Indirect Memory Tests Research Articles

Distinctiveness and serial position functions in implicit memory

ABSTRACTSerial position functions, with their characteristic primacy and recency effects, are ubiquitous in episodic memory tasks, and have also been observed in tasks tapping semantic memory. However, only one experiment, [Raanaas, R. K., & Magnussen, S. (2006a). Serial position effects in implicit memory. European Journal of Cognitive Psychology, 18, 398–414. doi:10.1080/09541440500162065], has demonstrated primacy and recency effects in implicit memory using an indirect memory test. In Experiment 1, we replicate this finding and in Experiment 2, we confirm a prediction that holds only if the serial position function observed in Experiment 1 was a “real” serial position function. These results confirm the presence of serial position functions in implicit memory and also support a general prediction of the relative distinctiveness principle that serial position functions should obtain whenever a set of items are ordered along a relevant dimension.

Subliminally and Supraliminally Acquired Long-Term Memories Jointly Bias Delayed Decisions.

Common wisdom and scientific evidence suggest that good decisions require conscious deliberation. But growing evidence demonstrates that not only conscious but also unconscious thoughts influence decision-making. Here, we hypothesize that both consciously and unconsciously acquired memories guide decisions. Our experiment measured the influence of subliminally and supraliminally presented information on delayed (30–40 min) decision-making. Participants were presented with subliminal pairs of faces and written occupations for unconscious encoding. Following a delay of 20 min, participants consciously (re-)encoded the same faces now presented supraliminally along with either the same written occupations, occupations congruous to the subliminally presented occupations (same wage-category), or incongruous occupations (opposite wage-category). To measure decision-making, participants viewed the same faces again (with occupations absent) and decided on the putative income of each person: low, low-average, high-average, or high. Participants were encouraged to decide spontaneously and intuitively. Hence, the decision task was an implicit or indirect test of relational memory. If conscious thought alone guided decisions (= H0), supraliminal information should determine decision outcomes independently of the encoded subliminal information. This was, however, not the case. Instead, both unconsciously and consciously encoded memories influenced decisions: identical unconscious and conscious memories exerted the strongest bias on income decisions, while both incongruous and congruous (i.e., non-identical) subliminally and supraliminally formed memories canceled each other out leaving no bias on decisions. Importantly, the increased decision bias following the formation of identical unconscious and conscious memories and the reduced decision bias following to the formation of non-identical memories were determined relative to a control condition, where conscious memory formation alone could influence decisions. In view of the much weaker representational strength of subliminally vs. supraliminally formed memories, their long-lasting impact on decision-making is noteworthy.

Suppressing Unwanted Memories Reduces Their Unintended Influences

The ability to control unwanted memories is critical for maintaining cognitive function and mental health. Prior research has shown that suppressing the retrieval of unwanted memories impairs their retention, as measured using intentional (direct) memory tests. Here, we review emerging evidence revealing that retrieval suppression can also reduce the unintended influence of suppressed traces. In particular, retrieval suppression (a) gradually diminishes the tendency for memories to intrude into awareness and (b) reduces memories’ unintended expressions on indirect memory tests. We present a neural account in which, during suppression, retrieval cues elicit hippocampally triggered neocortical activity that briefly reinstates features of the original event, which, in turn, are suppressed by targeted neocortical and hippocampal inhibition. This reactivation-dependent reinstatement principle could provide a broad mechanism by which suppressing retrieval of intrusive memories limits their indirect influences.

Application of item response theory to tests of substance-related associative memory.

A substance-related word-association test (WAT) is one of the commonly used indirect tests of substance-related implicit associative memory and has been shown to predict substance use. This study applied an item response theory (IRT) modeling approach to evaluate psychometric properties of the alcohol- and marijuana-related WATs and their items among 775 ethnically diverse at-risk adolescents. After examining the IRT assumptions, item fit, and differential item functioning (DIF) across gender and age groups, the original 18 WAT items were reduced to 14 and 15 items in the alcohol- and marijuana-related WAT, respectively. Thereafter, unidimensional one- and two-parameter logistic models (1PL and 2PL models) were fitted to the revised WAT items. The results demonstrated that both alcohol- and marijuana-related WATs have good psychometric properties. These results were discussed in light of the framework of a unified concept of construct validity (Messick, 1975, 1989, 1995).

