Perceptual Phenomena Research Articles

Presenças Impessoais: tons de humano na cena-paisagem

Resumo: Por ser considerada como uma propriedade daquele que atua, a presença costuma ser abordada do ponto de vista do trabalho do ator. Rompendo com essa concepção, o artigo pretende compreender a presença como uma qualidade relacional, e não pessoal. Para tanto, serão analisados dois espetáculos: Stifters Dinge, de Heiner Goebbels, e Variações sobre a morte, de Claude Régy. Compostos como paisagens, ambos desenvolvem uma estética não antropocêntrica da cena e permitem pensar a presença como um fenômeno da percepção e pelo prisma da atividade do espectador.

Correction: Experience with speech sounds is not necessary for cue trading by budgerigars (Melopsittacus undulatus).

[This corrects the article DOI: 10.1371/journal.pone.0177676.].

Audio-Visual Integration in a Redundant Target Paradigm: A Comparison between Rhesus Macaque and Man.

The mechanisms underlying multi-sensory interactions are still poorly understood despite considerable progress made since the first neurophysiological recordings of multi-sensory neurons. While the majority of single-cell neurophysiology has been performed in anesthetized or passive-awake laboratory animals, the vast majority of behavioral data stems from studies with human subjects. Interpretation of neurophysiological data implicitly assumes that laboratory animals exhibit perceptual phenomena comparable or identical to those observed in human subjects. To explicitly test this underlying assumption, we here characterized how two rhesus macaques and four humans detect changes in intensity of auditory, visual, and audio-visual stimuli. These intensity changes consisted of a gradual envelope modulation for the sound, and a luminance step for the LED. Subjects had to detect any perceived intensity change as fast as possible. By comparing the monkeys' results with those obtained from the human subjects we found that (1) unimodal reaction times differed across modality, acoustic modulation frequency, and species, (2) the largest facilitation of reaction times with the audio-visual stimuli was observed when stimulus onset asynchronies were such that the unimodal reactions would occur at the same time (response, rather than physical synchrony), and (3) the largest audio-visual reaction-time facilitation was observed when unimodal auditory stimuli were difficult to detect, i.e., at slow unimodal reaction times. We conclude that despite marked unimodal heterogeneity, similar multisensory rules applied to both species. Single-cell neurophysiology in the rhesus macaque may therefore yield valuable insights into the mechanisms governing audio-visual integration that may be informative of the processes taking place in the human brain.

Predictive coding in agency detection

ABSTRACTAgency detection is a central concept in the cognitive science of religion (CSR). Experimental studies, however, have so far failed to lend support to some of the most common predictions that follow from current theories on agency detection. In this article, I argue that predictive coding, a highly promising new framework for understanding perception and action, may solve pending theoretical inconsistencies in agency detection research, account for the puzzling experimental findings mentioned above, and provide hypotheses for future experimental testing. Predictive coding explains how the brain, unbeknownst to consciousness, engages in sophisticated Bayesian statistics in an effort to constantly predict the hidden causes of sensory input. My fundamental argument is that most false positives in agency detection can be seen as the result of top-down interference in a Bayesian system generating high prior probabilities in the face of unreliable stimuli, and that such a system can better account for the experimental evidence than previous accounts of a dedicated agency detection system. Finally, I argue that adopting predictive coding as a theoretical framework has radical implications for the effects of culture on the detection of supernatural agency and a range of other religious and spiritual perceptual phenomena.

