What is the interference in "verbal interference"?

Research on the interrelation between language and other components of cognition makes frequent use of verbal interference paradigms. In this, participants are engaged in a primary nonverbal task, while simultaneously repeating non-sense syllables from memory or playback to occupy their articulatory buffer, which is assumed to block internal language use. However, language production involves different subprocesses and levels of representation, and no previous study has explicitly investigated which of these are affected by an occupied articulatory buffer. Thus, the current study addresses the question whether an occupied articulatory buffer significantly interferes with conceptualization. In Experiment 1, speakers name simple objects as fast and as accurately as they can under three conditions. In an interference condition, the verbalization task runs in parallel to a secondary, syllable memorization/recall task, which was expected to induce a situation in which the articulatory buffer temporarily holds phonological information while speakers engage in conceptualization. The articulatory buffer was not occupied in two control conditions. In Experiment 2, speakers performed a similar but more complex task. They verbally responded to visual depictions of actions, again under an interference condition and two control conditions. Results obtained in both experiments suggested no interference. Taken together, the findings suggest that an occupied articulatory buffer does not significantly affect conceptualization.

Macro-event recognition in healthy ageing, Alzheimer's disease, and mild cognitive impairment.

Event perception and cognition is integral to our everyday experience and functional ability. A commonly reported complaint in Alzheimer's disease (AD) is the inability to follow narratives - be it textual, conversational, video, or pictures. This phenomenon has received little systematic research so far. In the current study, we developed a novel paradigm to examine macro-event recognition in individuals with AD in the early stage and its preceding stage of mild cognitive impairment (MCI) in comparison with cognitively healthy older adults, using pictures depicting events. In Experiment 1, we examined participants' ability to integrate pictorially depicted sub-events into macro-events. The pictures were presented in a scrambled order, and participants were expected to arrange them in the temporally and causally appropriate sequence, as dictated by the macro-event schema. Additionally, we investigated the effect of cueing the appropriate event schema by providing a word cue (verb). In Experiment 2, macro-event recognition was examined again using a cognitively less taxing paradigm, where pictures depicting sub-events were presented in correct order, but staggered, and recognition speed was measured. We observed significant deficits in the AD and MCI groups' performance compared with the cognitively healthy older adults, across both experiments, suggesting event perception and cognition is impaired early in the course of AD. There was no effect of cueing on the performance of any of the groups. The theoretical and clinical implications of these findings are discussed.

Can discourse processing performance serve as an early marker of Alzheimer's disease and mild cognitive impairment? A systematic review of text comprehension.

A number of linguistic and cognitive deficits have been reported during the course of Alzheimer's disease (AD) and its preceding stage of mild cognitive impairment (MCI), with some deficits appearing years before onset of clinical symptoms. It continues to be a critical task to identify tools that may serve as an early marker of pathology that are also reliably able to distinguish AD from normal ageing. Given the limited success of classic psychometric cognitive testing, a novel approach in assessment is warranted. A potentially sensitive assessment paradigm is discourse processing. The aim of this review was to synthesize original research studies investigating comprehension of discourse in AD and MCI, and to evaluate the potential of this paradigm as a promising avenue for further research. A literature search targeting studies with AD or MCI groups over 60 years of age was conducted in PubMed, Web of Science, and PsycINFO databases. Eight articles with good quality were included in the review. Six measures of discourse comprehension-naming latency, summary, lesson, main idea, proportion of inferential clauses, true/false questions-were identified. All eight studies reported significant deficits in discourse comprehension in AD and MCI groups on five of the six measures, when compared to cognitively healthy older adults. Mixed results were observed for associations with commonly used cognitive measures. Given the consistent findings for discourse comprehension measures across all studies, we strongly recommend further research on its early predictive potential, and discuss different avenues for research. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10433-021-00619-5.

Event segmentation: Cross-linguistic differences in verbal and non-verbal tasks.

Events, as fundamental units in human perception and cognition, are limited by quality changes of objects over time. In the present study, we investigate the role of language in shaping event units. Given fundamental cross-linguistic differences in the concepts encoded in the verb, as in French compared to German, event unit formation was tested for motion events in a verbal (online event description, experiment 1), as well as a non-verbal task (Newtson-test, experiment 2). In German, motion and direction are described by a single assertion, i.e. one verb encoding manner (to walk …), in conjunction with adpositional phrases for path and direction (… over x across y toward z). In contrast, when information on path and direction is encoded in the verb, as typically in French, each path segment requires a separate assertion (head for x, cross y, approach z). Both experiments were based on short naturalistic video clips showing a figure moving through space along a path either without changing orientation/direction (control), or with changes in orientation/direction (critical). Analysis of the verbal task concerned the probability of producing more than one assertion to refer to the motion events presented in the clips; in the non-verbal event segmentation task, the analysis concerned the probability of marking an event boundary, as indicated by pressing a button. Results show that in French, the probability of producing more than one assertion was significantly higher in the critical condition (experiment 1) and the probability to identify an event boundary was also significantly higher (experiment 2), compared to the German participants but only in the critical condition. The findings indicate language-driven effects in event unit formation. The results are discussed in the context of theories of event cognition, thereby focusing on the role of language in the formation of cognitive structures.

Language related differences of the sustained response evoked by natural speech sounds.

In tonal languages, such as Mandarin Chinese, the pitch contour of vowels discriminates lexical meaning, which is not the case in non-tonal languages such as German. Recent data provide evidence that pitch processing is influenced by language experience. However, there are still many open questions concerning the representation of such phonological and language-related differences at the level of the auditory cortex (AC). Using magnetoencephalography (MEG), we recorded transient and sustained auditory evoked fields (AEF) in native Chinese and German speakers to investigate language related phonological and semantic aspects in the processing of acoustic stimuli. AEF were elicited by spoken meaningful and meaningless syllables, by vowels, and by a French horn tone. Speech sounds were recorded from a native speaker and showed frequency-modulations according to the pitch-contours of Mandarin. The sustained field (SF) evoked by natural speech signals was significantly larger for Chinese than for German listeners. In contrast, the SF elicited by a horn tone was not significantly different between groups. Furthermore, the SF of Chinese subjects was larger when evoked by meaningful syllables compared to meaningless ones, but there was no significant difference regarding whether vowels were part of the Chinese phonological system or not. Moreover, the N100m gave subtle but clear evidence that for Chinese listeners other factors than purely physical properties play a role in processing meaningful signals. These findings show that the N100 and the SF generated in Heschl's gyrus are influenced by language experience, which suggests that AC activity related to specific pitch contours of vowels is influenced in a top-down fashion by higher, language related areas. Such interactions are in line with anatomical findings and neuroimaging data, as well as with the dual-stream model of language of Hickok and Poeppel that highlights the close and reciprocal interaction between superior temporal gyrus and sulcus.