okra

Task specifications

Cloze test

One segment of text is shown at a time, with a blank which has to be filled in by one of the options provided.

Digit span

A random sequence of digits is presented one digit at a time, and the participant is asked to type the sequence from memory. If the sequence was typed correctly, the next sequence will be one digit longer. The task ends after some number of errors has been made.

Lexical decision

One word is shown at a time. The task is to determine whether it is a real word or a non-word. Similar to the original experiment described by Meyer and Schvaneveldt (1971), but showing single words instead of word pairs (though the task implementation allows newlines in words to display pairs).

n-back

A single textual stimulus (usually a letter) is shown for 500 milliseconds with 2500 milliseconds between stimuli (these durations can be configured to different values). The participant taps the screen whenever they see the same stimulus as n stimuli back (a “positive” stimulus). Immediate positive or negative feedback is shown after each tap. The sequence of stimuli is randomly generated before each task.

Picture naming

A textual stimulus is shown above a number of pictures. One of the pictures (or optionally a question mark, meaning “don’t know”) has to be selected.

Reaction time

A single picture of a red balloon is shown at a time, which disappears with a popping animation as soon as it is being touched. A new one then appears in a (uniformly distributed) random location after a configurable amount of time.

Reading

A text is presented (optionally with a preceding introductory text for context), followed by a series of ratings, followed by a number of single-answer multiple-choice questions to be answered. The questions are shown on the same screen as the text. The text is scrollable, and scrolling events are logged such that the visible range of text at each point in time can be reconstructed.

NOTE: On smaller screen sizes, the entire text box (including the font size) is scaled down in order to preserve the number of characters per line across devices.

Simon game

Four buttons are shown. They light up in a specific sequence, which has to be repeated by pressing the buttons in the same order. After each successful repetition, a random item is added to the sequence, and the sequence is shown again. Inspired by the electronic game Simon.

Trail making

Circular buttons with numbers or letters are presented, which have to be connected in the correct order by tapping on them. In a variation of the task, the buttons have different colors and have to be connected in a trail of alternating colors (e.g. black 1white 2black 3 → …), avoiding distractors (cf. Kim et al., 2014).