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1.
PLoS One ; 15(8): e0224471, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797090

RESUMO

We present normative data for an expanded set of stimuli designed to investigate past experience effects on object detection. The stimuli are vertically-elongated "bipartite" displays comprising two equal-area regions meeting at an articulated central border. When the central border is assigned to one side, a shaped figure (i.e., an object) is detected on that side. Participants viewing brief masked exposures typically detect figures more often on the critical side of Intact displays where a common ("familiar") object is depicted than on a matched critical side of Part-Rearranged (PR) displays comprising the same parts arranged in novel configurations. This pattern of results showed that past experience in the form of familiar configuration rather than familiar parts is a prior for figure assignment. Spurred by research implicating a network involving the perirhinal cortex of the medial temporal lobe in these familiar configuration effects, we enlarged the stimulus set from 24 to 48 base stimuli to increase its usefulness for behavioral, neuropsychological, and neuroimaging experiments. We measured the percentage of participants who agreed on a single interpretation for each side of Intact, Upright PR, and Inverted PR displays (144 displays; 288 sides) under long exposure conditions. High inter-subject agreement is taken to operationally define a familiar configuration. This new stimulus set is well-suited to investigate questions concerning how parts and wholes are integrated and how high- and low-level brain areas interact in object detection. This set also allows tests of predictions regarding cross-border competition in figure assignment and assessments of individual differences. The displays, their image statistics, and normative data are available online (https://osf.io/j9kz2/).


Assuntos
Percepção de Forma/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Percepção Visual/fisiologia , Adulto , Encéfalo , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Estimulação Luminosa/métodos , Reconhecimento Psicológico , Lobo Temporal
2.
PLoS One ; 15(8): e0236321, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32776987

RESUMO

The widely known hue-heat effect, a multisensory phenomenon between vision and thermal sensing, is a hypothesis based on the idea that light and colors affect perceived temperature. However, the application of this effect has not been prevalent in our daily lives. To work towards developing more practical use of the hue-heat effect, we conducted a series of psychophysical experiments to investigate the relationship between perceived temperature and illumination in a well-controlled experimental environment. The results showed that illumination had three types of effects to change our sense of coolness/warmness: creating, eliminating, and exchanging effects. Furthermore, we confirmed the existence of two distinctive time courses for the three effects: creating effect started immediately, but the eliminating effect takes time. These findings provide us with a better understanding of the hue-heat effect and enable us to apply it in everyday life. Paired with the new technologies it can also help with energy conservation.


Assuntos
Percepção de Cores/fisiologia , Iluminação , Sensação Térmica/fisiologia , Feminino , Temperatura Alta , Humanos , Masculino , Estimulação Luminosa/métodos , Psicofísica , Adulto Jovem
3.
Nat Commun ; 11(1): 3886, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32753603

RESUMO

The ability to recognize written letter strings is foundational to human reading, but the underlying neuronal mechanisms remain largely unknown. Recent behavioral research in baboons suggests that non-human primates may provide an opportunity to investigate this question. We recorded the activity of hundreds of neurons in V4 and the inferior temporal cortex (IT) while naïve macaque monkeys passively viewed images of letters, English words and non-word strings, and tested the capacity of those neuronal representations to support a battery of orthographic processing tasks. We found that simple linear read-outs of IT (but not V4) population responses achieved high performance on all tested tasks, even matching the performance and error patterns of baboons on word classification. These results show that the IT cortex of untrained primates can serve as a precursor of orthographic processing, suggesting that the acquisition of reading in humans relies on the recycling of a brain network evolved for other visual functions.


