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Predictive coding theories of visual perception postulate that expectations based on prior knowledge modulate the processing of information by sharpening the representation of expected features of a stimulus in visual cortex but few studies directly investigated whether expectations qualitatively affect perception. Our study investigated the influence of expectations based on prior experience and contextual information on the perceived sharpness of objects and scenes. In Experiments 1 and 2, we used a perceptual matching task. Participants saw two blurred images depicting the same object or scene and had to adjust the blur level of the right image to match the blur level of the left one. We manipulated the availability of relevant information to form expectations about the image's content: one of the two images contained predictable information while the other one unpredictable. At an equal level of blur, predictable objects and scenes were perceived as sharper than unpredictable ones. Experiment 3 involving explicit sharpness judgments confirmed these results. Our findings support the sharpening account of predictive coding theories by showing that expectations increase the perceived sharpness of the visual signal. Expectations about the visual environment help us understand it more easily, but also makes us perceive it better. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Theories of visual recognition postulate that our ability to understand our visual environment at a glance is based on the extraction of the gist of the visual scene, a first global and rudimentary visual representation. Gist perception would be based on the rapid analysis of low spatial frequencies in the visual signal and would allow a coarse categorization of the scene. We aimed to study whether the low spatial resolution information available in peripheral vision could modulate the processing of visual information presented in central vision. We combined behavioral measures (Experiments 1 and 2) and fMRI measures (Experiment 2). Participants categorized a scene presented in central vision (artificial vs. natural categories) while ignoring another scene, either semantically congruent or incongruent, presented in peripheral vision. The two scenes could either share the same physical properties (similar amplitude spectrum and spatial configuration) or not. Categorization of the central scene was impaired by a semantically incongruent peripheral scene, in particular when the two scenes were physically similar. This semantic interference effect was associated with increased activation of the inferior frontal gyrus. When the two scenes were semantically congruent, the dissimilarity of their physical properties impaired the categorization of the central scene. This effect was associated with increased activation in occipito-temporal areas. In line with the hypothesis of predictive mechanisms involved in visual recognition, results suggest that semantic and physical properties of the information coming from peripheral vision would be automatically used to generate predictions that guide the processing of signal in central vision.

Predictive models of visual recognition state that predictions based on the rapid processing of low spatial frequencies (LSF) may guide the subsequent processing of high spatial frequencies (HSF). While the HSF signal necessarily comes from central vision, most of the LSF signal comes from peripheral vision. The present study aimed at understanding how LSF in peripheral vision may be used to generate predictive signals that guide visual processes in central vision. In two experiments, participants performed an object categorization task in central vision while a semantically congruent or incongruent scene background was displayed in peripheral vision. In Experiment 1, results showed a congruence effect when the peripheral scene was displayed before the object onset. In Experiment 2, results showed a congruence effect only when the peripheral scene was intact, thus carrying a semantic meaning, but not when it was phase-scrambled, thus carrying only low-level information. The study suggests that the low resolution of peripheral vision facilitates the processing of foveated objects in the visual scene, in line with predictive models of visual recognition.

International audience; In this dynamic causal modeling (DCM) study, we evaluated the effect of age on the effective connectivity of a cerebral network involved in lexical production. Younger and older adults performed an object naming task during fMRI. The DCM was used to explore the interactions between four regions of interest: the occipital cortex, OC; the lateral temporal cortex, LTC; the medial temporal cortex, MTC; and the inferior frontal cortex, IFC. We mainly focused on the modulation of the fronto-temporal interaction, according to the hypothesis that aging requires strategies that modulate the access to the semantic knowledge, either through a neural reserve mechanism (increased MTC-LTC connectivity) or through a neural compensation mechanism (supplementary IFC-MTC connectivity). For younger adults, our results indicated a bi-directional interaction between the left IFC and LTC suggesting a typical activation related to lexico-semantic representations. For older adults, our results reveal the existence of bi-directional interaction between the IFC and MTC, but not between the IFC and LTC – which in turn suggests that older adults adapt a new strategy, via supplemental access to conceptual access and semantic retrieval processes. This neural compensation strategy would be facilitated by a top-down mechanism from the IFC to the MTC. We discuss our results in the context of the possible additional strategies used by older compared to younger adults, to retrieve and produce words.

