perceptual distortions
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2021 ◽  
Author(s):  
Andrea De Angelis

Voters’ ability to perceive political parties’ positions on policy scales is a precondition for a functioning and responsive electoral democracy. Appropriate measures of policy distance are thus key to addressing the link between political parties and the citizens. This chapter reviews the scholarship on ideal point estimation, identifying the main methodological and substantial implications for empirical studies involving issue scales. Next, the chapter applies two-stage Bayesian Aldrich-McKelvey scaling to European Election Studies data to find evidence of systematic perceptual distortions: right-wing voters perceive political parties as more progressive than they actually are, while knowledgeable voters perceive greater differences between parties. Perceptual bias is also shown to correlate with standard polarization measures based on perceived party positions.


2021 ◽  
Vol 5 ◽  
pp. 239821282110077
Author(s):  
Joost Haarsma ◽  
Catherine J Harmer ◽  
Sandra Tamm

Ketamine, classical psychedelics and sleep deprivation are associated with rapid effects on depression. Interestingly, these interventions also have common psychotomimetic actions, mirroring aspects of psychosis such as an altered sense of self, perceptual distortions and distorted thinking. This raises the question whether these interventions might be acute antidepressants through the same mechanisms that underlie some of their psychotomimetic effects. That is, perhaps some symptoms of depression can be understood as occupying the opposite end of a spectrum where elements of psychosis can be found on the other side. This review aims at reviewing the evidence underlying a proposed continuum hypothesis of psychotomimetic rapid antidepressants, suggesting that a range of psychotomimetic interventions are also acute antidepressants as well as trying to explain these common features in a hierarchical predictive coding framework, where we hypothesise that these interventions share a common mechanism by increasing the flexibility of prior expectations. Neurobiological mechanisms at play and the role of different neuromodulatory systems affected by these interventions and their role in controlling the precision of prior expectations and new sensory evidence will be reviewed. The proposed hypothesis will also be discussed in relation to other existing theories of antidepressants. We also suggest a number of novel experiments to test the hypothesis and highlight research areas that could provide further insights, in the hope to better understand the acute antidepressant properties of these interventions.


2020 ◽  
pp. 027623662096963
Author(s):  
Giovanni B. Caputo ◽  
Steven Jay Lynn ◽  
James Houran

We critically reviewed the protocols, results, and potential implications from empirical studies ( n = 44) on mirror-gazing (including the “psychomanteum”) and eye-to-eye gazing, both in healthy individuals and clinical patients, including studies of hypnotic mirrored self-misidentification, mirror-gazing in body dysmorphic disorder and schizophrenia. We found these methods to be effective for eliciting altered states or anomalous experiences under controlled conditions and in non-clinical samples. Mirror-gazing and eye-to-eye-gazing produced anomalous experiences almost exclusively in the visual, bodily, and self-identity modalities, whereas psychomanteum experiences tended also to involve voices, smells, and bodily touches. The complexity, diversity, and specificity in contents across these anomalous experiences suggest mechanisms beyond perceptual distortions or illusions. We argue that mirror- and eye-gazing anomalous perceptions implicate different mechanisms that induce (i) Derealization (anomalous perceptions of external reality); (ii) Depersonalization (anomalous perceptions of the body), and (iii) Dissociated identity (anomalous perceptions of another identity in place of the self in mirror-gazing or in place of the other in eye-to-eye gazing). These interpretations suggest directions for future researches.


2020 ◽  
Vol 30 (20) ◽  
pp. 4071-4077.e4 ◽  
Author(s):  
Jorge Almeida ◽  
Andreia Freixo ◽  
Miguel Tábuas-Pereira ◽  
Sarah B. Herald ◽  
Daniela Valério ◽  
...  

Cognition ◽  
2020 ◽  
Vol 197 ◽  
pp. 104127 ◽  
Author(s):  
Frances Le Cornu Knight ◽  
Andrew J. Bremner ◽  
Dorothy Cowie

2020 ◽  
Author(s):  
Morfoisse Theo ◽  
Herrera Altamira Gabriela ◽  
Angelini Leonardo ◽  
Clément Gilles ◽  
Beraneck Mathieu ◽  
...  

