Elaboration effects in implicit and explicit memory tests

Dissociation effects in explicit and implicit tests of memory were examined in two experiments. In Experiment 1 serial-position effects were studied. Results showed that the standard primacy effect found in free recall is absent in an implicit word-stem completion test. In Experiment 2 a dissociation was found for the effect of high- and low-frequency words in free recall and word-stem completion tests. Both findings are explained in terms of a modified and extended version of the activation-elaboration learning account, which was inspired by attempts to simulate dissociation effects in connectionist models. The relationship between this account and two other leading accounts of dissociation effects in implicit and explicit memory is discussed, and a model to integrate aspects of all three accounts is suggested.     

The properties of retrieval cues constrain the picture superiority effect

In three experiments, we examined why pictures are remembered better than words on explicit memory tests like recall and recognition, whereas words produce more priming than pictures on some implicit tests, such as word-fragment and word-stem completion (e.g., completing -l-ph-nt or ele----- as elephant). One possibility is that pictures are always more accessible than words if subjects are given explicit retrieval instructions. An alternative possibility is that the properties of the retrieval cues themselves constrain the retrieval processes engaged; word fragments might induce data-driven (perceptually based) retrieval, which favors words regardless of the retrieval instructions. Experiment 1 demonstrated that words were remembered better than pictures on both the word-fragment and word-stem completion tasks under both implicit and explicit retrieval conditions. In Experiment 2, pictures were recalled better than words with semantically related extralist cues. In Experiment 3, when semantic cues were combined with word fragments, pictures and words were recalled equally well under explicit retrieval conditions, but words were superior to pictures under implicit instructions. Thus, the inherently data-limited properties of fragmented words limit their use in accessing conceptual codes. Overall, the results indicate that retrieval operations are largely determined by properties of the retrieval cues under both implicit and explicit retrieval conditions.     

Adult age differences in implicit and explicit memory: time course and encoding effects

Young and older adults were tested at three delays on word-stem completion or cued recall following semantic or structural word judgments. Identical three-letter stems were present at retrieval for both implicit (completion) and explicit (cued recall) tasks; only the intention to recall list words differed. The young adults outperformed the older adults on both implicit and explicit tasks at all test delays. Under some conditions, the older but not the young adults performed more poorly on cued recall than on stem completion, suggesting a possible failure to use implicitly available information to support explicit remembering. These results suggest that some forms of implicit memory decline with normal aging.     

A comparison of serial position effects in implicit and explicit word-stem completion

In this study I examined a further possible dissociation between implicit and explicit memory—whether implicit memory produces serial position effects that are similar to those found in explicit memory. When implicit word-stem completion and explicit word-stem cued recall were compared, only the explicit test showed significant primacy and recency effects. The explicit test was sensitive to the order in which stimuli words were encoded, but the implicit test was not. This dissociation between implicit and explicit memory provides further evidence that conscious retrieval processes were not involved in the implicit test.     

Priming and aging: further evidence of preserved memory function

Priming effects in word-stem completion were compared with cued recall in young and older adults. Cued recall showed large effects of age and also of levels of processing, but these variables had little influence on priming in word-stem completion. Free recall showed large effects of age as well as superior recall for words that had been generated rather than read at study, but priming in word-stem completion was little influenced by age, and it was greater for words that had been read at study rather than generated. These findings were interpreted as providing further evidence that age-related impairments in memory performance are greatly reduced in implicit compared with explicit tests. They also provide convergent evidence for classifying word-stem completion as a data-driven rather than conceptually driven task.     

Implicit memory for new associations: The pictorial influence

A series of experiments was conducted in order to show that implicit memory for new associations is not always dependent on semantic integrative processing during study. The material used in these experiments differed from traditional studies that employed pairs of unrelated words. Instead, targets (words in Exps. 1 and 2 and pictures in Exps. 3 and 4) were encoded in the context of an unrelated picture. The implicit tests used were word-stem completion (Exps. 1, 2, and 3) and picture-fragment identification (Exp. 4). The explicit test was word-stem cued recall (Exps. 1, 2, and 3) and picture-fragment cued recall (Exp 4). For implicit tests, context effects were not obtained using words as targets with a non-integrative semantic-elaboration encoding task (Exp. 1). When an integrative semantic-elaboration encoding task was used, a standard context effect emerged (Exp. 2) for implicit memory. Importantly, with pictures as targets, context effects appeared without integrative semantic encoding (Exps. 3 and 4). However, context effects were obtained for all conditions of cued recall. Results are discussed with regard to the concept of unitization.     