Prescription drug advertisements and older adults: a case for implicit memory

Purpose – Prescription drug advertisements are commonly seen in magazines and on television. Many drug ads are targeted toward older adults, who tend to use more medications and suffer from more chronic conditions. Nonetheless, the effectiveness of such advertising remains uncertain. The aim of this paper is to compare implicit and explicit memory for drug ads in older and younger adults. Design/methodology/approach – Older adults typically perform more poorly than young adults on explicit memory tasks, but not on implicit memory tasks. The current study measured implicit memory with an incidental ratings exercise and an indirect test of preference; explicit memory was also measured with intentional studying and a direct test of recognition. The study was a 2 x 2 mixed experimental design with one between-participants variable and one within-participants variable. The between-participants variable was age group (older vs younger adults) and the within-participants variable was implicit and explicit memory. The memory test measures were the outcome variables of the study. Findings – The results showed no age difference for implicit memory for drug ads, but an age difference was found for explicit memory for the ads. The implicit memory manipulation succeeded in demonstrating that drug ads are persuasive, suggesting that a complete assessment of advertising effectiveness should include a test of implicit memory. Research limitations/implications – The fact that age differences were not found for implicit memory, but were found for explicit memory, is not surprising. Practical implications – The study is of theoretical significance because it contributes to cognitive aging research and examines memory within an everyday context. The study is of practical significance because pharmaceutical companies spend vast amounts of money on prescription drug advertisements that may or may not be effective with older adults. The component of this study that may be most important is that the results expanded everyday memory research to another applied context using an implicit memory measure, and the indirect test of memory demonstrated that the prescription drug advertising was effective. Originality/value – Although the findings were consistent with previous research, the study focuses on the real-world context of direct-to-consumer advertising for prescription drugs. Given that older adults have poorer explicit memory than younger adults, but not poorer implicit memory, it is particularly important for advertisers to use implicit memory measures when assessing advertisements aimed at older adult consumers. Marketers of pharmaceutical drug companies must remain aware that the memory abilities of their potential customers are extremely variable, and in some cases, limited.

Metamemory for indirect memory test of English words that are required vocabulary for university enterance examination: A test of cue-familiarity hypothesis (2).

Metamemory for indirect memory test of English words that are required vocabulary for university enterance examination: A test of cue-familiarity hypothesis (2).

False recognition of objects in visual scenes: Findings from a combined direct and indirect memory test

We report an extension of the procedure devised by Weinstein and Shanks (Memory & Cognition 36:1415-1428, 2008) to study false recognition and priming of pictures. Participants viewed scenes with multiple embedded objects (seen items), then studied the names of these objects and the names of other objects (read items). Finally, participants completed a combined direct (recognition) and indirect (identification) memory test that included seen items, read items, and new items. In the direct test, participants recognized pictures of seen and read items more often than new pictures. In the indirect test, participants' speed at identifying those same pictures was improved for pictures that they had actually studied, and also for falsely recognized pictures whose names they had read. These data provide new evidence that a false-memory induction procedure can elicit memory-like representations that are difficult to distinguish from "true" memories of studied pictures.

Dynamic grammar in adults: Incidental learning of natural syntactic structures extends over 48 h

Three experiments examine whether a naturalistic reading task can induce long-lasting changes of syntactic patterns in memory. Judgment of grammatical acceptability is used as an indirect test of memory for sentences that are identical or only syntactically similar to those read earlier. In previous research ( Luka & Barsalou, 2005) both sorts of sentences were found more acceptable, yielding a structural preference for recently encountered syntactic patterns. The effect is evident across a very diverse set of some 60 distinct sentence constructions. This phenomenon may be similar to implicit learning paradigms using evaluative ratings as dependent measures, but also resembles a variety of shorter-lived structural priming effects observed for a handful of syntactic constructions that occur in binary alternate forms. Here we examine the duration of the structural preference effect to determine whether it is fleeting (suggesting transient priming) or long-lasting (suggesting enduring changes in representation). Experiments 1 and 2 show that the effect is evident after a 48-h delay between initial exposure (simple reading aloud) and test. Experiment 3 shows a persistent effect after 7 days, despite unrestricted exposure to natural language in the interim. Larger effects were observed for comparatively novel sentence constructions than common syntactic patterns. Experiments 2 and 3 also examine the role of the evaluation process itself, and find that reading for comprehension produces greater facilitation than reading while performing an evaluative categorization (grammaticality rating). These observations suggest that incremental adjustments to the language processing system occur on a continuous basis and may extend to acquisition of novel syntactic structures. We discuss whether and in what ways the structural preference effect can be integrated with the literature on structural priming. We interpret our results in the context of models of language comprehension, emphasize the dynamic nature of grammatical knowledge in memory, and argue that the current paradigm offers several advantages for elaborating the various systems of memory upon which linguistic representations depend.

