Milner and Goodale (the visual brain in action, Oxford University Press Inc., Oxford, 1995) proposed a functional dissociation between vision-for-action and vision-for-perception (i.e., the “two-visual system hypothesis”, TVSH). Supporting the TVSH, it has been claimed that visual illusions affect perception but not actions. However, at least for the Ebbinghaus illusion, numerous studies have revealed consistent illusion effects on grasping. Thus, whether illusions affect actions remains controversial. To further investigate the dissociation predicted by the TVSH, we used a visual version of the Uznadze illusion (the same stimulus will feel smaller after feeling a larger stimulus and larger after feeling a smaller stimulus). Based on kinematic recordings of finger aperture in a motor (precision grip) and a perceptual task (manual estimation), we report two main findings. First, both action and perception are strongly affected by the Uznadze illusion. Second, the illusion decreases similarly in both tasks when inducing-induced pairs had different shape and color, in comparison to the equivalent condition where these features are the same. These results are inconsistent with a perception–action dissociation as predicted by the TVSH and suggest that, at least in the present conditions, vision-for-perception and vision-for-action are similarly affected by contextual cues.

The Uznadze illusion reveals similar effects of relative size on perception and action / Uccelli, Stefano; Pisu, Veronica; Riggio, Lucia; Bruno, Nicola. - In: EXPERIMENTAL BRAIN RESEARCH. - ISSN 0014-4819. - 237:4(2019), pp. 953-965. [10.1007/s00221-019-05480-8]

The Uznadze illusion reveals similar effects of relative size on perception and action

UCCELLI, STEFANO
;
Riggio, Lucia;Bruno, Nicola
2019-01-01

Abstract

Milner and Goodale (the visual brain in action, Oxford University Press Inc., Oxford, 1995) proposed a functional dissociation between vision-for-action and vision-for-perception (i.e., the “two-visual system hypothesis”, TVSH). Supporting the TVSH, it has been claimed that visual illusions affect perception but not actions. However, at least for the Ebbinghaus illusion, numerous studies have revealed consistent illusion effects on grasping. Thus, whether illusions affect actions remains controversial. To further investigate the dissociation predicted by the TVSH, we used a visual version of the Uznadze illusion (the same stimulus will feel smaller after feeling a larger stimulus and larger after feeling a smaller stimulus). Based on kinematic recordings of finger aperture in a motor (precision grip) and a perceptual task (manual estimation), we report two main findings. First, both action and perception are strongly affected by the Uznadze illusion. Second, the illusion decreases similarly in both tasks when inducing-induced pairs had different shape and color, in comparison to the equivalent condition where these features are the same. These results are inconsistent with a perception–action dissociation as predicted by the TVSH and suggest that, at least in the present conditions, vision-for-perception and vision-for-action are similarly affected by contextual cues.
The Uznadze illusion reveals similar effects of relative size on perception and action / Uccelli, Stefano; Pisu, Veronica; Riggio, Lucia; Bruno, Nicola. - In: EXPERIMENTAL BRAIN RESEARCH. - ISSN 0014-4819. - 237:4(2019), pp. 953-965. [10.1007/s00221-019-05480-8]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2858058
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