The n-back task is a continuous performance task that is commonly used as an assessment in psychology and cognitive neuroscience to measure central executive function from working memory. The n-back was introduced by Wayne Kirchner in 1958. The subject is presented with a sequence of stimuli, and the task consists of indicating when the current stimulus matches the one from n steps earlier in the sequence. The load factor n can be adjusted to make the task more or less difficult. The dual-task n-back task is a variation that was proposed by Susanne Jaeggi et al. in 2003. In the dual-task paradigm, two independent sequences are presented simultaneously, typically using different modalities of stimuli, such as one auditory and one visual. This application allows simultaneous recording of the user's EEG signal, as well as other biosignals that can be transmitted via LSL.
Tested on MEDUSA© Platform v2024.0
Here we present the computerized version of Dual N-back test that is broadly applied in neuroconitive research and cognitive evaluation. This app is provided as a evaluation complement of ITACA NF framework.
In N-back test, users are presented with a sequence of stimulus and they must indicate when a stimulus matches the stimulus presented N-times before. The dual-task N-back task is a variation that was proposed by Susanne Jaeggi et al. in 2003. In the dual-task paradigm, two independent sequences are presented simultaneously, typically using different modalities of stimuli, such as one auditory and one visual.
The version implemented in MEDUSA© is provided with the following functionalities:
Welcome to the Dual N-back app tutorial! Here we will explain you step by step how to configure the different options presented by this app.
This application has been developed as a complement to the ITACA NF framework. Therefore, its design is intended to be as flexible as possible, providing different options to enable diverse assessment protocols.
The different configuration options are divided into the following sections: (i) Run settings; and (ii) App settings.
Below, we will go through each of the following sections specifying each of the parameters to be configured. In addition, the panel has 4 main buttons:
This section contains several fields aimed at defining experiment information that may be useful in posterior analyses. For instance, it can help in identifying and managing the different recordings throughout a study. Montage standard field is intented to save the standard used (i.e., 10-20, 10-10 or 10-05) in case you want to record the EEG signal during the experiment. Otherwise, this field should be ignored.
This section includes the options related to Dual N-back task. Number of trials allows to define how many stimulus will be presented during the task performance. Target trials establish the percentage with respect to total trials that will be target, that is, those stimulus which user will have to respond.
N-back mode allows to adjust the load factor N. A N value of 0 changes the task paradigm: User will have to respond only when an specific stimulus appears. For Visuo-spatial mode, this stimulus corresponds to the central square. For Auditory mode, this stimulus corresponds to R letter. For Dual mode, both mentioned stimulus.
Game mode establish the modality of the task: If Visuo-spatial mode, stimulus will be green squares appearing in different positions of a 3 x 3 grid, whereas Auditory mode, stimulus will be different letters pronounced in English or Spanish (depending on the selected option in Language field). The Dual mode will present both types of stimulus simultaneously, and the user will have to respond separately to each type of stimulus.
Once you have the configuration ready and you have overwritten the chosen options by pressing the Done button on the configuration panel, you must press the Power button of the MEDUSA© Platform with the Dual N-back app selected.
The first think you have to take into account is that this app enables the simultaneous recording of any kind of biosignal which device can be connected to MEDUSA© via LSL protocol. You will be reminded of this with a dialog box in case no LSL stream has been connected to the MEDUSA© Platform. The dialog is displayed bellow:
The Unity application will then be launched. Wait until the text Waiting appears in the application, then press the MEDUSA© Platform Play button. If you have chosen the option N = 0, you will be prompted with instructions for the buttons on your keyboard to press when the target stimuli are displayed. The buttons to be pressed are as follows:
|In order for the application to detect the user's responses, the focus must be on the application. This is done by clicking with the mouse on the application once it is started with Play.
When the test is completed, a summary will be displayed on the screen, including the number of target stimulus correctly answered, as well as the incorrect answers. Then, press Stop button in MEDUSA© Platform to close the app window. A dialog box will appear to save the experiment information. Among the information stored is the time instant at which each stimulus was presented, whether it was a target or not, the user's response time and whether the response was successful or not. In addition, if a biosignal is recorded, it is included in this file.
If you have any questions or suggestions for improvement, please do not hesitate to contact me.
The application has been modified to resemble more closely the classic test. The main new features are: (1) An explanation at the beginning of the test; (2) Language selection (Spanish and English); (3) Option to provide feedback on performance or not; and (4) Option to choose whether the sequences used are random or not.
Version for MEDUSA Platform v2023
Minor issue related to config panel solved
Dual N-back app now includes English as language to perform auditory an dual modes. In addition, it has been fixed the issue with "Pause" text. Now it correctly dissapears after resuming the app. Enjoy!
Fixed minor issue
Handled the error when forcibly closing from Unity.
Some improvements have been added to the graphical appearance and resolution of the application.
Initial version of Dual N-back application
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