Using spatially identical displays (variants of the Müller–Lyer illusion), we compared the accuracy of spatial verbal judgments with that of saccadic (eye) and pointing (hand) movements. Verbal judgments showed a clear effect of the illusion. The amplitude of the primary saccade from one endpoint of the pattern (at fixation) to the other also showed an effect of the illusion. Conversely, movement amplitudes when pointing from one endpoint (initial finger position) to the other were significantly more accurate than both saccades and verbal responses. In a control experiment in which the viewing conditions between the saccade and pointing experiments were equalized, saccade amplitude was again affected by the illusion. In several studies, systematic biases in conscious spatial judgments have been contrasted with accurate open-loop pointing in peripersonal space. It has been proposed that such seeming dissociations between vision- for-action and vision-for-consciousness might in fact be because of a simple oculomotor strategy: saccade to the target before it disappears, then use the efference copy of the (accurate) saccadic movement to drive pointing. The present data do not support the hypothesis in this simple form.

How does action resist visual illusion? Oculomotor information does not account for accurate pointing in peripersonal space

BERNARDIS, PAOLO;
2005-01-01

Abstract

Using spatially identical displays (variants of the Müller–Lyer illusion), we compared the accuracy of spatial verbal judgments with that of saccadic (eye) and pointing (hand) movements. Verbal judgments showed a clear effect of the illusion. The amplitude of the primary saccade from one endpoint of the pattern (at fixation) to the other also showed an effect of the illusion. Conversely, movement amplitudes when pointing from one endpoint (initial finger position) to the other were significantly more accurate than both saccades and verbal responses. In a control experiment in which the viewing conditions between the saccade and pointing experiments were equalized, saccade amplitude was again affected by the illusion. In several studies, systematic biases in conscious spatial judgments have been contrasted with accurate open-loop pointing in peripersonal space. It has been proposed that such seeming dissociations between vision- for-action and vision-for-consciousness might in fact be because of a simple oculomotor strategy: saccade to the target before it disappears, then use the efference copy of the (accurate) saccadic movement to drive pointing. The present data do not support the hypothesis in this simple form.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2297660
 Avviso

Registrazione in corso di verifica.
La registrazione di questo prodotto non è ancora stata validata in ArTS.

Citazioni
  • ???jsp.display-item.citation.pmc??? 6
  • Scopus 29
  • ???jsp.display-item.citation.isi??? 28
social impact