Event Definitions

Task events are saved as events.tsv and events.json files (see the BIDS Events specification).

In addition to the event definitions provided in the BIDS specification, M-BIDS requires event labels to be stored in an event_type column. The exact allowed event labels depend on the experiment type or benchmark challenge. For Calibench fear-conditioning datasets, these labels and the accompanying event columns are part of the importer contract and must be written exactly as documented.

Expected file location

Fear-conditioning event files should be stored together with the corresponding task recording files. The target folder depends on the available physiological modalities.

Table 1: Event file location by modality
Available data	Target folder	Reason
Eye-tracking only	`beh/`	Eye-tracking-only datasets can store task events and eye recordings in the behavioral folder.
SCR only	`physio/`	Skin conductance recordings are physiological recordings and should be stored in the physiology folder.
Eye-tracking and SCR	`physio/`	When physiological recordings are present together, the task recordings and corresponding events are stored in the physiology folder.

For Calibench BEP020/BEP045 datasets, physiology and eye-tracking recordings are stored together in physio/. The structure for one subject and task should look like this:

sub-<participant_label>/
└── physio/
    ├── sub-<participant_label>_task-acquisition_events.json
    ├── sub-<participant_label>_task-acquisition_events.tsv
    ├── sub-<participant_label>_task-acquisition_recording-scr_physio.json
    ├── sub-<participant_label>_task-acquisition_recording-scr_physio.tsv.gz
    ├── sub-<participant_label>_task-acquisition_recording-ecg_physio.json
    ├── sub-<participant_label>_task-acquisition_recording-ecg_physio.tsv.gz
    ├── sub-<participant_label>_task-acquisition_recording-resp_physio.json
    ├── sub-<participant_label>_task-acquisition_recording-resp_physio.tsv.gz
    ├── sub-<participant_label>_task-acquisition_recording-eye2_physio.json
    ├── sub-<participant_label>_task-acquisition_recording-eye2_physio.tsv.gz
    ├── sub-<participant_label>_task-acquisition_recording-eye2_physioevents.json
    └── sub-<participant_label>_task-acquisition_recording-eye2_physioevents.tsv.gz

The same pattern is used for task-extinction. A subject may contain only the modalities that were actually recorded, but every included recording must have a matching JSON sidecar.

For an SCR-only fear-conditioning dataset, the structure may look like this:

sub-<sub_id>/
└── physio/
    ├── sub-<sub_id>_task-acquisition_events.json
    ├── sub-<sub_id>_task-acquisition_events.tsv
    ├── sub-<sub_id>_task-acquisition_recording-scr_physio.json
    └── sub-<sub_id>_task-acquisition_recording-scr_physio.tsv.gz

If both eye-tracking and physiological recordings are present, the files should be placed under physio/. This placement follows the modality handling described by BEP020 and BEP045 and is supported by the BIDS importer.

Required M-BIDS columns

BIDS task events already define onset and duration columns. In addition to these BIDS columns, Calibench fear-conditioning events.tsv files MUST contain the following M-BIDS columns:

Table 2: Required additional `events.tsv` columns
Column	Description	Data Type	Example
`event_type`	Type of event, expressed as a character string. The allowed values depend on the experiment type.	String	`CSpr`, `CSpu`, `CSm`, `USp`
`task_name`	Experimental phase represented by the row.	String	`habituation`, `acquisition`, `extinction`

Optional columns

Additional columns may be included when available or required by a specific dataset, experiment, or benchmark challenge. They must not replace or rename the BIDS columns or required M-BIDS columns listed above.

Table 3: Optional event columns
Column	Description	Data Type	Example
`stimulus_name`	Name or identifier of the presented stimulus.	String	`square`, `diamond`, `shock`
`HED`	Hierarchical Event Descriptor tags describing the event.	String	`Sensory-event,Visual-presentation`
`response`	Participant response, when responses are part of the task.	String	`left`, `right`, `n/a`
`response_time`	Time between stimulus onset and participant response.	Number	`1.23`

Specific event types

The following generic event types may be used to describe common experimental events.

Table 4: Generic event types
Event Type	Description
`block_start`	Start of an experimental block.
`block_end`	End of an experimental block.
`response`	Generic participant response to stimuli.

Specific guidelines are different for different experiment types and are listed below:

Events:

Event definitions for Fear Conditioning experiments