Experimental control in COGENT/MATLAB

Christian Ruff

COGENT and MATLAB

• Cogent is a MATLAB-toolbox (set of functions and .dlls) that can be used for control

of behavioural and neuroimaging experiments

• Cogent functions can:

– Control timing

– Display pictures

– Display words

– Play sounds

– Collect responses

– Control serial and parallel ports

• Cogent runs in MATLAB (so that COGENT scripts can be set up as MATLAB

functions, and can access all other MATLAB functions)

• However, COGENT functions only run in a special ‘mode’ that has to be set up

How to obtain and run COGENT

• Cogent is programmed at UCL (FIL and LON ), and is freely available at

http://www.vislab.ucl.ac.uk/Cogent/

• All you have to do is:

– download the zip-files

– unpack the directory on your computer

– put this directory on the MATLAB path (so that MATLAB finds the functions)

• Cogent at present runs with all versions of MATLAB up to 7.1, but will be updated

within the next month or so to also run with more recent versions

• COGENT has its own excellent documentation (cogmanv125.pdf and

G2UsrManv124.pdf for graphics functions) in the folder ‘Documents’

• There are also many example scripts (in the folder ‘samples’)

Structure of COGENT

• There are two sets of COGENT-functions:

– COGENT 2000: High-level functions for experimental control (covered here)

– Low-level graphics functions (starting with cg*; covered in future sessions)

• Every COGENT script should have a certain structure:

(1) (Define experimental parameters)

(2) Initialise cogent

(3) Start cogent

(4) Execute cogent commands

(5) Terminate cogent

• Errors can occur if (4) is attempted before (2) and (3)