Response: When does grasping escape Weber's law?

Tzvi Ganel, Eran Chajut, Michal Tanzer, Daniel Algom

Research output: Contribution to journalLetterpeer-review


In a recent study [1], we found that Weber's law, a fundamental principle of perception, does not govern visual control of grasping and concluded that different representations of object size are used for action and for perception [1]. Smeets and Brenner [2] suggest instead that grasping is computed on the basis of position rather than on the basis of size, and that this accounts for the apparent absence of Weber's law. However, their alternative explanation cannot readily account for memory-based grasping, which does obey Weber's law. In this response, we present additional data to show that, even when memory-based and real-time grasping both are executed without visual feedback, only the former obeys Weber's law. This dissociation further supports the conclusion that action and perception are sustained by qualitatively different computations.

Original languageEnglish
Pages (from-to)R1090-R1091
JournalCurrent Biology
Issue number23
StatePublished - 9 Dec 2008

Bibliographical note

Funding Information:
This study was supported by an Israel National Science Foundation grant 830/07 to T.G. We thank Nachshon Meiran for his valuable advice.


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