Derived stimulus relations, semantic priming, and event-related potentials: testing a behavioral theory of semantic networks

Derived equivalence relations, it has been argued, provide a behavioral model of semantic or symbolic meaning in natural language, and thus equivalence relations should possess properties that are typically associated with semantic relations. The present study sought to test this basic postulate using semantic priming. Across three experiments, participants were trained and tested in two 4-member equivalence relations using word-like nonsense words. Participants also were exposed to a single- or two-word lexical decision task, and both direct (Experiment 1) and mediated (Experiments 2 and 3) priming effects for reaction times and event-related potentials were observed within but not across equivalence relations. The findings support the argument that derived equivalence relations provides a useful preliminary model of semantic relations.     

Morphed facial expressions elicited a N400 ERP effect: A domain‐specific semantic module?

Previous studies have revealed that decoding of facial expressions is a specific component of face comprehension and that semantic information might be processed separately from the basic stage of face perception. In order to explore event-related potentials (ERPs) related to recognition of facial expressions and the effect of the semantic content of the stimulus, we analyzed 20 normal subjects. Faces with three prototypical emotional expressions (fear, happiness, and sadness) and with three morphed expressions were presented in random order. The neutral stimuli represented the control condition. Whereas ERP profiles were similar with respect to an early negative ERP (N170), differences in peak amplitude were observed later between incongruous (morphed) expressions and congruous (prototypical) ones. In fact, the results demonstrated that the emotional morphed faces elicited a negative peak at about 360 ms, mainly distributed over the posterior site. The electrophysiological activity observed may represent a specific cognitive process underlying decoding of facial expressions in case of semantic anomaly detection. The evidence is in favor of the similarity of this negative deflection with the N400 ERP effect elicited in linguistic tasks. A domain-specific semantic module is proposed to explain these results.     

How do valence and meaning interact? The contribution of semantic control

The hub-and-spoke model of semantic cognition proposes that conceptual representations in a heteromodal ‘hub’ interact with and emerge from modality-specific features or ‘spokes’, including valence (whether a concept is positive or negative), along with visual and auditory features. As a result, valence congruency might facilitate our ability to link words conceptually. Semantic relatedness may similarly affect explicit judgements about valence. Moreover, conflict between meaning and valence may recruit semantic control processes. Here we tested these predictions using two-alternative forced-choice tasks, in which participants matched a probe word to one of two possible target words, based on either global meaning or valence. Experiment 1 examined timed responses in healthy young adults, while Experiment 2 examined decision accuracy in semantic aphasia patients with impaired controlled semantic retrieval following left hemisphere stroke. Across both experiments, semantically related targets facilitated valence matching, while related distractors impaired performance. Valence congruency was also found to facilitate semantic decision-making. People with semantic aphasia showed impaired valence matching and had particular difficulty when semantically related distractors were presented, suggesting that the selective retrieval of valence information relies on semantic control processes. Taken together, the results are consistent with the hypothesis that automatic access to the global meaning of written words affects the processing of valence, and that the valence of words is also retrieved even when this feature is task-irrelevant, affecting the efficiency of global semantic judgements.     

语音与词义激活的相对时间进程:来自儿童发展的证据

本研究从儿童语言发展的角度．在已有研究基础上．进一步考察了汉语视觉字词加工中语音与词义激活的相对时间进程。运用启动命名技术,比较了三年级和六年级儿童在语音和语义启动中的表现。结果发现,三年级和六年级儿童都有语音和语义启动效应,且六年级儿童更为显著。但语义启动和同音启动的促进效应之间没有差异,而同音不同声调启动则可能产生抑制作用。文章探讨了这些发现对汉语视觉字词加工中词义信息提取不同观点的含义。     

Semantic distance and single cue use in category search

Perceptual classification may be based either on the physical features of target and background items or on the semantic attributes of the presented items. In this paper we used enumeration tasks to study the role of semantic features in a categorial classification task. This means that subjects were asked to count the number of target words in a display belonging to one semantic category among a number of background items of other categories. Our goal was to study the decision logic in category search by manipulating target background conditions and the semantic distance between target and background classes. In the first experiment we found that the larger the semantic distance between targets and background words, the easier it was to find the targets. In the second experiment we found a "pop-out" effect, in which subjects could use and benefit from a single distinctive semantic feature, "part-likeness", in categorial classification. The results of the two experiments imply that the categorization decision logic is basically the same in physical and semantic perceptual classification.     

