Visual method

In the visual method lay trials out in one or more tables in any spreadsheet app. Columns correspond to properties of objects of various types (e.g. picture, text, sound, keyPress, etc.). Property values can be any MATLAB value or expression. You only need to write each distinct row (trial) once, and in any order. Then in an additional table use another MATLAB expression to set a list of trials to run through, including any repetition and ordering. Save or export to an Excel file, use the command loadExperiment in MATLAB to load it, and runExperiment to run it.

For example, the two tables below would make an experiment that runs two repetitions of three distinct trials, all in random order. In each trial, a picture of an animal shows at a height of 10 degrees visual angle. The picture stops showing when the subject presses any key. Experiment results report picture file name and response latency for each trial.

(This is an extremely minimal example—just enough to see the basic idea! Lots of options not shown here allow efficiently building complex experiments.)

Coding method

You can always use the coding method instead if you prefer. In the coding method make objects, set properties, and define trials line by line in a MATLAB script. You can use for loops through conditions to automate defining trials. For example, this script would build and run the same experiment as above:

Without PsychBench

Just for comparison, here is some compact Psychtoolbox code that would run the same experiment, with the same timing precision and error handling. The difference with/without PsychBench is already noticeable here but it balloons up for more realistic experiments.

If the library doesn't have the stimuli you need for an experiment, you can write your own code in MATLAB + Psychtoolbox. The approach is to write it as a new object type—this allows you to use the code anywhere in any experiment and have it work with all core functionality (timing, core visual options, staircasing, results output, etc.). You can make a quick type for a limited number of experiments, or you can make a durable type with more flexibility and a fuller interface for other users. All the standard types that come with PsychBench are open source, so you can use them as examples and/or build off them.

Sharing object types

You can share an object type with other people just by zipping the type's folder and emailing it.

You can also contribute a type to the library that comes with PsychBench. If you would like to do this, please contact us. We would be happy to credit you. And thank-you!