Movement Planning and the Role of End-State Comfort

Movement Planning and the Role of End-State Comfort Nicole George, Paula M. van Wyk & Adriana M. Duquette ABSTRACT The way individuals manipulate objects can provide insight into movement planning processes. It is common for individuals to adopt an initially awkward position when grasping an object in order to move with or towards a more comfortable position. This is known as the end-state comfort (ESC) effect [1]. While ESC has been considered a main influence on the process of movement selection, recent investigation has established that there are tasks which do not exhibit this effect [2]. Thus, the purpose of this study was to replicate four object manipulation tasks with a larger sample size than previous research, in an effort to provide further support for or against the traditionally accepted ESC effect of movement planning. Based on the robust support for ESC in the initial studies [3, 4, 5, 6], this effect was expected to be displayed in all tasks in the present study. Grasp selection strategies of 303 university-aged students (135 F, 168 M) were examined during two bar transport tasks (one seated, one standing), an overturned glass task and a cutlery transfer task. Hand orientations were recorded at the beginning and end of each movement, and the frequency of trials exhibiting ESC was quantified. Contrary to the initial studies [3, 4, 5, 6], ESC was not established in all of the tasks. ESC was not observed among 63.7% and 69.3% of participants for trials involving the cutlery transfer task to the left and right, respectively. Moreover, the magnitude of the effect was found to be less than what has been previously reported. Although ESC was demonstrated by all 12 participants in the seminal article [5], in the current study, only 55.4% of participants displayed the planning behaviour in all trials during the same bar transport task. The decreased display of ESC may support alternate theories of movement planning, such as recall of previous actions [7] and the influence of acquired habits [8]. REFERENCES [1] Rosenbaum, D. A., Marchak, F., Barnes, H. J., Vaughan, J., Slotta, J. D., & Jorgensen, M. J. (1990). Constraints for action selection: overhand versus underhand grips. In M. Jeannerod (Ed.), Attention and performance XIII. Motor representation and control (pp 211-265). Hillsdale, NJ: Erlbaum. [2] Hermens, F., Kral, D., & Rosenbaum, D. A. (2014). Limits of end-state planning. Acta Psychologica, 148, 148-162. [3] Fischman, M. G (1997). End-state comfort in object manipulation [Abstract]. Research Quarterly for Exercise and Sport, 68(Suppl.), A-60. [4] McCarty, M. E., Clifton, R. K., & Collard, R. R. (1999). Problem solving in infancy: The emergence of an action plan. Developmental Psychology, 35, 1091-1101. [5] Rosenbaum, D. A., & Jorgensen, M. J. (1992). Planning macroscopic aspects of manual control. Human Movement Science 11, 61-69. [6] Short, M. W., & Cauraugh, J. H. (1997). Planning macroscopic aspects of manual control: End-state comfort and point-of-change effects. Acta Psychologica 96, 133-147. [7] Cohen, R. G., & Rosenbaum, D. A. (2004). Where grasps are made reveals how grasps are planned: Generation and recall of motor plans. Experimental Brain Research, 157, 486-495. [8] Herbort, O., & Butz, M. (2011). Habitual and goal-related factors in (everyday) object handling. Experiential Brain Research, 213, 371-382