Formal reasoning in late adulthood: The role of semantic content and metacognitive strategy

Two experiments explored the availability of deductive or formal reasoning in late adulthood. In Experiment 1, fifty young (M=19.0 years) and 50 elderly adults (M=81.0 years) were assessed using adaptations of Wason's selection task and rated task content for familiarity, affect, and agreement. In Experiment 2, 100 young (M=21.0 years) and 100 elderly adults (M=81.0 years) were similarly assessed, with half of the subjects in each age group receiving a metacognitive strategy to facilitate reasoning. Results from Experiment 1 indicated equivalent reasoning among the groups on problems employed in earlier developmental research. In contrast, problems constructed to entail affect resulted in poorer performance by older adults. In Experiment 2, both young and older adults who used the metacognitive strategy reasoned equally acrossall problems. In both experiments, familiarity and agreement did not play a role in deductive reasoning performance, but affect seemed to be an interfering factor. Results are discussed in terms of competence-procedure and stability-decrement models of adult cognitive development.     

Psychobiological evidence for the distinction between episodic and semantic memory

The evidence for discrete neurobiological mechanisms that underlie episodic and semantic memory is reviewed. Published data from three separate lines of research are considered: studies of human amnesic patients, psychopharmacological studies of normal human subjects, and studies of working and reference memory in rodents, a distinction that is arguably analogous to the episodic/semantic dichotomy. It is concluded that the available evidence does not indicate that episodic and semantic memory are mediated by discrete neural subsystems. An alternative model of human memory is discussed, based on the concept of parallel distributed processing.An earlier version of this paper was submitted as part of the author's qualifying examination at Emory University.     

The attribute priming effect in patients with Alzheimer's disease

Experiments with semantic priming (SP) paradigms have documented early hypopriming in patients with AD when concepts are used as primes and attribute concept features as targets, suggesting that concept attributes are vulnerable to damage very early in the disease course. The aims of this study were to confirm early priming reduction in the attribute condition in patients with AD and to determine which of several semantic indexes (such as the level of distinctiveness, correlation or feature dominance of concept features) best predicts the priming effect size in AD. We administered an SP attribute condition paradigm to 20 mildly demented patients with AD and to 10 NCs. We used concept–attribute pairs for which normative data of semantic indexes relative to both concept primes (i.e., number, type, mean level of dominance, distinctiveness and correlation of features constituting the concepts) and target features (i.e., level of feature dominance, correlation and distinctiveness) were available. Results showed that compared to NCs, the AD group obtained very reduced priming facilitation. Furthermore, the item regression analyses showed that the priming decrement in the AD group was predicted by the feature dominance of the target in the related pairs; that is, the lower the target feature dominance, the lower the priming effect elicited. These results confirmed hypopriming in the attribute condition from the very early phase of AD and support the view that attributes which are more salient for the identification of a given concept are also those most resistant to semantic memory degradation in AD pathology.     

Mechanical knowledge does matter to tool use even when assessed with a non-production task: Evidence from left brain-damaged patients

In the literature on apraxia of tool use, it is now accepted that using familiar tools requires semantic and mechanical knowledge. However, mechanical knowledge is nearly always assessed with production tasks, so one may assume that mechanical knowledge and familiar tool use are associated only because of their common motor mechanisms. This notion may be challenged by demonstrating that familiar tool use depends on an alternative tool selection task assessing mechanical knowledge, where alternative uses of tools are assumed according to their physical properties but where actual use of tools is not needed. We tested 21 left brain-damaged patients and 21 matched controls with familiar tool use tasks (pantomime and single tool use), semantic tasks and an alternative tool selection task. The alternative tool selection task accounted for a large amount of variance in the single tool use task and was the best predictor among all the semantic tasks. Concerning the pantomime of tool use task, group and individual results suggested that the integrity of the semantic system and preserved mechanical knowledge are neither necessary nor sufficient to produce pantomimes. These results corroborate the idea that mechanical knowledge is essential when we use tools, even when tasks assessing mechanical knowledge do not require the production of any motor action. Our results also confirm the value of pantomime of tool use, which can be considered as a complex activity involving several cognitive abilities (e.g., communicative skills) rather than the activation of gesture engrams.     

ERP与语言研究

语言加工是连续的、具有多个分析层次的复杂过程。而新近发展起来的ERP技术具有精确的时间分辨率和多维探测指标,可以对语言进行连续的测量,同时对不同层次的分析有不同的敏感指标。该文着重介绍了与语音层次加工有关的ERP成分N200,与语义加工相关的RP和N400,以及与句法加工有关的LAN和P600,以期为语言领域的ERP研究提供启发和帮助作用。