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Basic Task Description

The Remember-Know (RK) task is intended to probe episodic memory, which we conceptualize as involving an information encoding phase during which stimulus features are bound into a unified mental representation and a recognition phase during which that representation is retrieved and judgments are made about that retrieval process.

Taking a cognitive neuroscience perspective, retrieval has been modeled various ways, including the approach that provided the basis for the RK task. This approach employs a distinction between recollection-based retrieval and familiarity-based retrieval. Recollection is thought to rely to a great extent on hippocampal activity inasmuch as the stimulus features that the hippocampus binds together at encoding are recalled (Eldridge et al., 2000). Retrieval involving a sense of familiarity is believed to rely on distributed temporal, parietal, and frontal lobe structures. Although familiarity-based retrieval is thought to rely on a memory cue (i.e., test word), it does not necessarily involve the recall of a bound stimulus representation (including non-cued details; Henson et al., 1999). Accordingly, during the test portion of the RK task, participants are asked to make a meta-cognitive judgment regarding whether words labeled as "old" or "studied" were recognized using recollection (or "remember") or a familiarity-based (or "know") process (Tulving, 1985).

From a behavioral standpoint, patients diagnosed with schizophrenia (e.g., van Erp et al., 2008), bipolar disorder (e.g., Kurtz and Gerraty, 2009), and ADHD (e.g., Castel et al., 2011), all show evidence of disrupted episodic memory functioning, although the nature and severity of these impairments may differ. Furthermore, behavioral performance on tests thought to assess episodic memory ability has been shown to be at least moderately heritable (e.g., Finkel and McGue, 1993), with a number of gene variants identified as promising leads in helping to account for variability in performance (Bearden et al., 2012).

Task Procedure

The RK test procedure is comprised of four phases (implemented as three E-Prime programs, indicated below).

First, participants receive instruction on the conceptual distinction between “remembering” and “knowing” processes of stimulus recognition. They then answer a series of questions in order to demonstrate that they understand the concepts adequately. This first phase is referred to as the pretest.

The second phase of the RK task is the encoding phase, during which participants see pairs of words (and congruent images) and indicate which of the two words is presented in all capital letters (also presented with a color picture). Subjects also know at this point that there will be a memory test next.

The third phase is the recognition test, in which words are presented, and participants are asked to indicate whether they remember that the words were presented during the encoding phase, whether they know that the words were presented during encoding, or whether the word is new, or not presented at encoding.

Finally, during a validation phase, participants are presented with a set of words and images, and must indicate which word was paired with the presented word (or whether it was new at recognition) and then what the color of the presented image was during encoding (or whether it was new).

Sample Text Describing the Procedure (from van Erp et al., 2008b):

The R–K paradigm was administered on a personal computer using E-Prime (Psychology Software Tools, Stimuli were presented as word and picture pairs in order to provide opportunities for use of relational information at encoding …. The paradigm comprised three phases: 1) encoding, 2) item recognition, and 3) stimulus feature recognition. Before the task began, participants were instructed to remember as much of the information presented on each trial as possible and were given examples of the types of questions that would be asked in the item and stimulus feature recognition phases. The explanation of “remember” and “know” responses was based on those by Gardiner and Java (1990), and those with regard to the stimulus feature recognition resembled those by Dudukovic and Knowlton (2006). As a pre-test measure, participants were given six example sentences describing memories and asked whether each was reflective of a “remember” or a “know” memory.

During the encoding phase, participants were shown sixty stimulus pairs, and explicitly asked to memorize as much about the items on the screen as possible: the words, pictures, colors of the pictures, and their location on the screen; they were also encouraged to develop other associations. As a check on task engagement, participants were asked to judge whether the colored target picture appeared on the left or right. During the item recognition phase, immediately following encoding, subjects were presented with the sixty previously presented targets and twenty new foil words. Participants were instructed to press one of three keys according to whether they remembered the word and could recall specific additional information presented with the word [“remember”], knew that the word was previously presented, but did not recall additional information [“know”], or thought the word was not previously presented [“unstudied”]. Immediately following the item recognition phase, subjects were given the feature recognition phase, in which they were first presented with a target word and asked to make a forced-choice recognition judgment between two possible paired words. A grayscale target picture was then presented and subjects were asked to make a forced-choice recognition judgment between two possible picture colors. Both judgments also offered the ‘unstudied’ option to indicate that the word or picture was not present in the encoding phase. The feature recognition phase was self-paced.”