Assuntos
Evolução Biológica , Macaca mulatta/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Lobo Temporal/fisiologia , Animais , Mapeamento Encefálico , Tomada de Decisões , Imagem por Ressonância Magnética , Masculino , Estimulação Luminosa/métodos , Leitura , Lobo Temporal/diagnóstico por imagem
4.
Br J Anaesth ; 125(3): 330-335, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32653082

RESUMO

BACKGROUND: Anaesthetic drugs may cause neuroapoptosis in children and are routinely used off-label in specific age groups. Techniques that reduce anaesthetic drug dose requirements in children may thus enhance the safety of paediatric sedation or anaesthesia. Brainwave entrainment, notably in the form of auditory binaural beats, has been shown to have sedative effects in adults. We evaluated the influence of brainwave entrainment on propofol dose requirements for sedation in children. METHODS: We randomised 49 boys scheduled for sub-umbilical surgery under caudal blockade to an entrainment or a control group. Small differences in pitch were applied to each ear to create binaural beats, supplemented by synchronous visual stimuli, within the electroencephalographic frequency bands seen during relaxation and (rapid eye movement/non-rapid eye movement) sleep. After establishment of caudal block, propofol infusion was started at 5 mg kg-1 h-1. Intraoperatively, the infusion rate was adjusted every 5 min depending on the sedation state judged by the bispectral index (BIS). The infusion rate was decreased by 1 mg kg-1 h-1 if BIS was <70, and was increased if BIS was >70, heart rate increased by 20%, or if there were other signs of inadequate sedation. RESULTS: Mean propofol infusion rates were 3.0 (95% confidence interval [CI]: 2.4-3.6) mg kg-1 h-1vs 4.2 (95% CI: 3.6-4.8) mg kg-1 h-1 in the entrainment and control groups, respectively (P<0.01). BIS values were similar in the two groups. CONCLUSIONS: Brainwave entrainment effectively reduced the propofol infusion rates required for sedation in children undergoing surgery with regional anaesthesia. Further studies are needed to investigate the possibility of phasing out propofol infusions completely during longer surgical procedures and optimising the settings of brainwave stimulation. CLINICAL TRIAL REGISTRATION: DRKS00005064.


Assuntos
Estimulação Acústica/métodos , Anestésicos Intravenosos/administração & dosagem , Ondas Encefálicas/fisiologia , Estimulação Luminosa/métodos , Propofol/administração & dosagem , Procedimentos Cirúrgicos Operatórios , Criança , Pré-Escolar , Relação Dose-Resposta a Droga , Eletroencefalografia , Humanos , Lactente , Masculino
5.
PLoS One ; 15(7): e0235309, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32614860

RESUMO

Recent researches revealed that the EEG component caused by the flickering visual stimulus, which is called steady-state visually evoked potential (SSVEP), might be a potential index for object recognition. This study examined whether SSVEP reflects different states during object recognition. In one trial, a binary image (BI), which is difficult to recognize, was followed by a grayscale image (GI) of the same object as the answer. Both BI and GI were presented in a flickering manner at a frequency of 7.5 Hz. Participants were first asked to answer whether they could recognize BI. Then, after GI was shown, participants were requested to answer whether they recognized it. We analyzed the evoked and induced component of SSVEPs from the two recognition conditions. As a result, the SSVEPs to BI were significantly larger than that to GI. In addition, induced component to GI after the BI was unrecognized was smaller than after the BI was recognized. The present data provide evidence that SSVEPs reflect a transition of cognitive state to ambiguous figures is reflected.


Assuntos
Eletroencefalografia/métodos , Potenciais Evocados Visuais , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
6.
PLoS One ; 15(6): e0234513, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525966

RESUMO

Fearful facial expressions tend to be more salient than other expressions. This threat bias is to some extent driven by simple low-level image properties, rather than the high-level emotion interpretation of stimuli. It might be expected therefore that different expressions will, on average, have different physical contrasts. However, studies tend to normalise stimuli for RMS contrast, potentially removing a naturally-occurring difference in salience. We assessed whether images of faces differ in both physical and apparent contrast across expressions. We measured physical RMS contrast and the Fourier amplitude spectra of 5 emotional expressions prior to contrast normalisation. We also measured expression-related differences in perceived contrast. Fear expressions have a steeper Fourier amplitude slope compared to neutral and angry expressions, and consistently significantly lower contrast compared to other faces. This effect is more pronounced at higher spatial frequencies. With the exception of stimuli containing only low spatial frequencies, fear expressions appeared higher in contrast than a physically matched reference. These findings suggest that contrast normalisation artificially boosts the perceived salience of fear expressions; an effect that may account for perceptual biases observed for spatially filtered fear expressions.


