Psychonomic Bulletin & Review

, Volume 13, Issue 1, pp 166–173

Comment and Reply Why eye movements and perceptual factors have to be controlled in studies on “representational momentum”


DOI: 10.3758/BF03193829

Cite this article as:
Kerzel, D. Psychonomic Bulletin & Review (2006) 13: 166. doi:10.3758/BF03193829


In order to study memory of the final position of a smoothly moving target, Hubbard (e.g., Hubbard & Bharucha, 1988) presented smooth stimulus motion and used motor responses. In contrast, Freyd (e.g., Freyd & Finke, 1984) presented implied stimulus motion and used the method of constant stimuli. The same forward error was observed in both paradigms. However, the processes underlying the error may be very different. When smooth stimulus motion is followed by smooth pursuit eye movements, the forward error is associated with asynchronous processing of retinal and extraretinal information. In the absence of eye movements, no forward displacement is observed with smooth motion. In contrast, implied motion produces a forward error even without eye movements, suggesting that observers extrapolate the next target step when successive target presentations are far apart. Finally, motor responses produce errors that are not observed with perceptual judgments, indicating that the motor system may compensate for neuronal latencies.

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© Psychonomic Society, Inc. 2006

Authors and Affiliations

  1. 1.Faculté de Psychologie et des Sciences de l’ÉducationUniversité de GenèveGenevaSwitzerland

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