Verbal mediation of number knowledge: evidence from semantic dementia and corticobasal degeneration

Patients with corticobasal degeneration (CBD) appear to have impaired number knowledge. We examined the nature of their number deficit while we tested the hypothesis that comprehension of larger numbers depends in part on verbal mediation. We evaluated magnitude judgments and performance on number conservation measures rooted in Piagetian theory in nonaphasic patients with CBD (n=13) and patients with a fluent form of progressive aphasia known as semantic dementia (SD; n=15). We manipulated the numbers of the arrays and the visual-spatial properties of the stimuli being compared during magnitude judgments and Piagetian conservation measures. CBD patients were consistently impaired judging the magnitudes of larger numbers (4-9), while they had minimal difficulty with smaller numbers (magnitudes < or = 3). By comparison, SD patients performed all measures of number knowledge at a ceiling level regardless of number magnitude. Neither patient group was significantly impacted by manipulations of the spatial properties of the stimuli. CBD patients' impairment with larger numbers despite minimal aphasia, and SD patients' intact performance despite an aphasia, challenge the proposal that understanding larger numbers depends on verbal mediation.     

Motor knowledge is one dimension for concept organization: Further evidence from a Chinese semantic dementia case

Neuropsychological and neuroimaging studies have indicated that motor knowledge is one potential dimension along which concepts are organized. Here we present further direct evidence for the effects of motor knowledge in accounting for categorical patterns across object domains (living vs. nonliving) and grammatical domains (nouns vs. verbs), as well as the integrity of other modality-specific knowledge (e.g., visual). We present a Chinese case, XRK, who suffered from semantic dementia with left temporal lobe atrophy. In naming and comprehension tasks, he performed better at nonliving items than at living items, and better at verbs than at nouns. Critically, multiple regression method revealed that these two categorical effects could be both accounted for by the charade rating, a continuous measurement of the significance of motor knowledge for a concept or a semantic feature. Furthermore, charade rating also predicted his performances on the generation frequency of semantic features of various modalities. These findings consolidate the significance of motor knowledge in conceptual organization and further highlights the interactions between different types of semantic knowledge.     

Visual and semantic effects in a serial word classification task

Subjects were asked to decide as quickly as possible whether each of a series of items was one of the four target words, ‘dog’, ‘rat’, ‘boar’ and ‘mole’. The relationship of distractors to the targets was varied. Distractors which were of high visual similarity to the targets took longer to reject than those which were of lower visual similarity, and distractors which were semantically related to the targets took longer to reject than those which were unrelated. These effects were independent. There was no effect of familiarity, with non-animal distractors and pronounceable non-words rejected equally quickly. These results are qualitatively the same as those earlier found with faces (Bruce, 1979).     

The focus of attention in working memory: evidence from a word updating task

Three experiments examined the cognitive costs of item switching within working memory with a novel word updating task, thereby extending previous research to the field of linguistic stimuli and linguistic-graphemic updating operations. In Experiments 1 and 2 costs for switching between working memory items were evident on the word level, and they increased with an increasing word set size (Experiment 2). In contrast, a surprisingly similar switch effect on the level of letters was not affected by word set size (Experiment 2). Experiment 3 showed that this effect is not simply based on the need for re-orienting visual spatial attention. To account for the overall picture of results, a recursive model of attentional foci is proposed. Moreover, individual working memory span appears to be associated with the accuracy of item switching, but not with its speed.     

Study-test awareness can enhance priming on an implicit memory task: evidence from a word completion task

The role of study-test awareness in implicit memory tasks has been an open question for some time. This study investigated the possibility that study-test awareness may enhance priming on an implicit memory task. In three experiments, subjects studied words under levels of processing conditions (nonsemantic vs. semantic) and then received a word stem completion priming task. The results of all three experiments showed that study-test awareness had no effect on priming for nonsemantic study but it did on semantic study, significantly enhancing priming for that study condition. The results are interpreted according to an involuntary aware memory framework.     

Implicit word learning benefits from semantic richness: electrophysiological and behavioral evidence

Words differ considerably in the amount of associated semantic information. Despite the crucial role of meaning in language, it is still unclear whether and how this variability modulates language learning. Here, we provide initial evidence demonstrating that implicit learning in repetition priming is influenced by the amount of semantic features associated with a given word. Electroencephalographic recordings were obtained while participants performed a visual lexical decision task; the complete stimulus set was repeated once. Repetition priming effects on performance accuracy and the N400 component of the event-related brain potential were enhanced for words with many semantic features. These findings suggest a novel and important impact of the richness of semantic representations on learning and plasticity within the lexical-conceptual system; they are discussed in their relevance for assumptions concerning basic mechanisms underlying word learning.     

