Implicit Memory Tests Research Articles

Word stem and word fragment completion following semantic activation and elaboration.

In 5 experiments subjects made timed lexical decisions to target words (or nonwords) preceded by primes that were semantically related or unrelated to them. Subsequently, a stem or fragment completion task was administered as an implicit memory test (e.g., complete bu ― ― ― ― for butter), followed by an explicit recognition test of memory for the previously seen primes and targets. Conditions of presentation for the lexical decision task were varied across experiments. In Experiment 1, both semantic relatedness and semantic elaboration (primes vs. targets) influenced performance on both the implicit and explicit tests. In Experiments 2-5, a dissociation was obtained between the tests, with reliable effects of relatedness and elaboration obtained for recognition but not completion

Dissociations among implicit and explicit memory tasks: the role of stimulus similarity.

This article compares the effect of picture fragmentation level at study on performance on a variety of implicit and explicit memory tests. Consistent with previous research, a moderately fragmented study picture produced the most learning on the implicit memory task of picture fragment completion (Experiment 1) and speeded picture identification (Experiment 4). In contrast, an intact study picture produced the most learning on the implicit memory task of naming intact pictures (Experiment 3). These results suggest that performance on 2 implicit memory tasks can be dissociated by differences in visual similarity between the study and test forms of a stimulus. More surprising, parallel effects were observed in recognition memory. Recognition memory was best when fragmentation levels of the study and test pictures matched (Experiment 2) or were comparable (Experiment 1). In contrast to many results in the literature, recognition memory was acutely sensitive to surface form differences. We discuss the results in terms of 2 types of study-test similarity-stimulus similarity and process similarity.

Effects of imagery on perceptual implicit memory tests.

Four experiments demonstrate that imagery can promote priming on perceptual implicit memory tests. When Ss were given words during a study phase and asked to form mental images of corresponding pictures, more priming was obtained on a picture fragment identification test than from a study condition in which Ss performed semantic analyses of words. Imaginal priming of picture fragment identification occurred for recoverable fragments, but not for nonrecoverable fragments. The imagery effect was restricted to the imaged type of material: Imagining pictures (when presented with words) enhanced priming on a picture fragment identification test but not on word fragment completion. Similarly, when pictures were presented, imagining the corresponding words increased priming on word fragment completion but not on picture fragment identification. Overall, results support the hypothesis that imagining engages some of the same mechanisms used in perception and thereby produces priming.

Effects of imagery on perceptual implicit memory tests.

Four experiments demonstrate that imagery can promote priming on perceptual implicit memory tests. When Ss were given words during a study phase and asked to form mental images of corresponding pictures, more priming was obtained on a picture fragment identification test than from a study condition in which Ss performed semantic analyses of words. Imaginal priming of picture fragment identification occurred for recoverable fragments, but not for nonrecoverable fragments. The imagery effect was restricted to the imaged type of material: Imagining pictures (when presented with words) enhanced priming on a picture fragment identification test but not on word fragment completion. Similarly, when pictures were presented, imagining the corresponding words increased priming on word fragment completion but not on picture fragment identification. Overall, results support the hypothesis that imagining engages some of the same mechanisms used in perception and thereby produces priming.

Implicit memory for stimuli presented during anaesthesia: Role of anaesthetic cocktail and memory test

Recently, investigators have used so-called implicit memory tests to investigate ‘hearing’ during general anaesthesia. Some of them were able to demonstrate auditory perception in anaesthetized patients, but others have failed to find any evidence for intraoperative stimulus registration. We argue that differences in anaesthetic cocktails and memory tests can explain why some researchers have produced positive results, supportive of information-processing under anaesthesia, and others have not. It appears that stimulus registration can occur during surgery, regardless of anaesthetic technique. However, processing of complex information may only be possible during nitrous oxide anaesthesia.

Locus of Control and Implicit Memory

Two experiments were conducted to investigate the influence of locus of control on implicit and explicit memory. We hypothesized that internals would rely on semantic processing, externals on perceptual processing. In Experiment 1, 80 college students studied 36 words and completed an implicit memory test in either a consistent or cross-modality condition. The results revealed that externals had higher priming scores than did internals, regardless of modality. In Experiment 2, 80 college students took either an implicit or explicit test. The results again revealed that externals showed higher priming scores than internals. The higher priming scores exhibited by the externals do not necessarily mean that they are more perceptually oriented than the internals are.

