Human recognition memory: a cognitive neuroscience perspective

For many years the cognitive processes underlying recognition memory have been the subject of considerable interest in experimental psychology. To account for a broad range of behavioral findings, psychologists have put forward a variety of 'dual-process' models, all of which propose that recognition memory is supported by two forms of memory - familiarity and recollection - that differ in their speed of operation and the specificity of the retrieved information. More recently, the dual-process framework has been extended to encompass findings from studies investigating the neural basis of recognition memory. Results from neuropsychological, ERP and functional neuroimaging studies can be accommodated within the framework, and suggest that familiarity and recollection are supported by distinct neural mechanisms.     

Models of recognition: A review of arguments in favor of a dual-process account

The majority of computationally specified models of recognition memory have been based on a single-process interpretation, claiming that familiarity is the only influence on recognition. There is increasing evidence that recognition is, in fact, based on two processes: recollection and familiarity. This article reviews the current state of the evidence for dual-process models, including the usefulness of the remember/know paradigm, and interprets the relevant results in terms of the source of activation confusion (SAC) model of memory. We argue that the evidence from each of the areas we discuss, when combined, presents a strong case that inclusion of a recollection process is necessary. Given this conclusion, we also argue that the dual-process claim that the recollection process is always available is, in fact, more parsimonious than the single-process claim that the recollection process is used only in certain paradigms. The value of a well-specified process model such as the SAC model is discussed with regard to other types of dual-process models.     

Old processes,new perspectives: Familiarity is correlated with (not independent of) recollection and is more (not equally) variable for targets than for lures

According to dual-process models of memory, recognition is subserved by two processes: recollection and familiarity. Many variants of these models assume that recollection and familiarity make stochastically independent contributions to performance in recognition tasks and that the variance of the familiarity signal is equal for targets and for lures. Here, we challenge these ‘common-currency’ assumptions. Using a model-comparison approach, featuring the Continuous Dual Process (CDP; Wixted & Mickes, 2010) model as the protagonist, we show that when these assumptions are relaxed, the model’s fits to individual participants’ data improve. Furthermore, our analyses reveal that across items, recollection and familiarity show a positive correlation. Interestingly, this across-items correlation was dissociated from an across-participants correlation between the sensitivities of these processes. We also find that the familiarity signal is significantly more variable for targets than for lures. One striking theoretical implication of these findings is that familiarity—rather than recollection, as most models assume—may be the main contributor responsible for one of the most influential findings of recognition memory, that of subunit zROC slopes. Additionally, we show that erroneously adopting the common-currency assumptions, introduces severe biases to estimates of recollection and familiarity.     

Familiarity supports associative recognition memory for face stimuli that can be unitised: Evidence from receiver operating characteristics

According to dual-process models, associative recognition memory mainly relies on recollection without benefiting from familiarity. This study investigates the circumstances under which familiarity may support associative recognition judgements by comparing recognition memory for arbitrarily paired items (i.e., pairs of face stimuli depicting two different persons; interitem associations) with recognition memory for pairs of items that are highly overlapping and can be unitised into a coherent whole (i.e., pairs of physically different but very similar face stimuli depicting the same person; intraitem associations). Estimates of familiarity and recollection were derived from receiver operating characteristics. Consistent with the hypothesis that familiarity is able to support associative recognition memory, but only when the to-be-associated stimuli can be unitised, results from two experiments revealed higher familiarity estimates for intra- compared to interitem associations. By contrast, recollection for recombined pairs was higher for inter- compared to intraitem associations. We propose a hypothetical model on how intraitem associations may benefit from familiarity.     

Recognition memory for source and occurrence: The importance of recollection

Previous recognition memory studies indicate that when both recollection and familiarity are expected to contribute to recognition performance (e.g., discriminating studied items from nonstudied items) the dual-process and the unequal-variance signal detection models provide comparable accounts of performance. When familiarity is not expected to be useful (e.g., when items from two equally familiar sources are discriminated between), the dual-process model provides a significantly better account of performance. In the present study, source recognition was tested under conditions in which familiarity could have been used to perform a list-discrimination task; participants were required to discriminate between strong studied items, weak studied items, and new items. The dual-process model provided a better account of performance than did the unequal-variance model. Moreover, the results indicated that the unequal-variance assumption in a single-process signal detection model was not a valid substitution for recollection and that recollection was used to make recognition judgments even when assessments of familiarity were useful.     

