In self-paced reading tasks, participants need to press a key to read a sentences word for word. There are different ways this can be implemented (Jegersky, 2013).

In this self-paced reading task, participants see an additional word each time they press a key (in this experiment, we use the N key). At the same time, the already read words are masked. This is a popular method in psycholinguistics

You can add sentences to the table.

See also the Same without masking.

About this implementation

This implementation uses various techniques. The sentences are as whole sentences in the table. The task breaks them apart into words, which then are added one to one to a textvariable (i.e., variables starting with a %).

In this implementation, a textbox is being used. Textboxes are good for rendering longer texts in PsyToolkit experiments. They make sure the text is wrapped appropriately.

The main difference with the other self-paced reading task are only two lines. The textbox now uses courier font (which is a monospace font in which each letter takes the same space). And there is one line that uses the mask instruction to change the letters of the sentence shown so far with, in this case, circles.
This experiment also uses the fillup array funtion. This makes sure that in the end, you have a data file with one row for each trial, and each trial is of the same size. Unused reaction time spots are filled up with -1 numbers. This can be handy when reading in your raw data files into statistical software. Make sure you fill up with at least as many values as the sentence with the maximum number of words.

Run the demo

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


number of words


the sentence used


the total reaction time (ms) for all words together


the reaction times for each word separately


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

  • Jegersky, J. (2013). Research Methods in Second Language Psycholinguistics. In Research Methods in Second Language Psycholinguistics by Jegerski, J. & VanPatten, B. Routledge: New York. ISBN: 9780203123430. Link to book overview.