HED task catalog¶
A curated vocabulary of the standard tasks used in cognitive and behavioral neuroscience experiments, and of the cognitive processes those tasks engage. It exists so that datasets can be tagged with what their participants were asked to do, in terms that are the same across laboratories.
What is the HED task catalog?¶
The HED task catalog consists of two interlinked lists Tasks and Cognitive processes.
Tasks are experimental paradigms each having a specific, reproducible procedure: the Stroop Color-Word Task, the N-Back Task, the Iowa Gambling Task. Each task specification has a canonical name, aliases, a description, an inclusion test stating the procedure, the manipulations and the measurements that make an experiment an instance of that task, a list of named variations with the reason each one counts as a variation, and verified references. Tasks are filed under 19 paradigm families according to what the participant does. The catalog also contains 3 pseudo tasks, which are block-level activities that may not have a distinct event structure but are important for understanding the participant’s state. See Task selection criteria for more detail about tasks and pseudo tasks.
Cognitive processes are the mental operations a task is designed to engage, e.g., response inhibition, working memory updating, reward anticipation. Each process has a definition, references, and a place in one of 19 categories.
Interlinkage: Every task states which processes it engages, and every process lists the tasks that engage it. The catalog is part of the HED (Hierarchical Event Descriptors) effort to make the events in neuroimaging and behavioral data machine-actionable; see HED resources for information on HED.
Why a task and process taxonomy?¶
A data repository knows what files a dataset contains but usually not what its
participants did beyond a free-text label such as task-flanker or task-rest. The
same paradigm goes by different names across laboratories, and related paradigms that
engage the same process are not connected at all. This catalog is meant to supply the
missing layer:
Tags for datasets. A dataset tagged with a task identifier from this catalog, and with the process identifiers that task engages, can be found by a repository search for the task, for any of its aliases, or for a process, whatever the dataset called it locally.
Commonalities across datasets. Two datasets tagged with the same task can be compared directly. Two datasets tagged with different tasks that share a process can be grouped for a question about that process.
Context for event annotation. A task tag tells a reader of a HED-annotated events file what the trial structure was designed to do, which the event-level annotations alone do not.
How these tags will be expressed in HED annotations and in dataset metadata is still being worked out; the identifiers here are the catalog’s own and are not HED schema terms.
What the catalog contains¶
What |
Count |
Where |
|---|---|---|
Tasks |
103 |
|
Pseudo tasks (rest, fixation and questionnaire blocks) |
3 |
|
Paradigm families the tasks are filed under |
19 |
|
Named task variations |
776 |
on each task page |
Cognitive processes |
172 |
|
Process categories |
19 |
|
Task-to-process links |
486 |
|
Processes engaged by at least one task |
152 |
Where to begin¶
103 tasks in 19 paradigm families, each with its inclusion test, variations, processes and references.
172 processes in 19 categories, each with a definition, references and the tasks that engage it.
The selection criteria, naming rules, inclusion test and the rules that decide what counts as a variation.
What the Atlas contains, how this catalog maps onto it entry by entry, and what each adds to the other.
New to the catalog? Start with the Introduction. Planning to tag a dataset or to read a task page closely? See How to use the catalog.
Status and how to contribute¶
This catalog is a work in progress and its curation is a continuing process, not a finished product. The task and process lists began from the Cognitive Atlas, were narrowed to paradigms that produce event-structured data, and have been added to, merged and redefined since. Tasks, processes, categories and paradigm families will keep changing as the catalog is used.
Suggestions, corrections and ideas are welcome: please open an issue at https://github.com/hed-standard/hed-task/issues. The repository’s contributing guide describes the process. A proposal for a new task is most useful when it comes with a procedure, a manipulation and a measurement in the form the inclusion tests use; a proposal for a new process is most useful when it says when in a trial the process happens, what elicits it and how it is measured.