Electrophysiological correlates of exemplar-specific processes in implicit and explicit memory

The present ERP study investigated the retrieval of task-irrelevant exemplar-specific information under implicit and explicit memory conditions. Subjects completed either an indirect memory test (a natural/artificial judgment) or a direct recognition memory test. Both test groups were presented with new items, identical repetitions, and perceptually different but conceptually similar exemplars of previously seen study objects. Implicit and explicit memory retrieval elicited clearly dissociable ERP components that were differentially affected by exemplar changes from study to test. In the indirect test, identical repetitions, but not different exemplars, elicited a significant ERP repetition priming effect. In contrast, both types of repeated objects gave rise to a reliable old/new effect in the direct test. The results corroborate that implicit and explicit memory fall back on distinct cognitive representation and, more importantly, indicate that these representations differ in the type of stimulus information stored. Implicit retrieval entailed obligatory access to exemplar-specific perceptual information, despite its being task irrelevant. In contrast, explicit retrieval proved to be more flexible with conceptual and perceptual information accessed according to task demands.

Implicit memory for object locations depends on reactivation of encoding-related brain regions

This study explored the correspondence between implicit memory and the reactivation of encoding-related brain regions. By using a classification method, we examined whether reactivation reflects only the similarities between study and test or voxels at the reactivated regions are diagnostic of facilitation in the implicit memory task. A simple detection task served as incidental encoding of object-location pairings. A subsequent visual search task served as the indirect (implicit) test of memory. Subjects did not know that their memory would be tested. Half of the subjects were unaware that some stimuli in the search task are the same as those that had appeared during the detection task. Another group of subjects was made aware of this relationship at the onset of the visual search task. Memory performance was superior for the study-test aware, compared to study-test unaware, subjects. Brain reactivation was calculated using a conjunction analysis implemented through overlaying the neural activity at encoding and testing. The conjunction analysis revealed that implicit memory in both groups of subjects was associated with reactivation of parietal and occipital brain regions. We were able to classify study-test aware and study-test unaware subjects based on the per-voxel reactivation values representing the neural dynamics between encoding and test. The classification results indicate that neural dynamics between encoding and test accounts for the differences in implicit memory. Overall, our study demonstrates that implicit memory performance requires and depends upon reactivation of encoding-related brain regions.

Time to Go Our Separate Ways: Opposite Effects of Study Duration on Priming and Recognition Reveal Distinct Neural Substrates

Amnesic patients have difficulties recognizing when stimuli are repeated, even though their responses to stimuli can change as a function of repetition in indirect tests of memory – a pattern known as priming without recognition. Likewise, experimental manipulations can impair recognition in healthy individuals while leaving priming relatively unaffected, and priming and recognition have been associated with distinct neural correlates in these circumstances. Does this evidence necessarily indicate that priming and recognition rely on distinct brain systems? An alternative explanation is that recognition is merely more sensitive to amnestic insults and experimental manipulations than is priming, and that both priming and recognition are produced by a single brain system. If so, then experimental manipulations would tend to drive priming and recognition in the same direction, albeit to a greater extent for one versus the other in some circumstances. We found evidence to the contrary – that manipulating study duration has opposite effects on priming versus recognition. Studying objects for one-quarter second led to worse recognition than studying objects for 2 s, whereas the opposite was true for priming (greater for one-quarter-second study than two-second study). Furthermore, distinct electrophysiological repetition effects were associated with priming versus recognition. We therefore conclude that study duration had opposite effects on priming and recognition, and on the engagement of implicit versus explicit memory systems. These findings call into question single-process accounts of priming and recognition, and substantiate previous behavioral, neuropsychological, and neuroimaging dissociations between implicit and explicit memory.

