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Institut
Language production ultimately aims to convey meaning. Yet words differ widely in the richness and density of their semantic representations, and these differences impact conceptual and lexical processes during speech planning. Here, we replicated the recent finding that semantic richness, measured as the number of associated semantic features according to semantic feature production norms, facilitates object naming. In contrast, intercorrelational semantic feature density, measured as the degree of intercorrelation of a concept's features, presumably resulting in the coactivation of closely related concepts, has an inhibitory influence. We replicated the behavioral effects and investigated their relative time course and electrophysiological correlates. Both the facilitatory effect of high semantic richness and the inhibitory influence of high feature density were reflected in an increased posterior positivity starting at about 250 ms, in line with previous reports of posterior positivities in paradigms employing contextual manipulations to induce semantic interference during language production. Furthermore, amplitudes at the same posterior electrode sites were positively correlated with object naming times between about 230 and 380 ms. The observed effects follow naturally from the assumption of conceptual facilitation and simultaneous lexical competition and are difficult to explain by language production theories dismissing lexical competition.
One of the ongoing debates about visual consciousness is whether it can be considered as an all-or-none or a graded phenomenon. While there is increasing evidence for the existence of graded states of conscious awareness based on paradigms such as visual masking, only little and mixed evidence is available for the attentional blink paradigm, specifically in regard to electrophysiological measures. Thereby, the all-or-none pattern reported in some attentional blink studies might have originated from specifics of the experimental design, suggesting the need to examine the generalizability of results. In the present event-related potential (ERP) study (N = 32), visual awareness of T2 face targets was assessed via subjective visibility ratings on a perceptual awareness scale in combination with ERPs time-locked to T2 onset (components P1, N1, N2, and P3). Furthermore, a classification task preceding visibility ratings allowed to track task performance. The behavioral results indicate a graded rather than an all-or-none pattern of visual awareness. Corresponding graded differences in the N1, N2, and P3 components were observed for the comparison of visibility levels. These findings suggest that conscious perception during the attentional blink can occur in a graded fashion.
A close call
(2018)
The present study investigated how lexical selection is influenced by the number of semantically related representations (semantic neighbourhood density) and their similarity (semantic distance) to the target in a speeded picture-naming task. Semantic neighbourhood density and similarity as continuous variables were used to assess lexical selection for which competitive and noncompetitive mechanisms have been proposed. Previous studies found mixed effects of semantic neighbourhood variables, leaving this issue unresolved. Here, we demonstrate interference of semantic neighbourhood similarity with less accurate naming responses and a higher likelihood of producing semantic errors and omissions over accurate responses for words with semantically more similar (closer) neighbours. No main effect of semantic neighbourhood density and no interaction between semantic neighbourhood density and similarity was found. We assessed further whether semantic neighbourhood density can affect naming performance if semantic neighbours exceed a certain degree of semantic similarity. Semantic similarity between the target and each neighbour was used to split semantic neighbourhood density into two different density variables: The number of semantically close neighbours versus distant neighbours. The results showed a significant effect of close, but not of distant, semantic neighbourhood density: Naming pictures of targets with more close semantic neighbours led to longer naming latencies, less accurate responses, and a higher likelihood for the production of semantic errors and omissions over accurate responses. The results show that word inherent semantic attributes such as semantic neighbourhood similarity and the number of coactivated close semantic neighbours modulate lexical selection supporting theories of competitive lexical processing.