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use HED in example
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sappelhoff committed Nov 6, 2023
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23 changes: 15 additions & 8 deletions src/modality-specific-files/task-events.md
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Expand Up @@ -82,10 +82,10 @@ A guide for using macros can be found at
Example of the content of the TSV file:

```Text
onset duration trial_type response_time stim_file channel artifact
onset duration trial_type response_time stim_file channel annots
1.23 0.65 start 1.435 images/red_square.jpg n/a n/a
5.65 0.65 stop 1.739 images/blue_square.jpg n/a n/a
12.1 2.35 n/a n/a n/a F,1|F,2|Cz sweat
12.1 2.35 n/a n/a n/a F,1|F,2|Cz musc
```

In the accompanying JSON sidecar, the `trial_type` column might look as follows:
Expand All @@ -104,8 +104,15 @@ In the accompanying JSON sidecar, the `trial_type` column might look as follows:
"Description": "Channel(s) associated with the event",
"Delimiter": "|"
},
"artifact": {
"Description": "Description of an artifact."
"annots": {
"LongName": "Annotations",
"Description": "Hierarchical Event Descriptors (HED) annotations",
"Levels": {
"musc": "Muscle artifact. A very common, high frequency, sharp artifact that corresponds with agitation/nervousness in a patient."
},
"HED": {
"musc": "EMG-artifact"
}
}
}
```
Expand All @@ -116,17 +123,17 @@ Note that in the example above:
In a real dataset, all other columns SHOULD also be described.

1. The `channel` column contains a list of values that are separated
by a non-default delimiter (that is, *not* with a comma `,`).
See the `Delimiter` field in the accompanying JSON sidecar.
by a delimiter (`|`), as is declared in the `Delimiter` metadata
field of the `events.json file.
Thus, the channels related to the event in the third row of the example
are called `F,1`, `F,2`, and `Cz`.

1. The example contains a column called `artifact`.
1. The example contains a column called `annots`.
This column is not defined in BIDS, and constitutes additional, arbitrary
(that is, unofficial) metadata.
In the present case, it is used to describe artifacts in the data,
in reference to the `channel` column.
Note that in practice, such a hypothetical `artifact` column should make
The `annots` column is making
use of the powerful HED system for documenting events, see below.

Events MAY also be documented in machine-actionable form
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