Dissociations of grammaticality and specific similarity effects in artificial grammar learning.

Three artificial grammar learning experiments investigated the memory processes underlying classification judgments. In Experiment 1, effects of grammaticality, specific item similarity, and chunk frequency were analogous between classification and recognition tasks. In Experiments 2A and 2B, instructions to exclude "old" and "similar" test items, under conditions that limited the role of conscious recollection, dissociated grammaticality and similarity effects in classification. Dividing attention at test also produced a dissociation in Experiment 3. It is concluded that a dual-process model of classification, whereby the grammaticality and specific similarity effects are based mostly on automatic and intentional memory processes, respectively, is consistent with the results, whereas a unitary mechanism account is not. This conclusion is further supported by evidence indicating that chunk frequency had both implicit and explicit influences on classification judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The information acquired during artificial grammar learning.

In an artificial grammar learning task, amnesic patients classified test items as well as normal Ss did. Item similarity did not affect grammaticality judgments when similar and nonsimilar test items were balanced for the frequency with which bigrams and trigrams (chunks) that appeared in the training set also appeared in the test items. Amnesic Ss performed like normal Ss. Results suggest that concrete information about letter chunks can influence grammaticality judgments and that this information is acquired implicitly. The similarity of whole test items to training items does not appear to affect grammaticality judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Defining the knowledge units of a synthetic language: Comment on Vokey and Brooks (1992).

J. R. Vokey and L. R. Brooks (see record 1992-18658-001) reported a set of experiments intended to demonstrate that judgments of grammaticality are determined by 2 characteristics of the test items: their similarity with a specific study item and their conformity with an abstract representation of the generative grammar. The author argues that both effects may be encompassed within a unified account, which requires neither a specific-item retrieval process nor an abstractive capacity. The basic assumption is that the primary knowledge units are not whole strings of letters, as postulated in models relying on specific similarity or abstraction, but rather fragments of 2 or 3 letters. Partial memorization of these small units provides a convenient account of the whole pattern of Vokey and Brooks's findings because study items have more units in common with similar than with dissimilar test items, and likewise with grammatical than with ungrammatical ones. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative chunk strength in artificial grammar learning.

In 4 experiments, adherence to grammatical rules and associative chunk strength (including different measures, each calculated on the basis of the frequency with which bigrams and trigrams present in the test strings appeared in the learning strings) were manipulated independently in the test phase of an artificial grammar learning task. When participants learned few items of the grammar (Experiments 1A and 2A), the associated items were more often classified as grammatical than the nonassociated ones. On the other hand, when the learning phase included most of the grammatical items (Experiments 1B and 2B), the only effect observed was an effect of grammaticality. These results suggest that, depending on the specific constraints of the tasks, knowledge based on bigrams and trigrams and knowledge based on the abstraction of the grammatical structure can be used for the classification task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abstract Analogies and Positive Transfer in Artificial Grammar Learning.

Following Brooks and Vokey (1991), we show that positive transfer to new items generated from an artificial grammar in which the vocabulary has been changed from training to test can be based on "abstract analogy" to specific training items (specific similarity) rather than abstraction of a grammar and symbol remapping rules, even with remapping unique to each test item. The results confirm that transcendence over symbols provides no support for the implicit learning of abstract structure. Ironically, they also show that the effect of specific similarity does not depend on surface characteristics of the items, but the residual effect of grammaticality does. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The conscious, the unconscious, and familiarity.

This article examines the role of subjective familiarity in the implicit and explicit learning of artificial grammars. Experiment 1 found that objective measures of similarity (including fragment frequency and repetition structure) predicted ratings of familiarity, that familiarity ratings predicted grammaticality judgments, and that the extremity of familiarity ratings predicted confidence. Familiarity was further shown to predict judgments in the absence of confidence, hence contributing to above-chance guessing. Experiment 2 found that confidence developed as participants refined their knowledge of the distribution of familiarity and that differences in familiarity could be exploited prior to confidence developing. Experiment 3 found that familiarity was consciously exploited to make grammaticality judgments including those made without confidence and that familiarity could in some instances influence participants' grammaticality judgments apparently without their awareness. All 3 experiments found that knowledge distinct from familiarity was derived only under deliberate learning conditions. The results provide decisive evidence that familiarity is the essential source of knowledge in artificial grammar learning while also supporting a dual-process model of implicit and explicit learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of similarity in artificial grammar learning.

