08:30 - 10:00
Tue-A7-Talk IV-
Tue-Talk IV-
Room: A7
Chair/s:
Belkis Ezgi Arikan, Dimitris Voudouris
Touch is one of the most critical senses, as it provides information about the state of our own body and of the external world. For instance, tactile input from different surfaces influences how humans interact with these surfaces. Meanwhile, tactile sampling and processing is also influenced by our movements. In the real world, touch can be directed to different textures, surfaces and objects, with different goals in mind (from contacting a texture to exploring a surface to changing an object’s position). The proposed symposium will discuss recent findings on the interplay between touch and movement in naturalistic settings. More specifically, we will address how tactile processing is
modulated by various tactile inputs, during motion, and under different tasks. Dione Mariama will talk about how humans explore natural textures and how mechanoreceptive afferents transform physical inputs into the perception of touch. Luigi Tamè will present evidence that distortions in the perceived distances between tactile stimuli on the hand can also be observed in early somatosensory and motor areas. Focusing on natural object manipulation, Benoit Delhaye will then address how tactile interactions between fingertips and objects provide grasp stability. Alessandro Moscatelli will talk about everyday interactions between hand movements and touch, and how optimal integration
models can predict tactile illusions of motion. Finally, Ezgi Arikan will discuss the role of approach-avoidance goals on tactile sensitivity when moving towards and away from objects in a virtual reality environment.
The perception of touch during approach-avoidance movements
Tue-A7-Talk IV-05
Presented by: Belkis Ezgi Arikan
Belkis Ezgi Arikan 1, 2, Meaghan McManus 1, Katja Fiehler 1, 2
1 Experimental Psychology, Justus Liebig University Giessen, Giessen, Germany, 2 Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
Tactile sensitivity on a moving limb is reduced during movement. This phenomenon, known as tactile suppression, is attributed to internal forward models in which predictions of upcoming movement consequences are used to down-regulate actual sensory feedback caused by the movement. Moreover, successful movement control requires the use of incoming sensory feedback. Suppression is therefore modulated by feedback relevancy. An open question is whether the goal, i.e. movement’s anticipated future consequences, modulates how predictive and feedback signals are utilized. For example, feedback signals may become more relevant during avoidance than approach behaviors, as erroneous avoidance can be more detrimental than erroneous approach. Here, we examined tactile sensitivity on a moving hand while participants approached or avoided a stimulus. Additionally, we tested whether movement type (arm extension or flexion), previously shown to facilitate behavioral tendencies of approach and avoidance, modulate tactile sensitivity when these goals were reached by both types of movement. Participants flexed and extended their arm towards a positive or away from a negative stimulus in virtual reality (VR). We probed tactile suppression by presenting brief vibrations during movement through the VR-controller. Participants then responded whether they detected this vibration or not. Detection thresholds were significantly larger in all movement conditions compared to when the arm was at rest, indicating tactile suppression. Importantly, detection thresholds were larger in the flexed compared to the extended arm, independent of the movement goal. These results suggest modulation of tactile sensitivity for movements towards the body, independent of the goal to avoid or approach.
Keywords: touch, tactile suppression, approach-avoidance, virtual reality