Strategic control in word reading: evidence from speeded responding in the tempo-naming task

To investigate strategic control over response initiation in word reading, the authors introduce the tempo-naming task. Relative to baseline performance in the standard-naming task, participants were induced to respond with faster latencies, shorter durations, and lower levels of accuracy by instructing them to time response initiation with an experimentally controlled tempo. The tempo response cue attenuated stimulus effects, and as faster tempos reduced latencies, the number of spelling-sound errors remained constant, whereas the number of word, nonword, and articulatory errors increased. To explain these results, the authors propose input gain as a mechanism of control over processing speed. The experimenters sketch how input gain could account for the current results as well as for the results from stimulus-blocking experiments testing the route emphasis and time criterion hypotheses of strategic control.     

The organization of conceptual knowledge: the evidence from category-specific semantic deficits

Questions about the organization of conceptual knowledge in the human brain can be addressed by studying patients with category-specific semantic deficits: disproportionate and even selective impairment of conceptual knowledge of one category of objects compared with other categories. Recently, consensus has emerged regarding the basic facts of category-specific semantic deficits: (1) the categories that can be disproportionately impaired or spared are 'animals', 'fruit/vegetables', and 'artifacts'; and (2) category-specific semantic deficits are not associated with disproportionate deficits for a type or modality of knowledge. Together with findings in functional neuroimaging, these data indicate a complex organization of conceptual knowledge characterized by several independent dimensions of organization.     

Accessing lexical memory: The transfer of word repetition effects across task and modality

Reading by literate adults is generally assumed to represent skill acquired years earlier. However, the present experiments show that aspects of that skill can be readily modified. In two experiments, pronunciation of visually presented common words speeded later recognition of those words. This facilitation of recognition occurred although subjects did not expect word repetition and the task was changed from pronunciation to recognition. In contrast, naming pictures did not facilitate later recognition of visually presented picture names. The occurrence of facilitation when the task was changed and the lack of facilitation when stimulus format was changed suggest that facilitation occurs in the processes of encoding and accessing memory, processes that may change little across tasks but may change substantially with stimulus format changes. This facilitation of recognition occurs automatically without mediation by subjects’ expectations. A third experiment indicates that this facilitation of recognition shows little relation to episodic memory.     

Evaluative priming in a semantic flanker task: ERP evidence for a mutual facilitation explanation

In semantic flanker tasks, target categorization response times are affected by the semantic compatibility of the flanker and target. With positive and negative category exemplars, we investigated the influence of evaluative congruency (whether flanker and target share evaluative valence) on the flanker effect, using behavioral and electrophysiological measures. We hypothesized a moderation of the flanker effect by evaluative congruency on the basis of the assumption that evaluatively congruent concepts mutually facilitate each other’s activation (see Schmitz & Wentura in Journal of Experimental Psychology: Learning, Memory, and Cognition 38:984–1000, 2012). Applying an onset delay of 50 ms for the flanker, we aimed to decrease the facilitative effect of an evaluatively congruent flanker on target encoding and, at the same time, increase the facilitative effect of an evaluatively congruent target on flanker encoding. As a consequence of increased flanker activation in the case of evaluative congruency, we expected a semantically incompatible flanker to interfere with the target categorization to a larger extent (as compared with an evaluatively incongruent pairing). Confirming our hypotheses, the flanker effect significantly depended on evaluative congruency, in both mean response times and N2 mean amplitudes. Thus, the present study provided behavioral and electrophysiological evidence for the mutual facilitation of evaluatively congruent concepts. Implications for the representation of evaluative connotations of semantic concepts are discussed.     

Visual word recognition and vowelization in Arabic: new evidence from lexical decision task performances

The effect of vowelization signs on the process of visual word recognition in Arabic was investigated among 41 native Arab skilled readers with age average of 30.66 ± 9.09. The participants performed a lexical decision task using three types of words and pseudowords; full, partial and non-vowelized. The results showed that for both words and pseudowords, response times were shorter and accuracy levels were higher for the non-vowelized condition compared to the other conditions of vowelization. The results reinforce the argument that automatic lexical processes during word recognition in Arabic orthography might be disturbed by supplementary information such as vowelization.     

Photograph method fosters direct access to second-language word meaning: Direct evidence from a word-picture matching task

This experiment was designed to investigate conceptual links directly through a word–picture matching task in children. Participants were asked to indicate between two pictures the one depicting the same concept as the newly learned L2 word (target). One of the two pictures was the target, while the other was either semantically related to it or was unrelated. To investigate whether learning methods modulate L2 word processing, two learning methods were compared: an L2-photograph method and an L1-L2 method. Results showed a semantic interference effect only with the L2-photograph method: Children responded more slowly in the related condition than in the unrelated one. The learning method modulated L2 word processing and L2 word meaning was not necessarily accessed through L1 mediation in the first steps of learning. The method used paves the way for the direct investigation of conceptual links.     

