Experiments

Experiments

The experiment, or exp structure holds basic information about your experiment in a standard format. Once you have created an exp structure that points to your data, you can begin creating Events and Patterns.

A vector structure, subj, holds information about each subject that has run in the experiment so far. A sub-structure of each subj called sess contains information about each session. If the subject ran in an EEG experiment, there will also be a chan structure to keep track of information about each electrode. See below for an explanation of each field.

Field	Type	Description
experiment	string	name of the experiment
recordingType	string	type of recording, if applicable (e.g. EEG, fMRI, ECoG)
resDir	string	path to the directory where results of analyses will be saved
file	string	path to the MAT-file where this object is saved
lastUpdate	string	last time this object was saved
subj	struct	vector structure containing information about subjects (see below)

Display

Use exp_disp or subj_disp to display a summary of an experiment object.

Moving and copying

Note that the exp object contains a number of filenames. If you change from working on a remote machine to working on a local machine (or vice versa), the filenames will be incorrect. To remedy this, use struct_strrep. It will run strrep recursively on every string in the struct or any of its sub-structs, and so can be used to change filenames systematically.

Let's say you want to take an experiment structure created by someone else, and work with it in your own directory. copy_exp is useful to create a copy that you can work from. However, you must be careful not to save new files to their directory. Most functions have an optional res_dir input you can use to override the default output directory.

move_exp can be used to move an entire set of results; it will move not only the exp object, but also all the results. This will only work if all of your results are saved under exp.resDir (the default).

Backups

Each time an exp object is saved using update_exp, a time-stamped backup is created; you may also specify a log message to help recover a specific backup later. Use exp_log to see a list of backups, and load_exp to load a specific backup.

Subjects

Information about the subjects who have run in the experiment is stored in a vector structure called subj:

Field	Type	Description
id	string	identifier of the subject
dir	string	(optional) path to the directory where raw data is saved
sess	struct	(optional) vector structure with "number" and "dir" fields for each session
chan	struct	(optional) vector structure containing electrode information

Generally, subj structs can be made automatically using get_sessdirs, and electrode information can be imported using import_channels. The dir, sess, and chan fields are necessary only for importing raw data; if you're importing segmented data from another toolbox like EEGLAB, these fields aren't necessary.