Mnestic performance profile of a bilateral diencephalic infarct patient with preserved intelligence and severe amnesic disturbances

The case of a patient with above-average intelligence and educational background, high motivation, and an approximate IQ-MQ difference of 40 points is documented. The patient has been examined repeatedly for nearly a decade. Extensive neuroradiological material of his focal bilateral brain damage in the dorsal diencephalon is available. A widespread range of cognitive tests was used to investigate his actual performance on all relevant aspects of intelligence, attention, subjective memory, immediate retention, learning, skill and problem solving abilities, concept formation, cognitive flexibility, priming, constructional ability, retrograde memory, and long-term retention. The total of more than 50 tests included German-language forms of the revised Wechsler Memory Scale and of the Rivermead Behavioural Memory Test. The patient's short-term memory and attention were, in spite of his advanced years, average or well above average. He gave a number of examples of still intact skills and implicit memory abilities, though there was no uniformity in his performance on implicit memory tests (e.g., with respect to stored vs. new implicit information). He had no awareness of his severe anterograde and retrograde amnesia, documented over a large range of verbal and figural tests. Taken together, the results from our patient confirm the principal dichotomy between declarative and nondeclarative mnestic functions, but give evidence for some restrictions as well. They furthermore demonstrate that focal diencephalic damage may result in profound anterograde and selective retrograde amnesia, especially with respect to data-based material, and that disconnecting portions of the medial and basolateral limbic circuits has devastating consequences on memory.

COMPARISON OF THE SEDATIVE AND AMNESIC EFFECTS OF MIDAZOLAM AND PROPOFOL

We have compared the sedative and amnesic effects of midazolam and propofol in 35 volunteers. Sedation was measured by simple reaction time immediately before and after a bolus injection and 1 h after the commencement of a subsequent continuous infusion. Memory was measured three times using two memory tests: perceptual facilitation provided an implicit memory measure and recognition provided an explicit memory measure. Propofol and midazolam had similar sedative effects both immediately after bolus doses and after 1-h continuous infusions of the drugs. In contrast, midazolam had a more profound amnesic effect than propofol on the recognition memory test. The drugs had little effect on performance with the implicit memory test. Performance on the memory tests was unrelated to sedation.

TAP, implicit and explicit memory, and adult memory development.

Three critical facts about explicit and implicit memory test performance were discovered in the early 1980s, and they provided the impetus for the current widespread research interest on this topic. First, there was the finding that patients with amnesia can show entirely normal performance on implicit memory tests, such as word stem completion, despite being severely impaired on traditional explicit memory tests, such as free and cued recall. Second, findings from healthy young adults showed that a variety of experimental manipulations have different effects on performance of explicit and implicit memory tests. Third, experiments on life - span development revealed that whereas explicit memory test performance increases in childhood and declines in late adulthood, implicit memory performance remains the same across this period.These basic facts about implicit and explicit memory led us (e.g., Graf, 1991; Graf & Mandler, 1984; Graf & Schacter, 1989) to propose a view of memory based on the notion of transfer appropriate processing (TAP) of Morris, Bransford, and Franks (1977). We make three specific assumptions to explain the disassociation between implicit and explicit memory. First, along with Mandler (1980), we distinguish between two memory organizing processes -- integration and elaboration. Integration is the process by which the various elements that make up an item are related to each other so as to form a single unit, and elaboration is the process by which such units are related to each other. Second, we assume that every kind of study task engages a combination of integrative and elaborative processing, but that some tasks focus primarily on integrative processing, and others focus more heavily on elaborative processing. Third, we also assume that every kind of test engages a combination of integrative and elaborative processing, but that implicit memory tests depend primarily on integrative processing, whereas explicit tests focus more heavily on elaborative processing. By these assumptions and the idea of TAP, it follows that implicit memory test performance is mediated by study/test overlaps in integrative processing, whereas performance of explicit tests is mediated by study/test overlaps in elaborative processing.A review of the literature shows that research has revealed a great deal about elaborative processing, and that we have much less insight intothe factors that control/guide integrative processing. One widespread assumption is that integrative processing is automatic, and is guided primarily by the data -- the sensory/perceptual properties of the stimuli that are presented for study and test. We have examined this assumption in several recent studies (e.g., Graf & Ryan, 1990; Ryan & Graf, 1992) and were surprised by the findings. They showed that just like elaborative processing, integrative processing is complex and dependent on many factors, including the strategies that are subject initiated and guided (thus, integrative processing not automatic) and the specific cues and requirements that define each study/test condition.We are also conducting investigations into what specific attributes of to - be - remembered targets and target contexts are effective as cues for implicit and explicit memory test performance. …

Sensitivity of Implicit Memory to Input Processing and the Zeigarnik Effect

Abstract Implicit memory is evidenced when a subject benefits from a previous experience without making a conscious effort to recollect that prior experience. In the present study, I examined the sensitivity of implicit memory to two variables: type of input processing and the temporal placement of the implicit memory test. Results indicated that although implicit memory occurred in all conditions, its magnitude was sensitive to both variables. The results are discussed in terms of the underlying nature of implicit memory, including the role of transfer-appropriate processing.