Effects of depth-of-processing and ageing on word-stem and word-fragment implicit memory tasks: Test of the lexical-processing hypothesis

The joint effects of depth-of-processing and age on repetition priming in implicit memory tests of word-fragment completion (WFC) and word-stem completion (WSC) were investigated. The experiment consisted of three study tasks (perceptual, lexical, and semantic) and four memory conditions: implicit (WSC and WFC) and explicit (WS cued recall and WF cued recall). In the WSC condition, semantic and lexical study processing produced equal priming, both superior to the perceptual study processing, whereas the WFC test showed equal priming for these three study conditions. This finding provides clear evidence, consistent with the lexical-processing hypothesis, that depth-of-processing in WSC priming reflects a lexical rather than a semantic process. It also provides support for the view that WSC and WFC involve different processes. However, there was no evidence of an age effect on either of these two implicit tasks. The data also revealed an overall significant effect of age and depth-of-processing, and an interaction between these variables on explicit cued recall tasks, indicating that older adults benefited less than younger ones from a deep encoding condition.     

A test of the survival processing advantage in implicit and explicit memory tests

The present study was designed to investigate the survival processing effect (Nairne, Thompson, & Pandeirada, Journal of Experimental Psychology: Learning, Memory, and Cognition, 33, 263–273, 2007) in cued implicit and explicit memory tests. The survival effect has been well established in explicit free recall and recognition tests, but has not been evident in implicit memory tests or in cued explicit tests. In Experiment 1 of the present study, we tested implicit and explicit memory for words studied in survival, moving, or pleasantness contexts in stem completion tests. In Experiment 2, we further tested these effects in implicit and explicit category production tests. Across the two experiments, with four separate memory tasks that included a total of 525 subjects, no survival processing advantage was found, replicating the results from implicit tests reported by Tse and Altarriba (Memory & Cognition, 38, 1110–1121, 2010). Thus, although the survival effect appears to be quite robust in free recall and recognition tests, it has not been replicated in cued implicit and explicit memory tests. The similar results found for the implicit and explicit tests in the present study do not support encoding elaboration explanations of the survival processing effect.     

Aging and memory for new associations: direct versus indirect measures.

Three experiments examined adult age differences in memory for new associations between unrelated words. On the indirect (word-stem completion) test, age differences appeared under the less-than-optimal study conditions of Experiments 1 and 3 but not under the self-paced study conditions of Experiment 2. In contrast, all experiments revealed significant age-related deficits on the direct tests, even those (word-stem cued recall) in which the cue was identical to those provided on the indirect test. The findings show that although age-related deficits in memory for new associations are particularly pronounced on tests requiring conscious recollection, age differences are not limited to such tests. Age deficits on both direct and indirect tests are related to the precision of elaborations produced during study. Similarities and differences between normal aging and amnesia are discussed, as are functional dissociations between direct and indirect measures.     

Recall and stem-completion priming have different electrophysiological correlates and are modified differentially by directed forgetting

The notion that different aspects of memory are assessed by explicit and implicit memory tests was supported by behavioral and electrophysiological results. In a study-test procedure, 24 subjects were instructed to remember some words and to forget other words. Free recall and cued recall were better for words associated with the remember instruction, whereas directed forgetting did not influence stem completion (an implicit memory test). Event-related brain potentials elicited during study differed as a function of subsequent memory performance for free recall and cued recall, but not for stem completion. These results implicate encoding differences in the distinction between the 2 types of memory test. Factors governing whether explicit retrieval affects performance on an implicit memory test, mechanisms that may underlie directed-forgetting effects, and the importance of electrophysiological correlates of memory are also discussed.     

Low Reliability of Perceptual Priming: Consequences for the Interpretation of Functional Dissociations Between Explicit and Implicit Memory

In this study, three experiments are presented that investigate the reliability of memory measures. In Experiment 1, the well-known dissociation between explicit (recall, recognition) and implicit memory (picture clarification) as a function of age in a sample of 335 persons aged between 65 and 95 was replicated. Test-retest reliability was significantly lower in implicit than in explicit measures. In Experiment 2, parallel-test reliabilities in a student sample confirmed the finding of Experiment 1. In Experiment 3, the reliability of cued recall and word stem completion was investigated. There were significant priming effects and a dissociation between explicit and implicit memory as a function of levels of processing. However, the reliability of implicit memory measures was again substantially lower than in explicit tests in all test conditions. As a consequence, differential reliabilities of direct and indirect memory tests should be considered as a possible determinant of dissociations between explicit and implicit memory as a function of experimental or quasi-experimental manipulations.     