Perceptual integration and attention in human extrastriate cortex

Visual crowding is a perceptual phenomenon with far-reaching implications in both perceptual (e.g., object recognition and reading) and clinical (e.g., developmental dyslexia and visual agnosia) domains. Here, we combined event-related fMRI measurements and wide-field brain mapping methods to investigate whether the BOLD response evoked by visual crowding is modulated by different attentional conditions. Participants underwent two sessions of psychophysical training outside the scanner, and then fMRI BOLD activity was measured simultaneously in early visual areas (including the visual word form area, VWFA), while they viewed strongly-crowded and weakly-crowded Gabor patches in attended and unattended conditions. We found that crowding increased BOLD activity in a network of areas including V1, V2, V3A, V4/V8, and VWFA. In V4/V8 and VWFA we found an increased activity related to attention. The effect of crowding in V1 was recorded only when attention was fully devoted to the target location. Our results provide evidence that some area beyond V1 might be the likely candidate for the site of crowding, thus supporting the view of visual crowding as a mid-level visual phenomenon.

Um Olhar sobre Material for the Spine, de Steve Paxton

Resumo: A pesquisa detalha alguns pontos fundamentais de Material for the spine, de Steve Paxton, para estabelecer relações entre o mesmo e posições acerca dos fenômenos sensação e percepção no contexto da performatividade na cena contemporânea. Analisa, ainda, a relação entre sensação interna do corpo e o desenho do corpo em movimento, que Paxton define como forma. A partir desses conceitos, discute a potência artística nessa abordagem, pautada numa prática cênica cujo objetivo está em criar dança.

Auditory-induced bouncing is a perceptual (rather than a cognitive) phenomenon: Evidence from illusory crescents

A central task for vision is to identify objects as the same persisting individuals over time and motion. The need for such processing is made especially clear in ambiguous situations such as the bouncing/streaming display: two discs move toward each other, superimpose, and then continue along their trajectories. Did the discs stream past each other, or bounce off each other? When people are likely to perceive streaming, playing a brief tone at the moment of overlap can readily cause them to see bouncing instead. Recent research has attributed this effect to decisional (rather than perceptual) processes by showing that auditory tones alter response biases but not the underlying sensitivity for detecting objective bounces. Here we explore the nature of this phenomenon using ‘illusory causal crescents’: when people perceive bouncing (or causal ‘launching’), they also perceive the second disc to begin moving before being fully overlapped with the first disc (i.e. leaving an uncovered crescent). Here we demonstrate that merely playing a sound coincident to the moment of overlap can also reliably induce the perception of such illusory crescents. Moreover, this effect is due to the coincidence of the tone, per se, since the effect disappears when the tone is embedded in a larger regular tone sequence. Because observers never have to explicitly categorize their percept (e.g. as streaming)—and because the effect involves a subtle quantitative influence on another clearly visual property (i.e. the crescent’s width)—we conclude that this audiovisual influence on the perception of identity over time reflects perceptual processing rather than higher-level decisions.

Emergence of the consonance pattern within synaptic weights of a neural network featuring Hebbian neuroplasticity

Consonance is a perception phenomenon that evokes pleasant feelings when listening to complex sounds. Since Pythagoras, people have attempted to explain consonance and dissonance, using various methodological means, with limited success and without providing convincing underlying causes. We demonstrate that a specific auditory spectral distribution caused by nonlinearities, as a first phenomenon, and the Hebbian neuroplasticity as a second, are sufficient set of phenomena a system should possess so it could generate the consonance pattern - the actual two-tone interval list ordered by consonance. The emergence of this pattern is explained in a step-by-step manner, utilizing an artificial neural network model. In a reverse engineering manner, our simulations are testing all the possible spectral distributions of auditory stimuli (within particular precision scales and applying certain abstractions) and reveal those that produce a result with a pattern perfectly matching the consonance ordered two-tone interval list, the one that is widely accepted in the Western musical culture. The results of this study suggest that the consonance pattern could be an expected outcome in any system containing the asserted set of features (including the higher animals). The intent of this study is not to realistically model the human auditory system, but to demonstrate a set of features an abstract and generic system should possess so it could produce the consonance pattern.

Size Aftereffects Are Eliminated When Adaptor Stimuli Are Prevented from Reaching Awareness by Continuous Flash Suppression.