Task Structure Detail

The RK task involves three E-Prime programs, including four task phases. The procedures included in the three programs are outlined below:

  • RKpretest (3-5 min)
    • Pretest Phase Instructions
    • Pretest Phase Questions
  • RKpart1 (17 min)
    • Encoding Phase Instructions
    • Encoding Phase Practice Trials – 2 trials
    • Recognition Phase Instructions
    • Recognition Phase Practice Trials – 3 trials
    • Encoding Task (Right-Left Judgment re. Capitalized Letters)
    • Recognition Phase Instructions Reminder
    • Recognition Task (3-Choice Word Recognition Trials)
  • RKpart2 (14 min)
    • Validation Phase Instructions
    • Validation Phase Practice Trials – 2 trials
    • Validation Phase Task (3-Choice, 2 options and “new”)

The four task phases are described in detail below:

  • Pretest Phase:Pretest serves to explain to subjects the difference between a ‘remember’ memory and a ‘know’ memory. All instruction and question slides present text and are self-paced. Test administrators are instructed to read the instructions aloud to the participant and to interact with the participant to assess comprehension.
    • Instruction Slide 1: Researchers believe that there is a distinction between ‘remember’ type memories and ‘know’ type memories. Press any key to continue.
    • Instruction Slide 2: When you ‘remember’ something, you consciously recall its occurrence. For example, you may remember a recent movie and be able to recall specific details about it (like where and with whom you saw it).
    • Instruction Slide 3: At other times you simply ‘know’ that something has occurred before, without being able to consciously recollect the experience. For example, you may recognize a person but not be able to recall any specific details about the person (such as her name).
    • Instruction Slide 4: Here is another example of the distinction between remembering and knowing. You may recall that you ate eggs for breakfast last Tuesday. In this case, you ‘remember’ eating breakfast that day. In contrast, you may know that you ate breakfast last Tuesday, but be unable to recall details such as what you ate. In this case, you ‘know’ that you ate breakfast that day.
    • Instruction Slide 5: You will now take a pretest to demonstrate that you understand the distinction between ‘remember’ and ‘know’ memories. For each of the following four questions, please indicate whether it is a ‘remember’ or ‘know’ memory.
    • Question Slide 1: You see your friend. You recall that his name is Mike and that you first met him at a car show three years ago. Is this a ‘remember’ or ‘know’ type memory? Press the left button if you think it is a ‘remember’ type memory and press the right button if you think it is a ‘know’ type memory.
    • Question Slide 2: You see someone who looks familiar, but you can’t recall his name or where you met him. Press the left button if you think it is a ‘remember’ type memory and press the right button if you think it is a ‘know’ type memory.
    • Question Slide 3: You read a book in the 7th grate. You recall that the title was “Gone and Back Again,” and that there was a main character named George with a long beard. Press the left button if you think it is a ‘remember’ type memory and press the right button if you think it is a ‘know’ type memory.
    • Question Slide 4: You read a book recently. You recall that the book had two main characters, but you do not recall their names or the title of the book. Press the left button if you think it is a ‘remember’ type memory and press the right button if you think it is a ‘know’ type memory.
    • Instruction Slide 5: You have completed the pretest for this experiment. Press the left button if you think it is a ‘remember’ type memory and press the right button if you think it is a ‘know’ type memory.

Task Schematic

RK task.jpg

Task Parameters Table


Dependent Variables

Cleaning Rules


Data Distributions


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