BOOK REVIEW: Touch by David J. Linden

Touch: The Science of the Sense that Makes Us HumanTouch: The Science of the Sense that Makes Us Human by David J. Linden
My rating: 5 of 5 stars

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“Touch” is a neuroscientist’s perspective on the human sense of touch, and the profound impact it has on life in our species.

It’s a short book, only about 200 pages of substantive text, arranged into eight chapters. The first chapter considers the role that our sense of touch plays in our lives as social animals. There are a number of studies described in this chapter, but I’ll cite only two that I think give an idea of what the chapter is all about. The first considers why a person holding a cold coffee is likely to be viewed more negatively than if that same person was holding a hot coffee after a handshake. The second reports that survey takers in a mall were more likely to gain compliance if they engaged in gentle, casual, and non-creepy touch—e.g. fingers to forearm.

The second chapter explores the combination of sensors we have in our skin—particularly in our fingers–that allow us to conduct feats of dexterity that (while we take them for granted) are phenomenally difficult. For all the billions put into robotics research, robots are nowhere close to being able to complete tasks that any five-year old can do. The third chapter examines how humans are uniquely geared to be able to give and recognize a particular type of touch sensation, the caress. Throughout the book there are a number of interesting stories, some of them are scientific case studies and others… not so much. This chapter begins with the story of a man on trial for flying into a rage because his girlfriend couldn’t get the pressure right when engaging in manual stimulation. (The author was actually on the jury.)

The fourth chapter delves more deeply and explicitly into sexual contact. Whereas chapter 3, dealt largely with hand against random skin, this chapter deals in genitals and erogenous zones more specifically. There are also a number of fascinating cases / stories herein. A lot of the chapter deals in how we experience and interpret pleasure.

Chapter five explains a specific type of sensation, that of temperature. It considers why crushed chili feels hot but crushed mint feels cool to the skin. While the focus of the book is on human anatomy, physiology, and social interaction, there are many cases from other species throughout the book. This chapter offers a prime example. It explains how Vampire Bats have a unique ability to sense infrared. This is of benefit to them, since they only take blood meals and, therefore, need to be able to sense where the blood is flowing and has the least insulation (fur) over it.

Continuing the examination of specific kinds of sensation, chapter six is about pain. This is where the neuroscientific perspective offers some interesting insight. In particular, because it considers why soldiers who had multiple gun wounds could do their job on the battlefield with nary a peep of complaint, but then would raise holy hell about a bad blood stick a few days later in the hospital. The case of a medic who was badly shot up but not cognizant of it until later is discussed in some detail.

Chapter 7 deals in the itchy, and asks and answers the question of whether or not itchiness is a particular case of low-intensity pain. By low intensity, I’m not speaking of the compulsive behavior sometimes spurred by such sensations.

Chapter 8 is also highly neuroscience influenced. It deals with various illusions of sensation, and how these illusions come about through the interaction of sense and the brain. While the most famous example of such an illusion is phantom limb pain experienced by amputees, Linden addresses less traumatic and more work-a-day tactile illusions for most of the chapter. (This may be because there are a number of popular works of neuroscience that deal in phantom limbs—most notably V.S. Ramachandran’s books.)

I enjoyed this book. It conveys significant technical detail, but does so in a fashion that is easy for a non-expert to follow both because of readable writing and the use of stories. The author uses frequent graphics to help clarify points, and the graphics (mostly line drawings and graphs) do their job by being easy to follow and interpret.

In short, the book was highly readable, concise, and informative. I’d recommend it for anyone interested in the sense of touch.

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TODAY’S RANDOM THOUGHT: Yoga, Mirrors, & Proprioception

OLYMPUS DIGITAL CAMERAThis morning a yoga teacher I’ve studied with posted this article on her Facebook feed. It’s by an Indian yogini who moved to the U.S., and it offers five differences between the practice of yoga in India and in America.

It occurred to me that one additional difference that’s frequently commented upon is that mirrors are ubiquitous in American yoga studios, but a rarity in Indian studios.

There are many possible explanations of this point of divergence. Among the more cynical interpretations is that when yoga spread internationally it was never explained that there are no asana (postures) whose drishti (focal point of gaze) is the reflected “bootilicious”, yoga-panted backside of other students.

The explanation one is likely to hear, however, is that a student needs mirrors to be able to see whether his or her alignment is correct. Sounds logical? Actually, it’s lazy in the same way as saying, “I wanted to know what Lord of the Flies is about, so I rented the movie.” (Read the damn book.)

Yes, looking in the mirror will give one instantaneous feedback, but it won’t help one develop the bodily awareness that’s a huge part of the value of yoga. One should be seeking to enhance one’s proprioception. That’s a fancy way of saying, “know where your parts are.” Proprioception is defined as:  “the ability to sense the position, location, orientation, and movement of the body and its parts.” The body has a built-in ability to determine where one’s various parts are in space and whether said parts are straight or crooked. One may not realize this because one may have poor proprioception… because one looks in the mirror instead of closing one’s eyes and listening to what one’s body has to say.