You Are What You Touch: How Tool Use Changes the Brain's Representations of the Body

"While we think of our body as a fixed feature of our lives, the brain displays a surprising ability to accept as part of ‘me’ whatever I happen to be touching and using at any given time."

How tools become a part of your body

By Patrick Haggard and Matthew R. Longo

All our experience of the world, and ability to act on it, are channelled through our body. The pioneering computer scientist, Alan Turing, correctly realised the human mind is special not particularly because of its computing power, but because the body provides it with a unique interface to the world. Current research in psychology and neuroscience is probing how the brain represents the body. Recent advances have revealed that body representation is fundamentally multisensory, arising from the combination of many different sensory signals. These include classical “senses,” such as touch and vision, and also much more specific signals, such as the flexion or extension of each muscle, which define the body’s posture in space. This information is integrated to construct a multisensory representation of the current state of the body. Intriguingly, multisensory signals also affect what we perceive our body to be like, for example by making us feel like a rubber hand really is our hand! Our thoughts about what our body is are highly flexible, and track the multisensory inputs that the brain receives.

A common illustration of just how flexible the sense of our body is comes from changes in the brain’s representation of the body due to tool use. Humans, and some other animals, are able to use tools as additions to the body. When we use a long pole to retrieve an object we couldn’t otherwise reach, the pole becomes, in some sense, an extension of our body. Is this merely a poetic way of speaking, or does the brain actually incorporate the tool into its representation of the body? Studies of monkeys learning to use a rake to obtain distant objects show that this may be more than a mere metaphor. Multisensory brain cells respond both to touch on the hand or visual objects appearing near the hand. When the monkeys used the rake, these cells began to respond to objects appearing anywhere along the length of the tool, suggesting the brain represented the rake as actually being part of the hand.

A recent paper in Psychological Science elegantly illustrates the plasticity of body representation, and provides further evidence that representations of the body really do expand to include ‘external’ objects we hold. Thomas Carlson of the University of Maryland and colleagues at Harvard University and Utrecht University in the Netherlands used an unusual subjective experience of the body first reported by Franklin Taylor of Princeton University in 1941. If you look towards your hand in a darkened room and see it illuminated by a bright flash, an afterimage of your hand remains after the flash. If you then move your hand, the afterimage changes, though no actual visual signal is present. The precise effect, like so much of the richness of human sensation, is difficult to catch in words, but is like a fading, or loss of clarity of the hand. This fading is normally explained by the multisensory nature of body representation: when the hand moves, but the afterimage does not, visual information and ‘proprioceptive’ information from muscles no longer agree about where the hand is. The visual impression of the hand fading may be a by-product of this inability to integrate different sensations due to conflict about where they are in space.

Carlson et al used this fading to investigate the limits of the brain’s representation of the body. When participants held an object and then moved their hand after the flash, the object’s afterimage faded as well. Further, if participants reached for the object after the flash, the object still faded. The brain may detect a conflict between the location of the object in the afterimage (on the table) and the location where the object is actually felt (in their hand). Alternatively, the object may be rapidly assimilated into the representation of the body and therefore subject to the same perceptual conflict.

The authors also ran additional tests in which volunteers dropped the object, providing new evidence for a spatial bound on plasticity of body representation. Objects released from a mechanical gripper held in the hand did not fade, while those released directly from the hand’s grasp did fade. These conditions suggest that direct contact with the skin may be an important cue to plastic bodily extension. A critical, though elaborate, test might involve forming an initial afterimage of the hand, gripper and object placed separately on the table, then picking up the gripper, and using this to pick up the object. The authors would predict a fading of the afterimage of the gripper, due to its incorporation in the body representation. However, the object should not be incorporated because it would not be touched directly.

These results elegantly confirm that the human brain maintains a highly flexible representation of the body, despite the tendency in everyday life to think of ourselves as having a fixed personal identity, linked to our body. Two distinctive features of mental body representation emerge. First, from the brain’s perspective, the body is by far the most familiar object in the world: the body, as William James elegantly put it, is “always there.” In these experiments, the mechanical gripper could be treated as part of one’s own body. However, this did not extend to an object held in the gripper, perhaps because this situation wasn’t familiar enough. We speculate that skilled prosthesis users might experience objects grasped in the prosthetic hand as fading, even though first-time users in the present experiment did not. Given the ability to move an object through voluntary action, and sufficient sensory experience of doing so, the capacity to extend the self may be virtually unlimited.

Second, these studies suggest a view of the body as an interface between the brain and the external world. This view has important implications for human psychology generally. The sensorimotor mechanisms of the body are effectively a tool for our voluntary actions to respond to the environment and to change it. While we think of our body as a fixed feature of our lives, the brain displays a surprising ability to accept as part of ‘me’ whatever I happen to be touching and using at any given time.