Unintended influences of perception and memory: Attention, awareness, and control.

There has been a great deal of recent interest in the finding of dissociations between performance implicit or indirect and explicit or direct tests of memory. Implicit tests (e.g., word stem completion) are said to primarily reflect automatic or unconscious uses of memory, whereas explicit tests (e.g., cued recall) primarily reflect strategic or consciously - controlled uses of memory. I argue that implicit tests of perception and memory share important characteristics with projective tests, such as the Rorschach test, that have traditionally been used to gain evidence of unconscious influences. For projective tests as well as implicit tests, it is dissociations with performance direct tests that provide evidence of unconscious influences. A Rorschach test is said to provide evidence of inner conflicts that could not be revealed by directly asking the person about those conflicts. Similarly, an implicit test of memory sometimes reveals evidence of memory, although when directly asked, a person is unable to report the relevant memory.Implicit and projective tests also share problems for interpretation. The major problem is that of relating processes to tasks. Most of us are not tempted to treat a Rorschach test as if it measures only unconscious influences. We realize that people may sometimes catch - on to the intent of a projective test, and fake performance. That is, we are convinced that a Rorschach test is not factor or process pure. Similarly, for the stem - completion task and other implicit tests of memory, people may sometimes intentionally use memory. Problems arising from the possibility of contamination of a supposed measure of unconscious influences is most obvious in the case of unconscious perception. The history of that area has been an apparently never ending circle of claimed demonstrations of unconscious perception, followed by disqualifying claims of contamination. Of course, it is well known that tests of unconscious perception sometimes reflect aware perception and that tests of implicit memory sometimes reflect intentional uses of memory. This possibility of contamination does, though, produce serious problems for interpretation. One strategy is to further refine the measure of unconscious influences in an attempt to produce a test that is process pure. This has been the strategy in investigations of unconscious perception and, to a lesser extent, in studies of implicit memory. However, it may be impossibleto construct a test of unconscious influences that is never contaminated by intentional uses of memory. …

Direct comparison of four implicit memory tests.

Four verbal implicit memory tests, word identification, word stem completion, word fragment completion, and anagram solution, were directly compared in one experiment and were contrasted with free recall. On all implicit tests, priming was greatest from prior visual presentation of words, less (but significant) from auditory presentation, and least from pictorial presentations. Typefont did not affect priming. In free recall, pictures were recalled better than words. The four implicit tests all largely index perceptual (lexical) operations in recognizing words, or visual word form representations.

Directed forgetting in implicit and explicit memory tests: A comparison of methods.

Directed forgetting has been studied by instructing Ss to forget either (a) an initial list or (b) individually selected words. Differential encoding was hypothesized to be responsible for word-method directed forgetting, and retrieval inhibition for list-method directed forgetting. In Experiments 1 and 2, directed forgetting was observed in recognition with the word method but not with the list method. Release from directed forgetting occurred in final recall after recognition but only with the list method. These results are interpreted in terms of a theoretical framework that integrates distinctive-relational processing theory with revised generation-recognition theory. In Experiments 1-3, predictions from that framework were generally well supported on implicit and explicit retention tests that provided the same stimulus conditions

Limits of the processing view in accounting for dissociations among memory measures in a clinical population

In three experiments, we examined the performance of patients with schizophrenia on implicit and explicit memory tests that have been shown to involve predominantly data-driven or predominantly conceptually driven processes. In Experiment 1, we compared the implicit tests of category production (conceptually driven) and word identification (data driven) and found that schizophrenic patients' performance on these tests did not differ from that of normal subjects. In Experiment 2, a comparison of the category-production and explicit cued-recall tests, both of which involve conceptual processes, showed that schizophrenic patients were impaired on the cued-recall test but not on the category-production test. In Experiment 3, a comparison of the word-identification and explicit graphemic cued-recall tests, both of which involve data-driven processes, showed that patients were impaired on the cued-recall test but not on the word-identification test. The results of both Experiments 2 and 3 revealed a dissociation between implicit and explicit test performance under conditions in which the two tests involve similar types of processes. These results support theoretical views that distinguish implicit from explicit modes of retrieval.

Dissociative effect of massed repetition on implicit and explicit measures of memory.

