Category: Python/PsychoPy

Software for graphical models

Tweet Share Email Share Share FollowI’m currently writing a paper on a new Bayesian method for scoring Complex Span tasks. I needed some software to represent it using plate notation of a directed acyclic graph (DAG). Many people have pointed to the Tikz/pgf drawing library for latex, but I did not want to install latex for this simple task. Here I briefly review yEd, Daft, and Libreoffice Draw. yEd I ended up using yEd and produced this graph which contains plates, estimated nodes, deterministic nodes (double-lined), observed nodes (shaded), and categorical nodes (rectangles).yEd is purely graphical editing which is fast to work with and great …

Five divided by forty-nine

Tweet Share Email Share Share FollowAt a family dinner, my brother told me that he had stumbled upon a curious number. Divide five by forty-nine and take a look at the digits: $$5 / 49 = 0.10204081632653061…$$ Do you see a pattern in the digits? Yes! It’s powers of two: (0.)1, 02, 04, 08, 16, 32, 65, … Huh, 65? Yes! The next number, 128, is a three-digit number and so the first digit “overlaps” the last digit of 64, making it 65. And this continues for the first digits of 256 (28 + 2 = 30), 512, the first two digits …

Renaming Brain Vision Recorder EEG recordings

Tweet Share Email Share Share FollowRenaiming Brain Vision Recorder files is a pain. Here’s a python script that makes it (more of) a breeze. The problem Brain Vision Recorder is a widely used software for EEG-recordings. Every EEG-recording is saved as three files: One .eeg file, containing all the data One .vmrk/.amrk/.bmrk file, containing markers and a reference to the .eeg file One .vhdr/.ahdr/.bhdr file, containing header information and references to the marker file and data file. This is the file that represents the recording and opened by analysis software Because of these internal references between the files, it is …

Calculating d’, beta, c and Ad’ in Python and PHP

Tweet Share Email Share Share FollowAbout d’ A central component of Signal Detection Theory is d’ – a measure of the ability to discriminate a signal from noise. The d’ is flanked by the parameters “beta” and c, which are measures of the criterion that the observer uses to discriminate between the two. These measures can be calculated in every experiment where there is a signal (e.g. target trials) and noise (e.g. nontarget trials), and the observer (e.g. subject) is to indicate whether the signal was present or not. d’, beta and c are statistical measures in a model where …

The case for PsychoPy

Tweet Share Email Share Share FollowMost researchers in cognitive neuroscience have to program an experiment in a stimulus-delivery environment at some time in their career. Everyone have heard about Presentation and E-prime but much fewer have heard about PsychoPy – a free cross-platform stimulus delivery environment. Advantages over Presentation and E-Prime: Free and open source, meaning no license problems! Cross-platform. You can develop on Windows, Mac or Linux and run your experiment on Windows, Mac and Linux! Limitless functionality. Psychopy is a Python module, which means that it can be heavily extended with other Python modules for e.g. Matlab-level matrix operations (numpy), …