Determinants of word fragment completion

A current debate in the memory literature concerns the validity of word fragment completion (WFC) as a test of implicit memory. It has been claimed that language variables exert a strong influence on the task, and that the task reflects memory only to a small extent (Hintzman & Hartry, 1990). For these reasons, the use of contingency analyses of recognition and WFC performance as a means of studying underlying memory processes has been criticized. The present study addressed this issue by examining the influence of language variables on completion of a set of computer generated single-solution fragments of Swedish words (Olofsson & Nyberg, 1992). It was found that language variables indeed had a large effect on completion performance, and that priming only accounted for a small portion of variance in the task. It is therefore suggested that the method of triangulation should be employed for contingency analyses involving WFC.     

On the logic of testing the independence assumption in the process-dissociation procedure

Theprocess-dissociation procedure is designed to provide quantitative estimates of the influence of explicit and implicit memory in a variety of tasks. The procedure relies on the assumption that these two forms of memory produce independent influences on performance. Prior investigators have attempted to test this assumption by determining whether the parameter representing the influence of implicit memory (denotedA) is constant across experimental conditions. I argue that the constancy of A cannot provide an appropriate test of the independence assumption, because (1) the prediction of constancy can be generated without the assumption of independence, obviating the need to posit independence; and (2) the constancy ofA does not necessarily imply independence, even if one assumes that a dependency hypothesis, supplemented by ancillary assumptions (Curran & Hintzman, 1995), predicts differences inA. I close by emphasizing that we can test the independence assumption by using standard procedures that compare the fit of a model that assumes independence with the fit of a model that assumes dependence.     

Contingent dissociation between recognition and fragment completion: the method of triangulation

Two experiments conforming to the logic of the method of triangulation were conducted. Following the study of a list of words, the first of two successive tests (recognition) was identical for two groups of subjects, but the second one, in which the same word-fragment cues were presented to both groups, differed with respect to retrieval instructions. Subjects in one group engaged in cued recall of study-list words, whereas those in the second group completed the fragments with the first word that came to mind. Both experiments yielded the same result: The dependency between the first and second tests, indexed by Yule's Q statistic, was greater for recognition and cued recall than it was for recognition and fragment completion. These results speak to the controversial issue of the usefulness of contingency analyses of data from successive memory tests. The results are interpreted in a theoretical framework consisting of an integration of the idea of a hypothetical quasi-memory system with the transfer-appropriate procedural approach.     

Direct comparison of two implicit memory tests: word fragment and word stem completion.

In 3 experiments, the implicit memory tests of word fragment and word stem completion showed comparable effects over several variables: Study of words produced more priming than did study of pictures, no levels-of-processing effect occurred for words, more priming was obtained from pictures when Ss imaged the pictures' names than when they rated them for pleasantness, and forgetting rates were generally similar for the tests. A different pattern of results for the first 3 variables occurred under explicit test conditions with the same word fragments or word stems as cues. We conclude that the 2 implicit tests are measuring a similar form of perceptual memory. Furthermore, we argue that both tests are truly implicit because they meet Schacter, Bowers, & Booker's (1989) retrieval intentionality criterion: Levels of processing of words have a powerful effect on explicit versions of the tests but no effect on implicit versions.     

Bias effects in word fragment completion in young and older adults

Young and older adults were tested on a word fragment completion task in which correct solutions were studied words, words orthographically similar to studied words, or new words. In Experiments 1 and 2, the standard production version of the word fragment completion task was used; older adults had reduced benefits of prior exposure to target words and slightly decreased costs. However, costs and benefits did not differ across age in a forced-choice version of the task (Experiment 3). At a behavioral level, the results are contrary to predictions that age differences in word fragment completion priming effects will be greater when there is a strong competitor for the correct solution and that age differences in both costs and benefits will be smaller for identification than for production tasks. Theoretical implications of these findings are considered.     

Affective valence and memory in depression: dissociation of recall and fragment completion.