Assuntos
Expressão Facial , Medo , Processamento de Imagem Assistida por Computador/métodos , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa/métodos , Adolescente , Adulto , Atenção/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
7.
Exp Psychol ; 67(1): 48-55, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32520669

RESUMO

Doing two things at once (vs. one in isolation) usually yields performance costs. Such decrements are often distributed asymmetrically between the two actions involved, reflecting different processing priorities. A previous study (Huestegge & Koch, 2013) demonstrated that the particular effector systems associated with the two actions can determine the pattern of processing priorities: Vocal responses were prioritized over manual responses, as indicated by smaller performance costs (associated with dual-action demands) for the former. However, this previous study only involved auditory stimulation (for both actions). Given that previous research on input-output modality compatibility in dual tasks suggested that pairing auditory input with vocal output represents a particularly advantageous mapping, the question arises whether the observed vocal-over-manual prioritization was merely a consequence of auditory stimulation. To resolve this issue, we conducted a manual-vocal dual task study using either only auditory or only visual stimuli for both responses. We observed vocal-over-manual prioritization in both stimulus modality conditions. This suggests that input-output modality mappings can (to some extent) attenuate, but not abolish/reverse effector-based prioritization. Taken together, effector system pairings appear to have a more substantial impact on capacity allocation policies in dual-task control than input-output modality combinations.


Assuntos
Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Voz/fisiologia , Adulto , Feminino , Humanos , Masculino
8.
PLoS One ; 15(6): e0234026, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525897

RESUMO

Social cognition is dependent on the ability to extract information from human stimuli. Of those, patterns of biological motion (BM) and in particular walking patterns of other humans, are prime examples. Although most often tested in isolation, BM outside the laboratory is often associated with multisensory cues (i.e. we often hear and see someone walking) and there is evidence that vision-based judgments of BM stimuli are systematically influenced by motor signals. Furthermore, cross-modal visuo-tactile mechanisms have been shown to influence perception of bodily stimuli. Based on these observations, we here investigated if somatosensory inputs would affect visual BM perception. In two experiments, we asked healthy participants to perform a speed discrimination task on two point light walkers (PLW) presented one after the other. In the first experiment, we quantified somatosensory-visual interactions by presenting PLW together with tactile stimuli either on the participants' forearms or feet soles. In the second experiment, we assessed the specificity of these interactions by presenting tactile stimuli either synchronously or asynchronously with upright or inverted PLW. Our results confirm that somatosensory input in the form of tactile foot stimulation influences visual BM perception. When presented with a seen walker's footsteps, additional tactile cues enhanced sensitivity on a speed discrimination task, but only if the tactile stimuli were presented on the relevant body-part (under the feet) and when the tactile stimuli were presented synchronously with the seen footsteps of the PLW, whether upright or inverted. Based on these findings we discuss potential mechanisms of somatosensory-visual interactions in BM perception.


Assuntos
Percepção de Movimento/fisiologia , Estimulação Luminosa/métodos , Estimulação Física/métodos , Percepção do Tato/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Julgamento/fisiologia , Masculino , Adulto Jovem
9.
Nat Commun ; 11(1): 3002, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32532982

RESUMO

Humans observe a wide range of actions in their surroundings. How is the visual cortex organized to process this diverse input? Using functional neuroimaging, we measured brain responses while participants viewed short videos of everyday actions, then probed the structure in these responses using voxel-wise encoding modeling. Responses are well fit by feature spaces that capture the body parts involved in an action and the action's targets (i.e. whether the action was directed at an object, another person, the actor, and space). Clustering analyses reveal five large-scale networks that summarize the voxel tuning: one related to social aspects of an action, and four related to the scale of the interaction envelope, ranging from fine-scale manipulations directed at objects, to large-scale whole-body movements directed at distant locations. We propose that these networks reveal the major representational joints in how actions are processed by visual regions of the brain.


