Adjectives Modulate Sensorimotor Activation Driven by Nouns

Syntax matters in shaping sensorimotor activation driven by nouns

Existing evidence has shown that adjectives modulate the grasp-compatibility effect elicited by object nouns. The aim of the present study was to investigate the role of syntax on the sensorimotor activation elicited by nouns in a grasp-compatibility task. We assessed two languages with different syntactic rules, Italian in Experiment 1 and English in Experiment 2. In both experiments, an adjective-noun pair was shown on the screen. The adjective was always in a pre-nominal position and denoted either a disadvantageous quality of the object graspability (e.g., sharp) or the object colour (e.g., reddish). Participants had to categorize the object nouns as natural or artifact, performing a precision or a power reach-to-grasp movement. On different trials, the grasp response was compatible or incompatible with the grip typically used to manipulate the object indicated by the noun. In Experiment 1 (Italian language) the adjective-noun order violated the syntactic order and no difference emerged between reaction times on compatible and incompatible trials (no grasp compatibility effect). In Experiment 2 (English language), the adjective-noun order followed the syntactic rule. Results showed a grasp-compatibility effect when a colour adjective was presented before a natural object noun. When a disadvantageous adjective preceded an artifact or a natural object noun, an inverted grasp-compatibility effect emerged with slower responses on compatible than incompatible trials. Taken together, these findings suggest that adjectives can shape the sensorimotor activation elicited by nouns of graspable objects only when the syntax is correct. Results are discussed with respect to embodied cognition theories.

Stimulus-response compatibility effects during object semantic categorisation: Evocation of grasp affordances or abstract coding of object size?

When the size of visual objects matches the size of the response required to perform the task, a potentiation effect has been reported, with faster responses in compatible than incompatible situations. Size compatibility effects have been taken as evidence of close perception-action interrelations. However, it is still unclear whether the effect arises from abstract coding of the size of stimulus and response or from the evocation of grasp affordances from visual objects. We aimed to disentangle the two interpretations. Two groups of 40 young adults categorised small and large objects presented in standardised size as natural or artefact objects. One group categorised manipulable objects that may be associated with small or large size properties and evoke power or precision grasp affordances. The other group categorised non-manipulable objects that may only be associated with small or large size properties. Categorisation responses were made by reaching and grasping a monotonic cylindric device with a power or precision grip in a grasping condition and with large or small touch responses in a control condition. Compatibility effects were found in both grasping and control conditions, independently of the manipulability or category of objects. Participants were faster when the size of the expected response matched the size of the object than when they mismatched, especially for power grasps or whole-hand touch responses. Overall findings support the abstract coding hypothesis and suggest that compatibility between the conceptual size of the object and the size of the hand response is sufficient to facilitate semantic categorisation judgements.

Grasping the semantic of actions: a combined behavioral and MEG study

There is experimental evidence that the brain systems involved in action execution also play a role in action observation and understanding. Recently, it has been suggested that the sensorimotor system is also involved in language processing. Supporting results are slower response times and weaker motor-related MEG Beta band power suppression in semantic decision tasks on single action verbs labels when the stimulus and the motor response involve the same effector. Attenuated power suppression indicates decreased cortical excitability and consequent decreased readiness to act. The embodied approach forwards that the simultaneous involvement of the sensorimotor system in the processing of the linguistic content and in the planning of the response determines this language-motor interference effect. Here, in a combined behavioral and MEG study we investigated to what extent the processing of actions visually presented (i.e., pictures of actions) and verbally described (i.e., verbs in written words) share common neural mechanisms. The findings demonstrated that, whether an action is experienced visually or verbally, its processing engages the sensorimotor system in a comparable way. These results provide further support to the embodied view of semantic processing, suggesting that this process is independent from the modality of presentation of the stimulus, including language.

Hand constraint reduces brain activity and affects the speed of verbal responses on semantic tasks

According to the theory of embodied cognition, semantic processing is closely coupled with body movements. For example, constraining hand movements inhibits memory for objects that can be manipulated with the hands. However, it has not been confirmed whether body constraint reduces brain activity related to semantics. We measured the effect of hand constraint on semantic processing in the parietal lobe using functional near-infrared spectroscopy. A pair of words representing the names of hand-manipulable (e.g., cup or pencil) or nonmanipulable (e.g., windmill or fountain) objects were presented, and participants were asked to identify which object was larger. The reaction time (RT) in the judgment task and the activation of the left intraparietal sulcus (LIPS) and left inferior parietal lobule (LIPL), including the supramarginal gyrus and angular gyrus, were analyzed. We found that constraint of hand movement suppressed brain activity in the LIPS toward hand-manipulable objects and affected RT in the size judgment task. These results indicate that body constraint reduces the activity of brain regions involved in semantics. Hand constraint might inhibit motor simulation, which, in turn, would inhibit body-related semantic processing.

