One Card Learning Test (OCL)

Background

The One Card Learning Test (OCL), part of the Cogstate Brief Battery (CBB), is a computerized test to measure visual learning and visual recognition memory using a pattern separation paradigm without cultural or language bias. The task is described in the 2021 article published by Joshua P. White and colleagues. In addition to the OCL, the Millisecond library also provides implementations of the CBB's 'Detection Task' 'Identification Task', and the 'NBack Task - Touchscreen' (aka the 'One-Back Task' of the CBB). All Millisecond implementations are based on publicly available information (e.g. White et al, 2021). All tasks of the CBB use a similar card-game user interface and are designed to run on touchscreens. Nevertheless, Millisecond's implementations will adapt to mouse-use on non-touchscreens.

Task Procedure

Participants learn about the task in a brief tutorial that includes a short practice. In addition, the entire tutorial can be repeated as often as necessary before starting the test phase.

The interface of the OCL consists of a 'deck' of cards (52 cards total) presented in the center of the screen, a 'YES' and a 'NO' response button as well as a circle-shaped home button on which the response finger rests until a card is turned over. The home button is implemented to ensure that response fingers are roughly equally distanced from the 'YES' response button for each trial. Once a card is turned over, participants are asked to press the 'YES' response button as fast as possible if they have seen this particular playing card before in the game. For new game cards, they are instructed to press 'NO'. After the response is made, a card-animation is started that 'returns' the card back to the stack.

At the beginning of the task, the playing cards are divided into Targets (yes-response), Lures (no-response) and Foils (no-response). For target assignments, the script randomly picks one card from each of the four suits (clubs, diamonds, hearts, spades) with the constraint that each of the selected targets has a different value. For each of the four targets, the script stores the same numerical value cards of the remaining three suits as lures (Example: the target is the ace of clubs. Lures therefore are the ace of diamonds, the ace of hearts, and the ace of spades). All remaining cards from the deck are assigned Foil status.

By default, the task runs the OCL-80 version. Under the cover, the task runs 8 rounds of 10 trials each (80 trials total: 32 Target trials, 12 Lure trials, 36 Foil trials). Each round presents the 4 Targets and 6 distractors (either Foils or Lures); order of trials within round is randomly decided. Note that during the first round targets are indistinguishable from distractors. Lures are only presented once the corresponding target has already been shown at least once, thus valid Lures CAN be presented during round 1.

During each trial, a card is turned over randomly with a 500-1500ms delay after the home button is pressed. A reminder to press the home button is presented after 2 seconds. Pressing the home button starts the random delay period. After a new card is revealed, the task waits until the correct response is made. If participants choose the incorrect response button, the card keeps sitting in the middle until the response is corrected. In addition, the correctly pressed button is 'rewarded' with a green frame; the incorrectly pressed button is marked by a red frame. Once the correct response is made, the 1s-card animation returns the card to the deck, and the next trial can start.

What it Measures

The One Card Learning Test (OCL) measures visual learning and visual recognition memory

Psychological domains

• Episodic Memory: Ability to remember a specific personal event in time.
• Recognition Memory: Capability to correctly identify previously encountered stimuli among unfamiliar distractors.
• Visual Long-Term Memory: Durability and storage capacity of high-detail visual representations over time
• Sustained Attention: Ability to maintain focus across a continuous stream of dozens of visual stimuli to catch subtle differences.

Main Performance Metrics

• Accuracy Measure: raw and arcsine converted proportion correct; main measure of recognition success

Psychiatric Conditions

The following patient groups have been assessed with the OCL

• Mild Cognitive Impairment (MCI)
• Alzheimer’s Disease (AD)
• Multiple Sclerosis (MS)
• Schizophrenia
• Traumatic Brain Injury (TBI)

References

Search Google Scholar for peer-reviewed, published research using the Inquisit One Card Learning Test (OCL).

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White, J.P., Schembri, A., Edgar,C.J., Lim, Y.Y., Masters, C.L., & Maruff, P. (2021). A Paradox in Digital Memory Assessment: Increased Sensitivity With Reduced Difficulty. Frontiers in Digital Health, 3, 1-12.