语义相似性下回忆和熟悉性的分离

该研究利用事件相关电位技术（ERPs）,采用以汉字为实验材料的学习-再认范式,考察了语义相似性下回忆和熟悉性的分离。本实验结果表明：熟悉性效应主要体现在330-430ms的额区,而回忆效应主要体现在430-600ms的中央区和顶区。本实验在以汉字为实验材料的情况下证明了,早期额区的N400新旧效应反映了熟悉性,晚期顶区LPC新旧效应反映了回忆,从汉语材料的角度,为双加工过程假说提供了新的证据。     

The dimensionality of the remember-know task: a state-trace analysis

This article addresses the issue of whether the remember-know (RK) task is best explained by a single-process or a dual-process model. All single-process models propose that remember and know responses reflect different levels of a single strength-of-evidence dimension. Thus, across conditions in which response criteria are held constant, these models predict that the RK task is unidimensional. Many dual-process models propose that remember and know responses reflect two qualitatively distinct processes underlying recognition memory, often characterized as recollection and familiarity. These models predict that the RK task is bidimensional. Using data from 37 studies, the author conducted a state-trace analysis to determine the dimensionality of the RK task. In those studies, non-memory-related differences between conditions were eliminated via decision criteria constrained to be constant across all levels of the independent variables. The results reveal little or no evidence of bidimensionality and lend additional support to the unequal-variance signal detection model. Other arguments supporting a bidimensional interpretation are examined, and the author concludes there is insufficient evidence for the RK task to be used to identify qualitatively different memory components.     

Moving beyond pure signal-detection models: comment on Wixted (2007)

The dual-process signal-detection (DPSD) model assumes that recognition memory is based on recollection of qualitative information or on a signal-detection-based familiarity process. The model has proven useful for understanding results from a wide range of memory research, including behavioral, neuropsychological, electrophysiological, and neuroimaging studies. However, a number of concerns have been raised about the model over the years, and it has been suggested that an unequal-variance signal-detection (UVSD) model that incorporates separate recollection and familiarity processes (J. T. Wixted, 2007) may provide an equally good, or even better, account of the data. In this article, the authors show that the results of studies that differentiate these models support the predictions of the DPSD model and indicate that recognition does not reflect the summing of 2 signal-detection processes, as the new UVSD model assumes. In addition, the assumptions of the DPSD model are clarified in order to address some of the common misconceptions about the model. Although important challenges remain, hybrid models such as this provide a more useful framework within which to understand human memory than do pure signal-detection models.     

Dual-process theory and signal-detection theory of recognition memory

Two influential models of recognition memory, the unequal-variance signal-detection model and a dual-process threshold/detection model, accurately describe the receiver operating characteristic, but only the latter model can provide estimates of recollection and familiarity. Such estimates often accord with those provided by the remember-know procedure, and both methods are now widely used in the neuroscience literature to identify the brain correlates of recollection and familiarity. However, in recent years, a substantial literature has accumulated directly contrasting the signal-detection model against the threshold/detection model, and that literature is almost unanimous in its endorsement of signal-detection theory. A dual-process version of signal-detection theory implies that individual recognition decisions are not process pure, and it suggests new ways to investigate the brain correlates of recognition memory.     

Brain potentials of recollection and familiarity

It is widely hypothesized that separate recollection and familiarity processes contribute to recognition memory. The present research measured event-related brain potentials (ERPs) from 128 head locations to identify patterns of brain activity related to recollection and familiarity. In two experiments, subjects performed a recognition memory task requiring discrimination between previously studied words, similar words that changed plurality between study and test, and new words (following Hintzman & Curran, 1994). The FN400 ERP component (300-500 msec) varied with the familiarity of words (new > studied = similar). The parietal component (400-800 msec) was associated with the recollection of plurality (studied > similar = new). Differences in the timing and spatial topography of the FN400 and parietal effects support the view that familiarity and recollection arise from distinct neurocognitive processes.     

Signal-Detection, Threshold, and Dual-Process Models of Recognition Memory: ROCs and Conscious Recollection

Threshold- and signal-detection-based models have dominated theorizing about recognition memory. Building upon these theoretical frameworks, we have argued for a dual-process model in which conscious recollection (a threshold process) and familiarity (a signal-detection process) contribute to memory performance. In the current paper we assessed several memory models by examining the effects of levels of processing and the number of presentations on recognition memory receiver operating characteristics (ROCs). In general, when the ROCs were plotted in probability space they exhibited an inverted U shape; however, when they were plotted inzspace they exhibited a U shape. An examination of the ROCs showed that the dual-process model could account for the observed ROCs, but that models based solely on either threshold or signal-detection processes failed to provide a sufficient account of the data. Furthermore, an examination of subjects' introspective reports using the remember/know procedure showed that subjects were aware of recollection and familiarity and were able to consistently report on their occurrence. The remember/know data were used to accurately predict the shapes of the ROCs, and estimates of recollection and familiarity derived from the ROC data mirrored the subjective reports of these processes.     

