's easy to use, has a sound theoretical
footing, and is robust. We use it for all our work and recommend it without
reservation. It's quite popular. It is included in the (free) Psychtoolbox, which can be downloaded from http://psychtoolbox.org. Quest can be used alone, without the rest of the Psychtoolbox. Publications of research using Quest
A. B., & Pelli, D. G. (1983) QUEST: a Bayesian adaptive psychometric
method. Percept Psychophys, 33 (2), 113-20.
VideoToolbox — A
free collection of two hundred C subroutines for Macintosh computers
to calibrate and control the computer-display interface, making it possible
to create accurately specified visual stimuli. This became the foundation
for the Psychophysics Toolbox.
Pelli, D. G. (1997) The VideoToolbox software for
visual psychophysics: transforming numbers into movies. Spatial
Vision, 10, 437-42.
Pelli, D. G., & Zhang, L. (1991)
Accurate control of contrast on microcomputer displays. Vision
Research 31, 1337-1350.
Brainard, D. H., Pelli, D. G., & Robson, T. (2002) Display characterization. In: J. Hornak (Ed.) Encyclopedia of Imaging Science and Technology (pp. 172-188): Wiley. [Online test patterns]
Pelli, D. G. (1997) Pixel independence: measuring
spatial interactions on a CRT display. Spatial Vision, 10,
Pelli, D. G., & Zhang, L. (1991) Accurate control of contrast on microcomputer displays. Vision Research 31, 1337-1350.
Sloan font — Based on Louise Sloan’s
design, which has been designated the US standard for acuity testing
by the National Academy of Sciences, National Research Council, Committee
on Vision (1980, Adv Ophthalmol, 41, 103-148. [PubMed]).
Note that the standard specifies only CDHKNORSVZ, whereas the font file
goes beyond that to provide a complete uppercase alphabet A-Z in a consistent
style. The C is a Landolt C. The C and O are particularly hard to discriminate
from each other, so some studies may wish to omit the C (see Elliott,
Whitaker, & Bonette,
1990. Ophthalmic Physiol Opt, 10(4), 323-326. [PubMed]).
This font was developed for the Pelli-Robson Contrast Sensitivity Chart. The Sloan font is available for noncommercial research use from GitHub: https://github.com/denispelli/Eye-Chart-Fonts/. Commercial use of this font would require a license from Denis
Pelli. Publications of research using this font
Pelli, D. G., Robson,
J. G., & Wilkins, A. J. (1988) The design of a new letter chart
for measuring contrast sensitivity. Clinical Vision Sciences
font — The characters 0,1,2,3,4,5,6,7,8,9 in the "Pelli" font, which is designed to be readable at extremely narrow width. For normal adults, we measure a width threshold of 0.02 deg. The Pelli font is available for noncommercial research use from GitHub: https://github.com/denispelli/Eye-Chart-Fonts/. Publications of research using this font
font — 26 Chinese characters a-z based on high-resolution scans
of Yung Chih-sheng’s beautiful calligraphy in a beginning Chinese
primer (DeFrancis, J., 1976, Character Text for Beginning Chinese, Second
Ed. New Haven, CT: Yale University Press.). To download, choose a format: Yung
for Macintosh OS X (zip archive)
or Windows (zip archive). This is
a PostScript Type 1 font, which you install like any other font. Adobe
instructions. Publications of research using this font should cite:
Pelli, D. G., Burns, C. W., Farell, B., & Moore-Page,
D. C. (2006) Detecting features and identifying letters. Vision
Research, 46(28), 4646-4674. [PubMed]
Toolbox is a set of MATLAB functions providing communication
with a particular USB data acquisition device (daq): the PMD-1208FS made
by Measurement Computing. This daq costs $150 and offers "50
kHz" input and output 12-bit sampling of analog voltages (8
in, 2 out) and 16 digital i/o lines, with signals brought out to
screw terminals. ("50 kHz" is a theoretical upper limit:
as of 18 April 2005 we attain 2 kHz.) The PMD-1208FS is the size
of a wallet and is powered through its USB cable. We have complete
control of it from within MATLAB, via the PsychHID extension. The
Daq Toolbox is free and can be downloaded from the Daq
Toolbox web page. It is self-contained, and may be used with
or without the rest of the Psychtoolbox. The only requirements are
MATLAB, Mac OS X 10.3 or better, and a USB port to connect the PMD-1208FS.
AutoBrightness.applescript and AutoBrightness.m (click to download) allow you to turn off a pesky feature of Apple's liquid crystal displays. In Mac OS X, this feature is manually enabled/disabled by the "Automatically adjust brightness" checkbox in the System Preferences: Displays panel. While the feature is enabled, your Mac slowly adjusts the screen luminance of your Apple liquid crystal display, to track the luminance of the room. That's nice for informal use, but bad for screen calibration and perhaps also bad for your experiments. My AutoBrightness routines allow your programs to read the on/off setting of that feature, and enable or disable it. The Applescript will work from any application (e.g. MATLAB, Mathematica) that can send it to the Mac OS. The MATLAB routine is trivial, merely calling the Applescript, and can easily be translated to any suitable language. For use in MATLAB, just put both files anywhere in MATLAB's path. They are now included in the Psychtoolbox. May 29, 2015: A new "screenNumber" argument has been added, so any programs that called the older version will need to be edited to include that new argument. June 1, 2015: Cope with spaces in file path. July, 2015: Enhanced to support Yosemite (Mac OS X 10.10).
ScreenProfile.applescript and ScreenProfile.m (included in AutoBrightness.zip, click to download) get and set the name of the color profile used on one Macintosh screen. June 1, 2015: Cope with spaces in file path. June 3, 2015: Convert returned values to expected type. July, 2015: Enhanced to support Yosemite (Mac OS X 10.10).
ScriptingOk.applescript and ScriptingOk.m (included in AutoBrightness.zip, click to download) check whether your application has permission to control the computer through applescripts. ScriptingOkShowPermission also opens the relevant System Preferences Permission panel.