Sublexical components in implicit memory for novel words.

Five experiments with 280 university students investigated the role of sublexical components in implicit memory for novel words. Priming on an implicit word judgment task occurred consistently for nonwords formed out of familiar linguistic components (morphemes and syllables) but minimally for nonwords formed out of unfamiliar pseudosyllabic components. This effect was dissociable from explicit memory and insensitive to changes in the surface features of the stimuli. Moreover, it depended on unitization of stimulus components as opposed to priming of individual components. Results are interpreted in terms of the activation and integration of prior linguistic knowledge and as evidence against the role of new (perceptual or episodic) representations in implicit memory for new information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term implicit memory for words and nonwords.

A short-term implicit memory effect is reported and interpreted as arising within the word recognition system. In Experiment 1, repetition priming in lexical decision was determined for low-frequency words and pseudowords at lags of 0, 1, 2, 3, 4, 5, 9, and 23 intervening items. For words, a large short-term priming component decayed rapidly but smoothly over the first 3 items (8 s) to a stable long-term value. For nonwords, priming dropped to the long-term value with a single intervening item. This Lag x Lexicality interaction was replicated with a naming task in Experiment 2 and with high-frequency words in Experiment 3. Word frequency affected long-term priming but not the size or decay rate of short-term priming, dissociating the two repetition effects. In Experiment 4, an old-new decision task was used to test explicit memory. Parallel word and nonword decay patterns were found, dissociating short-term priming from explicit working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual and nonperceptual components of implicit memory for pictures.

The transfer appropriate processing (TAP) framework posits that in data-driven tasks, such as picture naming (PN) or picture perceptual identification, repetition priming is greater when perceptual processes engaged at study are recapitulated at test. Thus, priming with pictures is greater after study-phase exposure to pictures than to words (picture names). A. S. Brown, D. R. Neblett, T. C. Jones, and D. B. Mitchell (see record 1991-26453-001) reported that a pure-list format eliminated perceptual priming: Participants who saw either pictures or words in a study phase showed equal priming in a PN task. In the present study, participants showed greater priming after exposure to pure lists of pictures than to pure lists of words in 3 PN and 1 picture perceptual identification experiments. Thus, perceptual priming occurred in 4 pure-list picture priming tasks, as predicted by the TAP framework. Priming also was found after exposure to words. In PN and picture perceptual identification tasks, implicit memory for pictures includes perceptual and nonperceptual components. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further evidence for feature correlations in semantic memory.

The role of feature correlations in semantic memory is a central issue in conceptual representation. In 2 versions of the feature verification task, participants were faster to verify that a feature () is part of a concept (grapefruit) if it is strongly rather than weakly intercorrelated with the other features of that concept. Contrasting interactions between feature correlations and stimulus onset asynchrony were found when the concept versus the feature was presented first. An attractor network model of word meaning that naturally learns and uses feature correlations predicted those interactions. This research provides further evidence that semantic memory includes implicitly learned statistical knowledge of feature relationships, in contrast to theories such as spreading activation networks, in which feature correlations play no role. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affective valence of words, explicit and implicit memory in clinical depression

Explicit and implicit memory for affectively valenced words (positive, negative or neutral) were investigated in 30 patients suffering from a major depressive episode (DSM-III-R criteria) and 30 normal control subjects. Explicit memory was assessed with a free-recall and a recognition task and implicit memory with a word-stem completion task. Depressed and control subjects recalled more emotional, i.e., positive and negative, words than neutral ones. They recognized less negative than neutral words. In contrast, to recall and recognition performance, word-completion performance was not sensitive to the affective valence of words: depressed and control subjects exhibited equivalent priming of positive, negative and neutral words. These results indicate that, in depressed and normal subjects, the affective valence of words influences memory when conscious, intentional recollection is required but is devoid of effect when such a recollection is not required.     

Further evidence for hierarchical chunking in rat spatial memory.

In Experiment 1, rats were given a test to determine the order of preference among 3 types of food. Two groups of rats then were trained on a 12-arm radial maze in Experiment 2, with the 3 foods placed in fixed-arm locations for 1 group and in locations that varied randomly across sessions for the other group. The results replicated those of Dallal and Meck (1990) by showing faster learning and more clustering of arm choices by food type in the fixed locations group than in the random-locations group. Two further experiments were performed to test the chunking hypothesis. Observations of working memory in Experiment 3 and the reorganization of reference memory in Experiment 4 both supported the chunking hypothesis by showing superior spatial memory and arm chunking by food type when chunk integrity was maintained than when it was compromised. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A sublexical locus for repetition blindness: Evidence from illusory words.