Color and context: An ERP study on intrinsic and extrinsic feature binding in episodic memory

Episodic memory for intrinsic item and extrinsic context information is postulated to rely on two distinct types of representation: object and episodic tokens. These provide the basis for familiarity and recollection, respectively. Electrophysiological indices of these processes (ERP old-new effects) were used together with behavioral data to test these assumptions. We manipulated an intrinsic object feature (color; Experiment 1) and a contextual feature (background; Experiments 1 and 2). In an inclusion task (Experiment 1), the study-test manipulation of color affected object recognition performance and modulated ERP old-new effects associated with both familiarity and recollection. In contrast, a contextual manipulation had no effect, although both intrinsic and extrinsic information was available in a direct feature (source memory) test. When made task relevant (exclusion task; Experiment 2), however, context affected the ERP recollection effect, while still leaving the ERP familiarity effect uninfluenced. We conclude that intrinsic features bound in object tokens are involuntarily processed during object recognition, thus influencing familiarity, whereas context features bound in episodic tokens are voluntarily accessed, exclusively influencing recollection. Figures depicting all the electrodes analyzed are available in an online supplement at www.psychonomic.org/archive.     

熟悉性与回想分离的新证据

人们常常发现自己对某一情景有些熟悉, 但又想不起以前有关的经历。对这种熟悉感的理论解释, 一种观点认为熟悉感来自一种较弱的记忆形式, 与有回忆情况下的再认属于同一加工过程(single-process models, SPM)。另一种观点则认为, 熟悉感来自一种基于熟悉性的再认, 与基于回想的再认相互独立(dual-process theories, DPT)。在实验室, 评估熟悉性与回想是否相互独立的基本方法是寻找两者分离的证据。本文尝试梳理无线索回忆再认(recognition without cued recall, RWCR)范式的研究, 结果显示：熟悉性对某种特殊的概念加工和整体特征的知觉加工要比回想更加敏感, 并没有支持SPM关于回想和熟悉性各自对意义加工和局部特征的知觉加工更加敏感的推断。而且RWCR研究还观测到熟悉性与回想在行为和神经成像方面的实验性分离, 支持了DPT关于熟悉性与回想相互独立的推断。最后, 本文从熟悉性的深层机制和中英文材料对RWCR的不同影响出发, 对未来研究提出展望。     

Recognition memory for faces: When familiarity supports associative recognition judgments

Recognition memory for single items can be dissociated from recognition memory for the associations between items. For example, recognition tests for single words produce curvilinear receiver operating characteristics (ROCs), but associative recognition tests for word pairs produce linear ROCs. These dissociations are consistent with dual-process theories of recognition and suggest that associative recognition relies on recollection but that item recognition relies on a combination of recollection and assessments of familiarity. In the present study, we examined associative recognition ROCs for facial stimuli by manipulating the central and external features, in order to determine whether linear ROCs would be observed for stimuli other than arbitrary word pairs. When the faces were presented upright, familiarity estimates were significantly above zero, and the associative ROCs were curvilinear, suggesting that familiarity contributed to associative judgments. However, presenting the faces upside down effectively eliminated the contribution of familiarity to associative recognition, and the ROCs were linear. The results suggest that familiarity can support associative recognition judgments, if the associated components are encoded as a coherent gestalt, as in upright faces.     

The contribution of recollection and familiarity to recognition and source-memory judgments: a formal dual-process model and an analysis of receiver operating characteristics

A formal dual-process model that assumes that memory judgments can be based on a threshold recollection process and a signal-detection-based familiarity process is proposed to account for both recognition and source-memory performance. The model was tested in 4 experiments by examining recognition and source-memory receiver operating characteristics (ROCs). In agreement with the predictions of the model, recognition and source memory dissociated in certain conditions. Recognition ROCs were curvilinear in probability space and relatively linear in z-space, as expected if recollection and familiarity contributed to performance. In contrast, source ROCs typically were linear and exhibited a pronounced U shape in z-space, as expected if performance primarily relied on recollection. However, in conditions in which familiarity was clearly indicative of an item's source, the source ROC became curvilinear, suggesting that participants could use familiarity as a basis for source judgments. Several alternative models, including the unequal-variance signal-detection model, were found to be inconsistent with the ROC data.     

