Reaching beyond reach

Martha Flanders, Linda Daghestani, Alain Berthoz

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


The analysis of errors in two-joint reaching movements has provided clues about sensorimotor processing algorithms. The present study extends this focus to situations where the head, trunk, and legs join with the arm to help reach targets placed slightly beyond arm's length. Subjects reached accurately to touch 'real targets' or reached to the remembered locations of 'virtual targets' (i.e., targets removed at the start of the reach). Subjects made large errors in the virtual-target condition and these errors were analyzed with the aim of revealing the implications fur whole-body coordination. Subjects were found to rotate the head less in the virtual-target condition (when compared with accurate movements to real targets). This resulted in a more limited range of head postures, and the final head angles at the end of the movements were geometrically related to the incorrect hand locations, perhaps accounting for some portion of the errors. This suggests that head-eye-hand coordination plays an important role in the organization of these movements and leads to the hypothesis that a representation of current gaze direction may serve as a reference signal for arm motor control.

Original languageEnglish (US)
Pages (from-to)19-30
Number of pages12
JournalExperimental Brain Research
Issue number1
StatePublished - 1999

Bibliographical note

Funding Information:
Acknowledgements This work was supported by National Institute of Neurological Disorders and Stroke grant R01 NS27484. We thank Alan C. League for data processing and John F. Soech-ting for valuable discussions and comments on the manuscript.


  • Arm movement
  • Gaze
  • Hand-eye coordination
  • Motor control
  • Posture
  • Reaching


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