scholarly journals The Importance of Amodal Completion in Everyday Perception

i-Perception ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 204166951878888 ◽  
Author(s):  
Bence Nanay

Amodal completion is the representation of those parts of the perceived object that we get no sensory stimulation from. In the case of vision, it is the representation of occluded parts of objects we see: When we see a cat behind a picket fence, our perceptual system represents those parts of the cat that are occluded by the picket fence. The aim of this piece is to argue that amodal completion plays a constitutive role in our everyday perception and trace the theoretical consequences of this claim.

Author(s):  
Bence Nanay

There has been a lot of discussion about how the cognitive penetrability of perception may or may not have important implications for understanding perceptual justification. The aim of this chapter is to argue that a different set of findings in perceptual psychology poses an even more serious challenge to the very idea of perceptual justification. These findings are about the importance of perceptual processing that is not driven by corresponding sensory stimulation in the relevant sense modality (such as amodal completion and multimodal completion). These findings show that everyday perception is in fact a mixture of sensory-stimulation-driven perceptual processing and perceptual processing that is not driven by corresponding sensory stimulation in the relevant sense modality and that we have strong reasons to doubt the epistemic pedigree of the latter process. The implication of this is not that we should become skeptics or deny the possibility of perceptual justification. It is, rather, that the only way in which we can understand when and whether a perceptual state justifies beliefs is by paying close attention to empirical facts about the reliability of perceptual processing that is not driven by corresponding sensory stimulation in the relevant sense modality. In this sense (a very narrow sense) epistemology needs to be naturalized.


2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Prevan Moodley ◽  
Francois Rabie

Many gay couples engage in nonmonogamous relationships. Ideas about nonmonogamy have historically been theorised as individual pathology and indicating relational distress. Unlike mixed-sex couples, boundaries for gay couples are often not determined by sexual exclusivity. These relationships are built along a continuum of open and closed, and sexual exclusivity agreements are not restricted to binaries, thus requiring innovation and re-evaluation. Three white South African gay couples were each jointly interviewed about their open relationship, specifically about how this is negotiated. In contrast to research that uses the individual to investigate this topic, this study recruited dyads. The couples recalled the initial endorsement of heteronormative romantic constructions, after which they shifted to psychological restructuring. The dyad, domesticated through the stock image of a white picket fence, moved to a renewed arrangement, protected by “rules” and imperatives. Abbreviated grounded theory strategies led to a core category, “co-creating porous boundaries”, and two themes. First, the couple jointly made heteronormative ideals porous and, second, they reconfigured the relationship through dyadic protection. The overall relationship ideology associated with the white picket fence remained intact despite the micro-innovations through which the original heteronormative patterning was reconfigured.


Author(s):  
Derek H. Brown

This chapter explores the broad thesis that most if not all perceptual experiences are infused or soaked with imaginings. To begin, the author articulates a sense of imagination useful for this discussion, avoids some pitfalls, and incorporates the result into a schematic guidance principle. The thought behind the principle is that imaginative contributions to perceptual experiences are self-generated ingredients to perception that have a reasonably direct, ampliative impact on the relevant perceptual experiences. This framework is then applied to three sets of case studies: object-kind and object-sameness experiences (Strawson 1970); colour (Macpherson 2012); and amodal completion (Nanay 2010) and perceptual constancy. Although the case studies have interesting differences, they all conform to the guidance principle. Since each has the potential to independently justify the thesis that perceptual experiences are infused with imaginings, they collectively provide sound motive to provisionally endorse it.


2002 ◽  
Vol 22 (12) ◽  
pp. 1476-1489 ◽  
Author(s):  
Nancy F. Cruz ◽  
Gerald A. Dienel

The concentration of glycogen, the major brain energy reserve localized mainly in astrocytes, is generally reported as about 2 or 3 μmol/g, but sometimes as high as 3.9 to 8 μmol/g, in normal rat brain. The authors found high but very different glycogen levels in two recent studies in which glycogen was determined by the routine amyloglucosidase procedure in 0.03N HCl digests either of frozen powders (4.8 to 6 μmol/g) or of ethanol-insoluble fractions (8 to 12 μmol/g). To evaluate the basis for these discrepant results, glycogen was assayed in parallel extracts of the same samples. Glycogen levels in ethanol extracts were twice those in 0.03N HCl digests, suggesting incomplete enzyme inactivation even with very careful thawing. The very high glycogen levels were biologically active and responsive to physiologic and pharmacological challenge. Glycogen levels fell after brief sensory stimulation, and metabolic labeling indicated its turnover under resting conditions. About 95% of the glycogen was degraded under in vitro ischemic conditions, and its “carbon equivalents” recovered mainly as glc, glc-P, and lactate. Resting glycogen stores were reduced by about 50% by chronic inhibition of nitric oxide synthase. Because neurotransmitters are known to stimulate glycogenolysis, stress or sensory activation due to animal handling and tissue-sampling procedures may stimulate glycogenolysis during an experiment, and glycogen lability during tissue sampling and extraction can further reduce glycogen levels. The very high glycogen levels in normal rat brain suggest an unrecognized role for astrocytic energy metabolism during brain activation.


Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 461
Author(s):  
Weslania Nascimento ◽  
Noemí Tomsen ◽  
Saray Acedo ◽  
Cristina Campos-Alcantara ◽  
Christopher Cabib ◽  
...  

Spontaneous swallowing contributes to airway protection and depends on the activation of brainstem reflex circuits in the central pattern generator (CPG). We studied the effect of age and gender on spontaneous swallowing frequency (SSF) in healthy volunteers and assessed basal SSF and TRPV1 stimulation effect on SSF in patients with post-stroke oropharyngeal dysphagia (OD). The effect of age and gender on SSF was examined on 141 healthy adult volunteers (HV) divided into three groups: GI—18–39 yr, GII—40–59 yr, and GIII—>60 yr. OD was assessed by the Volume–Viscosity Swallowing Test (VVST). The effect of sensory stimulation with capsaicin 10−5 M (TRPV1 agonist) was evaluated in 17 patients with post-stroke OD, using the SSF. SSF was recorded in all participants during 10 min using surface electromyography (sEMG) of the suprahyoid muscles and an omnidirectional accelerometer placed over the cricothyroid cartilage. SSF was significantly reduced in GII (0.73 ± 0.50 swallows/min; p = 0.0385) and GIII (0.50 ± 0.31 swallows/min; p < 0.0001) compared to GI (1.03 ± 0.62 swallows/min), and there was a moderate significant correlation between age and SFF (r = −0.3810; p < 0.0001). No effect of gender on SSF was observed. Capsaicin caused a strong and significant increase in SSF after the TRPV1 stimulation when comparing to basal condition (pre-capsaicin: 0.41 ± 0.32 swallows/min vs post-capsaicin: 0.81 ± 0.51 swallow/min; p = 0.0003). OD in patients with post-stroke OD and acute stimulation with TRPV1 agonists caused a significant increase in SSF, further suggesting the potential role of pharmacological stimulation of sensory pathways as a therapeutic strategy for CPG activation in patients with OD.


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