Six experiments used an illusory words paradigm to demonstrate that repetition blindness (RB) in orthographically similar words affects only the words' shared letters. Rapid serial visual presentation streams of words and word fragments allowed the unique letters of the 2nd critical word to combine with a subsequent fragment to create a word, as in rock shock ell. The illusory word shell was reported 2–3 times as frequently in RB conditions as in control conditions. Further experiments ruled out letter migration, contour summation, and differences in processing load as explanations for the results. These findings are inconsistent with current proposals that orthographic RB represents similarity inhibition or lexical competition or that it reflects problems with word-level token individuation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further evidence of the intricacy of memory span.

Memory span was measured for lists of verbal items constructed such that the items in the 1st half of the list were of one category and those of the 2nd half were of another. In Exp 1, the lists consisted of digits and words (e.g., 2, 8, 77, horse, cow, sheep or horse, cow, sheep, 2, 8, 7); in Exp 2, they consisted of words from the same semantic domain and words from different semantic domains; in Exps 3 and 4, they consisted of words that rhymed and words that did not rhyme. A category-order effect occurred in each experiment: Span was larger when the digits, same-domain words, or rhyming words occurred in the 1st half of the list than when they occurred in the 2nd half. These findings suggest that memory span is more complex than is generally assumed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Lexical, sublexical, and implicit memory processes in healthy young and healthy older adults and in individuals with dementia of the Alzheimer type.

Five groups of participants—healthy young, healthy young-old, healthy old-old, very mildly demented, and mildly demented individuals of the Alzheimer type (DAT)—participated in a 2-phase experiment that entailed a rhyme judgment task followed by a lexical decision task, in which half of the stimuli were earlier presented in the rhyme judgment task. The results of the rhyme task indicated that healthy young and older adults did not produce an influence of word frequency on rhyme decisions. However, the 2 groups of DAT individuals produced large word-frequency effects primarily for the nonrhyming pairs. The results of the lexical decision task indicated that (a) repetition facilitated lexical decisions to words, whereas there was evidence of inhibition for nonwords; and (b) there was an increasing influence of word frequency across the 5 groups of participants. The results are interpreted with respect to attentional control of appropriate (lexical and sublexical) processing pathways and the nature of processes that are disrupted and those that remain uninfluenced in healthy aging and DAT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial memory for objects and words.

Examined in 4 experiments whether spatial location information is more likely to be encoded with the memory representation of objects than of words. 16 objects or the 1-word verbal labels for each were studied on a matrix display, followed by a recall test and then a relocation test. In each experiment, an independent variable known to affect item recall was introduced to test whether spatial location memory would concomitantly vary for both objects and words. In Exp I, with 48 2nd graders, 48 5th graders, and 48 high school juniors and seniors, recall of both objects and words increased with age of the Ss. However, relocation accuracy increased for objects but not for words. In Exp II, with 64 4th graders and 64 high school juniors and seniors, visual imagery instructions generally improved memory for words without affecting relocation accuracy. In Exps III (with 56 undergraduates) and IV (with 80 adults, aged 26.2–52.3 yrs), prolonging the test delay diminished recall for objects and words. However, relocation accuracy decreased only for the objects. In each experiment, item memory was affected independently of location memory for words but not for objects. The results suggest that different processes are involved in encoding item and location information for words but not for objects. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Source memory enhancement for emotional words.

The influence of emotional stimuli on source memory was investigated by using emotionally valenced words. The words were colored blue or yellow (Experiment 1) or surrounded by a blue or yellow frame (Experiment 2). Participants were asked to associate the words with the colors. In both experiments, emotionally valenced words elicited enhanced free recall compared with nonvalenced words; however, recognition memory was not affected. Source memory for the associated color was also enhanced for emotional words, suggesting that even memory for contextual information is benefited by emotional stimuli. This effect was not due to the ease of semantic clustering of emotional words because semantically related words were not associated with enhanced source memory, despite enhanced recall (Experiment 3). It is suggested that enhancement resulted from facilitated arousal or attention, which may act to increase organization processes important for source memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer-appropriate processing for implicit and explicit memory.

To examine how feature-specific pattern-analyzing processes affect implicit and explicit memory test performance, words were displayed for study and testing in 2 visually distinct formats: upside down vs normal for Exp 1, upside down vs backward for Exp 2, and in Applesoft pudgy vs shadow typeface for Exp 3. Implicit and explicit memory performance were assessed with word identification and recognition tests, respectively. The results showed larger priming effects when the study and test formats were the same rather than different, but only in some experimental conditions. The discussion focuses on how skill and processing strategies contribute to format-specific effects on implicit and explicit memory test performance, and it outlines a theoretical account based on the idea of transfer-appropriate processing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Explicit and implicit memory for rotating objects.