Long-term priming of neighbours biases the word recognition process: evidence from a lexical decision task.

The role of orthographically similar words (i.e., neighbours) in the word recognition process has been studied extensively using short-term priming paradigms (e.g., Colombo, 1986). Here we demonstrate that long-term effects of neighbour priming can also be obtained. Experiment 1 showed that prior study of a neighbour (e.g., TANGO) increased later lexical decision performance for similar words (e.g., MANGO), but decreased performance for similar pseudowords (e.g., LANGO). Experiment 2 replicated this bias effect and showed that the increase in lexical decision performance due to neighbour priming is selectively due to words from a relatively sparse neighbourhood. Explanations of the bias effect in terms of lexical activation and episodic memory retrieval are discussed.     

Self-reference is a fast-acting automatic mechanism on emotional word processing: evidence from a masked priming affective categorisation task

This study examined the impact of self-referential information at early stages of emotional word processing using an affective masked-priming paradigm in which positive (e.g, espetacular[awesome]) and negative (e.g., horrível[awful]) trait-adjectives were preceded by briefly primes that could be self-related (Eu sou[I am]), other-related (Ela é[She is]), or a control (%%%%%). Trait-adjectives were selected from female norms and only females participants were used to control for sex differences. Results showed that positive words were categorised faster when preceded by self-related primes than by other-related primes, though not control primes. Negative trait-adjectives were not modulated by the type of prime, even though participants were slower when they were preceded by other-related than by control primes. These findings demonstrate that taking the other-perspective entails a cost, and that the amount of priming produced by self-related and control primes was virtually the same, thus suggesting that assuming the self-perspective is a cognitively effortless process.     

Lexical and semantic influences on item and order memory in immediate serial recognition: evidence from a novel task

Previous studies have reported that, in contrast to the effect on immediate serial recall, lexical/semantic factors have little effect on immediate serial recognition. This has been taken as evidence that linguistic knowledge contributes to verbal short-term memory in a redintegrative process at recall. Contrary to this view, we found that lexicality, frequency, and imageability all influenced matching span. The standard matching span task, requiring changes in item order to be detected, was less susceptible to lexical/semantic factors than was a novel task involving the detection of phoneme order and hence item identity changes. Therefore, in both immediate recognition and immediate serial recall, lexical/semantic knowledge makes a greater contribution to item identity than to item order memory. Task sensitivity, and not the absence of overt recall, may have underpinned previous failures to show effects of these variables in immediate recognition. We also compared matching span for pure and unpredictable mixed lists of words and nonwords. Lexicality had a larger impact on immediate recognition for pure than for mixed lists, in line with findings for immediate serial recall. List composition affected the detection of phoneme but not item order changes in matching span; similarly, in recall, mixed lists produce more frequent word phoneme migrations but not migrations of entire items. These results point to strong similarities between immediate serial recall and recognition. Lexical/semantic knowledge may contribute to phonological stability in both tasks.     

Response consistency on a semantic memory task in persons with dementia of the Alzheimer type

The purpose of this investigation was to determine the test-retest response consistency rate on a semantic memory task in persons with dementia of the Alzheimer type (DAT). Ten mildly and 13 moderately impaired DAT subjects and 14 normal controls matched for age, years of education, and estimated IQ participated in this study. The Peabody Picture Vocabulary Test (PPVT) was administered twice to each subject with a 7-day intertest interval. The mild and moderate DAT subjects responded inconsistently to significantly more PPVT items than normal controls. When the effects of guessing were considered, moderate DAT subjects gave significantly more inconsistent PPVT responses than normal controls and mild DAT subjects showed a trend toward giving more inconsistent responses. These results substantiate the conclusion that the impairment of specific conceptual knowledge in DAT subjects cannot be reliably measured with a single administration of a semantic memory task such as the PPVT.     

Accessing causal relations in semantic memory

Most studies investigating semantic memory have focused on taxonomic or associative relations. Little is known about how other relations, such as causal relations, are represented and accessed. In three experiments, we presented participants with pairs of words one after another, describing events that referred to either a cause (e.g., spark) or an effect (e.g., fire). We manipulated the temporal order of word presentation and the question participants had to respond to. The results revealed that questions referring to the existence of a causal relation are answered faster when the first word refers to a cause and the second word refers to its effect than vice versa. However, no such asymmetry was observed with questions referring to the associative relation. People appear to distinguish the roles of cause and effect when queried specifically about a causal relation, but not when the same information is evaluated for the presence of an associative relation.