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The Temporal Dynamics of Scene Processing: A Multifaceted EEG Investigation

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ABSTRACT

Our remarkable ability to process complex visual scenes is supported by a network of scene-selective cortical regions. Despite growing knowledge about the scene representation in these regions, much less is known about the temporal dynamics with which these representations emerge. We conducted two experiments aimed at identifying and characterizing the earliest markers of scene-specific processing. In the first experiment, human participants viewed images of scenes, faces, and everyday objects while event-related potentials (ERPs) were recorded. We found that the first ERP component to evince a significantly stronger response to scenes than the other categories was the P2, peaking ∼220 ms after stimulus onset. To establish that the P2 component reflects scene-specific processing, in the second experiment, we recorded ERPs while the participants viewed diverse real-world scenes spanning the following three global scene properties: spatial expanse (open/closed), relative distance (near/far), and naturalness (man-made/natural). We found that P2 amplitude was sensitive to these scene properties at both the categorical level, distinguishing between open and closed natural scenes, as well as at the single-image level, reflecting both computationally derived scene statistics and behavioral ratings of naturalness and spatial expanse. Together, these results establish the P2 as an ERP marker for scene processing, and demonstrate that scene-specific global information is available in the neural response as early as 220 ms.

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Stimuli and experimental design of Experiment 1 (category selectivity). a, Examples of the stimuli used in Experiment 1. The stimuli consisted of the following three categories: scenes, faces, and objects. Scenes were selected from the following six categories: churches, concert halls, living rooms, beaches, mountains, and deserts (top row, four categories are depicted here). The face stimuli comprised Asian and Caucasian, male and female faces presented in front view (middle row). The objects consisted of dressers, vases, motorbikes, and roller skates (bottom row). Note that in total there were 48 unique exemplars within each visual category. b, Participants viewed the stimuli and performed a simple one-back task, responding whenever the same image was presented twice in a row (in this example, the second presentation of the vase). The stimuli were presented pseudorandomly, with a trial beginning with the presentation of a scene image for 500 ms followed by a blank gray screen for the following 500 ms. c, Schematic representation of the 64 electrode sites from which EEG activity was recorded. The grouped electrodes are those analyzed in the 12 critical regions (see text for details).
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Figure 1: Stimuli and experimental design of Experiment 1 (category selectivity). a, Examples of the stimuli used in Experiment 1. The stimuli consisted of the following three categories: scenes, faces, and objects. Scenes were selected from the following six categories: churches, concert halls, living rooms, beaches, mountains, and deserts (top row, four categories are depicted here). The face stimuli comprised Asian and Caucasian, male and female faces presented in front view (middle row). The objects consisted of dressers, vases, motorbikes, and roller skates (bottom row). Note that in total there were 48 unique exemplars within each visual category. b, Participants viewed the stimuli and performed a simple one-back task, responding whenever the same image was presented twice in a row (in this example, the second presentation of the vase). The stimuli were presented pseudorandomly, with a trial beginning with the presentation of a scene image for 500 ms followed by a blank gray screen for the following 500 ms. c, Schematic representation of the 64 electrode sites from which EEG activity was recorded. The grouped electrodes are those analyzed in the 12 critical regions (see text for details).

Mentions: The stimuli consisted of 144 grayscale images from the following three visual categories: scenes, faces, and objects (Fig. 1a, stimulus examples). Each visual category contained 48 individual exemplars, spanning multiple subcategories to ensure a wide variety of visual stimulation. The scene stimuli comprised six subcategories, half of them indoor scene categories (churches, concert halls, living rooms), and half of them outdoor scenes (beaches, mountains, deserts). The face stimuli varied in sex and race, comprising Asian and Caucasian, male and female faces presented in front view. The objects consisted of dressers, vases, motorbikes, and roller skates. The mean luminance of all images was equated across categories, with a uniform gray background equated to the mean luminance of the objects. Images were 300 × 300 pixels subtending a square of 8º × 8º at the center of the visual field.


