Assesses visual working memory.
One of the most important tasks performed by working memory is to maintain and update visual material (verbal material is assessed by the test N-Back verbal NBV). In NBN the item material is difficult to verbalize: this ensures that apart from the central executive only the visual components of working memory are involved. The item design involves consistent implementation of the 2-back or 3-back paradigm. Disorders of working memory are well documented in a number of neurological and mental illnesses, such as Parkinson's disease, Huntington's chorea, ADHD and Alzheimer's disease. The test is therefore used mainly in clinical neuropsychology.

Highly abstract figures are presented one by one. The respondent’s task is to state whether the figure currently displayed is identical to the one shown two places back (2-back paradigm) or three places back (3-back paradigm). If it is, the respondent presses a button as quickly as he can.

S1: 2 back standard form
S2: 2 back parallel form
S3: 3 back standard form
S4: 3 back parallel form

The following main variables are scored:

• Correct and omissions: Measure of the ability to maintain and constantly update visual memory representations.
• Incorrect: Misjudgments – Measure of the executive abilities in goal management.

The subsidiary variables Mean time “correct”/”incorrect” function as a measure of working speed and reaction speed; they are independent of the quality of the respondent’s answers.