Interplay between acoustic/phonetic and semantic processes during spoken sentence comprehension: an ERP study

When listening to speech in everyday-life situations, our cognitive system must often cope with signal instabilities such as sudden breaks, mispronunciations, interfering noises or reverberations potentially causing disruptions at the acoustic/phonetic interface and preventing efficient lexical access and semantic integration. The physiological mechanisms allowing listeners to react instantaneously to such fast and unexpected perturbations in order to maintain intelligibility of the delivered message are still partly unknown. The present electroencephalography (EEG) study aimed at investigating the cortical responses to real-time detection of a sudden acoustic/phonetic change occurring in connected speech and how these mechanisms interfere with semantic integration. Participants listened to sentences in which final words could contain signal reversals along the temporal dimension (time-reversed speech) of varying durations and could have either a low- or high-cloze probability within sentence context. Results revealed that early detection of the acoustic/phonetic change elicited a fronto-central negativity shortly after the onset of the manipulation that matched the spatio-temporal features of the Mismatch Negativity (MMN) recorded in the same participants during an oddball paradigm. Time reversal also affected late event-related potentials (ERPs) reflecting semantic expectancies (N400) differently when words were predictable or not from the sentence context. These findings are discussed in the context of brain signatures to transient acoustic/phonetic variations in speech. They contribute to a better understanding of natural speech comprehension as they show that acoustic/phonetic information and semantic knowledge strongly interact under adverse conditions.     

Are depictive gestures like pictures? commonalities and differences in semantic processing

Conversation is multi-modal, involving both talk and gesture. Does understanding depictive gestures engage processes similar to those recruited in the comprehension of drawings or photographs? Event-related brain potentials (ERPs) were recorded from neurotypical adults as they viewed spontaneously produced depictive gestures preceded by congruent and incongruent contexts. Gestures were presented either dynamically in short, soundless video-clips, or statically as freeze frames extracted from gesture videos. In a separate ERP experiment, the same participants viewed related or unrelated pairs of photographs depicting common real-world objects. Both object photos and gesture stimuli elicited less negative ERPs from 400 to 600 ms post-stimulus when preceded by matching versus mismatching contexts (dN450). Object photos and static gesture stills also elicited less negative ERPs between 300 and 400 ms post-stimulus (dN300). Findings demonstrate commonalities between the conceptual integration processes underlying the interpretation of iconic gestures and other types of image-based representations of the visual world.     

Thinking ahead or not? Natural aging and anticipation during reading

Despite growing evidence of young adults neurally pre-activating word features during sentence comprehension, less clear is the degree to which this generalizes to older adults. Using ERPs, we tested for linguistic prediction in younger and older readers by means of indefinite articles (a’s and an’s) preceding more and less probable noun continuations. Although both groups exhibited cloze probability-graded noun N400s, only the young showed significant article effects, indicating probabilistic sensitivity to the phonology of anticipated upcoming nouns. Additionally, both age groups exhibited prolonged increased frontal positivities to less probable nouns, although in older adults this effect was prominent only in a subset with high verbal fluency (VF). This ERP positivity to contextual constraint violations offers additional support for prediction in the young. For high VF older adults, the positivity may indicate they, too, engage in some form of linguistic pre-processing when implicitly cued, as may have occurred via the articles.     

Event-related potentials indicate context effect in reading ambiguous words

The aim of the study was a comparison of lexical and contextual factors in understanding ambiguous words in German. First, a sample of native speakers selected 56 words having maximally strong differences between a dominant and a subordinate meaning. After this, another sample from the same population was visually presented with sentences that activated dominant or subordinate meanings of the words and were accompanied by probes associated with dominant or subordinate meanings. This resulted in a crossed design with two factors: sentence dominant vs. sentence subordinate and probe dominant vs. probe subordinate. An analysis of event-related brain potentials revealed a large, long-lasting and highly-significant N400 wave whenever the meaning of the probe was incongruent with the meaning of the sentence and the lack of this wave whenever the two meanings were congruent. In the typical N400 space and time, the effect was independent of whether the lexical word meaning was dominant or subordinate. At other sites and times, however (e.g., at lateral frontal electrodes F7/F8, and after 700 ms), the congruence effect was significant after dominant sentences only. The data indicate that lexical factors have a rather limited influence on the activation of a particular meaning of ambiguous words. A strong context can virtually override even a very strong difference in the preference for different meanings.     