AbstractHuman visual 3D perception is flawed by distortions, which are influenced by non-visual factors, such as gravitational vestibular signals. Distinct hypotheses regarding the sensory processing stage at which gravity acts may explain the influence of gravity: 1) a direct effect on the visual system, 2) a shaping of the internal representation of space that is used to interpret sensory signals, or 3) a role in the ability to build multiple, modalityspecific, internal depictions of the perceived object. To test these hypotheses, we performed experiments comparing visual versus haptic 3D perception, and the effects of microgravity on these two senses. The results show that visual and haptic perceptual anisotropies reside in body-centered, and not gravity-centered, planes, suggesting an ego-centric encoding of the information for both sensory modalities. Although coplanar, the perceptual distortions of the two sensory modalities are in opposite directions: depth is visually underestimated, but haptically overestimated, with respect to height and width. Interestingly microgravity appears to amplify the ‘terrestrial’ distortions of both senses. Through computational modeling, we show that these findings are parsimoniously predicted only by a gravity facilitation of cross-modal sensory reconstructions, corresponding to Hypothesis 3. This theory is able to explain not only how gravity can shape egocentric perceptions, but also the unexpected opposite effect of gravity on visual and haptic 3D perception. Overall, these results suggest that the brain uses gravity as a stable reference cue to reconstruct concurrent, modality-specific internal representations of 3D objects even when they are sensed through only one sensory channel.


2019 ◽  
Vol 127 (2) ◽  
pp. 490-509 ◽  
Author(s):  
Márcia Reis Guimarães ◽  
Douglas de Araújo Vilhena ◽  
Stephen J. Loew ◽  
Ricardo Queiroz Guimarães

This study analyzed the effects of spectral overlays on ocular motility during reading among a clinical group of children and adolescents experiencing visual–perceptual distortions of text. We reviewed the records of 323 eye-hospital patients diagnosed with visual stress and divided this participant sample into two age-based cohorts: children ( n =  184; Mean [ M] age = 10.1, standard deviation [ SD]  =  1.3 years) and adolescents ( n =  139; M age = 14.6, SD = 1.5 years). We used a Visagraph III Eye-Movement Recording System to record ocular motor efficiency while reading with and without spectral overlays, and we examined the following parameters: (a) Fixations, (b) Regressions, (c) Span of Recognition, (d) Reading Rate, (e) Relative Efficiency, and (f) Comprehension. Our results showed that using one or some combination of 10 participant-selected spectral overlays immediately and significantly ( p <  .001) reduced the number of Fixations and Regressions per 100 words, while there were significant ( p <  .001) gains in positive factors such as Span of Recognition, Reading Rate, Relative Efficiency, and Comprehension. Our findings indicate that spectral filtering can be an effective tool for helping many young patients who experience visual–perceptual distortions while reading. Future expanded research employing eye-tracking technology is clearly needed.


Author(s):  
Andrea De Angelis

Voters’ ability to perceive political parties’ positions on policy scales is a precondition for a functioning and responsive electoral democracy. Appropriate measures of policy distance are thus key to addressing the link between political parties and the citizens. This chapter reviews the scholarship on ideal point estimation, identifying the main methodological and substantial implications for empirical studies involving issue scales. Next, the chapter applies two-stage Bayesian Aldrich-McKelvey scaling to European Election Studies data to find evidence of systematic perceptual distortions: right-wing voters perceive political parties as more progressive than they actually are, while knowledgeable voters perceive greater differences between parties. Perceptual bias is also shown to correlate with standard polarization measures based on perceived party positions.


Perception ◽  
2019 ◽  
Vol 48 (8) ◽  
pp. 668-684
Author(s):  
Ebru Ecem Tavacioglu ◽  
Elena Azañón ◽  
Matthew R. Longo

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