Depressed (n = 16) and nondepressed (n = 16) subjects' memory for affectively valenced words was assessed by an explicit test (free recall) and an implicit test (word fragment completion). Under free-recall instructions, depressed subjects recalled significantly more negatively valenced than positively valenced words, whereas the opposite pattern was observed in nondepressed control subjects. These results replicate those previously reported in the literature. The differential effect of word valence was absent, however, when memory was tested implicitly: Depressed and nondepressed subjects exhibited equivalent priming of positive and negative words. These data are discussed in terms of Williams, Watts, MacLeod, and Mathews's (1988) model of depression.     

Repetition effects on word fragment completion: The role of competition among responses

Four experiments examined the effect of spaced repetition of study words on completion of word fragments with only one solution and word fragments with multiple solutions. Recognition was used as test of explicit memory in the first two experiments. The study words were presented either once or three times. Repetition was found to increase recognition memory substantially, and to affect fragment completion performance only marginally. This was true for both single- and multiple-solution fragments, showing that competition among responses is not critical for the magnitude of the repetition effect in fragment completion. This finding, that the repetition effect is marginal also when the type of cues provides an occasion for repetition effects to show up, suggests that the real effect of repetition on perceptual priming is borderline. It is proposed that memory from the first presentation eliminates necessary processing of items when they are re-exposed, and that the repetition effect thereby is reduced.     

A test of the optimal classifier's independence assumption in perceptual categorization

Observers completed perceptual categorization tasks that included separate base-rate/payoff manipulations, corresponding simultaneous base-rate/payoff manipulations, and conflicting simultaneous base-rate/payoff manipulations. Performance (1) was closer to optimal for 2:1 than for 3:1 base-rate/payoff ratios and when base rates as opposed to payoffs were manipulated, and (2) was more in line with the predictions from the flat-maxima hypothesis than from the independence assumption of the optimal classifier in corresponding and conflicting simultaneous base-rate/payoff conditions. A hybrid model that instantiated simultaneously the flat-maxima and the competition between reward and accuracy maximization (COBRA) hypotheses was applied to the data. The hybrid model was superior to a model that incorporated the independence assumption, suggesting that violations of the independence assumption are to be expected and are well captured by the flat-maxima hypothesis without requiring any additional assumptions. The parameters indicated that observers' reward-maximizing decision criterion rapidly approaches the optimal value and that more weight is placed on accuracy maximization in separate and corresponding simultaneous base-rate/payoff conditions than in conflicting simultaneous base-rate/payoff conditions.     

A paradoxical dissociation in the effects of midazolam on recollection and automatic processes in the process dissociation procedure

This study used midazolam-induced amnesia to explore the plausibility of the estimates provided by the process dissociation procedure (PDP), which is designed to estimate the contributions of recollection (R) and automatic (A) processes to implicit memory performance. In a double-blind, placebo-controlled, within-subject design with 24 participants, single midazolam doses were administered intravenously, and word stem completion performance was used to calculate PDP estimates. A dissociation was observed such that midazolam decreased R but increased A estimates relative to placebo. Given that a manipulation that induces amnesia would not be expected to facilitate a memory process, these results add to the accumulating body of evidence suggesting that PDP estimates are not always theoretically plausible. Such evidence raises important questions about the use of the PDP.     

Cue depreciation: when word fragment completion is undermined by prior exposure to lesser fragments

The ability to think of a previously studied item has often been shown to be impaired when, in one way or another, the extraitem context is changed from study to test. In a series of five experiments, such impairment is induced in a somewhat different way. A fragment (e.g. r-i--rop) of a just-studied word (raindrop) is shown to be less readily completed if it is presented bit by bit (r------p, r----r-p, r-i--r-p, r-i--rop) rather than all at once (Experiments 1, 3, 4, and 5). No such effect is found if the word has not been studied beforehand (Experiments 2, 3, 4, and 5). This pattern of results occurs even when fragments of studied and nonstudied words occur in the same test and under conditions in which subjects cannot tell whether a given fragment is of a studied or nonstudied word (Experiments 4 and 5). In addition, for words that have been studied beforehand, the impairment is shown to increase systematically with the number of steps involved in the presentation of the word fragment (Experiment 3) and also to persist when the time allowed for completion of the final version of the fragment is increased from 4 s to a full minute (Experiment 5).     

