Correlation between prime duration and semantic priming effect: Evidence from N400 effect

The stimulus-driven and representation-driven cross-modal attentional spreading are both modulated by audiovisual temporal synchrony

Multisensory integration and attention can interact in a way that attention to the visual constituent of a multisensory object results in an attentional spreading to its ignored auditory constituent, which can be either stimulus-driven or representation-driven depending on whether the object's visual constituent receives extra representation-based selective attention. Previous research using simple unrelated audiovisual combinations has shown that the stimulus-driven attentional spreading is contingent on audiovisual temporal simultaneity. However, little is known about whether this temporal constraint applies also to the representation-driven attentional spreading, and whether it holds for the stimulus-driven process elicited by real-life multisensory objects. The current event-related potential study investigated these questions by systematically manipulating the visual-to-auditory stimulus onset asynchrony (SOA: 0/100/300 ms) in an object-selective visual recognition task wherein the representation-driven and stimulus-driven spreading processes, measured as two distinct auditory negative difference (Nd) components, could be isolated independently. Our results showed that both the representation-driven and stimulus-driven Nds decreased as the SOA increased. Interestingly, the representation-driven Nd was completely absent, whereas the stimulus-driven Nd was still robust, when the auditory constituents were delayed by 300 ms. These findings not only indicate that the role of audiovisual simultaneity in the representation-driven attentional spreading has been underestimated, but also suggest that learned associations between the unisensory constituents of real-life objects render the stimulus-driven attentional spreading more tolerant of audiovisual asynchrony.

Children with autism spectrum disorder show atypical electroencephalographic response to processing contextual incongruencies

Children with autism spectrum disorder (ASD) experience difficulties with social communication, making it challenging to interpret contextual information that aids in accurately interpreting language. To investigate how the brain processes the contextual information and how this is different in ASD, we compared event-related potentials (ERPs) in response to processing visual and auditory congruent and incongruent information. Two groups of children participated in the study: 37 typically developing children and 15 children with ASD (age range = 6 to 12). We applied a language task involving auditory sentences describing congruent or incongruent images. We investigated two ERP components associated with language processing: the N400 and P600. Our results showed how children with ASD present significant differences in their neural responses in comparison with the TD group, even when their reaction times and correct trials are not significantly different from the TD group.

Equivalence relations do exist before they are tested: Confirmatory evidence revealed by EEG measurements

We examined equivalence-based N400 effects by comparing EEG data from participants with different experiences with equivalence testing. Before a priming task used in EEG measurement, Group 1 was given only matching-to-sample training trials whereas Group 2 was exposed to matching-to-sample training and equivalence probe trials. We asked whether exposure to the reinforcement contingency was sufficient to bring about an N400 outcome that might indicate potentially emergent equivalence relations or if such a response depended on experience with equivalence tests. Results showed robust N400 in both groups. Experience with equivalence tests did not further increase the N400 effects. Our findings add confirmatory evidence that equivalence relations may originate via the reinforcement contingency alone. Furthermore, complementary EEG data collected from priming tasks involving words from natural language showed functional overlap between laboratory-defined equivalence and natural word-based N400 effects.

Perceptual elaboration paradigm (PEP): A new approach for investigating mental representations of language

To examine hemispheric differences in accessing a mental representation that embodies perceptual elements and their spatial relationships (i.e., perceptual elaboration and integration), we developed a cross-modal perceptual elaboration paradigm (PEP) in which an imagined percept, rather than a propositional concept, determined congruency. Three target image conditions allow researchers to test which mental representation is primarily accessed when the target is laterally presented. For example, the “Integrated” condition is congruent with either propositional or perceptual mental representations; therefore, results from both hemifield conditions (RVF/LH vs. LVF/RH) should be comparable. Similarly, the “Unrelated” condition is incongruent with either propositional or perceptual mental representations; therefore, results from both hemifield conditions should be comparable as well. However, the “Unintegrated” condition is congruent with the propositional mental representation but not the perceptual mental representation. Should either hemisphere access one representation initially, differences will be revealed in either behavioural or electroencephalography results. This paradigm:•

is distinct from existing paired paradigms that emphasize semantic associations.

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is important given increasing evidence that discourse comprehension involves accessing perceptual information.

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allows researchers to examine the extent to which a mental representation of discourse can embody perceptual elaboration and integration.

Masked priming for the comparative evaluation of camouflage conspicuity

Human observer test and evaluation of camouflage patterns is critical for understanding relative pattern conspicuity against a range of background scenes. However, very few validated methodologies exist for this purpose, and those that do carry several limitations. Five experiments examined whether masked priming with a dot probe could be used to reliably differentiate camouflage patterns. In each experiment, participants were primed with a camouflaged target appearing on the left or right of the screen, and then made a speeded response to a dot probe appearing on the same (congruent) or different (incongruent) side. Across experiments we parametrically varied prime duration between 35, 42, 49, 56, and 63 ms. Results demonstrated that as prime duration increased, a response time disadvantage for incongruent trials emerged with certain camouflage patterns. Interestingly, the most conspicuous patterns showed behavioral differences at a relatively brief (49 ms) prime duration, whereas behavioral differences were only found at longer prime durations for less conspicuous patterns; this overall results pattern matched that predicted by a visual salience model. Together, we demonstrate the viability of masked priming for the test and evaluation of camouflage patterns, and correlated outcomes for saliency models and primed object processing.

Influence of auditory spatial attention on cross-modal semantic priming effect: evidence from N400 effect

Semantic priming is an important research topic in the field of cognitive neuroscience. Previous studies have shown that the uni-modal semantic priming effect can be modulated by attention. However, the influence of attention on cross-modal semantic priming is unclear. To investigate this issue, the present study combined a cross-modal semantic priming paradigm with an auditory spatial attention paradigm, presenting the visual pictures as the prime stimuli and the semantically related or unrelated sounds as the target stimuli. Event-related potentials results showed that when the target sound was attended to, the N400 effect was evoked. The N400 effect was also observed when the target sound was not attended to, demonstrating that the cross-modal semantic priming effect persists even though the target stimulus is not focused on. Further analyses revealed that the N400 effect evoked by the unattended sound was significantly lower than the effect evoked by the attended sound. This contrast provides new evidence that the cross-modal semantic priming effect can be modulated by attention.