Aging and posture in the memory of manipulable objects

The role of implicit motor simulation on action verb memory

Observation is known to improve memory for action. Previous findings linked such an effect with an easier relation processing of action components following observation compared to mere sentence reading. However, action observation also elicits implicit motor simulation, that is a processing of one's movement through the observer own motor system. We aimed to assess whether encoding of implicit motor simulation can also explain why observation is better than reading for action memory. To prevent influence of item relation processing, two studies about isolated action verbs learning were designed. In Experiment 1, action verbs were encoded with short videos of point-light human movements or with written definitions. Subsequent free recall indicated better memory for the verbs within the video clip condition. Experiment 2 compared two encoding conditions based on point-light human movement videos. Half of the verbs were learned with their normal corresponding movement (biological kinematic). For the other half of the verbs, the velocity of point-light movements was modified to create abnormal nonbiological kinematic actions. We observed better free recall for the verbs learned with biological kinematics. Taken together, those results suggest that action observation is beneficial because it allows the encoding of motor-related information (implicit motor simulation). Semantic resonance between linguistic and motor representations of action could also contribute to memory improvement. Contrary to previous studies, our results cannot be explained by an improvement of items relation processing. However, it suggests that the basic level of action verb memory is sensorimotor perception, such as implicit motor simulation.

The Postural Effect on the Memory of Manipulable Objects

The grounded cognition approach posits the involvement of sensory-motor processes in the representation of knowledge. However, the functional impact of these processes on cognition has been questioned, and some authors have explored the effect of motor interference on memory to test causally this hypothesis. In a seminal study, Dutriaux and Gyselinck (2016) showed that keeping the hands behind the back during learning decreases the memory of manipulable objects, but not the memory of nonmanipulable objects. The aim of this paper is to shed light on the mechanism behind the effect of posture in memory observed by Dutriaux and Gyselinck. The present experiment replicated the posture manipulation during learning but asked participants to keep their hands behind the back during recall. Results showed a similar detrimental effect of the hands behind the back specific to manipulable objects. This shows that the mechanism behind this effect arises from postural interference rather than from a compatibility between the posture during learning and the posture during recall and adds new evidence in favor of the sensory-motor grounding of knowledge.

Short-term upper limb immobilization and the embodied view of memory: A pilot study

The present study aimed to explore the contribution of the manual sensorimotor system to the memory of graspable objects. Participants in the experimental group underwent a short-term upper limb immobilization design to decrease arousal to their dominant hand. Such designs are known to elicit updating of sensorimotor representations and to hardened use of implicit motor simulation, a process that occurs when observing graspable objects. Subsequently, a free recall and a recognition task of graspable and non-graspable objects took place. We found slower recognition for graspable than for non-graspable objects in the control group, while no differences appeared for the immobilized group. Moreover, the recognition latency for graspable objects tended to be slower for the control than for the immobilized group. These results suggest that a time demanding reactivation of motor simulation is elicited when a graspable object is correctly recognized by control participants. The effect of immobilization could prevent this reactivation, leading to faster recognition. Hence, immobilization selectively affects graspable object memory, showing a close relationship with the manual sphere of the sensorimotor system. We suggest that recognition accuracy would probably be affected in cases of stronger disruption of sensorimotor arousal.