视觉工作记忆负载类型对注意选择的影响

通过操纵Flanker任务相对于视觉工作记忆任务的呈现位置, 探讨在视觉工作记忆编码和保持阶段, 精度负载和容量负载对注意选择的影响。行为结果发现, Flanker任务呈现位置和视觉工作记忆负载类型影响注意选择; ERP结果发现, 在保持阶段, 当搜索目标和干扰项不一致时, 负载类型影响N2成分。研究表明, 在编码阶段, 视觉工作记忆负载主要通过占用更多知觉资源降低干扰效应, 支持知觉负载理论; 而在保持阶段, 当Flanker任务位于记忆项内部时, 两类负载在工作记忆表征过程中不同的神经活动导致投入到注意选择的认知控制资源不同, 可能是两类负载影响保持阶段注意选择的机制。     

Electrophysiological Evidence of Different Interpretative Strategies in Irony Comprehension

We explore the hypothesis that induction of holistic or analytic strategies influences comprehension and processing of highly contextualized expressions of ordinary language, such as irony. Twenty undergraduate students were asked to categorize as coherent or incoherent a group of sentences. Each sentence completed a previous story, so that they could be ironical, literal or nonsensical endings. Participants were asked to evaluate whether each sentence was coherent or incoherent. Half of them were initially instructed to consider whether the sentences made sense (holistic condition); the other half were instructed to consider whether the sentences were congruent or incongruent (analytic condition). Behavioral responses and Event Related Potentials were registered during the experiment. Both behavioral and electrophysiological results allow clearly distinguishing between the holistic and the analytic strategies. The fact that the same set of stimuli elicits different ERP waveforms, depending on the strategy with which they are analyzed, suggests that different cognitive processes and different areas of the brain are operating in each case.     

How iconic gestures enhance communication: an ERP study

EEG was recorded as adults watched short segments of spontaneous discourse in which the speaker's gestures and utterances contained complementary information. Videos were followed by one of four types of picture probes: cross-modal related probes were congruent with both speech and gestures; speech-only related probes were congruent with information in the speech, but not the gesture; and two sorts of unrelated probes were created by pairing each related probe with a different discourse prime. Event-related potentials (ERPs) elicited by picture probes were measured within the time windows of the N300 (250-350 ms post-stimulus) and N400 (350-550 ms post-stimulus). Cross-modal related probes elicited smaller N300 and N400 than speech-only related ones, indicating that pictures were easier to interpret when they corresponded with gestures. N300 and N400 effects were not due to differences in the visual complexity of each probe type, since the same cross-modal and speech-only picture probes elicited N300 and N400 with similar amplitudes when they appeared as unrelated items. These findings extend previous research on gesture comprehension by revealing how iconic co-speech gestures modulate conceptualization, enabling listeners to better represent visuo-spatial aspects of the speaker's meaning.     

Is word perception in a second language more vulnerable than in one's native language? Evidence from brain potentials in a dual task setting

We assessed the effect of additional tasks on language perception in second-language and native speakers. The N400 component of the event-related potential was recorded to spoken nouns that had to be judged for synonymity with a preceding word, while additional choice responses were required to visual stimuli. In both participant groups N400 was delayed as a function of temporal overlap with the additional task. In second-language speakers there was a global delay of N400 independent of additional task load and a decrease of accuracy at highest overlap. These findings are interpreted within a single channel account of language perception.     

Domain specificity versus expertise: factors influencing distinct processing of faces

To explore face specificity in visual processing, we compared the role of task-associated strategies and expertise on the N170 event-related potential (ERP) component elicited by human faces with the ERPs elicited by cars, birds, items of furniture, and ape faces. In Experiment 1, participants performed a car monitoring task and an animacy decision task. In Experiment 2, participants monitored human faces while faces of apes were the distracters. Faces elicited an equally conspicuous N170, significantly larger than the ERPs elicited by non-face categories regardless of whether they were ignored or had an equal status with other categories (Experiment 1), or were the targets (in Experiment 2). In contrast, the negative component elicited by cars during the same time range was larger if they were targets than if they were not. Furthermore, unlike the posterior-temporal distribution of the N170, the negative component elicited by cars and its modulation by task were more conspicuous at occipital sites. Faces of apes elicited an N170 that was similar in amplitude to that elicited by the human face targets, albeit peaking 10 ms later. As our participants were not ape experts, this pattern indicates that the N170 is face-specific, but not specie-specific, i.e. it is elicited by particular face features regardless of expertise. Overall, these results demonstrate the domain specificity of the visual mechanism implicated in processing faces, a mechanism which is not influenced by either task or expertise. The processing of other objects is probably accomplished by a more general visual processor, which is sensitive to strategic manipulations and attention.     