Size aftereffects are a compelling perceptual phenomenon in which we perceive the size of a stimulus as being different than it actually is following a period of visual stimulation of an adapter stimulus with a different size. Here, we used continuous flash suppression (CFS) to determine if size aftereffects require a high-level appraisal of the adapter stimulus. The strength of size aftereffects was quantified following a 3-s exposure to perceptually visible and invisible adapters. Participants judged the size of a target that followed the adapter in comparison to a subsequent reference. Our experiments demonstrate that the adapter no longer influenced the perceived size of the subsequent target stimulus under CFS. We conclude that the perception of size aftereffects is prevented when CFS is used to suppress the conscious awarness of the adapting stimulus.

Blends of Non-caloric Sweeteners Saccharin and Cyclamate Show Reduced Off-Taste due to TAS2R Bitter Receptor Inhibition

Non-caloric sweeteners are widely used for the formulation of calorie-reduced beverages for health-conscious consumers. However, disadvantages such as undesired off-tastes limit the use of non-nutritive sweeteners. Therefore, the food industry isconstantly searching for novel sweeteners and frequently resorts to using blends combining non-caloric sweeteners in a single formulation. The earliest blend allowing higher sweetness levels with reduced bitter off-taste combined saccharin with cyclamate. However, the mechanism by which sweetener blends become superior to single compounds remained obscure. By functional expression of human bitter taste receptors, we found the explanation for the phenomenon observed ∼60 years ago. We demonstrate that cyclamate potently blocks the receptors responsible for saccharin's bitter off-taste.This effect occurs at concentrations where cyclamateitself does not elicit a side taste. Intriguingly, also saccharin inhibits cyclamate-activated bitter receptors. Our experiments demonstrate that heterologous assays are useful for understanding perceptual phenomena and the development of novel tastant formulations.

The Oddball Effect and Inattentional Blindness: How Unexpected Events Influence Our Perceptions Of Time

Inattentional blindness is a phenomenon in which an unexpected event goes unnoticed (at a conscious level) during a demanding task. The oddball effect is a perceptual phenomenon whereby novel or unexpected stimuli result in longer perceived time durations. The two phenomenon – inattentional blindness and the oddball effect—seem to have no surface relationship, however they share an important commonality: both occur in the presence of unexpected events. The present research aims to connect the two bodies of work, and examine if and how the oddball effect manifests itself within an inattentional blindness paradigm. The results of this research have important implications including understanding the effect of unexpected events on conscious attention and how the conscious processing of the event influences time perception. Results may also inform the design of systems that support tasks that require keeping track of elapsed duration when unexpected events may occur.

Percepção e Ontogênese: modulações transdisciplinares da subjetividade

Crossing the main theories and systems of psychology where the problem of perception is discussed, there is not a deep commitment to the processes by which the perceptual phenomena are constituted. There prevails the assumption of perception and perceived object as ontologically “given” elements, i.e., constituted previously to the perceptual experience. Against this ontological approach, we seek to understand the ontogenetic processes through which the perceptual phenomena are created, structured and modified. In order to do so, we will address the perception from a transdisciplinary perspective which resounds elements of biology, ethology, philosophy and arts. In the center of this investigation, the body emerges as source of cognitive processes and focus of clinical interventions as a means of formation and transformation of subjectivity.

Cinema e incorporações: reflexões e possibilidades educativas

Neste artigo apresentamos uma pesquisa sobre as possibilidades de ampliar a compreensão da relação entre cinema e educação a partir dos fenômenos e mecanismos da percepção e da cognição numa dimensão corporal, que estamos denominando de incorporações. O objetivo é especificar novas possibilidades e discutir novos limites teóricos e didáticos do ensino aprendizagem do cinema através das incorporações. Para isso, realizamos um estudo teórico e uma pesquisa aplicada articulando a didática e o cinema em diálogo com a mídia-educação. Entre as considerações, identificamos uma trilha fértil de novas possibilidades para ensinar e aprender cinema, a partir do cruzamento dos pontos de vista cognitivo, estético, cultural, social e político considerando o corpo como sujeito da percepção e da cognição. Enviado em: 29 de junho de 2017.Aprovado em: 13 de julho de 2017.