A comparison of conscious and automatic memory processes for picture and word stimuli: a process dissociation analysis

Four experiments were conducted to evaluate explanations of picture superiority effects previously found for several tasks. In a process dissociation procedure (Jacoby, 1991) with word stem completion, picture fragment completion, and category production tasks, conscious and automatic memory processes were compared for studied pictures and words with an independent retrieval model and a generate-source model. The predictions of a transfer appropriate processing account of picture superiority were tested and validated in "process pure" latent measures of conscious and unconscious, or automatic and source, memory processes. Results from both model fits verified that pictures had a conceptual (conscious/source) processing advantage over words for all tasks. The effects of perceptual (automatic/word generation) compatibility depended on task type, with pictorial tasks favoring pictures and linguistic tasks favoring words. Results show support for an explanation of the picture superiority effect that involves an interaction of encoding and retrieval processes.     

The nature of memory processes underlying recognition judgments in the process dissociation procedure

The hypothesis is tested that the memory processes involved in recognition judgments in the process dissociation procedure are the same as those involved in standard source-monitoring tasks. It is shown how source-monitoring response categories can be mapped onto process dissociation response categories. On the basis of this observation, an experiment was conducted in which it was possible to compare, using a multinomial modeling approach, the parameters representing memory processes in the process dissociation procedure with those involved in source monitoring. For the two different encoding conditions realized, the results are compatible with the hypothesis that the same processes are involved in source monitoring and in recognition judgments in the process dissociation procedure. Implications for the interpretation of the model’s parameters are discussed.     

Effects of age on estimated familiarity in the process dissociation procedure: The role of noncriterial recollection

Research on recognition memory using the process dissociation procedure has suggested that although recollection (R) declines with age, familiarity (F) remains age invariant. However, this research has used relatively broad definitions of R. An important question concerns age-related changes in memory when R is defined in terms of specific event details. Yonelinas and Jacoby (1996a) required young participants to recollect specific, criterial details of a prior event and found evidence that recollection of noncriterial details elevated estimates of F yet still operated automatically. In the present study, the issue of noncriterial recollection was examined in the context of aging. The results replicated the effects of noncriterial recollection for the young, but not for the older adults, who also showed overall reduced levels of familiarity.     

Use of the mutual exclusivity assumption by young word learners

A critical question about early word learning is whether word learning constraints such as mutual exclusivity exist and foster early language acquisition. It is well established that children will map a novel label to a novel rather than a familiar object. Evidence for the role of mutual exclusivity in such indirect word learning has been questioned because: (1) it comes mostly from 2 and 3-year-olds and (2) the findings might be accounted for, not by children avoiding second labels, but by the novel object which creates a lexical gap children are motivated to fill. Three studies addressed these concerns by having only a familiar object visible. Fifteen to seventeen and 18-20-month-olds were selected to straddle the vocabulary spurt. In Study 1, babies saw a familiar object and an opaque bucket as a location to search. Study 2 handed babies the familiar object to play with. Study 3 eliminated an obvious location to search. On the whole, babies at both ages resisted second labels for objects and, with some qualifications, tended to search for a better referent for the novel label. Thus mutual exclusivity is in place before the onset of the naming explosion. The findings demonstrate that lexical constraints enable babies to learn words even under non-optimal conditions--when speakers are not clear and referents are not visible. The results are discussed in relation to an alternative social-pragmatic account.     