About the authors:

Patrick Haggard leads a research group at the Institute of Cognitive Neuroscience, University College London. His research interests include the brain's representation of one's own body, and the control of voluntary action. Matthew Longo is a postdoctoral fellow at the Institute of Cognitive Neuroscience, University College London, and soon to be a lecturer at Birkbeck College, University of London. He is interested in how we represent our bodies and how this shapes how we perceive the external world.

Source: Scientific American via Body in Mind

Touch influences social judgements and decisions

Neuro Philosophy, Category: Psychology Posted on: June 25, 2010 10:05 AM, by Mo

Applying for a job? The weight of the clipboard to which your CV is attached may influence your chances of getting it. Negotiating a deal? Sitting in a hard chair may lead you to drive a harder bargain. Those are two of the surprising conclusions of a study published in today's issue of Science, which shows that the physical properties of objects we touch can unconsciously influence our first impressions of other people and the decisions we make about them.

Josh Ackerman of the Sloan School of Management at MIT, and psychologists Chris Nocera and John Bargh of Harvard and Yale Universities, respectively, performed a series of six experiments designed to investigate whether or not the weight, texture and hardness of objects can influence our judgements of, and decisions about, unrelated events and situations. Their findings provide yet more evidence for the embodied cognition hypothesis, which states that bodily perceptions can exert a strong influence on the way we think.

In the first experiment, 54 passersby were asked to evaluate a job candidate on the basis of a CV attached to either a light (0.34 kg) or a heavy (2 kg) clipboard. Those given the CV on the heavier clipboard generally rated the candidate as being better and having a more serious interest in the position than those given the lighter clipboard, even though the CVs used in both cases were identical. Those given the heavy clipboard also rated their accuracy on the task as more important than those given the lighter one, but did not report putting more effort into it. They did not, however, rate the candidate as more likely to get along with co-workers. This suggests that the weight cue affected their impressions of the candidate's performance and seriousness, but not the irrelevant trait of social likeability, and that the observed effects were not due their perception of their own actions.

The effect of an object's weight on decision-making was explored in a second, smiilarly designed experiment. Again, 43 passersby were asked to complete a "social action survey", asking whether various public issues should receive more or less government funding. And again, the weight of the clipboard was found to affect the participants' responses, although an interesting sex difference was observed: men allocated more money when given the survey on the heavier clipboard than when handed the lighter one, whereas women chose to allocate as much funding as possible in both the "heavy" and "light" conditions.

Next, the researchers looked at the effects of an object's texture on participants' perceptions of a social interaction. Participants read a passage describing an ambiguous interaction between two people, and were then asked about their impressions of the situation - whether it was confrontational or friendly, competitve or co-operative, a discussion or an argument. Beforehand, they were asked to complete a five-piece jigsaw puzzle; in one version of the puzzle, the pieces were covered in rough sandpaper, and in the other, they were smooth. Those who completed the rough puzzle perceived the situation as being confrontational and more competitive than those who completed the smooth puzzle.

Texture was also found to affect the decisions made in a social situation. Participants completed either the rough or the smooth puzzle before playing a version of the Ultimatum game. They were given 10 tickets for a $50 lottery, and made to give any number of them to a second anonymous participant. If the second participant rejected the offer, all the tickets are forfeited. Those who had first completed the rough puzzle offered more tickets to the second participant than those who did the smmoth puzzle. The roughness of the puzzle pieces apparently made them perceive the situation as being more difficult and consequently caused them to behave in a compensatory way - they offered more tickets to increase the chances that their offer would be accepted.

The researchers then investigated the effects of an object's hardness. Another group of participants was asked to watch a magic trick, and to try to figure out how it was done. Beforehand, they were asked to examine the object to be used in the trick - either a soft pice of blanket or a hard wooden block. They were then told that the trick was to be postponed, and asked to give their impressions of two individuals (an "employee" and the "boss") involved in an hypothetical interaction. Those previously given the blanket evaluated the employee as being kinder than those given the wooden block.

Finally, texture was also found to affect peoples' behaviour in a bargaining situation. But whereas the other five experiments examined the effects of actively touching an object, this one investigated passive touch. The participants were seated in either a hard wooden chair or a soft cushioned chair, and asked to perform two tasks. In one, they gave their impression of an hypothetical employee. In the second they were required to imagine shopping for a new car priced $16,500 and to negotiate a lower price. In this bargaining task, they were allowed to make two offers on the car, the assumption being that their first offer would be rejected. The participants who sat in the hard chair judged the employee to be more stable and less emotional than those seated in the soft chair. They also deviated less from their first rejected offer.