Tuned by experience: How orientation probability modulates early perceptual processing

Probable stimuli are more often and more quickly detected. While stimulus probability is known to affect decision-making, it can also be explained as a perceptual phenomenon. Using spatial gratings, we have previously shown that probable orientations are also more precisely estimated, even while participants remained naive to the manipulation. We conducted an electrophysiological study to investigate the effect that probability has on perception and visual-evoked potentials. In line with previous studies on oddballs and stimulus prevalence, low-probability orientations were associated with a greater late positive ‘P300’ component which might be related to either surprise or decision-making. However, the early ‘C1’ component, thought to reflect V1 processing, was dampened for high-probability orientations while later P1 and N1 components were unaffected. Exploratory analyses revealed a participant-level correlation between C1 and P300 amplitudes, suggesting a link between perceptual processing and decision-making. We discuss how these probability effects could be indicative of sharpening of neurons preferring the probable orientations, due either to perceptual learning, or to feature-based attention.

The curvature calculation mechanism based on simple cell model.

A conclusion has not yet been reached on how exactly the human visual system detects curvature. This paper demonstrates how orientation-selective simple cells can be used to construct curvature-detecting neural units. Through fixed arrangements, multiple plurality cells were constructed to simulate curvature cells with a proportional output to their curvature. In addition, this paper offers a solution to the problem of narrow detection range under fixed resolution by selecting an output value under multiple resolution. Curvature cells can be treated as concrete models of an end-stopped mechanism, and they can be used to further understand "curvature-selective" characteristics and to explain basic psychophysical findings and perceptual phenomena in current studies.

The recalibration of tactile perception during tool use is body-part specific.

Two decades of research have demonstrated that using a tool modulates spatial representations of the body. Whether this embodiment is specific to representations of the tool-using limb or extends to representations of other body parts has received little attention. Several studiesof other perceptual phenomena have found that modulations to the primary somatosensory representation of the hand transfers to the face, due in part to their close proximity in primary somatosensory cortex. In the present study, we investigated whether tool-induced recalibration of tactile perception on the hand transfers to the cheek. Participants verbally estimated the distance between two tactile points applied to either their hand or face, before and after using a hand-shaped tool. Tool use recalibrated tactile distance perception on the hand-in line with previous findings-but left perception on the cheek unchanged. This finding provides support for the idea that embodiment is body-part specific. Furthermore, it suggests that tool-induced perceptual recalibration occurs at a level of somatosensory processing, where representations of the hand and face have become functionally disentangled.

Retinal lateral inhibition revisited

Retinal lateral inhibition has long been known as the ‘contrast encoder’ and the relationship among retinal processing, lateral inhibition, and contrast perception has been discussed in the conventional scheme of difference-of-Gaussian (DoG). However, many studies argued that the classic DoG RF failed to explain contrast perception phenomena involving large spatial scale surface interaction (~1 deg). On the other hand, we recently showed that one of the neglected retinal features, wide-RF of retinal interneurons, explains how the visual system performs long-range interaction (Kim & Bertalmio, 2015). The long-range effect was previously explained by the multiscale DoG model (Blakeslee & McCourt, 1997) that proposes a varying spatial-frequency-bandwidth-channel processing. Here we show that the the retinal hierarchical center-surround processing architecture combined with interneurons of narrow and wide RFs accomplishes multi-channel-like results. We propose an update to the conventional view on lateral inhibition.

Experience with speech sounds is not necessary for cue trading by budgerigars (Melopsittacus undulatus).