Although both the object and the observer often move in natural environments, the effect of motion on visual object recognition has not been well documented. The authors examined the effect of a reversal in the direction of rotation on both explicit and implicit memory for novel, 3-dimensional objects. Participants viewed a series of continuously rotating objects and later made either an old-new recognition judgment or a symmetric-asymmetric decision. For both tasks, memory for rotating objects was impaired when the direction of rotation was reversed at test. These results demonstrate that dynamic information can play a role in visual object recognition and suggest that object representations can encode spatiotemporal information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic processing and memory for attended and unattended words in dichotic listening: Behavioral and electrophysiological evidence.

Thirty-two Ss studied words presented to 1 ear, while ignoring a concurrent word list presented to the opposite ear. The N400 component of the event-related potentials elicited by attended words was modulated by semantic priming between successive words. The N400 elicited by unattended words was insensitive to semantic manipulation. Recognition memory was better for attended than for unattended words. However, the percentage of false positives was elevated equally for lures that were semantically related to "old" words, whether they had been attended or unattended. Words that were initially attended induced similar repetition effects in a lexical decision task as words that were initially unattended. Hence, both attended and unattended words are semantically processed and activate semantic representations. However, attended words form traces that are subsequently more available to conscious recollection than unattended words. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adding new word associations to semantic memory: evidence for two interactive learning components

The addition of newly learned word associations to semantic memory was investigated in three experiments. In these experiments word pairs were repeatedly presented as prime-target pairs in a lexical decision task. Performance on repeated pairs (both pre-experimentally associated and initially unrelated pairs) was compared to that on neutral pairs. In Experiments 1 and 2, effects of prior study (episodic priming) were observed but since this episodic priming effect was equal for both conditions it could not be concluded that the new associations has been added to semantic memory. In Experiment 3 some evidence was found that the newly learned word associations had been added to semantic memory. This occurred only after presenting the word pairs for several trials in paired-associate learning. The results are interpreted as supporting a model that distinguishes two memory components that mediate the effects of new learning, an episodic and a semantic one.     

Age differences in explicit and implicit memory for pictures.

In the present study, the authors examined age effects in memory for nonverbal material. A picture fragment completion task was used to test explicit and implicit memory in a younger and an older group. Explicit memory was indexed by free recall of pictures, whereas implicit memory was indexed by perceptual learning (priming). Both free recall and perceptual learning performance were found to be impaired in the older group. A measure of executive functioning was found to be predictive of both explicit and implicit memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Explicit contamination in "implicit" memory for new associations

In one view of implicit memory, priming arises from modification of preexisting representations; however, the role of such representations is currently in doubt following findings of implicit memory for newly formed associations. Closer consideration of studies reporting this effect, and of others that have failed to obtain it, suggests that such priming might results from the employment of explicit memory strategies. With measures designed to permit exclusion of such strategies, three experiments using lexical decision and stem-completion tasks found no evidence of truly implicit memory for unrelated pairs. Instead, priming was found only in those subjects (50% of the total in one experiment) who reported using explicit memory in stem completion. Contrary to previous conclusions, the results indicate a role for established representations in explaining implicit memory.     

Bias effects in implicit memory tasks.

A major focus of recent research in memory has been performance on implicit tasks. The phenomenon of most interest has been repetition priming, the effect that prior exposure to a stimulus has on later perception of the stimulus or on a later decision about the stimulus. Picture naming, word identification, and word production in stem- and fragment-completion tasks all show repetition priming effects. The separation of implicit from explicit memory systems provides 1 account of this data, but a different theoretical view is proposed here: Repetition-priming effects come about because the processes that perform a task are biased by prior exposure to a stimulus. The processing of the prior stimulus leaves behind byproducts, temporary modifications of the processes, which influence later processing. The aim of this article is to demonstrate the potential of this view for developing new theories and for prompting new empirical questions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further evidence for temporal decay in working memory: Reply to Lewandowsky and Oberauer (2009).

The sources of forgetting in working memory (WM) are a matter of intense debate: Is there a time-related decay of memory traces, or is forgetting uniquely due to representation-based interference? In a previous study, we claimed to have provided evidence supporting the temporal decay hypothesis (S. Portrat, P. Barrouillet, & V. Camos, 2008). However, reanalyzing our data, S. Lewandowsky and K. Oberauer (2009) demonstrated that they do not provide compelling evidence for temporal decay and suggested a class of alternative models favoring a representation-based interference account. In this article, we develop from the most recent proposals made by Lewandowsky and Oberauer 2 of the most plausible extensions of these alternative models. We show that neither of these extensions can account for recent findings related to between-domain WM performance and that both lead to predictions that are contradicted by new empirical evidence. Finally, we show that recent studies that have been claimed to rule out the temporal decay hypothesis do not resist close scrutiny. We conclude that the time-based resource-sharing model remains the most parsimonious way to account for forgetting and restoration of memory traces in WM. (PsycINFO Database Record (c) 2011 APA, all rights reserved)