These experiments show that touch sensations have a strong influence on our impressions of people and the decisions we make about them, even when the people and events are completely unrelated to the objects being touched. Thus, hardness is associated with rigidity, roughness with difficulty, and heavy objects with seriousness. Our metaphors reflect these associations: we sometimes describe people as having a "hard hearted", "rough day", and serious matters are often said to be "weighty". The weight, texture and hardness of touched objects evidently has a strong priming effect on the thought processes that immediately follow, and can trigger the associated concepts. These findings suggest various "tactile tactics" that could be very useful to job seekers, marketers and negotiators.

Reference:
Ackerman, J., Nocera, C. John A. Bargh, J. (2010). Incidental Haptic Sensations Influence Social Judgments and Decisions. Science 328: 1712-1715. DOI: 10.1126/science.1189993.

Abstract:
Touch is both the first sense to develop and a critical means of information acquisition and environmental manipulation. Physical touch experiences may create an ontological scaffold for the development of intrapersonal and interpersonal conceptual and metaphorical knowledge, as well as a springboard for the application of this knowledge. In six experiments, holding heavy or light clipboards, solving rough or smooth puzzles, and touching hard or soft objects nonconsciously influenced impressions and decisions formed about unrelated people and situations. Among other effects, heavy objects made job candidates appear more important, rough objects made social interactions appear more difficult, and hard objects increased rigidity in negotiations. Basic tactile sensations are thus shown to influence higher social cognitive processing in dimension-specific and metaphor-specific ways.

Touch: Stories of Contact by South African Writers

TOUCH : STORIES OF CONTACT BY SOUTH AFRICAN WRITERS
Karina Magdalena Szczurek (Editor)
Zebra press, Cape Town. (Hardcover, 226 pages, Isbn 09 781 77022 046 1.)

This is a book that looks like it is worth reading – an investigation into the act of touching, through narrative.

Earlier this month Zebra Press published a collection of short stories by twenty-two of South Africa's best writers on the theme of 'touch'.

According to the publishers some of the stories remember lost love or intimate encounters; some deal with everyday and chance meetings that are in some way transformative; others deal with familial interactions; one or two explore the idea of 'staying in touch'.

All royalties will be donated to the Treatment Action Campaign.

Here follows a review of the book by well-known Afrikaans poet Joan Hambidge. It appeared in Die Burger on 27 July 2009.

Sterk kortverhale oor aanraking in al sy vorme vra vir herlees

Waarom moet ’n mens Touch, ’n versameling kortverhale onder redaksie van Karina Magdalena Szczurek, aanskaf?

Aanraking, en die afwesigheid daarvan, bepaal ons lot. Vir my was dit ’n besonderse leeservaring omdat dit die belangrikste aspekte van die kortverhaal bevestig.

Daar is onder meer verhale met ’n verrassende slot of wending:
André P. Brink se “Surprise Visit” is ’n gedronge verhaal waarin die konfrontasie met die moeder in ’n siekeboeg komplekse herinneringe aktiveer. Die misverstand oor die herkenning van die moeder, ’n verhaal gelade met oedipale spanninge, bring interessante per¬spektiewe na vore. Dis vintage-Brink, met fyn toespelings vir verdere naspeur en herlees.

Met die wete van die slot lees jy ook Emma van der Vliet se “Threesome” anders, omdat sy jou verwagting ten slotte ondermyn. Die driemanskap is nie seksueel nie, maar die vrou se ervaring van durende aanraking, naamlik die ervaring van moederskap.

Damon Galgut se “The Crossing” ondersoek die impak van ’n toevallige ontmoeting of aanraking. ’n Vrou op haar wittebrood het ’n gesprek met ’n vreemdeling.

In die terloopsheid van dié aanraking word die spanninge in haar huwelik uitgespeel: wou die man haar dalk besteel? Wat sou gebeur het as sy wel die oorvaart meegemaak het? Tentatiewe ontmoetings, huidige en afgelope verhoudings word saamgebring in haar gemoed. Die aksie, of die afwesigheid daarvan, verander haar lewe.

Die vreemdeling het verdrink. Sy gaan hom nooit weer sien nie, en in dié Katherine Mansfield-verhaal word die leser aan die binnespraak van ’n karakter voorgestel. (Dis ook belangrik dat mans in dié boek met groot gevoeligheid oor intiem vroulike emosies skryf.)

Imraan Coovadia se “File Under: Touch (Avoidance of, Writers); Love (Avoidance of, Writers). (1000 Words)” is ’n metarefleksiewe verhaal wat die struk- tuur van die opdragverhaal onder die loep neem met ’n Duisend en Een Nagte as ’n subteks.

