The role of fragility information in the guidance of the precision grip

G. J.P. Savelsbergh*, B. Steenbergen, J. Van Der Kamp

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


In order to investigate which kind of information is coupled to which part of the prehensile action, subjects reached for and picked up a tube of 15 mm in diameter. The following tubes were used: one transparent and one black tube both 20 grams in weight, and one transparent and one black tube both 200 grams in weight. The transparent tubes gave a fragile impression in contrast to the black tubes. Weight of the tubes was not visually accessible. The prehension movement was divided into a free-motion phase and an in-contact phase. The free-motion phase refers to the period between the moment of initiation of the reaching movement and the moment of first contact with the object. The in-contact phase refers to the period between the moment of contact and the moment the tube is lifted. The results showed that fragility information influenced the duration of the free-motion phase: the deceleration phase was significantly longer and the appearance of the peak closing velocity of the fingers occurred significantly later. The weight information influenced the in-contact phase: for the 200 grams tube this phase was significant longer in comparison to the 20 grams tube. The findings imply that the movement towards the object, and in particular the closing of the fingers, is controlled by visual (fragility) information, while the in-contact phase is coupled to weight information. Furthermore, the experiment showed that previous haptic information about fragility is actually used in the visual regulation of a subsequent prehensile movement, because after contact with a fragile looking, but in fact solid tube, the free-motion phase of the subsequent prehensile action is shortened.

Original languageEnglish
Pages (from-to)115-127
Number of pages13
JournalHuman Movement Science
Issue number1
Publication statusPublished - 1 Jan 1996


  • Anticipation effect
  • Fragile impression
  • Free motion phase
  • Weight information


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