EEG
Sternberg Working Memory

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Sternberg Working Memory
Sternberg Working Memory
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  •   README
  •   task-WorkingMemory_events.json
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README

Modified Sternberg Working Memory Experiment

Project name: EEG and working memory

Years the project ran: 2004-05

Brief overview of experiment task: The purpose of this Modified Sternberg task study was to explore source-resolved EEG brain dynamics associated with selectively committing a series of letters to memory, then after a brief maintenance period responding by button press either yes or no to the question of whether a presented query letter had been in the just-presented set of to-be-memorized letters.

The task is a modified version of the classic Sternberg working memory task, with two added features: (1) interspersing the sequence of presented (black) letters to be memorized with (green) letters to be ignored, and (2) delivering auditory feedback on each trial as to the correctness of the participant response (beep = correct, buzz = incorrect).

Data collection: Scalp EEG data were collected from 71 scalp electrode channels, each referred to a right mastoid electrode, at a sampling rate of 250 Hz/channel within an analog passband of 0.1 to 100 Hz.

**Contact person: Julie Onton julieonton@gmail.com, ORCID#:0000-0002-5602-3557.

Access information: Contributed to OpenNeuro.org and NEMAR.org in BIDS format following annotation using HED 8.0.0 in April, 2022.

Independent variables: Letter category (to_memorize, to_ignore); numbers of presented letters to_memorize/to_ignore (3/5, 5/3, 7/1); probe letter category (in/not in the presented set). Note, only letters to be memorized appear as in set probe letters.

Dependent variables: EEG; button press response latency; participant response (correct/incorrect).

Participant pool: The dataset includes data collected from 23 healthy young adult subjects (7 male, 6 female, 11 unidentified) between the ages of 19 and 40 years of age.

Apparatus: A Neurobehavioral Systems, Inc. EEG system running under Window98 acquired the data. The experiment control program was Presentation (Neurobehavioral Systems, Inc.).

Initial setup: EEG data were collected from 71 channels (69 scalp and two periocular electrodes, all referred to right mastoid) with an analog pass band of 0.01 to 100 Hz (SA Instrumentation, San Diego). Input impedances were brought under 5 kOhms by careful scalp preparation.

Data for subjects 1-12 was acquired at a sampling rate of 250Hz. The data for subject 14 was acquired at 1000 Hz and the data for subjects 15-24 was a acquired using a 500 Hz sampling rate.

Task organization: Data was organized into runs of 25 trials each followed by a rest. Each block was a separate run in the BIDS dataset.

Task details: Each trial consisted of the following sequence of events:

[Trial initiation]. After a self-selected, variable delay, the subject initiated the next trial by pressing either response button, triggering the reappearance of the fixation cross.

[Letter sequence presentation]. In these experiments, following a 5s presentation of a central fixation cross cue, a series of 8 visual letters (~2 deg of visual angle) were presented at screen center for 1.2s followed by a 0.2s ISI:

  • Either 3, 5, or 7 of these were colored black.
  • The participant was to memorize as letters in this set.
  • The other 5, 3, or 1 letters in the sequence were colored green and participants were to ignore these.
  • The letters were drawn without substitution from the English alphabet (omitting only A, E, I, O, and U).
  • The presentation order of black and green letters was pseudo-random.

[Memory maintenance]. In place of a ninth letter, a dash appeared on the screen to signal the beginning of a Memory Maintenance period lasting between 2 to 4 s. During this period subjects were to silently rehearse the identities of the memorized letters.

[Memory probe]. A (red) probe letter then appeared, prompting the subject to respond by pressing one of two buttons (with the thumb or index finger of their dominant hand) to indicate whether or not the probe letter had been in the trial?s to-be-memorized letter set.

[Response feedback]. An auditory feedback signal (a confirmatory beep or cautionary buzz), then presented beginning at 400 ms after the button press, informed the subject whether their response was correct or incorrect. Note: responses in the task were largely correct.

[Session time structure]. Each task session comprised of 3 or 4 task blocks of 25 trials each separated into individual run files.

Experiment location: Swartz Center for Neural Computation (SCCN), University of California San Diego, La Jolla CA (USA).

Note 1: Results presented in Onton, J., Delorme, A. and Makeig, S., 2005. Frontal midline EEG dynamics during working memory. Neuroimage, 27(2), pp.341-356.

Note 2: This paradigm is one of 20 event-related EEG task paradigms selected for replication by the EEGManyLabs project. For details, see https://psyarxiv.com/528nr/. Contact: Yuri Pavlov pavlovug@gmail.com.

Note 3: Participant 5 did not have feedback events in the trials.

Note 4: The code subdirectory has several auxilliary files that were produced during the curation process. The curation was done using a series of Jupyter notebooks that are available as run in the code/curation_notebooks subdirectory.

During the running of these curation notebooks information about the status was logged using the HEDLogger. The output of the logging process is in code/curation_logs.

Updated versions of the curation notebooks can be found at: https://github.com/hed-standard/hed-examples/tree/main/hedcode/jupyter_notebooks/dataset_specific_processing/sternberg

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