Assuntos
Encéfalo/fisiologia , Movimento/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Desempenho Psicomotor/fisiologia , Córtex Visual/fisiologia , Adulto , Fenômenos Biomecânicos , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Feminino , Neuroimagem Funcional/métodos , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Estimulação Luminosa/métodos , Comportamento Social , Córtex Visual/diagnóstico por imagem , Adulto Jovem
10.
PLoS One ; 15(6): e0235128, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32589671

RESUMO

Segmentation of a natural scene into objects and background is a fundamental but challenging task for recognizing objects. Investigating intermediate-level visual cortical areas with a focus on local information is a crucial step towards understanding the formation of the cortical representations of figure and ground. We examined the activity of a population of macaque V4 neurons during the presentation of natural image patches and their respective variations. The natural image patches were optimized to exclude the influence of global context but included various characteristics of local stimulus. Around one fourth of the patch-responsive V4 neurons exhibited significant modulation of firing activity that was dependent on the positional relation between the figural region of the stimulus and the classical receptive field of the neuron. However, the individual neurons showed low consistency in figure-ground modulation across a variety of image patches (55-62%), indicating that individual neurons were capable of correctly signaling figure and ground only for a limited number of stimuli. We examined whether integration of the activity of multiple neurons enabled higher consistency across a variety of natural patches by training a support vector machine to classify figure and ground of the stimuli from the population firing activity. The integration of the activity of a few tens of neurons yielded discrimination accuracy much greater than that of single neurons (up to 85%), suggesting a crucial role of population coding for figure-ground discrimination in natural images.


Assuntos
Neurônios/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Feminino , Macaca fuscata , Estimulação Luminosa/métodos
11.
PLoS One ; 15(5): e0232349, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32365070

RESUMO

A popular model for sensory processing, known as predictive coding, proposes that incoming signals are iteratively compared with top-down predictions along a hierarchical processing scheme. At each step, error signals arising from differences between actual input and prediction are forwarded and recurrently minimized by updating internal models to finally be "explained away". However, the neuronal mechanisms underlying such computations and their limitations in processing speed are largely unknown. Further, it remains unclear at which step of cortical processing prediction errors are explained away, if at all. In the present study, human subjects briefly viewed the superposition of two orthogonally oriented gratings followed by abrupt removal of one orientation after either 33 or 200 milliseconds. Instead of strictly seeing the remaining orientation, observers report rarely but highly significantly an illusory percept of the arithmetic difference between previous and actual orientations. Previous findings in cats using the identical paradigm suggest that such difference signals are inherited from first steps of visual cortical processing. In light of early modeling accounts of predictive coding, in which visual neurons were interpreted as residual error detectors signaling the difference between actual input and its temporal prediction based on past input, our data may indicate continued access to residual errors. Such strategy permits time-critical perceptual decision making across a spectrum of competing internal signals up to the highest levels of processing. Thus, the occasional appearance of a prediction error-like illusory percept may uncover maintained flexibility at perceptual decision stages when subjects cope with highly dynamic and ambiguous visual stimuli.


Assuntos
Ilusões/fisiologia , Estimulação Luminosa/instrumentação , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Orientação Espacial , Estimulação Luminosa/métodos , Adulto Jovem
12.
PLoS Comput Biol ; 16(5): e1007614, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32421716

RESUMO

For stimuli near perceptual threshold, the trial-by-trial activity of single neurons in many sensory areas is correlated with the animal's perceptual report. This phenomenon has often been attributed to feedforward readout of the neural activity by the downstream decision-making circuits. The interpretation of choice-correlated activity is quite ambiguous, but its meaning can be better understood in the light of population-wide correlations among sensory neurons. Using a statistical nonlinear dimensionality reduction technique on single-trial ensemble recordings from the middle temporal (MT) area during perceptual-decision-making, we extracted low-dimensional latent factors that captured the population-wide fluctuations. We dissected the particular contributions of sensory-driven versus choice-correlated activity in the low-dimensional population code. We found that the latent factors strongly encoded the direction of the stimulus in single dimension with a temporal signature similar to that of single MT neurons. If the downstream circuit were optimally utilizing this information, choice-correlated signals should be aligned with this stimulus encoding dimension. Surprisingly, we found that a large component of the choice information resides in the subspace orthogonal to the stimulus representation inconsistent with the optimal readout view. This misaligned choice information allows the feedforward sensory information to coexist with the decision-making process. The time course of these signals suggest that this misaligned contribution likely is feedback from the downstream areas. We hypothesize that this non-corrupting choice-correlated feedback might be related to learning or reinforcing sensory-motor relations in the sensory population.


