Optional experiment settings

Below are descriptions of experimental settings that can be changed to suit a particular study or paradigm. Within a protocol, these lines can be added anytime after the starting definitions and before the first STEP.

Key assignments

Transitions between STEPs, trials, and phases can be controlled by participant looking time, recorded by an experimenter via live coding. To live-code an experiment or have looking-controlled timing, the keys you will use for coding need to be assigned to the looking direction so that they can be matched to stimuli being presented on that side.

If you do not explicitly assign keys for coding, BITTSy will use the following default keys:


Key assignments can be changed with the following command:

ASSIGN <side> KEY <key>

where <side> is any side named in the SIDES starting definition, or AWAY, and <key> is any alphanumeric key or arrow key. (Arrow keys are denoted by the codes UP, DOWN, LEFT, and RIGHT.)

Below are several examples.


Keys on the number pad have different encoding than their equivalents on the standard keyboard; at this time, number pad keys cannot be assigned to sides through key assignment definitions and cannot be used for live coding.

If you name sides in the opening SIDES definitions with keywords other than CENTER, LEFT, and RIGHT, and wish to use live coding, be sure to include key assignment definitions: BITTSy will not be able to pair default keys with sides that have different names.

Minimum look lengths

COMPLETELOOK and COMPLETELOOKAWAY define the minimum length that a look should be in order to be counted in live coding - that is, the threshold below which any look is considered to be a mistake (as in an accidental double-press of a key, or pressing a wrong key and immediately correcting). Looks below this threshold will have their time folded into the length of a look (in a valid direction) that follows them.

DEFINE COMPLETELOOK <time in milliseconds>
DEFINE COMPLETELOOKAWAY <time in milliseconds>

For example,


By default, these times are each 100 milliseconds. The COMPLETELOOK and COMPLETELOOKAWAY settings allow you to change these thresholds up or down, depending on what is appropriate for your study.

These values must be nonzero, but can be set effectively low enough that they will not ever discount any looks (there is a limit on how quickly two keys on the keyboard can be pressed!) However, note that the COMPLETELOOKAWAY value also determines how often time spent looking away is written to the detailed log file during a run. If you are setting this value very low, test your protocol to ensure that the frequent logging is not resulting in any undue load on your computer.

Background color

For any protocol using external displays, at the start of the run, BITTSy will cover them with a solid color background to show whenever they are not actively displaying an image or video. The background color can also show around the edges of images/videos if they do not take up the whole screen, and prevents the desktop from showing if there are any brief gaps between stimuli being displayed.

By default, the background color is black. It can be changed to white by adding the following line to your protocol, anywhere before the beginning of the first STEP.


Habituation-specific settings

Habituation can require many additional experimental settings. Within the protocol, these are defined, like the settings above, anywhere between the starting definitions and the first STEP statement. See the habituation section for more details on these experimental settings.

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