Dissociable effects of stimulus range on perception and action

Namdar, Gal; Algom, Daniel; Ganel, Tzvi

doi:10.1016/j.cortex.2016.12.017

Cited by 10 publications

(12 citation statements)

References 26 publications

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“…The findings indicate that the compliance to the RSE is a general property of 2D visuomotor control. Namdar et al (2017) recently showed that visually guided actions directed at 3D objects are not influenced by the RSE. Unlike for perceptual judgments, JNDs for the common standard were unaffected by the context range in which it was embedded, indicating the operation of a selective processing style, typical to visuomotor control toward real objects (Goodale & Ganel, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Unlike in studies of visual illusions, which focus on the bias of the average response, the current study focused on response resolution, measured by the variblity of the withinsubject response (Ganel et al, 2008;Namdar et al, 2016Namdar et al, , 2017. In the context of the discussion on the adherence of grasping movements to Weber's law, it has been proposed that several factors should be considered when looking at the varbility of the grip aperture.…”

Section: Discussionmentioning

confidence: 99%

“…For the main analysis, the effect of context range (two levels) on the target (40 mm) stimulus served as the withinsubject independent variable. In an additional analysis that focused at the possible adherence of 2D grasping to Weber's law, Object size (three levels) and Context range (two levels) served as within-subject independent variables (for a similar analysis, see Namdar et al, 2017). The average aperture and the JND at the point in time in which MGAs were achieved served as the dependent variables.…”

Section: Data Analysis and Designmentioning

confidence: 99%

“…The purpose of the current study was to test this issue by focusing at the resolving power of the response-a basic psychophysical aspect of performance (Ganel et al, 2008;Namdar, Ganel, & Algom, 2016;Zitron-Emanuel & Ganel, 2017). To this purpose, we tested the effect of contextual information on the visual resolution of 2D (and 3D) grasping using a simple psychophysical tool, recently developed in our laboratory (Namdar, Algom, & Ganel, 2017;Namdar et al, 2016).…”

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confidence: 99%

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Dissociable effects of irrelevant context on 2D and 3D grasping

Ozana

Ganel

2017

Atten Percept Psychophys

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Grasping movements directed toward real objects are typically unaffected by irrelevant aspects of the object and its surroundings, indicating that such interactions are based on analytic processing of object shape and size. However, recent findings show that grasping directed toward two-dimensional (2D) objects is subjected to perceptually mediated effects of relative shape and size. It is unclear however, whether context-dependent processing-a hallmark of visual perception-affects 2D grasping in the same fashion. Here, we explored this possibility by comparing the influence of a newly discovered contextual effect on 2D and on 3D grasping. According to the range of standard effect (RSE), the perceptual resolution for a stimulus depends on the range of the other stimuli presented within the same session, with higher resolution obtained under narrow compared to wide context range. In two experiments, participants were asked to grasp 3D and 2D objects embedded in a wide or a narrow range. The results showed that, unlike 3D grasping, which was immune to contextual information, the resolution during 2D grasping was significantly modulated by the range of the irrelevant context. The findings suggest that visuomotor control directed to 2D objects is intruded by irrelevant perceptual information, making it context-dependent.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Data Analysis and Designmentioning

confidence: 99%

mentioning

confidence: 99%

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Dissociable effects of irrelevant context on 2D and 3D grasping

Ozana

Ganel

2017

Atten Percept Psychophys

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“…Major visual-perceptual illusions diminish or disappear altogether when the responses are motor actions under direct visuomotor control 7 , 34 – 40 (but see 10 , 41 , 42 ). Grasping is immune to contextual information to the extent that it has been shown to violate even such a fundamental psychophysical principle as Weber’s Law 36 , 43 – 45 . If context independence prevails, then the SCE should vanish when people grasp numbers of different physical size, i.e., numerical magnitude should not affect the grasping response.…”

Section: Introductionmentioning

confidence: 99%

The Size Congruity Effect Vanishes in Grasping: Implications for the Processing of Numerical Information

Namdar

Ganel

Algom

2018

Sci Rep

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Judgments of the physical size in which a numeral is presented are often affected by the task-irrelevant attribute of its numerical magnitude, the Size Congruity Effect (SCE). The SCE is typically interpreted as a marker of the automatic activation of numerical magnitude. However, a growing literature shows that the SCE is not robust, a possible indication that numerical information is not always activated in an automatic fashion. In the present study, we tested the SCE via grasping by way of resolving the automaticity debate. We found results that challenge the robustness of the SCE and, consequently, the validity of the automaticity assumption. The SCE was absent when participants grasped the physically larger object of a pair of 3D wooden numerals. An SCE was still recorded when the participants perceptually indicated the general location of the larger object, but not when they grasped that object. These results highlight the importance of the sensory domain when considering the generality of a perceptual effect.

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Priors Bias Perceptual Decisions in Autism, But Are Less Flexibly Adjusted to the Context

2020

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According to the predictive coding framework, percepts emerge from combinations of sensory input and prior knowledge, whose relative contributions depend on their reliability. Recent predictive coding theories suggest that Autism Spectrum Disorder (ASD) could be characterized by an atypical weighting of priors. Here, we assessed whether individuals with ASD can flexibly adjust the weight (precision) of the prior to the context. Thirty‐one neurotypical adults (NT) and 26 adults with ASD participated in a visual discrimination task designed to elicit a time‐order effect (TOE). The TOE reflects the integration of priors with sensory estimates. We used two experimental contexts: a narrow stimulus range (Narrow condition) and a broader range (Broad condition) in order to induce a prior with a higher and lower precision, respectively. Both groups learned a prior that biased their perception, as shown with the TOE. As expected, the NT group had a larger TOE in the Narrow condition than in the Broad condition, revealing a contextual adjustment of the prior precision. In contrast, ASD participants were more inflexible: the extent of the TOE was not modulated by the context. In addition, the accuracy increased when the stimulus range decreased in both group, which may be interpreted as a contextual adjustment of the sensory precision. To conclude, adults with and without ASD implicitly learned a prior mean, but ASD participants failed to flexibly adjust the prior precision to the context. This increased inflexibility in ASD could account for many symptoms, such as their intolerance of uncertainty. Lay Summary Based on our experience, we have expectations about our environment. Theories suggest that the symptoms encountered in autism could be due to atypical expectations, leading to an impression of an unpredictable world. Using a visual discrimination task, we showed that adults with and without autism were biased by their expectations. Yet, the extent to which expectations biased perception did not depend on the context in autism. This higher inflexibility found in autism may explain symptoms such as resistance to change.

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Dissociable effects of stimulus range on perception and action

Cited by 10 publications

References 26 publications

Dissociable effects of irrelevant context on 2D and 3D grasping

Dissociable effects of irrelevant context on 2D and 3D grasping

The Size Congruity Effect Vanishes in Grasping: Implications for the Processing of Numerical Information

Priors Bias Perceptual Decisions in Autism, But Are Less Flexibly Adjusted to the Context

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