Subjects saw or heard words presented once, or repeated 4 or 16 times in massed fashion, and then received an implicit or explicit memory test. Massed repetition did not increase priming on word fragment completion beyond that obtained from a single presentation but did enhance performance on various explicit tests (free recall, recognition, question cued recall, and word fragment cued recall) and an implicit general knowledge test. Modality of presentation affected implicit and explicit word fragment cued tests but did not affect performance on any of the other tests. Levels of processing affected performance on implicit and explicit question cued tests. These results are consistent with a transfer appropriate processing account of dissociations among memory measures and imply that massed repetition promotes conceptual processing but does not entail a repetition of perceptual-based processes responsible for priming on word fragment completion.

Directed forgetting in implicit and explicit memory tests: A comparison of methods.

Directed forgetting in implicit and explicit memory tests: A comparison of methods.

Implicit and explicit memory and response bias

The influence of response bias on tests of implicit and explicit memory was assessed by using word-stem completion and recognition. During acquisition, subjects were presented either with a list of words unrelated to the task in the retrieval phase or with a list of words whose stems could be completed in only two ways (e.g. “appeal,” “appear”). In the word-stem-completion retrieval phase, the subjects, who were given either explicit or implicit memory instructions, were asked to complete these stems. Retrieval of items in implicit and explicit memory tasks was highly correlated (r =.593 and.625, respectively) when the acquisition list had contained the words completing the stems and similarly correlated (r =.667) when the acquisition list had contained no words completing the stems. There was no correlation between recognition and explicit stem completion. In contrast to stem completion, there was no overall correlation between “recognition” in the condition in which the acquisition list contained words to be recognized later and the guessing condition, in which the acquisition list had contained no words presented during the retrieval phase. However, when the items were divided into two groups differing in memorability, a negative correlation appeared between recognition and guessing probability with the more memorable items, and a positive correlation appeared with the less memorable items. This suggests that response bias, rather than the memory the tasks are designed to test, is responsible for the normally reported lack of correlation between recognition and word completion.

The dissociation of repetition priming and recognition memory in language/learning-disabled children

Recent research has found that the performance of learning-disabled and nondisabled children is dissociated on explicit and implicit tests of memory ( Lorsbach & Worman, 1989). The current study further examined this phenomenon by comparing language/learning-disabled ( L LD ) and nondisabled children (NLD) on tasks measuring primed picture-naming and item recognition. Included within the design of the experiment was the manipulation of both presentation format (pictures or words) and retention interval (immediate or 1 day). Children were initially presented with pictures and words. Performance was measured both immediately and follwing a 1-day retention interval on a picture naming task, an item recognition task, and a supplementary measure of memory for presentation format. The magnitude of facilitation associated with primed picture-naming was found to be independent of item recognition performance. In addition, the effects of population ( L LD and NLD) and retention interval (immediate test or 1 day) each produced dissociations between the magnitude of naming facilitation and item recognition performance. Results were discussed in terms of their implications for our understanding of the nature of memory difficulties in L LD children.

Intact implicit memory in patients with frontal lobe lesions

Patients with frontal lobe lesions and control subjects were administered tests of word-stem completion priming. In this implicit memory test, subjects are first presented words (e.g. MOTEL, PARADE) in an incidental learning paradigm. Following word presentation, subjects are shown word stems (e.g. MOT, PAR) and asked to produce the first word that comes to mind. Patients with frontal lobe lesions exhibited normal levels of word-stem completion. These findings indicate that implicit memory can operate normally despite damage to the prefrontal cortex. The present results substantiate previous neuropsychological and positron emission tomography findings which indicate that word priming depends critically on posterior cortical areas.

Dissociations among memory measures in memory-impaired subjects: evidence for a processing account of memory.

Deficits in conceptual transfer on both implicit and explicit memory tests were obtained for memory-impaired temporal lobe epileptic (TLE) subjects in three studies. In Experiment 1, in which a generate-read paradigm was employed, memory-impaired TLEs failed to show normal generation effects on conceptually driven tests of semantic cued recall and general knowledge questions, although their data-driven memory as measured by word-fragment completion and graphemic cued recall tasks was normal. In Experiment 2, memory-impaired patients having left temporal lobe seizure foci were tested on these four tasks and compared with nonimpaired TLEs having right temporal foci. The left TLEs showed deficits on conceptually driven tasks and normal memory for data-driven tests. These findings were extended in Experiment 3, in which left TLE patients failed to show any benefit from blocked study, as compared with random study, on category production and semantic cued-recall tests, although right TLEs and normal controls showed blocking effects on both tasks. These findings may be accommodated by a processing framework of memory in which memory-impaired patients are characterized as having deficits in conceptual, but not in data-driven, processing capabilities.