Familiarity is related to conceptual implicit memory: An examination of individual differences

Explicit memory is thought to be distinct from implicit memory. However, growing evidence has indicated that explicit familiarity-based recognition memory judgments rely on the same process that supports conceptual implicit memory. We tested this hypothesis by examining individual differences using a paradigm wherein we measured both familiarity and conceptual implicit memory within the same participants. In Experiments 1a and 1b, we examined recognition memory confidence ROCs and remember/know responses, respectively, to estimate recollection and familiarity, and used a free association task to measure conceptual implicit memory. The results demonstrated that, across participants, familiarity, but not recollection, was significantly correlated with conceptual priming. In contrast, in Experiment 2, utilizing a similar paradigm, a comparison of recognition memory ROCs and explicit associative cued-recall performance indicated that cued recall was related to both recollection and familiarity. These results are consistent with models assuming that familiarity-based recognition and conceptual implicit memory rely on similar underlying processes.     

Evidence for the contribution of a threshold retrieval process to semantic memory

It is widely held that episodic retrieval can recruit two processes: a threshold context retrieval process (recollection) and a continuous signal strength process (familiarity). Conversely the processes recruited during semantic retrieval are less well specified. We developed a semantic task analogous to single-item episodic recognition to interrogate semantic recognition receiver-operating characteristics (ROCs) for a marker of a threshold retrieval process. We fitted observed ROC points to three signal detection models: two models typically used in episodic recognition (unequal variance and dual-process signal detection models) and a novel dual-process recollect-to-reject (DP-RR) signal detection model that allows a threshold recollection process to aid both target identification and lure rejection. Given the nature of most semantic questions, we anticipated the DP-RR model would best fit the semantic task data. Experiment 1 (506 participants) provided evidence for a threshold retrieval process in semantic memory, with overall best fits to the DP-RR model. Experiment 2 (316 participants) found within-subjects estimates of episodic and semantic threshold retrieval to be uncorrelated. Our findings add weight to the proposal that semantic and episodic memory are served by similar dual-process retrieval systems, though the relationship between the two threshold processes needs to be more fully elucidated.     

Dual-process models of associative recognition in young and older adults: evidence from receiver operating characteristics

In 3 experiments, young and older adults studied lists of unrelated word pairs and were given confidence-rated item and associative recognition tests. Several different models of recognition were fit to the confidence-rating data using techniques described by S. Macho (2002, 2004). Concordant with previous findings, item recognition data were best fit by an unequal-variance signal detection theory model for both young and older adults. For both age groups, associative recognition performance was best explained by models incorporating both recollection and familiarity components. Examination of parameter estimates supported the conclusion that recollection is reduced in old age, but inferences about age differences in familiarity were highly model dependent. Implications for dual-process models of memory in old age are discussed.     

从认知神经科学的角度看熟悉性和回想

双加工模型认为再认记忆有两种不同的形式：熟悉性和回想。认知神经科学对熟悉性和回想进行了大量的研究,认为熟悉性和回想是功能上分离的两个过程,并且这两个过程依赖于性质上不同的神经机制。通过对健忘症病人的研究发现海马区域对于回想是重要的,而颞中回和颞下回的周围结构对于熟悉性是重要的。ERP研究发现熟悉性和回想有不同的头皮分布,fMRI研究表明左侧前额叶和稍后的顶骨活动分别与熟悉性和回想有关。     

Dissociating familiarity from recollection in human recognition memory: Different rates of forgetting over short retention intervals

Two functionally distinct forms of recognition memory have been identified in human and nonhuman species—the ability to recollect qualitative information about previous events, and the ability to differentiate between familiar and novel stimuli. Separate dual-process theories have been developed in the animal and human literatures to account for these findings. However, it is not clear whether these theories describe the same two underlying memory processes. On the basis of animal studies of medial temporal lobe function, familiarity is expected to exhibit disproportionately fast forgetting compared with recollection over short retention intervals. We tested this prediction in healthy human subjects by examining recognition forgetting rates across a range of 8–32 intervening items and found significant forgetting in the accuracy of familiarity-based discriminations and no evidence of forgetting in the accuracy of recollection-based discriminations. In agreement with the results from nonhuman species, the present results indicate that item familiarity decreases more rapidly than recollection over short retention intervals.