The authors examine the role of similarity in artificial grammar learning (AGL; A. S. Reber, 1989). A standard finite-state language was used to create stimuli that were arrangements of embedded geometric shapes (Experiment 1), connected lines (Experiment 2), and sequences of shapes (Experiment 3). Main effects for well-known predictors from the literature (grammaticality, associative global and anchor chunk strength, novel global and anchor chunk strength, length of items, and edit distance) were observed, thus replicating previous work. However, the authors extend previous research by using a widely known similarity-based exemplar model of categorization (the generalized context model; R. M. Nosofsky, 1989) to fit grammaticality judgments, by nested regression analyses. The results suggest that any explanation of AGL that is based on the existing theories is incomplete without a similarity process as well. Also, the results provide a foundation for further interpreting AGL in the wider context of categorization research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What is learned from artificial grammars? Transfer tests of simple association.

Ss were trained on letter pairs or letter strings in an artificial grammar learning paradigm to determine the extent to which implicit learning is driven by simple associative knowledge. Learning on strings resulted in sensitivity to violations of grammaticality and in transfer to a changed letter set. Learning on letter pairs resulted in less sensitivity and no transfer. Discrepancies in performance were later reduced, but not eliminated, by equating the task demands of the conditions during learning. A direct test of associative knowledge showed that training on letter pairs resulted in knowledge of legal bigrams, but this knowledge was only weakly related to violation sensitivity. The experiments demonstrate that knowledge of isolated associations is sufficient to support some learning, but this knowledge cannot explain the more abstract knowledge that results from learning on complete exemplars. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Artificial grammar learning depends on implicit acquisition of both abstract and exemplar-specific information.

The contributions of exemplar-specific and abstract knowledge to artificial grammar learning were examined in amnesic patients and controls. In Experiment 1, grammatical rule adherence and chunk strength exerted separate effects on grammaticality judgments. Amnesic patients exhibited intact classification performance, demonstrating the same pattern of results as controls. In Experiment 2, amnesic patients exhibited impaired declarative memory for chunks. In Experiment 3, both amnesic patients and controls exhibited transfer when tested with a letter set different than the one used for training, although performance was better when the same letter sets were used at training and test. The results suggest that individuals learn both abstract information about training items and exemplar-specific information about chunk strength and that both types of learning occur independently of declarative memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition priming for newly formed and preexisting associations: Perceptual and conceptual influences.

Three experiments demonstrate that association-specific repetition effects can be obtained for both newly formed and preexisting associations and that these effects are sensitive to modality of presentation. After studying a list of word pairs, participants were shown the original intact pairs and pairs formed by recombining the original pairs. In a lexical-decision task in which participants were asked to indicate whether both items were words, responses were faster to newly formed associations in the intact than in the recombined condition. This association-specific repetition priming effect was also observed for preexisting associations when a speeded relatedness judgment task was used. Both effects were found to be attenuated under cross-modal presentation. Finally, an explicit speeded recognition task revealed an associative effect that was not attenuated when modality was crossed for newly formed associations and was actually exaggerated for preexisting associations, suggesting that the repetition priming effects were not produced by conscious recollection. Results are discussed in terms of frameworks that are based either on perceptual representation systems or on a transfer-appropriate processing model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Item stability as related to implicit set and subject-item distance.