Effects of attentional load and ageing on word-stem and word-fragment implicit memory tasks

The joint effects of reduced attention and age on repetition priming in implicit memory tests of word-fragment completion (WFC) and word-stem completion (WSC) were investigated. An attention load during the study phase reduced the extent of repetition priming in the WSC condition but not in WFC. This finding provides support for the view that WSC and WFC involve different processes. However, there was no evidence of an age effect on either of these two types of implicit tasks. The data also revealed an overall significant effect of age and reduced attention on explicit cued recall tasks.     

An investigation of cross-modality effects in implicit and explicit memory

Three experiments are reported which investigate the effects of study/test compatibility on implicit and explicit memory performance. In the first experiment subjects either named each visually presented target item, or generated each item from a close semantic associate. They were then given either a free recall test or a visual word-stem completion task. A generation effect was evident in the free recall data (generated items were better recalled than named items) and this pattern was reversed for word-stem completion. In the second experiment subjects again named or generated items and were then given an auditory word-stem completion task. Under these conditions, cross-modal priming was found both for named and for generated items, but the reverse generation effect, which was evident in Experiment 1 with word-stem completion, was eliminated. In the final experiment, subjects were asked to name the targets, read them silently, or read them under conditions of articulatory suppression, and were then given an auditory stem completion task. Significant cross-modal priming was observed under all three conditions. The strongest priming was found in the naming condition and the weakest in the suppression condition. The results are interpreted within the transfer appropriate processing framework.     

Age differences in collaborative memory: the role of retrieval manipulations

In two experiments, we examined age differences in collaborative inhibition (reduced recall in pairs of people, relative to pooled individuals) across repeated retrieval attempts. Younger and older adults studied categorized word lists and were then given two consecutive recall tests and a recognition test. On the first recall test, the subjects were given free-report cued recall or forced-report cued recall instructions (Experiment 1) or free recall instructions (Experiment 2) and recalled the lists either alone or in collaboration with another subject of the same age group. Free-report cued recall and free recall instructions warned the subjects not to guess, whereas forcedreport cued recall instructions required them to guess. Collaborative inhibition was obtained for both younger and older adults on initial tests of free-report cued recall, forced-report cued recall, and free recall, showing that the effect generalizes across several tests for both younger and older adults. Collaborative inhibition did not persist on subsequent individual recall or recognition tests for list items. Older adults consistently falsely recalled and recognized items more than did younger adults, as had been found in previous studies. In addition, prior collaboration may exaggerate older adults’ tendency toward higher false alarms on a subsequent recognition test, but only after a free recall test. The results provide generality to the phenomenon of collaborative inhibition and can be explained by invoking concepts of strategy disruption and source monitoring.     

Retrieval contexts and the concreteness effect: Dissociations in memory for concrete and abstract words

Decades of research on the concreteness effect, namely better memory for concrete as compared with abstract words, suggest it is a fairly robust phenomenon. Nevertheless, little attention has been given to limiting retrieval contexts. Two experiments evaluated intentional memory for concrete and abstract word lists in three retrieval contexts: free recall, explicit word-stem completion, and implicit word-stem completion. Concreteness effects were observed in free recall and in explicit word-stem completion, but not in implicit word-stem completion. These findings are consistent with both a bidirectional version of the relational-distinctiveness processing framework (Ruiz-Vargas, Cuevas, & Marschark, 1996) and a second framework combining insights from dual coding theory (Paivio, 1971, 1986) and the transfer appropriate processing framework (Roediger, Weldon, & Challis, 1989). Also, consistent with the relational-distinctiveness framework, the second experiment suggested that concreteness effects might depend on relational processing at encoding: Concreteness effects were observed in explicit memory for related word lists but not for unrelated word lists.     

