From Action Representation to Action Execution: Exploring the Links Between Mental Representation and Movement William Land1,2,3 Dima Volchenkov3 & Thomas Schack1,2,3 1 Neurocognition and Action – Biomechanics Research Group, Bielefeld University 2 Center of Excellence - Cognitive Interaction Technology (CITEC), Bielefeld University 3 CoR-Lab: Research Institute for Cognition and Robotics, Bielefeld University Introduction Results Along with superior performance, research indicates that expertise is associated with a number of mediating cognitive adaptations. To this extent, practice is associated with the development of general and task-specific mental representations, which play an important role in the organization and control of action. Research employing the structural dimensional analysis of mental representations (SDA-M) indicates distinct differences in the cognitive representation of actions between novice and expert performers. To this extent, experts’ representations are organized in a distinctive tree-like structure, comprised of cognitive units (BACs) which are functionally related to the biomechanical demands of the task. Given that movements are structured and controlled via these cognitive representations, an important theoretical advancement would be to identify direct links between the cognitive representations of actions and the underlying movement kinematics. Purpose: The present investigation provides a first step in linking the structure found within the cognitive representation of an action to the kinematic movement structure derived from motion capture data. Group Mean Comparison Cognitive Representation Kinematic Structure Head Chest Left shoulder Left elbow Left hand Right shoulder Right elbow Right hand Hips Left thigh Left knee Left foot Right thigh Right knee Right foot Upper Body Lower Body Upper Body Lower Body Results: Statistically similar structures in memory and movement kinematics ( = .71, p < .001). Movement was structured in terms of the upper and lower body, both in memory and in kinematics. Individual Level Comparisons Method Cognitive Representation Kinematic Structure Kinematic Analysis Participants performed 5 golf swings. Swing kinematics were captured using a Vicon motion capture system. Marker trajectories were subjected to the STKD analysis (see below) Participants (N = 17) Various skill levels (0 to 50 years of golf experience). Mental Representation Analysis SDA (see below) Group- and Individual-Level Analyses Upper Body Lower Body Upper Body Lower Body Structural Dimensional Analysis Results: For all participants, significant correlations existed between the memory and kinematic distance matrices ranging from (r = .242 to r = .712, all p’s < .001). The SDA method is an experimental approach for ascertaining the relational structure of cognitive primitives in memory from a given set of concepts. Examining Outliers Participants sorted a list of concepts (in this case body parts) according to their functional relationship during the execution of the golf swing Right Foot Examining the scatter plot of the relationship between the mental and kinematic distance matrices also provides important insights into the link between representation and movement. Specifically, examination of outliers can be used as a diagnostic procedure to identify mismatches between an individual's movement representation and the physical execution of that movement. Ex: Left knee and left thigh were not similarly coupled in memory as in movement execution Left Elbow Left Hand Head Mental representation dendrogram derived from SDA analysis. Spatio-Temporal Kinematic Decomposition The STKD method, based on singular value decomposition, utilizes motion capture data to provide the kinematic structure of movement relating to the spatio-temporal coupling of motion trajectories. Conclusion Dendrogram based on STKD relating to the structure of movement. Results from our analyses indicated a high degree of consistency and similarity between the structure of mental representations and movement kinematics on both a group and individual level. These findings support the theoretical perspective that complex actions are planned and performed with the help of structured cognitive representations in long-term memory that act to guide the biomechanical organization of movements. The extent to which artificial cognitive systems efficiently represent and guide complex actions may be distinguishable based upon our proposed method, which would indicate a level of cognitive sophistication similar to that of its biological counterparts. The degree of coupling between a pair of markers, k1and k2, can be attested on the largest scale of the movement by means of the distance between related vectors in feature space. References [1] Schack, T. & Ritter, H. (2009). The Cognitive Nature of Action - Functional Links between Cognitive Psychology, Movement Science and Robotics. Progress in Brain research: Mind and Motion - The Bidirectional Link between Thought and Action. (pp 231-252). Elsevier. [2] Schack, T. & Mechsner, F. (2006). Representation of motor skills in human long-term memory. Neuroscience Letters, 391, 77-81. [3] Land, W. M., Volchenkov, D., Bläsing, B., & Schack, T. (submitted). From action representation to action execution: Exploring the links between mental representation and movement. Frontiers in Computational Neuroscience.