Visual extinction, a parietal syndrome in which patients exhibit perceptual impairments when two objects are simultaneously presented in the visual field, is reduced when objects are correctly positioned for action, indicating that action helps patients' visual attention. Similarly, healthy individuals make faster action decisions on object pairs that appear in left/right standard co-location for actions in comparison to object pairs that appear in a mirror location, a phenomenon called the paired-object affordance effect. However, the neural locus of such effect remains debated and may be related to the activity of ventral or dorsal brain regions. The present fMRI study aims at determining the neural substrates of the paired-object affordance effect. Fourteen right-handed participants made decisions about semantically related (i.e. thematically related and co-manipulated) and unrelated object pairs. Pairs were either positioned in a standard location for a right-handed action (with the active object - lid - in the right visual hemifield, and the passive object - pan - in the left visual hemifield), or in the reverse location. Behavioral results showed a suppression of the observed cost of correctly positioning related pairs for action when performing action decisions (deciding if the two objects are usually used together), but not when performing contextual decisions (deciding if the two objects are typically found in the kitchen). Anterior regions of the dorsal stream (e.g. supplementary motor area) responded to inadequate object co-positioning for action, but only when the perceptual task required action decisions. In the ventral cortex, the left lateral occipital complex showed increased activation for objects correctly positioned for action in all conditions except when neither task demands nor object relatedness was relevant for action. Thus, fMRI results demonstrated a joint contribution of ventral and dorsal cortical streams to the paired-affordance effect. They further suggest that this contribution may depend on contextual situations and task demands, in line with flexible views of affordance evocation.

International audience; Current models of visual perception suggest that, during scene categorization, low spatial frequencies (LSF) are rapidly processed and activate plausible interpretations of visual input. This coarse analysis would be used to guide subsequent processing of high spatial frequencies (HSF). The present study aimed to further examine how information from LSF and HSF interact and influence each other during scene categorization. In a first experimental session, participants had to categorize LSF and HSF filtered scenes belonging to two different semantic categories (artificial vs. natural). In a second experimental session, we used hybrid scenes as stimuli made by combining LSF and HSF from two different scenes which were semantically similar or dissimilar. Half of the participants categorized LSF scenes in hybrids, and the other half categorized HSF scenes in hybrids. Stimuli were presented for 30 or 100 ms. Session 1 results showed better performance for LSF than HSF scene categorization. Session 2 scene categorization was faster when participants attended and categorized LSF than HSF scene in hybrids. The semantic interference of a semantically dissimilar HSF scene on LSF scene categorization was greater than the semantic interference of a semantically dissimilar LSF scene on HSF scene categorization, irrespective of exposure duration. These results suggest a LSF advantage for scene categorization, and highlight the prominent role of HSF information when there is uncertainty about the visual stimulus, in order to disentangle between alternative interpretations.

International audience; Age-related macular degeneration (AMD) is characterized by a central vision loss. Here, we investigated the ability of AMD patients to process the spatial frequency content of scenes in their residual vision, depending of the luminance contrast level. AMD patients and normally-sighted elderly participants (controls) performed a categorization task involving large scenes (outdoors vs. indoors) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and non-filtered scenes (NF). Luminance contrast of scenes was equalized between stimuli using a root-mean square (RMS) contrast normalization. In Experiment 1, we applied an RMS contrast of 0.1 (for luminance values between 0 and 1), a value situated between the mean contrast of LSF and HSF scenes in natural conditions. In Experiment 2, we applied an RMS contrast of 0.3, corresponding to the mean contrast of HSF scenes in natural conditions. In Experiment 3, we manipulated four levels of linearly-increasing RMS contrasts (0.05, 0.10, 0.15, and 0.20) for HSF scenes only. Compared to controls, AMD patients gave more non-responses in the categorization of HSF than NF or LSF scenes, irrespective of the contrast level of scenes. Performances improved as contrast increased in HSF scenes. Controls were not differentially affected by the spatial frequency content of scenes. Overall, results suggest that LSF processing is well preserved in AMD patients and allows efficient scene categorization in their parafoveal residual vision. The HSF processing deficit could be partially restored by enhancing luminance contrast.