Directed forgetting in direct and indirect tests of memory: Seeking evidence of retrieval inhibition using electrophysiological measures

We investigated whether directed forgetting as elicited by the item-cueing method results solely from differential rehearsal of to-be-remembered vs. to-be-forgotten words or, additionally, from inhibitory processes that actively impair retrieval of to-be-forgotten words. During study, participants ( N = 24) were instructed to remember half of a series of presented words (TBR) and to forget the other half (TBF), as indicated by an instruction cue shown shortly after each word. During test, accuracy and reaction time measures from lexical decisions (indirect memory test) followed by recognition-memory judgements (direct memory test) were supplemented with event-related potential (ERP) recordings. Results from the behavioural measures revealed directed forgetting in the recognition-memory test but not the lexical-decision test. ERPs obtained during recognition indicated that TBR words elicited a larger parietal old/new effect than TBF words overall, suggesting that remember/forget instructions impaired conscious recollection processes more severely than familiarity processes. Moreover, TBF words that were successfully forgotten elicited less parietal activity than correctly rejected new words ( the reversed old/ new effect; Nowicka, A., Jednorórog, K., Wypych, M., & Marchewka, A. (2009). Reversed old/new effect for intentionally forgotten words: An ERP study of directed forgetting. International Journal of Psychophysiology, 71, 97–102). This was taken to implicate that inhibitory processes likely affected these items. Enhanced negativities for successfully forgotten TBF words relative to new words were observed in the lexical-decision task at early (150–250 ms) and late (800–1000 ms) time windows, suggesting that inhibitory influences disrupt more than just conscious recollection when memory retrieval is tested indirectly.

Long-term repetition priming of briefly identified objects.

The authors provide evidence that long-term memory encoding can occur for briefly viewed objects in a rapid serial visual presentation list, contrary to claims that the brief presentation and quick succession of objects prevent encoding by disrupting a memory consolidation process that requires hundreds of milliseconds of uninterrupted processing. Subjects performed a search task in which each item was presented for only 75 ms. Nontargets from the search task generated priming on 2 subsequent indirect memory tests: a search task and a task requiring identification of visually masked objects. Additional experiments revealed that information encoded into memory for these nontargets included perceptual and conceptual components, and that these results were not due to subjects maintaining items in working memory during list presentation. These results are consistent with recent neurophysiological evidence showing that stimulus processing can occur at later stages in the cognitive system even when a subsequent new stimulus is presented that initiates processing at earlier stages.

Neurophysiological evidence for transfer appropriate processing of memory: Processing versus feature similarity

Transfer appropriate processing (TAP) accounts propose that memory is a function of the degree to which the same neural processes transfer appropriately from the study experience to the memory test. However, in prior research, study and test stimuli were often similar physically. In two experiments, event-related brain potentials (ERPs) were recorded to fragmented objects during an indirect memory test to isolate transfer of a specific perceptual process from overlap of physical features between experiences. An occipitotemporoparietal P2(00) at 200 msec showed implicit memory effects only when similar perceptual grouping processes of good continuation were repeatedly engaged-despite physical feature differences--as TAP accounts hypothesize. This result provides direct neurophysiological evidence for the critical role of process transfer across experiences for memory.

Neurophysiological Evidence for the Time Course of Activation of Global Shape, Part, and Local Contour Representations during Visual Object Categorization and Memory

Categorization of visual objects entails matching a percept to long-term representations of structural knowledge. This object model selection is central to theories of human visual cognition, but the representational format(s) is largely unknown. To characterize these neural representations, event-related brain potentials (ERPs) to fragmented objects during an indirect memory test were compared when only local contour features, but not global shapes of the object and its parts, differed between encoding and retrieval experiences. The ERP effects revealed that the format of object representations varies across time according to the particular neural processing and memory system currently engaged. An occipito-temporal P2(00) showed implicit memory modulation to items that repeatedly engaged similar perceptual grouping processes but not items that merely reinstantiated visual features. After 500 msec, memory modulation of a late positive complex, indexing secondary categorization and/or explicit recollection processes, was sensitive to local contour changes. In between, a frontocentral N350, indexing the model selection and an implicit perceptual memory system, showed reactivation of object representations whenever the same global shapes were reactivated, despite local feature differences. These and prior N350 findings provide direct neurophysiological evidence that the neural representations supporting object categorization include knowledge beyond local contours and about higher-order perceptual structures, such as the global shapes of the object and its parts, that can differ between object views. The N350 is proposed to index a second state of interactive, recurrent, and feedback processing in occipital and ventral temporal neocortex supporting higher-order cognitive abilities and phenomenological awareness with objects.

Probabilistic retroactive interference: The role of accessibility bias in interference effects.

