Archers tell small differences in pressure on the drawing finger apart less well than non-archers

The summary today

There is a single measurement, from 2007, of eight Japanese university archers with one to three years of practice and six students who did not shoot. An air jet pressed on the centre of the index fingertip of the drawing hand with forces of 2 to 7 grams, and the subjects had to say when two pressures were different. The smallest difference the archers recognise is larger, 0.63 against 0.50 gram-force, and relative to the stimulus the Weber ratio is higher too, 0.15 against 0.12. In the same study the archers' fingertip skin is harder, 49.3 against 39.8 on a durometer, and the threshold rises with hardness: the authors conclude that the callus left by the string, rather than a change in sensitivity, is what takes the fineness away, but in fourteen people this is an association, and it cannot separate the skin from the nervous system. Nor is the picture simply one of a less sensitive finger: in the archers the threshold rises steadily with the reference force (0.93 against 0.40 in the non-archers), and since each force was measured on a different day the authors read this regularity as a sensitivity that is more stable from one day to the next. The 82 degrees of freedom of the main comparison suggest that the six reference forces of each person, rather than the fourteen people, were counted as independent, so the p values are probably more optimistic than the sample allows. Nobody has checked whether this threshold has anything to do with the release.

Also phrased as: "sensitivity of the string fingers"; "calluses reduce feel"; "feeling the string on the fingers"; "less sensitive fingers in archers"

Evidence

• 2007
  For Archers Published later

  8 Japanese university archers and 6 students who did not shoot, stimuli of 2 to 7 gram-force from an air jet on the index fingertip of the drawing hand: mean differential threshold 0.63 against 0.50 gf (t(82) = 2.89, p < 0.01) and Weber ratio 0.15 against 0.12 (t(82) = 2.13, p < 0.05).

  Evaluating Tactile Sensitivity Adaptation by Measuring the Differential Threshold of Archers · Kentaro Kotani, Seiji Ito, Toshihiro Miura, Ken Horii

• 2007
  Context Archers Published later

  The Weber ratio stays constant, at around 0.13, in the archers only above 5 gf and, at around 0.10, in the non-archers only above 4 gf; below these forces it rises as the stimulus falls. The range in which perception worsens therefore starts higher in the archers.

  Evaluating Tactile Sensitivity Adaptation by Measuring the Differential Threshold of Archers · Kentaro Kotani, Seiji Ito, Toshihiro Miura, Ken Horii

• 2007
  Context Archers Published later

  In the archers the differential threshold rises steadily with the reference force (0.93 against 0.40 in the non-archers; the paper calls it a correlation coefficient in the results and a coefficient of determination in the discussion). Since each reference force was measured on a different day, the authors read this regularity as a sensitivity that is more stable between days: more stable as well as less fine.

  Evaluating Tactile Sensitivity Adaptation by Measuring the Differential Threshold of Archers · Kentaro Kotani, Seiji Ito, Toshihiro Miura, Ken Horii

• 2007
  Context Archers Published later

  Fingertip skin, measured with a durometer after the trials, is harder in the archers, 49.3 against 39.8 (t(12) = 2.199, p < 0.05), and the mean differential threshold rises with hardness. The authors conclude that the callus masks sensitivity, but they do not report the value of that correlation.

  Evaluating Tactile Sensitivity Adaptation by Measuring the Differential Threshold of Archers · Kentaro Kotani, Seiji Ito, Toshihiro Miura, Ken Horii

Status history

1. 1990 Not studied In the registry's bibliography nobody has yet measured the sensitivity of the skin on the fingers that hold the string, or compared it with that of people who do not shoot.
2. 2007 Reported Eight archers and six controls, with air-jet stimuli on the index fingertip of the drawing hand: the threshold for telling two pressures apart is higher in the archers, 0.63 against 0.50 gram-force, so they feel small differences less, and their skin is harder, with a threshold that rises with hardness. In the archers, though, the threshold rises steadily with the reference force, which the authors read as a more stable sensitivity. It is a single study of fourteen people in all: evidence in favour, and limited.

Related

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• Dexterity, sensitivity and grip: how archers' hands differ, and how much that weighs on the scoreFine dexterity, fingertip sensitivity, grip strength and hold time: how archers' hands differ, and which of these goes with the score among archers.
• Hands, fingers and calluses: skin, small vessels and injuries in archers who shoot a lotHarder skin, calluses, the small vessels of the fingers and acute injuries: what studies have measured in archers' hands, and how firm the findings are.

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