Studied the responses of 156 high school students to a list of interest items, 1st under standard conditions and then after a 3-wk period, under an implicit set designed to influence responses in a specific direction. 4 instruments were employed: the interest scale (using selected items from the strong vocational interest blank, kuder preference record, and french's interest index), the post-experimental inquiry, the scientific knowledge survey, and the artistic knowledge survey, and the artistic knowledge survey. An attempt was made to determine whether responses to items affected by an implicit set could not only be identified by their relevant content but also be shown to lie close to ss' scale points. Some positive results were obtained. Ss tended to change more responses to items that were (a) relevant in content, (b) close to their scale point, and (c) answered in the unkeyed direction on the 1st trial. Differential effects are noted and analyzed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit memory and test awareness.

In three experiments we examined whether normal subjects can perform an implicit test without becoming aware that the test items were previously encountered in the study phase of the experiment. Experiment 1 assessed single word priming with the stem completion task, and subjects who reported awareness/unawareness that the test items were previously encoded in the study task showed equivalent priming. Experiments 2a–c and 3 assessed associative priming with the stem completion task, and in this case, only subjects who were aware that the test items were previously encountered showed associative priming effects. These findings suggest that single word priming and associative priming reflect different memory processes because the former and not the latter effect can be observed in unaware subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition priming effects for newly formed associations are perceptually based: Evidence from shallow encoding and format specificity.

This article is concerned with memory for newly formed associations as displayed on implicit and explicit tests of memory. After studying a list of word pairs, participants were shown the original intact pairs and pairs formed by recombining the original pairs. Pairs were simultaneously presented both at study and at test. In a lexical-decision task in which participants were asked to indicate whether both items were words, responses to intact pairs were faster than to recombined pairs. The size of this association-specific repetition effect was relatively unaffected by a levels-of-processing manipulation, indicating that conceptual processes did not likely contribute to the production of the effect. Furthermore, the effect was not produced when pairs were presented simultaneously at study but sequentially at test, thus highlighting the importance of format of presentation. Finally, in an explicit speeded-recognition task the size of the association-specific effect was largely affected by levels-of-processing manipulation and was revealed even under sequential test presentation suggesting that the associative repetition effects were not contaminated by conscious recollection.?.?.?.? (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The production of specific and generic associates of living and nonliving, high- and low-familiarity stimuli in Alzheimer's disease

The goal of this paper was to address three issues relevant to the semantic-lexical deficit of Alzheimer's disease (AD) patients: (1) the nature of the deficit (contrasting the loss of information with the difficulty of intentional access hypothesis), (2) stimulus familiarity effects, (3) semantic category effects (contrasting living with nonliving categories). Sixteen patients affected by AD and 11 matched control subjects were given a naming task, a word-picture matching task and a generative associative naming task, constructed by using as stimuli the same 40 items. Stimuli were either living or nonliving items of high, medium, and low familiarity. Responses given on the generative associative naming task were classified as generic (poorly informative) or specific (more informative). As expected, AD patients were poorer than controls both in naming and in word-to-picture matching tasks. In the generative associative naming task, AD patients tended to produce fewer specific than generic associations with respect to controls. Category effects had a significant influence on performance only on the naming task, but not on the word-to-picture matching or on the generative associative naming task. Stimulus familiarity, on the other hand, strongly influenced performance both in AD patients and in controls: naming and comprehension were better for high familiarity items with respect to low familiarity items. For generative associative naming, the tendency of AD patients to produce fewer specific than generic associations was mainly significant for low familiarity items.     

Memorability judgments for high- and low-frequency words

Five experiments were conducted in order to examine subjects' judgments of the memorability of high- (HF) and low-frequency (LF) words in the context of a recognition memory task. In Experiment 1, the subjects were provided study/test experience with a list of HF and LF words prior to making memorability judgments for a new list of HF and LF items. The findings were consistent with previous evidence (Greene & Thapar, 1994; Wixted, 1992) suggesting that subjects are not explicitly aware of the greater recognition memorability of LF words. Experiments 2-5 embedded the memorability judgment task within the recognition test itself. In these experiments, the subjects consistently gave higher memorability ratings to LF items. The contrast between the pattern of results found when the subjects made their judgments at the time of list presentation (Experiment 1) and that when they made their judgments during the recognition test (Experiments 2-5) is consistent with recent evidence that even seemingly highly related metamnemonic judgments (e.g., ease of learning judgments vs. judgments of learning for the same items) may be based on very different factors if they occur at different points in the study/test cycle. The present findings are also consistent with the possibility that very rapid retrieval of memorability information for HF and LF words may affect recognition decisions and may contribute to the recognition memory word frequency effect.     

