Stabilization of the total force in multi-finger pressing tasks studied with the 'inverse piano' technique

J. R. Martin, M. K. Budgeon, V. M. Zatsiorsky, M. L. Latash

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


When one finger changes its force, other fingers of the hand can show unintended force changes in the same direction (enslaving) and in the opposite direction (error compensation). We tested a hypothesis that externally imposed changes in finger force predominantly lead to error compensation effects in other fingers thus stabilizing the total force. A novel device, the "inverse piano", was used to impose controlled displacements to one of the fingers over different magnitudes and at different rates. Subjects (n = 10) pressed with four fingers at a constant force level and then one of the fingers was unexpectedly raised. The subjects were instructed not to interfere with possible changes in the finger forces. Raising a finger caused an increase in its force and a drop in the force of the other three fingers. Overall, total force showed a small increase. Larger force drops were seen in neighbors of the raised finger (proximity effect). The results showed that multi-finger force stabilizing synergies dominate during involuntary reactions to externally imposed finger force changes. Within the referent configuration hypothesis, the data suggest that the instruction "not to interfere" leads to adjustments of the referent coordinates of all the individual fingers.

Original languageEnglish (US)
Pages (from-to)446-458
Number of pages13
JournalHuman Movement Science
Issue number3
StatePublished - Jun 2011

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine
  • Experimental and Cognitive Psychology


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