Feature-Specific Event-Related Potential Effects to Action- and Sound-Related Verbs during Visual Word Recognition

Task cue influences on lexical decision performance and masked semantic priming effects: The role of cue-task compatibility

Recent research demonstrated that mere presentation of a task cue influences subsequent unconscious semantic priming by attentional sensitization of related processing pathways. The direction of this influence depended on task-set dominance. Dominant task sets with a compatible cue-task mapping were supposed to be rapidly suppressed, while weak task sets showed more sustainable activation. Building on this research, we manipulated cue-task compatibility as instance of task-set dominance in two experiments and tested how masked semantic priming was influenced by actually performing the cued task (induction-task trials) or by mere cue presentation (task cue-only trials). In induction-task trials, the results of earlier research were replicated; semantic priming was larger following a semantic induction task compared to a perceptual induction task. In task cue-only trials, priming effects were reversed compared to induction-task trials in both experiments. Priming was larger for a perceptual compared to a semantic task set in task cue-only trials, indicating suppression of task sets following mere cue presentation in preparation for the upcoming lexical decision task. This notion of an inhibition of task sets after mere cue presentation was further supported by switching-related costs and changes of task-set implementation throughout the experiment. The absence of a moderator role of cue-task compatibility for task cue effects on priming in the present study suggests that the precise time course of task-set activation and inhibition in response to task cues as a function of cue-task compatibility might depend on specific experimental settings.

Time course of brain activity during the processing of motor- and vision-related abstract concepts: flexibility and task dependency

Grounded cognition theories assume that conceptual processing depends on modality-specific brain systems in a context-dependent fashion. Although the relation of abstract concepts to modality-specific systems is less obvious than for concrete concepts, recent behavioral and neuroimaging studies indicated a foundation of abstract concepts in vision and action. However, due to their poor temporal resolution, neuroimaging studies cannot determine whether sensorimotor activity reflects rapid access to conceptual information or later conceptual processes. The present study therefore assessed the time course of abstract concept processing using event-related potentials (ERPs) and compared ERP responses to abstract concepts with a strong relation to vision or action. We tested whether possible ERP effects to abstract word categories would emerge in early or in later time windows and whether these effects would depend on the depth of the conceptual task. In Experiment 1, a shallow lexical decision task, early feature-specific effects starting at 178 ms were revealed, but later effects beyond 300 ms were also observed. In Experiment 2, a deep conceptual decision task, feature-specific effects with an onset of 22 ms were obtained, but effects again extended beyond 300 ms. In congruency with earlier neuroimaging work, the present feature-specific ERP effects suggest a grounding of abstract concepts in modal brain systems. The presence of early and late feature-specific effects indicates that sensorimotor activity observed in neuroimaging experiments may reflect both rapid conceptual and later post-conceptual processing. Results furthermore suggest that a deep conceptual task accelerates access to conceptual sensorimotor features, thereby demonstrating conceptual flexibility.

Brain Activation During Conceptual Processing of Action and Sound Verbs

Grounded cognition approaches to conceptual representations postulate a close link between conceptual knowledge and the sensorimotor brain systems. The present fMRI study tested, whether a feature-specific representation of concepts, as previously demonstrated for nouns, can also be found for action- and sound-related verbs. Participants were presented with action- and soundrelated verbs along with pseudoverbs while performing a lexical decision task. Sound-related verbs activated auditory areas in the temporal cortex, whereas action-related verbs activated brain regions in the superior frontal gyrus and the cerebellum, albeit only at a more liberal threshold. This differential brain activation during conceptual verb processing partially overlapped with or was adjacent to brain regions activated during the functional localizers probing sound perception or action execution. Activity in brain areas involved in the processing of action information was parametrically modulated by ratings of action relevance. Comparisons of action- and sound-related verbs with pseudoverbs revealed activation for both verb categories in auditory and motor areas. In contrast to proposals of strong grounded cognition approaches, our study did not demonstrate a considerable overlap of activations for action- and sound-related verbs and for the corresponding functional localizer tasks. However, in line with weaker variants of grounded cognition theories, the differential activation pattern for action- and sound-related verbs was near corresponding sensorimotor brain regions depending on conceptual feature relevance. Possibly, action-sound coupling resulted in a mutual activation of the motor and the auditory system for both action- and sound-related verbs, thereby reducing the effect sizes for the differential contrasts.

Processing of Action and Sound Verbs in Context: An FMRI Study

Recent theories propose a flexible recruitment of sensory and motor brain regions during conceptual processing depending on context and task. The present functional magnetic resonance imaging study investigated the influence of context and task on conceptual processing of action and sound verbs. Participants first performed an explicit semantic context decision task, in which action and sound verbs were presented together with a context noun. The same verbs were repeatedly presented in a subsequent implicit lexical decision task together with new action and sound verbs. Thereafter, motor and acoustic localizer tasks were administered to identify brain regions involved in perception and action. During the explicit task, we found differential activations to action and sound verbs near corresponding sensorimotor brain regions. During the implicit lexical decision task, differences between action and sound verbs were absent. However, feature-specific repetition effects were observed near corresponding sensorimotor brain regions. The present results suggest flexible conceptual representations depending on context and task. Feature-specific effects were observed only near, but not within corresponding sensorimotor brain regions, as defined by the localizer tasks. Our results therefore only provide limited evidence in favor of grounded cognition theories assuming a close link between the conceptual and the sensorimotor systems.

Action Semantic Deficits and Impaired Motor Skills in Autistic Adults Without Intellectual Impairment

Several studies indicate the functional importance of the motor cortex for higher cognition, language and semantic processing, and place the neural substrate of these processes in sensorimotor action-perception circuits linking motor, sensory and perisylvian language regions. Interestingly, in individuals with autism spectrum disorder (ASD), semantic processing of action and emotion words seems to be impaired and is associated with hypoactivity of the motor cortex during semantic processing. In this study, the relationship between semantic processing, fine motor skills and clinical symptoms was investigated in 19 individuals with ASD and 22 typically-developing matched controls. Participants completed two semantic decision tasks involving words from different semantic categories, a test of alexithymia (the Toronto Alexithymia Scale), and a test of fine motor skills (the Purdue Pegboard Test). A significant Group × Word Category interaction in accuracy (p < 0.05) demonstrated impaired semantic processing for action words, but not object words in the autistic group. There was no significant group difference when processing abstract emotional words or abstract neutral words. Moreover, our study revealed deficits in fine motor skills as well as evidence for alexithymia in the ASD group, but not in neurotypical controls. However, these motor deficits did not correlate significantly with impairments in action-semantic processing. We interpret the data in terms of an underlying dysfunction of the action-perception system in ASD and its specific impact on semantic language processing.