Assuntos
Comportamento de Escolha/fisiologia , Tomada de Decisões/fisiologia , Retroalimentação Sensorial/fisiologia , Animais , Córtex Cerebral , Percepção de Profundidade/fisiologia , Feminino , Macaca mulatta , Masculino , Modelos Teóricos , Estimulação Luminosa/métodos , Células Receptoras Sensoriais , Lobo Temporal/fisiologia , Percepção Visual/fisiologia
13.
PLoS One ; 15(5): e0232928, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433672

RESUMO

The information available through our senses is noisy, incomplete, and ambiguous. Our perceptual systems have to resolve this ambiguity to construct stable and reliable percepts. Previous EEG studies found large amplitude differences in two event-related potential (ERP) components 200 and 400 ms after stimulus onset when comparing ambiguous with disambiguated visual information ("ERP Ambiguity Effects"). These effects so far generalized across classical ambiguous figures from different visual categories at lower (geometry, motion) and intermediate (Gestalt perception) levels. The present study aimed to examine whether these ERP Effects are restricted to ambiguous figures or whether they also occur for different degrees of visibility. Smiley faces with low and high visibility of emotional expressions, as well as abstract figures with low and high visibility of a target curvature were presented. We thus compared ambiguity effects in geometric cube stimuli with visibility in emotional faces, and with visibility in abstract figures. ERP Effects were replicated for the geometric stimuli and very similar ERP Effects were found for stimuli with emotional face expressions but also for abstract figures. Conclusively, the ERP amplitude effects generalize across fundamentally different stimulus categories and show highly similar effects for different degrees of stimulus ambiguity and stimulus visibility. We postulate the existence of a high-level/meta-perceptual evaluation instance, beyond sensory details, that estimates the certainty of a perceptual decision. The ERP Effects may reflect differences in evaluation results.


Assuntos
Potenciais Evocados Visuais/fisiologia , Percepção/fisiologia , Percepção Visual/fisiologia , Adulto , Eletroencefalografia , Emoções , Potenciais Evocados/fisiologia , Feminino , Humanos , Masculino , Ilusões Ópticas , Estimulação Luminosa/métodos , Sorriso
14.
Acta Psychol (Amst) ; 206: 103064, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32416329

RESUMO

The current study investigates whether statistical regularities that change over time affect attentional selection. While searching for a target singleton, the distractor singleton was presented much more often in one location than in all other locations. Crucially, the location that had a distractor much more often, changed to new locations during the course of the experiment. Here we established exactly how the bias of attention followed these changes in the display. Unlike previous studies, we show that selection was remarkably flexible as the attentional bias followed the changes in the environment incorporating contributions of previous contingencies to the current attentional bias. Importantly, the initial learning experience had a lingering and enduring effect on subsequent attentional biases. We argue that the weights within the spatial priority map of selection are adjusted to changing environments, even though observers are unaware of these changes in the environment.


Assuntos
Viés de Atenção/fisiologia , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Adolescente , Feminino , Humanos , Masculino , Adulto Jovem
15.
PLoS One ; 15(4): e0232099, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32330183

RESUMO

Food cues affect hunger and nutritional choices. Omnipresent stimulation with palatable food contributes to the epidemics of obesity. The objective of the study was to investigate the impact of food cues on appetite-related hormones and to assess the functionality of the secreted hormones on macronutrient uptake in healthy subjects. Additionally, we aimed at verifying differences in the response of total and active ghrelin to stimulation with food pictures and to a meal followed by the stimulation. We were also interested in the identification of factors contributing to response to food cues. We recruited healthy, non-obese participants for two independent cross-over studies. During the first study, the subjects were presented random non-food pictures on the first day and pictures of foods on the second day of the study. Throughout the second study, following the picture session, the participants were additionally asked to drink a milkshake. Concentrations of blood glucose, triglycerides and hunger-related hormones were measured. The results showed that concentrations of several hormones measured in the blood are interdependent. In the case of ghrelin and gastric inhibitory peptide (GIP) as well as ghrelin and glucagon-like peptide-1 (GLP-1), this co-occurrence relies on the visual cues. Regulation of total ghrelin concentration following food stimulation is highly individual and responders showed upregulated total ghrelin, while the concentration of active ghrelin decreases following a meal. Protein content and colour intensity of food pictures reversely correlated with participants' rating of the pictures. We conclude that observation of food pictures influences the concentration of several appetite-related hormones. The close link of visual clues to physiological responses is likely of clinical relevance. Additionally, the protein content of displayed foods and green colour intensity in pictures may serve as a predictor of subjective attractiveness of the presented meal.


