There is evidence suggesting that different processes are involved in remembering something versus knowing whether it is familiar.Mickley, K.R., Kensinger, E.A. (2008). Emotional valence influences the neural correlates associated with remembering and knowing. Cognition, affective & behavioural neuroscience, 8(2), 143-152. It appears that "remembering" and "knowing" represent relatively different characteristics of memory as well as reflect different ways of using memory.
To remember is the conscious recollection of many vivid contextual details, such as "when" and "how" the information was learned. Remembering utilizes episodic memory and requires a deeper level of processing (e.g. undivided attention) than knowing. Errors in recollection may be due to source-monitoring errors that prevent an individual from remembering where exactly a piece of information was received. On the other hand, source monitoring may be very effective in aiding the retrieval of episodic memories. Remembering is a knowledge-based and conceptually-driven form of processing that can be influenced by many things. It is relevant to note that under this view both kinds of judgments are characteristics of individuals and thus any distinctions between the two are correlational, not causal, events.
To know is a feeling (unconscious) of familiarity. It is the sensation that the item has been seen before, but not being able to pin down the reason why. Knowing simply reflects the familiarity of an item without recollection. Knowing utilizes semantic memory that requires perceptually based, data-driven processing. Knowing is the result of shallow maintenance rehearsal that can be influenced by many of the same aspects as semantic memory.
Remember and know responses are quite often differentiated by their functional correlates in specific areas in the brain. For instance, during "remember" situations it is found that there is greater EEG activity than "knowing", specifically, due to an interaction between frontal and posterior regions of the brain.Gardiner, J.M., Gregg, V.H., Karayianni, I. (2006). Recognition memory and awareness: occurrence of perceptual effects in remembering or in knowing depends on concscious resources at encoding, but not at retrieval. Memory & cognition, 34(2), 227-239. It is also found that the hippocampus is differently activated during recall of "remembered" (vs. familiar) stimuli.Eldridge, L. L., Knowlton, B. J., Furmanski, C. S., Bookheimer, S. Y., & Engel, S. A. (2000). Remembering episodes: A selective role for the hippocampus during retrieval. Nature Neuroscience, 3. 1149–1152. On the other hand, items that are only "known", or seem familiar, are associated with activity in the rhinal cortex.
Origins The remember-know paradigm began its journey in 1985 from the mind of Endel Tulving. He suggested that there are only two ways in which an individual can access their past. For instance, we can recall what we did last night by simply traveling back in time through memory and episodically imagining what we did (remember) or we can know something about our past such as a phone number, but have no specific memory of where the specific memory came from (know).Tulving, E. (1999). Memory, Consciousness, and the Brain: The Tallinn Conference. (pp. 66-68). Psychology Press. Recollection is based on the episodic memory system, and familiarity is based on the semantic memory system. Tulving argued that the remember-know paradigm could be applied to all aspects of recollection.
In 1988 the application of the paradigm was refined to a set of instructions that could elicit reliable judgments from subjects that can be found using many variables. The remember-know paradigm has changed the way in which researchers can study memory tasks and has had implications on what were originally considered purely "episodic" memories, which can now be thought of as a combination of both remembering and knowing or episodic and semantic.
Possible theories Remembering and knowing have been linked to dual-component theories, as well as unitary trace-strength/signal detection models.
Tulving's theory Episodic and semantic memory give rise to two different states of consciousness, autonoetic and noetic, which influence two kinds of subjective experience: remembering and knowing, respectively. Autonoetic consciousness refers to the ability of recovering the episode in which an item originally occurred. In noetic consciousness, an item is familiar but the episode in which it was first encountered is absent and cannot be recollected. Remembering involves retrieval from episodic memory and knowing involves retrieval from semantic memory.
In his SPI model, Tulving stated that encoding into episodic and semantic memory is serial, storage is parallel, and retrieval is independent. By this model, events are first encoded in semantic memory before being encoded in episodic memory; thus, both systems may have an influence on the recognition of the event.