Probabilistic retroactive interference (RI) refers to the interfering effects of intermixing presentations of an earlier studied response (A-B) with presentations of a competing response (A-D). As an example, for a 2/3 condition, a cue word was presented with its earlier studied response twice and its competing response once during the interference phase. Performance on direct and indirect tests of memory for earlier studied responses was combined to reveal dissociations between effects on recollection and accessibility bias. Manipulating probabilistic RI influenced accessibility bias but left recollection unchanged. Effects of probabilistic RI were compared with effects of traditional, nonprobabilistic RI. The authors contrast their dual-process model with traditional accounts of RI and discuss the importance of distinguishing between recollection and accessibility bias for understanding interference effects.

Assessing activation without source monitoring in the DRM false memory paradigm

Four experiments examined whether studying a single Deese/Roediger-McDermott (DRM) list produces semantic priming for nonstudied critical items (CIs) and semantic + repetition priming for studied associates. After 30 s of mental arithmetic that followed the study of a DRM list, priming was assessed in a lexical decision task when the nonwords were either pronounceable (Experiment 1) or pseudohomophones (Experiments 2–4). Priming was measured relative to a baseline containing exactly the same CIs and associates that had not been primed by their related DRM lists. Significant CI semantic priming effects occurred in all four experiments, whether or not there was within-test priming from a related associate preceding the CI by 3–7 items. To our knowledge, these are the first experiments using standard DRM study procedures to provide a convincing demonstration of a genuine CI semantic priming effect in a delayed indirect memory test that should be free of intentional retrieval strategies. Discussion focuses on measuring long-term semantic activation effects without the influence of source monitoring in a lexical decision task.

Aging and the Deletion Function of Inhibition

The present study was adapted from the sentence completion task of Hartman and Hasher (1991). We addressed the question raised by Burke (1997): are the age-related differences in priming effects found in that task better explained by deficits in explicit memory or by inefficient inhibitory mechanisms? In the study phase, older and younger adults read high cloze sentences ending with an expected or an unexpected final word. In the second phase, participants were asked to complete sentence frames with either the final word presented during the study phase (inclusion condition) or with another, new word (exclusion condition). The third phase was an indirect memory test of perceptual identification. Finally, we compared explicit memory for recalled and inhibited words in a recognition test. In perceptual identification by older adults, priming was equivalent for recalled and inhibited words, whereas in younger adults priming was higher for recalled than for inhibited words. In the explicit memory test, recognition scores were lower for inhibited words in both age groups. These results are consistent with the view of Hasher and Zacks (1988), who assume an age-related decline in the ability to suppress no-longer-relevant information

A test of the orthographic recoding hypothesis

The Orthographic Recoding Hypothesis [D. E. Gaygen and P. A. Luce, Percept. Psychophys. 60, 465–483 (1998)] was tested. According to this hypothesis, listeners recognize spoken words heard for the first time by mapping them onto stored representations of the orthographic forms of the words. Listeners have a stable orthographic representation of words, but no phonological representation, when those words have been read frequently but never heard or spoken. Such may be the case for low frequency words such as jargon. Three experiments using visually and auditorily presented nonword stimuli tested this hypothesis. The first two experiments were explicit tests of memory (old–new tests) for words presented visually. In the first experiment, the recognition of auditorily presented nonwords was facilitated when they previously appeared on a visually presented list. The second experiment was similar, but included a concurrent articulation task during a visual word list presentation, thus preventing covert rehearsal of the nonwords. The results were similar to the first experiment. The third experiment was an indirect test of memory (auditory lexical decision task) for visually presented nonwords. Auditorily presented nonwords were identified as nonwords significantly more slowly if they had previously appeared on the visually presented list accompanied by a concurrent articulation task.

The orthographic distinctiveness effect on direct and indirect tests of memory: delineating the awareness and processing requirements

We examined the processing and awareness requirements that mediate superior memory for distinct items in long-term memory by studying the effects of orthographic distinctiveness. Orthographically distinct words are remembered better than common words on the direct test of free recall but not on the indirect test of perceptual identification. These results suggest that the orthographic distinctiveness effect requires test awareness. But interestingly, this distinctiveness effect has also been reported in one indirect test, that of word fragment completion ( Hunt & Toth, 1990). We examined the locus of the orthographic distinctiveness effect in the indirect test of word fragment completion and the direct tests of word fragment cued recall and free recall and assessed the role of awareness (Experiment 1) and conceptual processes (Experiments 2a–2c) in mediating this effect. Our results support the proposal that the distinctiveness effect depends on direct reference to the study context and further specify that this effect is mediated, to a large extent, by comparative processes even when distinctiveness emerges from surface-level differences.