Andrew P. Yonelinas

Separating conscious and unconscious influences of memory: Measuring recollection

How can conscious and unconscious influences of memory be measured? In this article, a processdissociation procedure (L. L. Jacoby, 1991) was used to separate automatic (unconscious) and consciously controlled influences within a task. For recall cued with word stems, automatic influences of memory (a) remained invariant across manipulations of attention that substantially reduced conscious recollection and (b) were highly dependent on perceptual similarity from study to test. Comparisons with results obtained through an indirect test show the advantages of the process-dissociation procedure as a means of measuring unconscious influences. The measure of recollection derived from this procedure is superior to measures gained from classic test theory and signal-detection theory. The process-dissociation procedure combines assumptions from these 2 traditional approaches to measuring memory. Dissociations between performance on direct and indirect tests of memory supply examples of effects of the past in the absence of remembering (for reviews, see Hintzman, 1990; Richardson-Klavehn & Bjork, 1988). In an indirect test, subjects are not asked to report on memory for an event as they would be in a direct test, such as in a test of recognition or recall; rather, they engage in some task that can indirectly reflect memory for the occurrence of that event. Word stemand fragment-completion tasks are among the most popular indirect tests of memory (e.g., Graf & Mandler, 1984; Tulving, Schacter & Stark, 1982; Warrington & Weiskrantz, 1974). For a stem-completion task, subjects might read the word scalp and then be presented with the stem sea— with instructions to complete that stem with the first word that comes to mind. Evidence of automatic influences of memory that are dissociated from performance on a direct test is provided by the finding that prior presentation of a word increases the likelihood of that word being used to complete a stem, even though a direct test reveals no memory for the prior presentation of the word. Some of the most striking examples of dissociations come from the performance of patients suffering a neurological deficit. Korsakoff amnesics, for example, show near-normal effects of memory in their performance of a stem-completion task, even though

Separating the brain regions involved in recollection and familiarity in recognition memory

The neural substrates of recognition memory retrieval were examined in a functional magnetic resonance imaging study designed to separate activity related to recollection from that related to continuous variations in familiarity. Across a variety of brain regions, the neural signature of recollection was found to be distinct from familiarity, demonstrating that recollection cannot be attributed to familiarity strength. In the prefrontal cortex, an anterior medial region was related to recollection, but lateral regions, including the anterior and dorsolateral prefrontal cortex, were related to familiarity. Along the lateral parietal cortex, two functionally distinct regions were also observed: a lateral parietal/temporal region related to recollection and a more superior parietal region involved in familiarity. Similarly, in medial parietal regions, the posterior cingulate was related to recollection, whereas the precuneus was related to familiarity. The hippocampus was related to recollection, but also exhibited an inverse relationship to familiarity-driven recognition confidence. The results indicate that recollection and familiarity rely on different networks of brain regions and provide insights into the functional roles of different regions involved in episodic recognition memory.

Dissociable correlates of recollection and familiarity within the medial temporal lobes

Regions in the medial temporal lobes (MTL) have long been implicated in the formation of new memories for events, however, it is unclear whether different MTL subregions support different memory processes. Here, we used event-related functional magnetic resonance imaging (fMRI) to examine the degree to which two recognition memory processes-recollection and familiarity-were supported by different MTL subregions. Results showed that encoding activity in the rhinal cortex selectively predicted familiarity-based recognition, whereas, activity in the hippocampus and posterior parahippocampal cortex selectively predicted recollection. Collectively, these results support the view that different subregions within the MTL memory system implement unique encoding processes that differentially support familiarity and recollection.

Effects of extensive temporal lobe damage or mild hypoxia on recollection and familiarity

Memory for past events can be based on recollection or on assessments of familiarity. These two forms of human memory have been studied extensively by philosophers and psychologists, but their neuroanatomical substrates are largely unknown. Here we examined the brain regions that are involved in these two forms of memory by studying patients with damage to different temporal lobe regions. Our results come from (i) structural covariance modeling of recall and recognition, (ii) introspective reports during recognition and (iii) analysis of receiver operating characteristics. In sum, we found that the regions disrupted in mild hypoxia, such as the hippocampus, are centrally involved in conscious recollection, whereas the surrounding temporal lobe supports familiarity-based memory discrimination.

Recognition memory ROCs for item and associative information: The contribution of recollection and familiarity

Receiver-operating characteristics (ROCs) were examined in three recognition memory experiments. ROCs for item information (i.e., was this word presented?) were found to be curvilinear. However, ROCs for associative information (i.e., were these two words presented together?) were found to be linear. The results are in agreement with the predictions of a dual-process model that assumes that recognition judgments are -based on familiarity and recollection. Familiarity reflects the assessment of a continuous strength dimension and is well described as a signal detection process, whereas recollection reflects the retrieval of qualitative information about the study episode and behaves like a discrete threshold process. The results showed that memory judgments about items relied on a combination of recollection and familiarity, but that judgments about associations relied primarily on recollection. Further examination of the associative ROCs suggested that subjects were able to recollect that old pairs of items were in the study list, and, under some conditions, that new pairs were not in the study list.