ERP evidence for conceptual mappings and comparison processes during the comprehension of conventional and novel metaphors

Cognitive linguists suggest that understanding metaphors requires activation of conceptual mappings between the involved concepts. We tested whether mappings are indeed in use during metaphor comprehension, and what mapping means as a cognitive process with Event-Related Potentials. Participants read literal, conventional metaphorical, novel metaphorical, and anomalous target sentences preceded by primes with related or unrelated mappings. Experiment 1 used sentence-primes to activate related mappings, and Experiment 2 used simile-primes to induce comparison thinking. In the unprimed conditions of both experiments, metaphors elicited N400s more negative than the literals. In Experiment 1, related sentence-primes reduced the metaphor-literal N400 difference in conventional, but not in novel metaphors. In Experiment 2, related simile-primes reduced the metaphor-literal N400 difference in novel, but not clearly in conventional metaphors. We suggest that mapping as a process occurs in metaphors, and the ways in which it can be facilitated by comparison differ between conventional and novel metaphors.     

Electrophysiological evidence for modulation of lexical processing after repetitive exposure to foreign phonotactic rules

In two experiments we investigate how repeated exposure to native and non-native phonotactic regularities alters the N400, an event-related potential related to lexico-semantic access. Participants underwent a Passive Listening (Experiment 1) or a Categorization Training (Experiment 2) for monosyllabic pseudowords over 3 days. During Passive Listening participants solely listened to the stimuli while for Categorization Training they learned to assign items to two arbitrary categories by feedback. Notably, this task did not rely on phonotactic regularities. Before training, N400 was larger for legal compared to illegal items. Over the 3-day exposure Passive Listening yielded a significant decrease in N400-amplitude for illegal pseudowords, however, this effect was abolished and partially inverted by the Categorization Training. We suggest the decrease in N400-amplitude indicates more efficient discrimination between native and non-native pseudowords since only the former are potential lexical candidates. On the contrary, Categorization Training introduces a ‘protosemantic’ context overriding prelexical selection processes.     

Many-body potential for nitrogen in α-iron

N atom is one of the most frequent foreign interstitial atoms in α-iron along with C atoms. The Fe–C potential has been well-developed and can reproduce many significant interactions of C with point defects present in α-iron. However, there exists no satisfactory Fe–N potential to describe the interactions of N with point defects. Here, we develop a many-body potential for N in α-iron. The potential parameters are determined by fitting to ab initio data, which includes energetics, configurations, and relaxations of Fe atoms close to N atom. This potential successfully describes the interactions of Fe–N across a wide range of defect environments. The potential employs the embedded atom method form and hence is appropriate for large-scale molecular dynamics simulation.     

Emoción expresada: Introducción al concepto,evaluación e implicaciones pronosticas y terapéuticas

RESUMEN

Los autores comienzan analizando el concepto de emoción expresada y los modos de evaluarla en el nucleo familiar de pacientes esquizofrénicos, clarificando sus dos componentes básicos: implicación emocional excesiva y actitud crítica. Seguidamente repasan diversos estudios en torno a la validez y utilidad de este constructo y otros en relación con cuestiones de carácter conceptual y metodológico. Finalmente abordan las implicaciones y desarrollos terapéuticos, centrándose en las intervenciones sociales llevadas a cabo en Gran Bretaña y en la terapia familiar conductual y ofreciendo algunos de sus resultados. El trabajo concluye que la revisión de los estudios sobre emoción expresada en familiares de sujetos esquizofrénicos pone de relieve la adecuación y utilidad de estas medidas, ofreciendo algunas pautas para investigaciones futuras.     

Comprensión del lenguaje y potenciales evocados

Resumen

En este trabajo se pretende dar cuenta de los últimos adelantos en el campo de los procesos relacionados con la comprensión del lenguaje y los potenciales evocados. Estos han mostrado ser herramientas útiles para el estudio de dichos procesos. Para ello se revisan una serie de estudios relacionados con los componentes que clásicamente han venido recibiendo una mayor atención. Así, el Potencial de Reconocimiento y la N400, parecen guardar relación con aspectos semánticos. Por otro lado, la Negatividad Izquierda Anterior Temprana y la P600 estarían más relacionados con los sintácticos. También se mencionan otros componentes, como la P300 y algunos que ha recibido menor atención.