Touch

Introduction

As I approach the door to my office, I unzip the pouch where I keep the keys to my office and fumble for my keys. I am engaging in a haptic search where I will use only my sense of touch to locate the keys. Specifically, I am attempting to use the low-threshold mechanoreceptors (LTMRs) of the skin on the tip of my fingers to find the sharp metallic edge of my keys or the soft woven strap that is a part of the key chain holding the keys. In attempting to use only the sense of touch in searching for my keys, I am using the receptors found in the skin, the largest and most versatile organ of the human body which covers an area of approximately 2 m² (McGlone and Reilly 2010). Many times, the search is successful using only the receptors found in my skin. However, sometimes I cannot locate the important signs that distinguish the keys with my sense of touch alone and must resort to other sensory signals to find them (e.g., the sound the keys make as they jingle in the pocket...