Ian Deary is a famous professor in psychology, in particular known for his work in differential psychology and general intelligence. Together with members of his Edingburgh (Scotland) research group, he published an article about a four-choice response task.

Given that we know that response times correlate with general intelligence, it is useful to have an agreed standard procedure, and the Deary-Liewald task provides this (in a similar way as the Jensen task, Jensen, 2006).

The PsyToolkit implementation can be run in the browser or as native Linux program if you compile the code (below) on a Linux system.

The original software made by Deary’s research team (for the Microsoft Windows operating system) as well as their standard operating procedure can be downloaded from this external link.

About this implementation

  • The task follows the paper by Deary and colleagues (2011) as closely as possible.

If you have a German or French style keyboard, it makes sense to use different keys! Look at the lesson about simple and choice reaction time tasks, where this task has been modified to use the x,c,b, and n keys (which works on English/US/German/French-style keyboards). Click here to go to that lesson.

Run the demo

In this example, you will do a simple response time task and a choice response time task (for an explanation, read this in the PsyToolkit lessons).

Data output file

In PsyToolkit, the data output file is simply a textfile. The save line of the PsyToolkit experiment script determines what is being saved in the data output file. Typically, for each experimental trial, you would have exactly one line in your text file, and each number/word on that line gives you the information you need for your data analysis, such as the condition, response speed, and whether an error was made.

Meaning of the columns in the output datafile. You need this information for your data analysis.

Colum Meaning




training (1=training, 0=real data collection)


number of choices (1 in simple block, 4 in choice block)


time between response and next trial (between 1 and 3 seconds)


the x-coordinate of the target stimulus


the response time (ms)


status (1=correct, 2=error, 3=too slow)


If you have a PsyToolkit account, you can upload the zipfile directly to your PsyToolkit account. Watch a video on how to do that. If you want to upload the zipfile into your PsyToolkit account, make sure the file is not automatically uncompressed (some browsers, especially Mac Safari, by default uncompress zip files). Read here how to easily deal with this.

Further reading

  • Deary, Liewald & Nissan (2011). Behaviour Research Methods, 43, 258-268.

  • Jensen, A. R. (2006). Clocking the mind: mental chronometry and individual differences. Amsterdam, The Netherlands: Elsevier.