Assuntos
Fome/fisiologia , Obesidade/psicologia , Estimulação Luminosa/métodos , Adolescente , Adulto , Apetite/fisiologia , Glicemia/metabolismo , Comportamento de Escolha/fisiologia , Sinais (Psicologia) , Comportamento Alimentar/fisiologia , Feminino , Polipeptídeo Inibidor Gástrico/sangue , Grelina/sangue , Peptídeo 1 Semelhante ao Glucagon/sangue , Humanos , Insulina/sangue , Masculino , Nutrientes , Peptídeo YY/sangue
16.
PLoS One ; 15(4): e0232290, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32330199

RESUMO

Previous research suggests that the size of one's body is used as a metric to scale the external world. On the other hand, the influence of information from the external world on the perception of body size is unclear. It has been suggested that increased inter-pupillary distance (IPD) leads people to perceive the external world as smaller than it actually is. The present study investigated the effect of the IPD on body size perception, and the relationship between the perceived scale of the body and the external world when the IPD is manipulated. To this end, in a virtual environment, we manipulated the IPD as well as the size and presence of participants' hands, while participant's eye height was increased vertically. Results showed that, when participants' eye height was increased and their hands were enlarged, people with a fixed IPD perceived the size of their body to be large (like a giant) while the external world was perceived to be changed minimally. Alternatively, people with increased IPD perceived that the external world as having shrank, whereas their perception of their body size changed little. However, when a viewers' virtual hands were not shown, the IPD did not affect the individual's percept of body size, although the IPD did affect one's perception of the external world. These results suggest that, when the ratio of the size between one's body and the external world are explicit, the perceived size of one's body is affected by the IPD or perceived scale of the external world that is affected by the IPD.


Assuntos
Tamanho Corporal/fisiologia , Percepção de Distância/fisiologia , Percepção de Tamanho/fisiologia , Percepção Visual/fisiologia , Adulto , Imagem Corporal , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Interface Usuário-Computador , Adulto Jovem
17.
Nat Commun ; 11(1): 1753, 2020 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-32273500

RESUMO

Perceptual decisions are accompanied by feelings of confidence that reflect the likelihood that the decision was correct. Here we aim to clarify the relationship between perception and confidence by studying the same perceptual task across three different confidence contexts. Human observers were asked to categorize the source of sequentially presented visual stimuli. Each additional stimulus provided evidence for making more accurate perceptual decisions, and better confidence judgements. We show that observers' ability to set appropriate evidence accumulation bounds for perceptual decisions is strongly predictive of their ability to make accurate confidence judgements. When observers were not permitted to control their exposure to evidence, they imposed covert bounds on their perceptual decisions but not on their confidence decisions. This partial dissociation between decision processes is reflected in behaviour and pupil dilation. Together, these findings suggest a confidence-regulated accumulation-to-bound process that controls perceptual decision-making even in the absence of explicit speed-accuracy trade-offs.


Assuntos
Algoritmos , Tomada de Decisões/fisiologia , Modelos Psicológicos , Desempenho Psicomotor/fisiologia , Percepção Visual/fisiologia , Adulto , Simulação por Computador , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos
18.
PLoS Comput Biol ; 16(4): e1007720, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32282795

RESUMO

Humans routinely face novel environments in which they have to generalize in order to act adaptively. However, doing so involves the non-trivial challenge of deciding which aspects of a task domain to generalize. While it is sometimes appropriate to simply re-use a learned behavior, often adaptive generalization entails recombining distinct components of knowledge acquired across multiple contexts. Theoretical work has suggested a computational trade-off in which it can be more or less useful to learn and generalize aspects of task structure jointly or compositionally, depending on previous task statistics, but it is unknown whether humans modulate their generalization strategy accordingly. Here we develop a series of navigation tasks that separately manipulate the statistics of goal values ("what to do") and state transitions ("how to do it") across contexts and assess whether human subjects generalize these task components separately or conjunctively. We find that human generalization is sensitive to the statistics of the previously experienced task domain, favoring compositional or conjunctive generalization when the task statistics are indicative of such structures, and a mixture of the two when they are more ambiguous. These results support a normative "meta-generalization" account and suggests that people not only generalize previous task components but also generalize the statistical structure most likely to support generalization.