The Temporal Dynamics of Scene Processing: A Multifaceted EEG Investigation
Stimuli and experimental design of Experiment 1 (category selectivity). a, Examples of the stimuli used in Experiment 1. The stimuli consisted of the following three categories: scenes, faces, and objects. Scenes were selected from the following six categories: churches, concert halls, living rooms, beaches, mountains, and deserts (top row, four categories are depicted here). The face stimuli comprised Asian and Caucasian, male and female faces presented in front view (middle row). The objects consisted of dressers, vases, motorbikes, and roller skates (bottom row). Note that in total there were 48 unique exemplars within each visual category. b, Participants viewed the stimuli and performed a simple one-back task, responding whenever the same image was presented twice in a row (in this example, the second presentation of the vase). The stimuli were presented pseudorandomly, with a trial beginning with the presentation of a scene image for 500 ms followed by a blank gray screen for the following 500 ms. c, Schematic representation of the 64 electrode sites from which EEG activity was recorded. The grouped electrodes are those analyzed in the 12 critical regions (see text for details).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5037322&req=5

Figure 1: Stimuli and experimental design of Experiment 1 (category selectivity). a, Examples of the stimuli used in Experiment 1. The stimuli consisted of the following three categories: scenes, faces, and objects. Scenes were selected from the following six categories: churches, concert halls, living rooms, beaches, mountains, and deserts (top row, four categories are depicted here). The face stimuli comprised Asian and Caucasian, male and female faces presented in front view (middle row). The objects consisted of dressers, vases, motorbikes, and roller skates (bottom row). Note that in total there were 48 unique exemplars within each visual category. b, Participants viewed the stimuli and performed a simple one-back task, responding whenever the same image was presented twice in a row (in this example, the second presentation of the vase). The stimuli were presented pseudorandomly, with a trial beginning with the presentation of a scene image for 500 ms followed by a blank gray screen for the following 500 ms. c, Schematic representation of the 64 electrode sites from which EEG activity was recorded. The grouped electrodes are those analyzed in the 12 critical regions (see text for details).
Mentions: The stimuli consisted of 144 grayscale images from the following three visual categories: scenes, faces, and objects (Fig. 1a, stimulus examples). Each visual category contained 48 individual exemplars, spanning multiple subcategories to ensure a wide variety of visual stimulation. The scene stimuli comprised six subcategories, half of them indoor scene categories (churches, concert halls, living rooms), and half of them outdoor scenes (beaches, mountains, deserts). The face stimuli varied in sex and race, comprising Asian and Caucasian, male and female faces presented in front view. The objects consisted of dressers, vases, motorbikes, and roller skates. The mean luminance of all images was equated across categories, with a uniform gray background equated to the mean luminance of the objects. Images were 300 × 300 pixels subtending a square of 8º × 8º at the center of the visual field.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Our remarkable ability to process complex visual scenes is supported by a network of scene-selective cortical regions. Despite growing knowledge about the scene representation in these regions, much less is known about the temporal dynamics with which these representations emerge. We conducted two experiments aimed at identifying and characterizing the earliest markers of scene-specific processing. In the first experiment, human participants viewed images of scenes, faces, and everyday objects while event-related potentials (ERPs) were recorded. We found that the first ERP component to evince a significantly stronger response to scenes than the other categories was the P2, peaking ∼220 ms after stimulus onset. To establish that the P2 component reflects scene-specific processing, in the second experiment, we recorded ERPs while the participants viewed diverse real-world scenes spanning the following three global scene properties: spatial expanse (open/closed), relative distance (near/far), and naturalness (man-made/natural). We found that P2 amplitude was sensitive to these scene properties at both the categorical level, distinguishing between open and closed natural scenes, as well as at the single-image level, reflecting both computationally derived scene statistics and behavioral ratings of naturalness and spatial expanse. Together, these results establish the P2 as an ERP marker for scene processing, and demonstrate that scene-specific global information is available in the neural response as early as 220 ms.

No MeSH data available.


Related in: MedlinePlus