Qingfei Chen

Automatic processing of taxonomic and thematic relations in semantic priming - Differentiation by early N400 and late frontal negativity.

Most current models of knowledge organization are based on hierarchical (plant-pine) or taxonomic categories (animal-plant). Another important organizational pattern is thematic categories, which performs external or complementary roles in the same scenario or event (bee-honey). The goal of this study was to explore the processing of hierarchical categories and thematic categories under automatic processing conditions that minimize strategic influences. The Evoked response potential (ERP) procedure was used to examine the time course of semantic priming for category members with a short stimulus onset asynchrony (SOA) of 300ms as participants performed a lexical decision task. Six experimental conditions were compared: hierarchical relations (offspring-grandson), internal features (gold-golden), productive relations (bee-honey), script relations (room-tenant), unrelated (star-spoon), and non-word trials (star-derf). We found faster reaction times for related prime-target pairs than unrelated pairs except for productive relations. The ERP data showed that an early N400 effect (200-400ms) was more negative for unrelated words than for all related words. Furthermore, a frontal negativity (400-550ms) elicited by productive relations was smaller (more positive) than other related words. We suggest that the smaller frontal negativity in the processing of productive relations indicates their increased salience in knowledge structure compared to less prominent hierarchical relations. Indeed, the allocation of attentional resources and subsequent recruitment of additional memory processing might be two of the hallmarks of thematic relations.

Accessing the asymmetrical representations of causal relations and hierarchical relations in semantic memory

Recent studies of causal relations have reported faster verification if two words appear in “cause–effect” order than if they appear in “effect–cause” order. The current study investigated whether such differences are specific to causal relations or exist for other types of asymmetric relations, such as hierarchical relations. Participants were asked to decide whether two simultaneously presented words were causally related or hierarchically related, when the word pair was vertically aligned (Experiment 1) or horizontally aligned (Experiment 2). Both causal and hierarchical relationships were verified faster if “cause”/“superordinate-level” appeared vertically above “effect”/“subordinate-level” than the reverse. However, if word pairs were presented horizontally, only causal relationships were verified faster when cause preceded effect. People appear to represent the causal asymmetry based on temporal order when queried about causal relationships, whereas the representation of hierarchical asymmetry is based on spatial arrangement when queried about hierarchical relationships.

How types of premises modulate the typicality effect in category-based induction: diverging evidence from the P2, P3, and LPC effects

Behavioural studies have indicated that semantic typicality influences processing time and accuracy during the performance of inductive reasoning (i.e., the typicality effect). The present study examines this effect by manipulating the types of premises and conclusions (i.e., general, typical, or atypical) at an electrophysiological level using a semantic category-based induction task. With regard to behavioural results, higher inductive strength was found in typical conclusions in all premise conditions, whereas a longer response time for atypical conclusions was only found in general and typical premise conditions. The ERP results had different response patterns: in the general premise condition, a larger P2, as well as a smaller P3 and LPC (500–600 ms), were elicited by atypical conclusions relative to typical ones; in the typical premise condition, a larger P2 and LPC (600–700 ms) were found for atypical conclusions; in the atypical premise condition, however, only a larger P2 was found for atypical conclusions. The divergent evidence for the typicality effect indicated that the processing of the typicality effect in general, and specific premise conditions, might involve different cognitive processes, such as resource allocation and inference violation, which yielded new insights into the neural underpinnings of the typicality effect in a category-based induction.

The Temporal Order of Word Presentation Modulates the Amplitudes of P2 and N400 during Recognition of Causal Relations

The processing of causal relations has been constantly found to be asymmetrical once the roles of cause and effect are assigned to objects in interactions. We used a relationship recognition paradigm and recorded electroencephalographic (EEG) signals to explore the neural mechanism underlying the asymmetrical representations of causal relations in semantic memory. The results revealed that the verification of causal relations is faster if two words appear in “cause-effect” order (e.g., virus-epidemic) than if they appear in “effect-cause” order (e.g., epidemic-virus), whereas no such asymmetrical representation was found for the verification of hierarchical relations with reverse orders (e.g., bird-sparrow vs. sparrow-bird) in Experiment 1. Furthermore, the P2 amplitude elicited by “superordinate-subordinate” order was larger than that when in reverse order, whereas the N400 effect elicited by “cause-effect” order was smaller (more positive) than when in reverse order. However, no such asymmetry, as well as P2 and N400 components, were observed when verifying the existence of a general associative relation in Experiment 2. We suggested that the smaller N400 in cause-effect order indicates their increased salience in semantic memory relative to the effect-cause order. These results provide evidence for dissociable neural processes, which are related to role binding, contributing to the generation of causal asymmetry.