Recollection and familiarity deficits in amnesia: convergence of remember-know, process dissociation, and receiver operating characteristic data.

Previous studies using the process dissociation and the remember-know procedures led to conflicting conclusions regarding the effects of anterograde amnesia on recollection and familiarity. We argue that these apparent contradictions arose because different models were used to interpret the results and because differences in false-alarm rates between groups biased the estimates provided by those models. A reanalysis of those studies with a dual-process signal-detection model that incorporates response bias revealed that amnesia led to a pronounced reduction in recollection and smaller but consistent reduction in familiarity. To test the assumptions of the model and to further assess recognition deficits in amnesics, we examined receiver operating characteristics (ROCs) in amnesics and controls. The ROCs of the controls were curved and asymmetrical, whereas those of the amnesics were curved and symmetrical. The results supported the predictions of the model and indicated that amnesia was associated with deficits in both recollection and familiarity.

Consciousness, control, and confidence: the 3 Cs of recognition memory.

The contributions of recollection and familiarity to recognition memory performance were examined using the process dissociation, remember-know, and receiver operating characteristic (ROC) procedures. Under standard test conditions the 3 measurement procedures led to process estimates that were almost identical and to similar conclusions regarding the effects of different encoding manipulations. Dividing attention led to a large decrease in recollection and a smaller, sometimes nonsignificant, decrease in familiarity. Semantic compared with perceptual processing led to a large increase in recollection and a moderate increase in familiarity. Moreover, the results showed that familiarity was well described by classical signal-detection theory but that recollection reflected a threshold process. The convergence observed across the 3 measurement procedures shows that the 3 procedures tap similar underlying processes and that recollection and familiarity differ in terms of conscious awareness, intentional control, and the manner in which they contribute to the shape of response confidence ROCs.

Receiver Operating Characteristics (ROCs) in Recognition Memory: A Review

Receiver operating characteristic (ROC) analysis is being used increasingly to examine the memory processes underlying recognition memory. The authors discuss the methodological issues involved in conducting and analyzing ROC results, describe the various models that have been developed to account for these results, review the behavioral empirical literature, and assess the models in light of those results. The empirical literature includes studies of item recognition, relational recognition (e.g., source and associative tests), as well as exclusion and remember-know tasks. Nine empirical regularities are described, and a number of unresolved empirical issues are identified. The results indicate that several common classes of recognition models, such as pure threshold and pure signal detection models, are inadequate to account for recognition memory, whereas several hybrid models that incorporate a signal detection-based process and a threshold recollection or attention process are in better agreement with the results. The results indicate that there are at least 2 functionally distinct component/processes underlying recognition memory. In addition, the ROC results have various implications for how recognition memory performance should be measured.

Impaired familiarity with preserved recollection after anterior temporal-lobe resection that spares the hippocampus

It is well established that the medial-temporal lobe (MTL) is critical for recognition memory. The MTL is known to be composed of distinct structures that are organized in a hierarchical manner. At present, it remains controversial whether lower structures in this hierarchy, such as perirhinal cortex, support memory functions that are distinct from those of higher structures, in particular the hippocampus. Perirhinal cortex has been proposed to play a specific role in the assessment of familiarity during recognition, which can be distinguished from the selective contributions of the hippocampus to the recollection of episodic detail. Some researchers have argued, however, that the distinction between familiarity and recollection cannot capture functional specialization within the MTL and have proposed single-process accounts. Evidence supporting the dual-process view comes from demonstrations that selective hippocampal damage can produce isolated recollection impairments. It is unclear, however, whether temporal-lobe lesions that spare the hippocampus can produce selective familiarity impairments. Without this demonstration, single-process accounts cannot be ruled out. We examined recognition memory in NB, an individual who underwent surgical resection of left anterior temporal-lobe structures for treatment of intractable epilepsy. Her resection included a large portion of perirhinal cortex but spared the hippocampus. The results of four experiments based on three different experimental procedures (remember-know paradigm, receiver operating characteristics, and response-deadline procedure) indicate that NB exhibits impaired familiarity with preserved recollection. The present findings thus provide a crucial missing piece of support for functional specialization in the MTL.

Recollection and Familiarity: Examining Controversial Assumptions and New Directions

It is well accepted that recognition memory reflects the contribution of two separable memory retrieval processes, namely recollection and familiarity. However, fundamental questions remain regarding the functional nature and neural substrates of these processes. In this article, we describe a simple quantitative model of recognition memory (i.e., the dual‐process signal detection model) that has been useful in integrating findings from a broad range of cognitive studies, and that is now being applied in a growing number of neuroscientific investigations of memory. The model makes several strong assumptions about the behavioral nature and neural substrates of recollection and familiarity. A review of the literature indicates that these assumptions are generally well supported, but that there are clear boundary conditions in which these assumptions break down. We argue that these findings provide important insights into the operation of the processes underlying recognition. Finally, we consider how the dual‐process approach relates to recent neuroanatomical and computational models and how it might be integrated with recent findings concerning the role of medial temporal lobe regions in other cognitive functions such as novelty detection, perception, implicit memory and short‐term memory.