experiment object

An object of type experiment provides some options and record properties for a whole experiment. An experiment can only have one experiment object. In the coding method, you can make an experiment object outside trials using function experimentObject, set properties using dot syntax, and input it to addToExperiment. In the visual method, you can add columns setting properties for an experiment object in the optional table for objects not specific to trial.

showOpening

Default, changeable in pb_prefs: show opening display and prompt to start

showOpening = <cd>true<cd>/<cd>false<cd>: show opening display and prompt to press Space to start. <cd>false<cd> = open the experiment with a black screen and start it immediately when ready.

backColor

Default, changeable in pb_prefs: black

A 1×3 RGB vector with numbers between 0–1 setting background color for the experiment.​ You can override this for a given trial using trial object property backColor or for a given pretrial interval using preTrialBackColor. You can also override this for any part of a trial using a backColor element.

showFrameworkMessages

Default, changeable in pb_prefs: current Psychtoolbox settings (Psychtoolbox default: 3 = standard messages)

A number setting the types of messages Psychtoolbox shows in the MATLAB command window. Note this doesn’t affect all Psychtoolbox messages, but many of them.

<cd>0 <cd> – minimal
<cd>1 <cd> – add error messages
<cd>2 <cd> – add warnings
<cd>3 <cd> – add standard messages
<cd>4 <cd> – add extra messages

This goes to Psychtoolbox Screen('Preference', 'Verbosity') and similar commands.

<cd>[]<cd> (default) = current Psychtoolbox settings. Psychtoolbox defaults in turn are generally 3 (standard messages). If you leave showFrameworkMessages at default, you can also use the corresponding Psychtoolbox commands directly before the experiment.

priority

Default, changeable in pb_prefs: current Psychtoolbox setting (Psychtoolbox default: 0 = lowest priority, highest compatibility)

An integer ≥ 0 setting MATLAB CPU usage priority. Higher priorities may improve timing precision in experiments where that’s important, but high priorities may cause compatibility problems. This goes to Psychtoolbox Priority. See help text there for more information.

<cd>[]<cd> (default) = current Psychtoolbox setting. Psychtoolbox default in turn is 0 (lowest priority, highest compatibility). If you leave priority at default, you can also use the Psychtoolbox command directly before the experiment.

preload

Default, changeable in pb_prefs: load all element content into memory at experiment startup

By default PsychBench loads all element content (images, sound, etc.) for the experiment into memory (RAM) at experiment startup. Alternatively if you set preload = <cd>false<cd> then it loads each element's content into memory only before the trial the element runs in, and releases it after the trial. This prevents PsychBench from using too much memory at once, which may be necessary on some systems/experiments. However, the tradeoff is PsychBench needs to do more work between trials, which can limit how short pre-trial intervals can be (see trial object property pretrialInterval).

You can also set preload at the trial level (affects elements in the trial only) and the element level. This simply overrides experiment preload for those trials or elements.

duration

Experiment duration from trial 1 start to last trial end (sec).