The Processing of Causal and Hierarchical Relations in Semantic Memory as Revealed by N400 and Frontal Negativity

Most current studies investigating semantic memory have focused on associative (ring-emerald) or taxonomic relations (bird-sparrow). Little is known about the question of how causal relations (virus- epidemic) are stored and accessed in semantic memory. The goal of this study was to examine the processing of causally related, general associatively related and hierarchically related word pairs when participants were required to evaluate whether pairs of words were related in any way. The ERP data showed that the N400 amplitude (200-500ms) elicited by unrelated related words was more negative than all related words. Furthermore, the late frontal distributed negativity (500-700ms) elicited by causally related words was smaller than hierarchically related words, but not for general associated words. These results suggested the processing of causal relations and hierarchical relations in semantic memory recruited different degrees of cognitive resources, especially for role binding.

The Rule Expectancy Effect on the Electrophysiological Correlates underlying Numerical Rule Acquisition.

The present study aimed to provide electrophysiological evidence about acquiring complex numerical rules when unexpected numbers were presented. Hence, we compared the neural correlates underlying the acquisition of unexpected complex rules (e.g., 12, 14, 18, 24) compared to expected simple rules (e.g., 12, 14, 16, 18). The event-related potential (ERP) results for the rule acquisition process for the third numbers showed that, in contrast to expected simple rules, unexpected complex rules elicited: an enhanced N200, reflecting the detection of a conflict between the expected numbers and the displayed numbers; a decreased P300, indicating a feeling of uncertainty accompanied by identifying numerical regularity; and an increased LPC, reflecting the working-memory updating caused by expectancy violation and rule acquisition. These results describe the precise time course of acquiring novel and complex rules when unexpected numbers were presented.

The time course of indirect moral judgment in gossip processing modulated by different agents

Previous studies have investigated personal moral violations with different references (i.e., the protagonists in moral scenarios are the participants themselves or unknown other individuals). However, the roles of various agents in moral judgments have remained unclear. In the present study, ERPs were used to investigate moral judgments when the participants viewed gossip that described (im)moral behaviors committed by different agents (self, friend, celebrity). The results demonstrate that the P2 and late positive component (LPC) correspond to two successive processes of indirect moral judgment when individuals process gossip. Specifically, the P2 amplitude in the celebrity condition was more sensitive in distinguishing immoral behaviors from moral behaviors than that in the other two conditions, whereas the moral valence effect on the LPC was predominately driven by the self-reference. These findings expand our current understanding of moral judgments in a gossip evaluation task and demonstrate that the early processing of gossip depends on both the entertainment value of the agent and the salience of moral behaviors. Processing in the later stage reflects reactions to intensified affective stimuli, or reflects cognitive effort that was required to resolve the conflict between negative gossip about self and the self-positivity bias.

The modulation of causal contexts in motion processes judgment as revealed by P2 and P3

The evoked response potential (ERP) procedure was used to investigate the representation of motion processes in different causal contexts, such as the collision of two squares or the repulsion of two magnets with like poles facing. Participants were required to judge whether each movement was plausible according to the causal context depicted by the cover story. Three main differences after the movement of the second object were found. First, the amplitudes at 70-170ms (N1) and 170-370ms (P2) elicited by a no-contact condition were more negative than a contact condition in the square context, whereas larger N1 and more positive amplitudes at 370-670ms were elicited by a no-contact condition in the magnet context. Second, larger P2 and more positive amplitudes at 370-670ms were elicited by inconsistent direction relative to consistent condition in the square context, whereas smaller N1 and more positive amplitudes at 370-670ms were elicited by inconsistent direction in the magnet context. Finally, larger P2 and more negative amplitudes at 370-470ms were elicited by plausible conditions relative to implausible conditions in a square context, whereas larger N1 and more positive amplitudes at 370-670ms were elicited by plausible conditions in the magnet context. These results suggested that the conceptual knowledge with different causal contexts have distinct effects on the judgment of objects interactions.