Assuntos
Generalização Psicológica/fisiologia , Generalização da Resposta/fisiologia , Aprendizagem/fisiologia , Tomada de Decisões/fisiologia , Humanos , Estimulação Luminosa/métodos , Desempenho Psicomotor , Reforço Psicológico
19.
PLoS One ; 15(4): e0230847, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32240209

RESUMO

The number of elements in two stereo-surfaces parallelly overlapped in depth is overestimated compared to that in a single flat surface, even when both have the same number of elements. Using stereoscopic pairs of elements, we evaluated two hypotheses on the overestimation: one that a higher-order process, forming a background surface, increases the number of perceived elements, and the other that the number of elements potentially occluded by the elements on a front surface is taken accounted for. The data from four experiments showed that (a) when binocular disparity between (or among) stereoscopic elements was small, the overestimation occurred for the stimuli we used-a two-surface-overlapping stimulus, where the likelihood for the process to operate was manipulated by changing the averaged luminance of each surface, a volumetric stimulus, where the likelihood for the background surface to be formed would decrease, and a two-non-overlapping-surface stimulus, where the surfaces in depth were not overlapped-, and (b) when binocular disparity was large, the overestimation occurred for the two-surfaces-overlapping stimulus, when the averaged luminance of the two surfaces were the same, and for the volumetric stimulus, but diminished for the surface-overlapping stimulus, when the averaged luminance differed between the surfaces and for the surfaces-non-overlapping stimulus. These results cannot be explained either hypothesis only. We explain the results by postulating that the sensory system processing disparities of elements interferes with that estimating the number of elements, resulting in an overestimation of the elements in a stereo-stimulus, and the disparity range within which the interference occurs may depend on the stimulus depth structure.


Assuntos
Percepção de Profundidade/fisiologia , Disparidade Visual/fisiologia , Visão Binocular/fisiologia , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos
20.
PLoS One ; 15(4): e0231152, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267886

RESUMO

The increasing interest in Virtual Reality (VR) as a tool for neuroscientific research contrasts with the current lack of established toolboxes and standards. In several recent studies, game engines like Unity or Unreal Engine were used. It remains to be tested whether these software packages provide sufficiently precise and accurate stimulus timing and time measurements that allow inferring ongoing mental and neural processes. We here investigated the precision and accuracy of the timing mechanisms of Unreal Engine 4 and SteamVR in combination with the HTC Vive VR system. In a first experiment, objective external measures revealed that stimulus durations were highly accurate. In contrast, in a second experiment, the assessment of the precision of built-in timing procedures revealed highly variable reaction time measurements and inaccurate determination of stimulus onsets. Hence, we developed a new software-based method that allows precise and accurate reaction time measurements with Unreal Engine and SteamVR. Instead of using the standard timing procedures implemented within Unreal Engine, time acquisition was outsourced to a background application. Timing benchmarks revealed that the newly developed method allows reaction time measurements with a precision and accuracy in the millisecond range. Overall, the present results indicate that the HTC Vive together with Unreal Engine and SteamVR can achieve high levels of precision and accuracy both concerning stimulus duration and critical time measurements. The latter can be achieved using a newly developed routine that allows not only accurate reaction time measures but also provides precise timing parameters that can be used in combination with time-sensitive functional measures such as electroencephalography (EEG) or transcranial magnetic stimulation (TMS).


Assuntos
Neurociências/métodos , Estimulação Luminosa/métodos , Tempo de Reação , Interface Usuário-Computador , Realidade Virtual , Animais , Humanos , Neurociências/instrumentação , Estimulação Luminosa/instrumentação , Estudo de Prova de Conceito , Fatores de Tempo
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