The information that amnesic patients do not forget

The performance of three kinds of amnesic patients and control subjects was assessed using four methods for testing memory: free recall, recognition, cued recall, and word completion. Whereas amnesic patients were impaired on free recall, recognition, and cued recall, they were normal on word completion. Moreover, performance on the word-completion test declined at a normal rate reaching chance after about 120 min. The word-completion test resembled the cued-recall test in that the initial letters of previously presented words were given as cues. It differed from cued recall only in the instructions, which directed subjects away from the memory aspects of the test and asked them to complete each three-letter cue with the first word that came to mind. The present results offer an explanation of conflicting findings that have been obtained with amnesic patients on tests of the cued-recall type. The results are considered in terms of a process (activation or procedural learning), which is spared in amnesia and not dependent on the integrity of the damaged brain regions.     

Effects of color on perceptual and conceptual tests of implicit memory

Two experiments are reported that explore why recent investigations of implicit memory failed to find any effects of color information on test performance. In the first experiment, participants studied colored pictures as well as words printed in colored ink without any memory instructions. During the test phase, a verbal and a pictorial version of a color-choice task (a conceptual priming test) were compared to two perceptual tests (word-stem completion and picture-fragment identification). Similar and significant amounts of priming to color occurred in both color-choice tasks. The perceptual tests were found to be sensitive to changes in the stimulus-presentation mode from study to test, but stimuli remaining the same color and those changed to black-and-white did not differ in the priming scores. In the second experiment, a mild division of attention was introduced in the study phase. Once again, priming to color was observed only in the verbal version of a color-choice test and not in the word-stem completion test. Dividing attention did not decrease performance on both implicit tests, whereas an explicit test of color recall for studied pictures suffered from dividing attention at encoding. It is concluded that a perceptual attribute such as color may be represented and coded by conceptual processing. Furthermore, automatic (or not attention-demanding) encoding processes may suffice for later conceptual tests of implicit memory. Previous failures to find any effects of color information on implicit performance are attributed to the use of perceptual priming tests. Received: 30 June 1997 / Accepted: 20 April 1998     

Search and selection processes in implicit and explicit word-stem completion performance in young, middle-aged, and older adults

In the present investigation, we sought to (1) replicate previous reports of impaired word-stem completion (WSC) priming and cued recall performance in older adults, (2) gain a better understanding of the differential roles of search and selection processes in implicit and explicit WSC, and (3) determine the particular aspects of WSC performance that are influenced by age. Experiment 1 demonstrated that older adults primed and recalled fewer items on a WSC task than middle-aged adults did, who in turn primed and recalled fewer items than young adults did. A series of item analyses indicated that choice of a stem completion is influenced by two independent sources of information: the familiarity of the completion reflected by word frequency and the cue-specific match between the stem and the completion word based on the common pronunciation of the stem. Experiment 2 demonstrated that older adults utilized cue-specific matching to the same degree as young and middle-aged adults. However, the impact of target familiarity changed across the lifespan. Older adults produced and recalled high-frequency targets as well as young adults but produced and recalled fewer low-frequency targets than did young participants. The results are consistent with the view that older adults rely on familiarity to a greater degree than do young adults.     

Musical stem completion: humming that note

This study looked at how people store and retrieve tonal music explicitly and implicitly using a production task. Participants completed an implicit task (tune stem completion) followed by an explicit task (cued recall). The tasks were identical except for the instructions at test time. They listened to tunes and were then presented with tune stems from previously heard tunes and novel tunes. For the implicit task, they were asked to sing a note they thought would come next musically. For the explicit task, they were asked to sing the note they remembered as coming next. Experiment 1 found that people correctly completed significantly more old stems than new stems. Experiment 2 investigated the characteristics of music that fuel retrieval by varying a surface feature of the tune (same timbre or different timbre) from study to test and the encoding task (semantic or nonsemantic). Although we did not find that implicit and explicit memory for music were significantly dissociated for levels of processing, we did find that surface features of music affect semanticjudgments and subsequent explicit retrieval.     

Environmental context effects in conceptual explicit and implicit memory

Previous research has found environmental context effects for both conceptual explicit and conceptual implicit memory (Parker, Gellatly, & Waterman, 1999). The research presented here challenges these findings on methodological grounds. Experiment 1 assessed the effects of context change on category-exemplar generation (conceptual implicit memory test) and category-cued recall (conceptual explicit memory test). Experiment 2 assessed the effects of context change on word association (conceptual implicit memory test) and word associate cued recall (conceptual explicit memory test). In both experiments, study-test changes in environmental context were found to influence performance only on tests of explicit memory. It is concluded that when retrieval cues across explicit and implicit tests are matched, and the probability of explicit contamination is reduced, then only conceptual explicit test performance is reduced by study-test changes in environmental context.