Die verwisselbaarheid van karakters en hul universaliteit kom ter sprake, soos in Maureen Isaacson se verhaal waarin Tolstoi se Anna Karenina ’n interteks en romantiese toespeling is.

Nooit sal reis weer meegemaak word sonder die herinnering aan Ivan Vladislavic se “Lullaby” nie. Wat ’n verhaal! Die atmosfeer wat in dié verhaal opgeroep word, die uitbeelding van ruimte en die onafwendbare slot is so pakkend dat dit ’n mens se kop laat draai.

Die dood van ’n toeris op ’n reisbesoek, en die impak daarvan op sy ervaring van ’n vakansie en van die terugreis, aktiveer die boodskap van weerloosheid. ’n Moeder se wiegelied vir haar baba kry ’n groter, dwingende impak vir al die reisigers op die vlug wat onder hul babakombersies slaap.

Willemien Brümmer se “A Cat of Many Tales” skep besonderse atmosfeer; ’n inbeweeg in die “unheimliche”, nes die verhaal van Alistair Morgan, “Living Arrangements”. Laasgenoemde lewer fel politieke kommentaar op ons huidige situasie en die kwessie van haweloosheid.

Fokalisasie en perspektief kom knap aan bod in Michiel Heyns se “Long Perspectives”, waarin die hede en verlede gesinkopeer word.

Die verhaal speel af in ’n skoolbadkamer. Rondom ’n seksuele aanraking met ’n skolier kry die hoofkarakter perspektief op homself en ’n jeugmaat, nou die onderwyser in die skool. Twee wêrelde, twee perspektiewe, wat beklemtoon word deur die hoofkarakter se bril vol vingerafdrukke. (Waarom die voetnoot dat die omstrede gegewe fiktief is? Dis tog onnodig!)

Vanselfsprekend het elke kortverhaalskrywer ’n eie styl, maar in die algemeen is die kort en kragtige segging, die amper poëtiese aanslag, van hierdie subgenre algemeen bekend.

Die tema in dié boek is aanraking in al sy vorme. Die kort, kragtige impak van die kortverhaal waarin ’n situasie of konflik uitgebeeld word, is kenmerkend. Dit is ’n sterk versameling en die meeste verhale tref ’n mens so sekuur dat jy ’n blaaskans moet neem om eers ’n verhaal of vinjet te verteer.

Goeie kortverhale werk soos gedigte: jy lees ’n tweede, derde keer om ’n beeld se effek te verstaan: soos Mary Watson of Susan Mann by uitnemendheid vereis.

Al die verhale is nuut, behalwe vir Nadine Gordimer se bydrae, ’n wonderbaarlike verhaal waarin die leser uiteindelik moet besluit of die man werklik ontrou was. Ons weet egter dat net die vermoede die vrou se verhouding met hom verander het.

Interessant hoe mans (Brink, Johnny Steinberg) oor die moeder skryf. ’n Klein kragtoer is “Your Stop” van Byron Loker. Bekendes en bekroondes, minder bekendes en debutante, lewer boeiend verslag oor menswees: letterlike, simboliese of metafisiese aanraking.

Hoekom is daar net twee Afrikaanse skrywers in vertaling?

Die opbrengs gaan na die Treatment Action Campaign.

(Bronne: An Approach to Literature deur Cleanth Brooks et al. [Prentice Hall, New Jersey, 1975]; Principles of a Story deur Raymond Carver: www.theshortstory.org.uk/downloads/Essay-Carver-3. pdf [oorspronklik in die New York Times Book Review, 1981].)

Massage and Embodiment

Article by Keith Eric Grant, PhD, NCTMB in Massage Today June, 2006, Vol. 06, Issue 06

Grant reflects on touch and the two best known paradigms of massage in the U.S. context namely massage for relaxation and massage as health care. (Despite legislation in South Africa attempting to bring all types of massage under the same umbrella, the same distinction exists here - EK)

He then discusses a third paradigm of massage that has an impact on the quality of body-sense or embodiment of the person, an approach that has been largely ignored "by those looking at massage as tissue-specific health care".

According to Grant, practising massage as sensory re-framing has no lack for material to draw from. He points to the work of:

• Maurice Merleau-Ponty who sets out a philosophical framework more than a half century ago
  

• Deane Juhan, best known as the author of Job's Body: A Handbook for Bodywork and

• Donald Bakal who lays the same stress on developing body awareness as a path to healing in his book Minding the Body: Clinical Uses of Somatic Awareness.

Read the full article at: http://www.massagetoday.com/mpacms/mt/article.php?id=13431

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