"Big" versus "little" science: comparative analysis of program projects and individual research grants

The verbal fluency task requires generation of category exemplars and appears to be an example of what M. Moscovitch (1995) calls a strategic test of memory retrieval. Four experiments explored the role of individual differences in working memory (WM) capacity on verbal fluency under various secondary load conditions. High WM participants consistently recalled more exemplars. However, load conditions caused a decline in recall only for high WM participants. Low WM participants showed no effect of secondary workload on exemplar generation. WM group differences and load effects were observed even in the 1st min of retrieval, which suggests that differences were not due to differences in knowledge. A model of retrieval is supported that relies on cue-based-automatic activation, monitoring of output for errors, controlled suppression of previously recalled items, and controlled strategic search.     

The role of working memory capacity in retrieval.

The verbal fluency task that requires generation of category exemplars and appears to be an example of what M. Moscovitch (1995) calls a strategic test of memory retrieval. Four experiments explored the role of individual differences in working memory (WM) capacity on verbal fluency under various secondary load conditions. High WM participants consistently recalled more exemplars. However, load conditions caused a decline in recall only for high WM participants. Low WM participants showed no effect of secondary workload on exemplar generation. WM group differences and load effects were observed even in the 1st min of retrieval, which suggests that differences were not due to differences in knowledge. A model of retrieval is supported that relies on cue-based-automatic activation, monitoring of output for errors, controlled suppression of previously recalled items, and controlled strategic search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comprehension of concrete and abstract words in semantic dementia.

The vast majority of brain-injured patients with semantic impairment have better comprehension of concrete than abstract words. In contrast, several patients with semantic dementia (SD), who show circumscribed atrophy of the anterior temporal lobes bilaterally, have been reported to show reverse imageability effects, that is, relative preservation of abstract knowledge. Although these reports largely concern individual patients, some researchers have recently proposed that superior comprehension of abstract concepts is a characteristic feature of SD. This would imply that the anterior temporal lobes are particularly crucial for processing sensory aspects of semantic knowledge, which are associated with concrete not abstract concepts. However, functional neuroimaging studies of healthy participants do not unequivocally predict reverse imageability effects in SD because the temporal poles sometimes show greater activation for more abstract concepts. The authors examined a case-series of 11 SD patients on a synonym judgment test that orthogonally varied the frequency and imageability of the items. All patients had higher success rates for more imageable as well as more frequent words, suggesting that (1) the anterior temporal lobes underpin semantic knowledge for both concrete and abstract concepts, (2) more imageable items—perhaps because of their richer multimodal representations—are typically more robust in the face of global semantic degradation and (3) reverse imageability effects are not a characteristic feature of SD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive penetrability of syntactic priming in Broca's aphasia.

Agrammatic Broca's aphasia has been explained as an impairment of automatic syntactic processes. The present study investigated whether controlled processes play a role in agrammatics' handling of syntactic information. Agrammatic patients and normal controls performed a cross-modal priming task with sentence fragments and visual targets forming either grammatical or ungrammatical pairs. In Exp 1, Ss of both groups were instructed to ignore the auditory prime. The grammaticality effect observed in a previous study disappeared for the aphasic Ss but not for normal controls. Exp 2 demonstrated that for normal controls, the grammaticality effect was present even with a larger prime-target interval. These findings indicate that although automatic parsing routines in normal Ss are impervious to strategic effects, agrammatic Broca patients appear to use syntactic information in a controlled fashion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)