An ERP investigation of conditional reasoning with emotional and neutral contents

In two experiments we investigate conditional reasoning using event-related potentials (ERPs). Our goal was to examine the time course of inference making in two conditional forms, one logically valid (Modus Ponens, MP) and one logically invalid (Affirming the Consequent, AC). We focus particularly on the involvement of semantically-based inferential processes potentially marked by modulations of the N400. We also compared reasoning about emotional and neutral contents with separate sets of stimuli of differing linguistic complexity across the two experiments. Both MP and AC modulated the N400 component, suggesting the involvement of a semantically-based inferential mechanism common across different logical forms, content types, and linguistic features of the problems. Emotion did not have an effect on early components, and did not interact with components related to inference making. There was a main effect of emotion in the 800–1050 ms time window, consistent with an effect on sustained attention. The results suggest that conditional reasoning is not a purely formal process but that it importantly implicates semantic processing, and that the effect of emotion on reasoning does not primarily operate through a modulation of early automatic stages of information processing.     

外倾个体的自我参照加工程度效应

采用事件相关电位技术和三类刺激的经典oddball范式,以内隐的方式探讨外倾特质个体的自我参照加工程度效应及其神经机制。实验发现,外倾被试的高自我相关名字在各个ERP成分上都比其他刺激诱发了更大波幅。在P2上,高自我相关的刺激比其他刺激诱发了更大的P2波幅和更长的P2潜伏期,其中中线脑区的效应最大。在N2上,高自我相关的刺激比其他刺激诱发了更大的N2波幅和更短的N2潜伏期,其中额区位置的效应最大。控制组被试的高自我相关名字比外倾型被试的高自我相关名字诱发了更大的N2的波幅和更短的N2潜伏期。在P3平均波幅上,高自我相关的刺激比其他刺激诱发了更大的P3波幅,其中中线效应最大。对比外倾型被试,控制组被试的自我参照刺激诱发了更大的P3波幅。研究结果表明外倾特质个体的自我参照加工具有程度效应,但对比控制组被试,外倾特质个体的自我参照加工的程度效应更弱。     

Developmental considerations in the study of childhood depression

Although a great deal of research has been conducted examining biological and psychological factors related to adult depression, relatively little attention has been given to the study of depression in children. The purpose of the present article is to illustrate the importance of considering normal developmental processes in the study of childhood depression. Epidemiological data, diagnostic issues, and methods of assessment in childhood depression are discussed from a developmental perspective, and the role of developmental issues in both the manifestation of depression and its assessment is outlined. Four major theories of depression—biological, psychoanalytic, behavioral, and cognitive—are presented, and developmental issues are discussed in relation to each theory's formulation of the etiology, maintenance, and treatment of depression. Finally, alternative methodologies for the study of childhood depression are considered, and directions for future research, particularly for investigations examining the relationship between childhood and adult depression, are advanced.     

Verbal-manual time sharing in children as a function of task priority

Eighty-three normal, right-handed children performed (a) unimanual finger tapping, (b) recitation of a tongue twister, and (c) both tasks concurrently. Tradeoffs in dual-task performance were measured as the priority assigned to each task was manipulated. Irrespective of task priority, speaking interfered to a greater degree with right-hand tapping than with left-hand tapping, but the effect of tapping upon verbal production and speech errors was not lateralized. The asymmetric effect of speech upon tapping, which was seen in 85.5% of the children, cannot be attributed to the disparity between hands in baseline tapping rate. The findings suggest that time-sharing asymmetry reflects cerebral lateralization of speech, but only some of the results would be predicted on the basis of a functional distance principle of cerebral organization.     

Comparing natural and abstract categories: A case study from computer science

In order to address the issue of whether abstract and concrete objects are categorized similarly, this paper looks at how computer scientists categorize the common concepts of their field. Using the methodology of Rosch, Mervis, Gray, Johnson, and Boyes-Braem (1976) and of Rosch and Mervis (1975) to identify the categorizations used by computer scientists, this study found that the categorization phenomena reported for concrete objects are quite general, operating over a wider range than was previously thought.