Influence of colour on object motor representation

Colour conveys specific information about the status/quality of an object; whereas its role in object recognition has been widely studied, little is known about its role in sensorimotor processes. We performed three experiments to assess whether colour influences the motor representation of graspable objects. In Experiment 1, we used a grasp compatibility task, in which participants categorized each object as natural or artifact, by performing reach-to-grasp movements. Response grasps could be compatible or incompatible with the ones normally used to manipulate the objects. Results showed faster reaction times for natural objects displayed in the correct colour compared with both opposite colour and correct colour artifact objects. In Experiment 2, to directly assess the effect of colour on object motor representation, we used an interference task in which an irrelevant object was shown while performing a pre-specified reach-to-grasp movement (i.e., verbal cues: small vs. large). Results highlighted a reversed compatibility effect when objects were shown in their correct colour, but only at the beginning of the movement (10 ms SOA). Finally, we run a third experiment using the same task as in Experiment 2. In this experiment, we compared the grasp compatibility effect driven by natural objects with the grasp compatibility effect driven by dangerous natural objects (e.g., cactus), which are objects that should not elicit a grasping program. The results of Experiment 3 confirm those of Experiment 2, highlighting also specific processes related to dangerous objects. Taken together, these results revealed that colour can be significant for the motor system, highlighting the close link between colour and shape, and also specific processes related to dangerous objects.

What matters is the underlying experience: Similar motor responses during processing observed hand actions and hand-related verbs

It is well-accepted that processing observed actions involves at some extent the same neural mechanisms responsible for action execution. More recently, it has been forwarded that also the processing of verbs expressing a specific motor content is subserved by the neural mechanisms allowing individuals to perform the content expressed by that linguistic material. This view is also known as embodiment and contrasts with a more classical approach to language processing that considers it as amodal. In the present study, we used a go/no-go paradigm, in which participants were requested to respond to real words and pictures and refrain from responding when presented stimuli were pseudowords and scrambled images. Real stimuli included pictures depicting hand- and foot-related actions and verbs expressing hand- and foot-related actions. We, therefore, directly compared the modulation of hand motor responses during the observation of actions and the presentation of verbs, expressing actions in the same category. The results have shown that participants gave slower hand motor responses during the observation of hand actions and the processing of hand-related verbs as than observed foot actions and related verbs. These findings support embodiment showing that whatever the modality of presentation (observed action or verb), the modulation of hand motor responses was similar, thus suggesting that processing seen actions and related verbs shares common mechanisms most likely involving the motor system and the underlying motor experience.

Evidence for the Concreteness of Abstract Language: A Meta-Analysis of Neuroimaging Studies

The neural mechanisms subserving the processing of abstract concepts remain largely debated. Even within the embodiment theoretical framework, most authors suggest that abstract concepts are coded in a linguistic propositional format, although they do not completely deny the role of sensorimotor and emotional experiences in coding it. To our knowledge, only one recent proposal puts forward that the processing of concrete and abstract concepts relies on the same mechanisms, with the only difference being in the complexity of the underlying experiences. In this paper, we performed a meta-analysis using the Activation Likelihood Estimates (ALE) method on 33 functional neuroimaging studies that considered activations related to abstract and concrete concepts. The results suggest that (1) concrete and abstract concepts share the recruitment of the temporo-fronto-parietal circuits normally involved in the interactions with the physical world, (2) processing concrete concepts recruits fronto-parietal areas better than abstract concepts, and (3) abstract concepts recruit Broca's region more strongly than concrete ones. Based on anatomical and physiological evidence, Broca's region is not only a linguistic region mainly devoted to speech production, but it is endowed with complex motor representations of different biological effectors. Hence, we propose that the stronger recruitment of this region for abstract concepts is expression of the complex sensorimotor experiences underlying it, rather than evidence of a purely linguistic format of its processing.