Does valence influence perceptual bias towards incongruence during binocular rivalry?

Frontal activation as a key for deciphering context congruity and valence during visual perception: An electrical neuroimaging study

The object-context associations and the valence are two important stimulus attributes that influence visual perception. The current study investigates the neural sources associated with schema congruent and incongruent object-context associations within positive, negative, and neutral valence during an intermittent binocular rivalry task with simultaneous high-density EEG recording. Cortical sourceswere calculated using the sLORETA algorithm in 150 ms after stimulus onset (Stim + 150) and 400 ms before response (Resp-400) time windows. No significant difference in source activity was found between congruent and incongruent associations in any of the valence categories in the Stim + 150 ms window indicating that immediately after stimulus presentation the basic visual processing remains the same for both. In the Resp-400 ms window, different frontal regions showed higher activity for incongruent associations with different valence such as the superior frontal gyrus showed significantly higher activations for negative while the middle and medial frontal gyrus showed higher activations for neutral and finally, the inferior frontal gyrus showed higher activations for positive valence. Besides replicating the previous knowledge of frontal activations in response to context congruity, the current study provides further evidence for the sensitivity of the frontal lobe to the valence associated with the incongruent stimuli.

You won't believe what this guy is doing with the potato: The ObjAct stimulus-set depicting human actions on congruent and incongruent objects

Perception famously involves both bottom-up and top-down processes. The latter are influenced by our previous knowledge and expectations about the world. In recent years, many studies have focused on the role of expectations in perception in general, and in object processing in particular. Yet studying this question is not an easy feat, requiring-among other things-the creation and validation of appropriate stimuli. Here, we introduce the ObjAct stimulus-set of free-to-use, highly controlled real-life scenes, on which critical objects are pasted. All scenes depict human agents performing an action with an object that is either congruent or incongruent with the action. The focus on human actions yields highly constraining contexts, strengthening congruency effects. The stimuli were analyzed for low-level properties, using the SHINE toolbox to control for luminance and contrast, and using a deep convolutional neural network to mimic V1 processing and potentially discover other low-level factors that might differ between congruent and incongruent scenes. Two online validation studies (N = 500) were also conducted to assess the congruency manipulation and collect additional ratings of our images (e.g., arousal, likeability, visual complexity). We also provide full descriptions of the online sources from which all images were taken, as well as verbal descriptions of their content. Taken together, this extensive validation and characterization procedure makes the ObjAct stimulus-set highly informative and easy to use for future researchers in multiple fields, from object and scene processing, through top-down contextual effects, to the study of actions.

State-dependent perception and perceptual reversals during intermittent binocular rivalry: An electrical neuroimaging study

The object-context relationship and valence are two important stimulus attributes that affect visual perception. Although previous studies reveal how these two factors affect visual perception individually, the interplay between valence with congruent or incongruent object-context associations during visual perception is explored scarcely. Further, what is perceived, is affected by the intrinsic state of the brain at the moment of appearance of the stimulus which could be assessed by EEG microstates. Hence, the current study was designed to explore how the pre-stimulus EEG microstate influences the perception of emotional congruent and incongruent stimuli as well as perceptual reversals and stability during an intermittent binocular rivalry. Results revealed the association of specific pre-stimulus microstates with the perception of neutral and negative congruent stimuli as well as perceptual reversals and stability. Electrical neuroimaging of these microstates showed higher activation in the precuneus and middle occipital gyrus preceding the perception of neutral congruent stimuli and lingual gyrus preceding the perception of negative congruent stimuli. Increased source activity in superior temporal gyrus and superior frontal gyrus was found preceding stability and lower activation in parahippocampal gyrus was observed preceding reversals. Together these results suggest that the pre-stimulus activation of areas involved in visual priming, retrieval, and semantics leads to congruent perception. Pre-stimulus DMN suppression was required for perceptual reversals whereas stability was accompanied by pre-stimulus activation of areas related to the specific nature of the stimulus. Therefore, we propose that in addition to stimulus attributes, the pre-stimulus intrinsic brain activity could be an important determinant of the performance.