John M. Gardiner

Functional aspects of recollective experience

The functional relationship between recognition memory and conscious awareness was examined in two experiments in which subjects indicated when recognizing a word whether or not they could consciously recollect its prior occurrence in the study list. Both levels of processing and generation effects were found to occur only for recognition accompanied by conscious recollection. Recognition in the absence of conscious recollection, although less likely, was generally reliable and uninfluenced by encoding conditions. These results are consistent with dual-process theories of recognition, which assume that recognition and priming in implicit memory have a common component. And they strengthen the case for making a functional distinction between episodic memory and other memory systems.

Recollective experience in word and nonword recognition

The functional relationship between memory and consciousness was investigated in two experiments in which subjects indicated when recognizing an item whether they could consciously recollect its prior occurrence in the study list or recognized it on some other basis, in the absence of conscious recollection. Low-frequency words, relative to high-frequency words, enhanced recognition accompanied by conscious recollection but did not influence recognition in the absence of conscious recollection. By contrast, nonwords compared with words enhanced recognition in the absence of conscious recollection and reduced recognition accompanied by conscious recollection. A third experiment showed that confidence judgments in recognizing nonword targets corresponded with recognition performance, not with recollective experience. These measures of conscious awareness therefore tap qualitatively different components of memory, not some unitary dimension such as “trace strength.” The findings are interpreted as providing further support for the distinction between episodic memory and other memory systems, and also as providing more qualified support for theories that assume that recognition memory entails two components, one of which may also give rise to priming effects in implicit memory.

Remembering and knowing

Remembering and knowing are two states of awareness that, respectively, entail conscious recollection or feelings of familiarity in the absence of any recollective experiences. This chapter reviews what has been learned about remembering and knowing from experimental investigations of participants’ reports of them. Remembering and knowing have been shown to be selectively affected by many different experimental manipulations and to differ systematically in different populations. They also have distinct neural correlates. Theoretically, remembering and knowing have, respectively, been identified with episodic and semantic memory systems or with different memory processes. The responses have also been modeled using signal detection methods.

Attention and recollective experience in recognition memory.

The functional relation between recognition memory and conscious awareness was assessed in an experiment in which undivided attention at study was compared with two divided attention conditions, one more demanding than the other. When recognizing a word from the study list, subjects indicated whether they could consciously recollect its-prior occurrence or recognized it on some other basis, in the absence of consciousrecollection. Divided attention at study progressively impaired word recognition accompanied by conscious recollection. Recognition in the absence of conscious recollection was not affected by divided attention. These findings are interpreted as providing further support for the idea that recognition memory entails two distinct components, one based on associative and contextual information, the other based on a “traceless” awareness of familiarity.

Experiences of Remembering, Knowing, and Guessing

This article presents and discusses transcripts of some 270 explanations subjects provided subsequently for recognition memory decisions that had been associated with remember, know, or guess responses at the time the recognition decisions were made. Only transcripts for remember responses included reports of recollective experiences, which seemed mostly to reflect either effortful elaborative encoding or involuntary reminding at study, especially in relation to the self. Transcripts for know responses included claims of just knowing, and of feelings of familiarity. These transcripts indicated that subjects were often quite confident of the accuracy of their decisions, compared with those for guess responses. Transcripts for decisions associated with guess responses also expressed feelings of familiarity but additionally revealed various strategies and inferences that did not directly reflect memory for studied items. The article concludes with a historical and theoretical overview of some interpretations of the states of awareness measured by these responses.

Forgetting in recognition memory with and without recollective experience.

Retention interval was manipulated in two recognition-memory experiments in which subjects indicated when recognizing a word whether its recognition was accompanied by some recollective experience (“remember”) or whether it was recognized on the basis of familiarity without any recollective experience (“know”). Experiment 1 showed that between 10 mm and 1 week, “remember” responses declined sharply from an initially higher level, whereas “know” responses remained relatively unchanged. Experiment 2 showed that between 1 week and 6 months, both kinds of responses declined at a similar, gradual rate and that despite quite low levels of performance after 6 months, both kinds of responses still gave rise to accurate discrimination between target words and lures. These findings are discussed in relationship to current ideas about multiple memory systems and processing accounts of explicit and implicit measures of retention.

Episodic Memory and Remembering in Adults with Asperger Syndrome

A group of adults with Asperger syndrome and an IQ-matched control group were compared in remember versus know recognition memory. Word frequency was also manipulated. Both groups showed superior recognition for low-frequency compared with high-frequency words, and in both groups this word frequency effect occurred in remembering, not in knowing. Nor did overall recognition differ between the two groups. However, recognition in the Asperger group was associated with less remembering, and more knowing, than in the control group. Since remembering reflects autonoetic consciousness, which is the hallmark of an episodic memory system, these results show that episodic memory is moderately impaired in individuals with Asperger syndrome even when overall recognition performance is not.

Recognition memory and decision processes: A meta-analysis of remember, know, and guess responses

A meta-analysis of proportions of remember, know, and guess responses was carried out on observations from 86 experimental conditions in 23 different recognition memory experiments. Unlike remember and know responses, guess responses revealed no memory for the test items that elicited them. A signal detection analysis of these data showed that A′ estimates of the strength of the memory trace depended on response criteria. A′ estimates increased significantly when know responses were added to remember responses, and decreased significantly when guess responses were added to remember and know responses. It was guessing, rather than knowing, that was most strongly correlated with overall response criteria. Nor were remembering and knowing correlated significantly. These results do not support a quantitative trace strength model according to which these responses merely reflect different response criteria. They support theories that ascribe remembering and knowing to qualitatively distinct memory systems or processes.

Asperger's syndrome and memory: Similarity to autism but not amnesia

Two experiments are described in which the memory of adults with Aspergers syndrome is compared with that of verbal IQ controls. The results of the first experiment showed that the Asperger subjects resembled autistic adults and children in their failure to use category information to aid their free recall. In the second experiment, both groups of subjects showed similar priming effects in an implicit stem completion task and similar performance on an explicit cued recall task. Moreover, both groups also showed more priming for items that they had read at study and better recall for items that they had to generate at study, suggesting that the cued recall of the Asperger subjects did not result from contamination by automatic or involuntary processes.

Involuntary conscious memory and the method of opposition

Priming in an indirect test of stem completion should reflect involuntary memory, but can be accompanied by conscious awareness of the past (involuntary conscious memory) or unaccompanied by such awareness (involuntary unconscious memory). We adapted the method of opposition developed by Jacoby, Woloshyn, and Kelley (1989) to obtain a measure of stem-completion priming that should reflect only involuntary unconscious memory. Subjects completed stems with the first word coming to mind, but wrote down a different word if the word that came to mind first had been previously encountered. Facilitatory priming was expected only when involuntary unconscious influences outweighed inhibitory effects of involuntary conscious memory, or of intentional retrieval. We observed a facilitation effect for items processed graphemically at encoding, in conjunction with an inhibition effect for items processed semantically at encoding. In contrast, a standard indirect test showed similar levels of priming following graphemic and semantic encoding, whereas a direct test showed a strong advantage of semantic over graphemic encoding. We argue that the two encoding activities produced approximately equivalent involuntary influences of memory, but that items encoded semantically were associated with involuntary conscious memory to a greater extent than were items encoded graphemically. Comparing indirect and opposition test performance can provide a quantitative index of relative levels of involuntary conscious and involuntary unconscious memory.