Automatic processing influences free recall: converging evidence from the process dissociation procedure and remember-know judgments

Dual-process theories of retrieval suggest that controlled and automatic processing contribute to memory performance. Free recall tests are often considered pure measures of recollection, assessing only the controlled process. We report two experiments demonstrating that automatic processes also influence free recall. Experiment 1 used inclusion and exclusion tasks to estimate recollection and automaticity in free recall, adopting a new variant of the process dissociation procedure. Dividing attention during study selectively reduced the recollection estimate but did not affect the automatic component. In Experiment 2, we replicated the results of Experiment 1, and subjects additionally reported remember–know–guess judgments during recall in the inclusion condition. In the latter task, dividing attention during study reduced remember judgments for studied items, but know responses were unaffected. Results from both methods indicated that free recall is partly driven by automatic processes. Thus, we conclude that retrieval in free recall tests is not driven solely by conscious recollection (or remembering) but also by automatic influences of the same sort believed to drive priming on implicit memory tests. Sometimes items come to mind without volition in free recall.     

Further evidence on the similarity of memory processes in the process dissociation procedure and in source monitoring

Buchner, Erdfelder, Steffens, and Martensen (1997) proposed that the memory processes involved in recognition judgments in the process dissociation procedure are the same as those involved in standard source monitoring tasks. Two extensions of that research are presented here. First, following a line of reasoning recently brought forward by Jacoby (1998), the instructions in the earlier study could have triggered different processes from those triggered by his instructions. However, with instructions conforming as closely as possible to those reported by Jacoby (1991), Experiment 1 replicated the earlier recognition judgment finding almost perfectly. Second, the memory processes underlying fame judgments in the process dissociation procedure could also resemble those involved in source monitoring tasks. Indeed, the results of Experiment 2 are compatible with the hypothesis that the same processes are involved in fame judgments given a source monitoring or a process dissociation procedure.     

Priming effects in picture fragment completion: support for the perceptual closure hypothesis

The perceptual closure hypothesis says that priming will be optimum when just enough information is available in the prime to support closure. Across 5 experiments, a moderately complete fragmented image (Level 4) produced more priming than an almost complete (Level 7) or a very incomplete (Level 1) fragmented image. Only Level 4 priming was improved by increases in prime duration and by showing the prime again after Ss attempted to identify it. Explicit memory played little role in primed fragment completion except for Level 1 priming, in which specific fragment memory was responsible for the entire effect. In contrast, true perceptual learning was shown to be responsible for Level 4 and Level 7 priming. These priming effects cannot be accounted for by the transfer-appropriate procedures approach of Roediger and his colleagues because Level 1 priming produced less transfer to Level 1 identification at test than Level 4 priming did.     

A developmental trajectory in implicit memory is revealed by picture fragment completion

Dissociations between performance on implicit and explicit tasks have often been taken as evidence that different neural structures subserve the two types of memory. One such dissociation involves developmental differences that emerge in explicit tasks, but which appear to be absent in implicit tasks. Such findings are consistent with the idea that implicit memory is subserved by a more primitive system that evolves earlier at both phylogenetic and ontogenetic levels. The present paper reviews previous studies that claimed to find evidence that implicit memory is fully developed in very young children. Issues of measurement error, ceiling effects, and insufficient power brought up questions about those studies with respect to the developmental issue. The present study compares performance on implicit (picture fragment completion) and explicit (free recall and recognition) memory tasks with groups ranging in age from 5-28 years. We find a reliable developmental trend in both implicit and explicit performance in which the former cannot be attributed to the operation of explicit memory processes. Thus, we conclude that implicit memory, like explicit memory, develops with age.     

-ity: A study in word formation restrictions

Subjects judged the acceptability of pseudo words formed a stem, an optional affix, and-ity. The results show that those words in which-ity was adjacent to a latinate morpheme were more acceptable than those in which it was not. Other factors which influenced the acceptability ratings were familiarity and homogeneity of morpheme types. In their evaluations of the possible words, subjects were sensitive to historical class distinctions of stems and affixes.