The influence of experience with human speech sounds on speech perception in budgerigars, vocal mimics whose speech exposure can be tightly controlled in a laboratory setting, was measured. Budgerigars were divided into groups that differed in auditory exposure and then tested on a cue-trading identification paradigm with synthetic speech. Phonetic cue trading is a perceptual phenomenon observed when changes on one cue dimension are offset by changes in another cue dimension while still maintaining the same phonetic percept. The current study examined whether budgerigars would trade the cues of voice onset time (VOT) and the first formant onset frequency when identifying syllable initial stop consonants and if this would be influenced by exposure to speech sounds. There were a total of four different exposure groups: No speech exposure (completely isolated), Passive speech exposure (regular exposure to human speech), and two Speech-trained groups. After the exposure period, all budgerigars were tested for phonetic cue trading using operant conditioning procedures. Birds were trained to peck keys in response to different synthetic speech sounds that began with “d” or “t” and varied in VOT and frequency of the first formant at voicing onset. Once training performance criteria were met, budgerigars were presented with the entire intermediate series, including ambiguous sounds. Responses on these trials were used to determine which speech cues were used, if a trading relation between VOT and the onset frequency of the first formant was present, and whether speech exposure had an influence on perception. Cue trading was found in all birds and these results were largely similar to those of a group of humans. Results indicated that prior speech experience was not a requirement for cue trading by budgerigars. The results are consistent with theories that explain phonetic cue trading in terms of a rich auditory encoding of the speech signal.

A mathematical model of embodied consciousness

We introduce a mathematical model of embodied consciousness, the Projective Consciousness Model (PCM), which is based on the hypothesis that the spatial field of consciousness (FoC) is structured by a projective geometry and under the control of a process of active inference. The FoC in the PCM combines multisensory evidence with prior beliefs in memory and frames them by selecting points of view and perspectives according to preferences. The choice of projective frames governs how expectations are transformed by consciousness. Violations of expectation are encoded as free energy. Free energy minimization drives perspective taking, and controls the switch between perception, imagination and action. In the PCM, consciousness functions as an algorithm for the maximization of resilience, using projective perspective taking and imagination in order to escape local minima of free energy. The PCM can account for a variety of psychological phenomena: the characteristic spatial phenomenology of subjective experience, the distinctions and integral relationships between perception, imagination and action, the role of affective processes in intentionality, but also perceptual phenomena such as the dynamics of bistable figures and body swap illusions in virtual reality. It relates phenomenology to function, showing the computational advantages of consciousness. It suggests that changes of brain states from unconscious to conscious reflect the action of projective transformations and suggests specific neurophenomenological hypotheses about the brain, guidelines for designing artificial systems, and formal principles for psychology.

Transformation of Perception from Sensory to Motor Cortex

SummaryTo better understand how a stream of sensory data is transformed into a percept, we examined neuronal activity in vibrissal sensory cortex, vS1, together with vibrissal motor cortex, vM1 (a frontal cortex target of vS1), while rats compared the intensity of two vibrations separated by an interstimulus delay. Vibrations were “noisy,” constructed by stringing together over time a sequence of velocity values sampled from a normal distribution; each vibration’s mean speed was proportional to the width of the normal distribution. Durations of both stimulus 1 and stimulus 2 could vary from 100 to 600 ms. Psychometric curves reveal that rats overestimated the longer-duration stimulus—thus, perceived intensity of a vibration grew over the course of hundreds of milliseconds even while the sensory input remained, on average, stationary. Human subjects demonstrated the identical perceptual phenomenon, indicating that the underlying mechanisms of temporal integration generalize across species. The time dependence of the percept allowed us to ask to what extent neurons encoded the ongoing stimulus stream versus the animal’s percept. We demonstrate that vS1 firing correlated with the local features of the vibration, whereas vM1 firing correlated with the percept: the final vM1 population state varied, as did the rat’s behavior, according to both stimulus speed and stimulus duration. Moreover, vM1 populations appeared to participate in the trace of the percept of stimulus 1 as the rat awaited stimulus 2. In conclusion, the transformation of sensory data into the percept appears to involve the integration and storage of vS1 signals by vM1.