High-threshold model The original high-threshold model held that recognition is a probabilistic process. It is assumed that there is some probability that previously studied items will exceed a memory threshold. If an item exceeds the threshold then it is in a discrete memory state. If an item does not exceed the threshold then it is not remembered, but it may still be endorsed as old on the basis of a random guess. According to this model, a test item is either recognized (i.e., it falls above a threshold) or it is not (i.e., it falls below a threshold), with no degrees of recognition occurring between these extremes. Only target items can generate an above-threshold recognition response because only they appeared on the list. The lures, along with any targets that are forgotten, fall below threshold, which means that they generate no memory signal whatsoever. For these items, the participant has the option of declaring them to be new (as a conservative participant might do) or guessing that some of them are old (as a more liberal participant might do). False alarms in this model reflect memory-free guesses that are made to some of the lures. This simple and intuitively appealing model yields the once-widely-used correction for guessing formula, and it predicts a linear receiver operating characteristic (ROC). An ROC is simply a plot of the hit rate versus the false alarm rate for different levels of bias. A typical ROC is obtained by asking participants to supply confidence ratings for their recognition memory decisions. Several pairs of hit and false alarm rates can then be computed by accumulating ratings from different points on the confidence scale (beginning with the most confident responses). The high-threshold model of recognition memory predicts that a plot of the hit rate versus the false alarm rate (i.e., the ROC) will be linear it also predicts that the z-ROC will be curvilinear.
Dual-process accounts The dual-process account states that recognition decisions are based on the processes of recollection and familiarity.Wixted, J.T. (2007). Dual-Process Theory and Signal-Detection Theory of Recognition Memory. Psychological Review, 114(1), 152-176. Recollection is a conscious, effortful process in which specific details of the context in which an item was encountered are retrieved. Familiarity is a relatively fast, automatic process in which one gets the feeling the item has been encountered before, but the context in which it was encountered is not retrieved. According to this view, "remember" responses reflect recollections of past experiences and "know" responses are associated with recognition on the basis of familiarity.
Signal-detection theory According to this theory, recognition decisions are based on the strength of a memory trace in reference to a certain decision threshold. A memory that exceeds this threshold is perceived as old, and trace that does not exceed the threshold is perceived as new. According to this theory, "remember" and "know" responses are products of different degrees of memory strength. There are two criteria on a decision axis; a point low on the axis is associated with a "know" decision, and a point high on the axis is associated with a "remember" decision. If memory strength is high, individuals make a "remember" response, and if memory strength is low, individuals make a "know" response.
Probably the strongest support for the use of signal detection theory in recognition memory came from the analysis of ROCs. An ROC is the function that relates the proportion of correct recognitions (hit rate) to the proportion of incorrect recognitions (false-alarm rate).
Signal-detection theory assumed a preeminent position in the field of recognition memory in large part because its predictions about the shape of the ROC were almost always shown to be more accurate than the predictions of the intuitively plausible high-threshold model. More specifically, the signal-detection model, which assumes that memory strength is a graded phenomenon (not a discrete, probabilistic phenomenon) predicts that the ROC will be curvilinear, and because every recognition memory ROC analyzed between 1958 and 1997 was curvilinear, the high-threshold model was abandoned in favor of signal-detection theory. Although signal-detection theory predicts a curvilinear ROC when the hit rate is plotted against the false alarm rate, it predicts a linear ROC when the hit and false alarm rates are converted to z scores (yielding a z-ROC).
“The predictive power of the signal detection modem seems to rely on know responses being related to transient feelings of familiarity without conscious recollection, rather than Tulving’s (1985) original definition of know awareness.
Dual-process signal-detection/high-threshold theory The dual-process signal-detection/high-threshold theory tries to reconcile dual-process theory and signal-detection theory into one main theory. This theory states that recollection is governed by a threshold process, while familiarity is not. Recollection is a high-threshold process (i.e., recollection either occurs or does not occur), whereas familiarity is a continuous variable that is governed by an equal-variance detection model. On a recognition test, item recognition is based on recollection if the target item has exceeded threshold, producing an "old" response. If the target item does not reach threshold, the individual must make an item recognition decision based on familiarity. According to this theory, an individual makes a "remember" response when recollection has occurred. A know response is made when recollection has not occurred, and the individual must decide whether they recognize the target item solely on familiarity. Thus, in this model, the participant is thought to resort to familiarity as a backup process whenever recollection fails to occur.
Distinctiveness/fluency model In the past, it was suggested that remembering is associated with conceptual processing and knowing is associated with perceptual processing. However, recent studies have reported that there are some conceptual factors that influence knowing and some perceptual factors that influence remembering. Findings suggest that regardless of perceptual or conceptual factors, distinctiveness of processing at encoding is what affects remembering, and fluency of processing is what affects knowing. Remembering is associated with distinctiveness because it is seen as an effortful, consciously controlled process. Knowing, on the other hand, depends on fluency as it is more automatic and reflexive and requires much less effort.
Influences on remembering and knowing Factors that influence remember responses but not know responses are Frequency