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1.
Commun Biol ; 4(1): 588, 2021 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-34002006

RESUMO

Dorsolateral prefrontal cortex (dlPFC) is proposed to drive brain-wide focus by biasing processing in favour of task-relevant information. A longstanding debate concerns whether this is achieved through enhancing processing of relevant information and/or by inhibiting irrelevant information. To address this, we applied transcranial magnetic stimulation (TMS) during fMRI, and tested for causal changes in information coding. Participants attended to one feature, whilst ignoring another feature, of a visual object. If dlPFC is necessary for facilitation, disruptive TMS should decrease coding of attended features. Conversely, if dlPFC is crucial for inhibition, TMS should increase coding of ignored features. Here, we show that TMS decreases coding of relevant information across frontoparietal cortex, and the impact is significantly stronger than any effect on irrelevant information, which is not statistically detectable. This provides causal evidence for a specific role of dlPFC in enhancing task-relevant representations and demonstrates the cognitive-neural insights possible with concurrent TMS-fMRI-MVPA.


Assuntos
Mapeamento Encefálico/métodos , Imageamento por Ressonância Magnética/métodos , Neuroimagem/métodos , Córtex Pré-Frontal/fisiologia , Estimulação Magnética Transcraniana/métodos , Adulto , Feminino , Humanos , Masculino , Análise e Desempenho de Tarefas , Adulto Jovem
2.
Elife ; 102021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33830017

RESUMO

There are many monitoring environments, such as railway control, in which lapses of attention can have tragic consequences. Problematically, sustained monitoring for rare targets is difficult, with more misses and longer reaction times over time. What changes in the brain underpin these 'vigilance decrements'? We designed a multiple-object monitoring (MOM) paradigm to examine how the neural representation of information varied with target frequency and time performing the task. Behavioural performance decreased over time for the rare target (monitoring) condition, but not for a frequent target (active) condition. This was mirrored in neural decoding using magnetoencephalography: coding of critical information declined more during monitoring versus active conditions along the experiment. We developed new analyses that can predict behavioural errors from the neural data more than a second before they occurred. This facilitates pre-empting behavioural errors due to lapses in attention and provides new insight into the neural correlates of vigilance decrements.


Assuntos
Atenção/fisiologia , Encéfalo/fisiologia , Tempo de Reação/fisiologia , Vigília/fisiologia , Adulto , Feminino , Humanos , Masculino , New South Wales , Adulto Jovem
3.
Proc Natl Acad Sci U S A ; 118(6)2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33526693

RESUMO

Grapheme-color synesthetes experience color when seeing achromatic symbols. We examined whether similar neural mechanisms underlie color perception and synesthetic colors using magnetoencephalography. Classification models trained on neural activity from viewing colored stimuli could distinguish synesthetic color evoked by achromatic symbols after a delay of ∼100 ms. Our results provide an objective neural signature for synesthetic experience and temporal evidence consistent with higher-level processing in synesthesia.


Assuntos
Percepção de Cores/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Sinestesia/fisiopatologia , Adolescente , Adulto , Idoso , Feminino , Humanos , Magnetoencefalografia , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa , Tempo de Reação/fisiologia , Sinestesia/diagnóstico por imagem , Adulto Jovem
4.
Schizophr Res ; 228: 534-540, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33234423

RESUMO

Body perception can be altered in individuals with schizophrenia resulting in experiences of undefined boundaries, loss of ownership, and size changes. These individuals may also be more susceptible to the rubber hand illusion (RHI: an illusion of body perception that can also be induced in neurotypical populations), but the findings are mixed. Furthermore, the perception of multisensory timing, which is thought to be fundamental for body perception, is altered in schizophrenia. We tested whether altered perception of the temporal relationship between visual and tactile signals in schizophrenia predicts self-reported perceptual aberrations and RHI susceptibility. We found that the sensitivity to detect temporal asynchronies is reduced in schizophrenia and this is a significant predictor for bodily perceptual symptoms. In contrast, we found no evidence for a direct relationship between asynchrony detection sensitivity and RHI susceptibility. Instead, our findings suggest that experiencing more bodily perceptual symptoms increases the likelihood of endorsing unusual bodily experiences, resulting in higher RHI self-ratings but not higher proprioceptive drift scores. Our findings provide new insight into factors that may underlie the report of unusual body perceptions in schizophrenia.


Assuntos
Ilusões , Esquizofrenia , Percepção do Tato , Imagem Corporal , Mãos , Humanos , Percepção Visual
5.
J Speech Lang Hear Res ; 63(7): 2361-2385, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32640176

RESUMO

Purpose We aimed to develop a noninvasive neural test of language comprehension to use with nonspeaking children for whom standard behavioral testing is unreliable (e.g., minimally verbal autism). Our aims were threefold. First, we sought to establish the sensitivity of two auditory paradigms to elicit neural responses in individual neurotypical children. Second, we aimed to validate the use of a portable and accessible electroencephalography (EEG) system, by comparing its recordings to those of a research-grade system. Third, in light of substantial interindividual variability in individuals' neural responses, we assessed whether multivariate decoding methods could improve sensitivity. Method We tested the sensitivity of two child-friendly covert N400 paradigms. Thirty-one typically developing children listened to identical spoken words that were either strongly predicted by the preceding context or violated lexical-semantic expectations. Context was given by a cue word (Experiment 1) or sentence frame (Experiment 2), and participants either made an overall judgment on word relatedness or counted lexical-semantic violations. We measured EEG concurrently from a research-grade system, Neuroscan's SynAmps2, and an adapted gaming system, Emotiv's EPOC+. Results We found substantial interindividual variability in the timing and topology of N400-like effects. For both paradigms and EEG systems, traditional N400 effects at the expected sensors and time points were statistically significant in around 50% of individuals. Using multivariate analyses, detection rate increased to 88% of individuals for the research-grade system in the sentences paradigm, illustrating the robustness of this method in the face of interindividual variations in topography. Conclusions There was large interindividual variability in neural responses, suggesting interindividual variation in either the cognitive response to lexical-semantic violations and/or the neural substrate of that response. Around half of our neurotypical participants showed the expected N400 effect at the expected location and time points. A low-cost, accessible EEG system provided comparable data for univariate analysis but was not well suited to multivariate decoding. However, multivariate analyses with a research-grade EEG system increased our detection rate to 88% of individuals. This approach provides a strong foundation to establish a neural index of language comprehension in children with limited communication. Supplemental Material https://doi.org/10.23641/asha.12606311.


Assuntos
Eletroencefalografia , Idioma , Criança , Compreensão , Potenciais Evocados , Feminino , Humanos , Masculino , Semântica
6.
J Neurosci ; 40(35): 6779-6789, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32703903

RESUMO

The ability to rapidly and accurately recognize complex objects is a crucial function of the human visual system. To recognize an object, we need to bind incoming visual features, such as color and form, together into cohesive neural representations and integrate these with our preexisting knowledge about the world. For some objects, typical color is a central feature for recognition; for example, a banana is typically yellow. Here, we applied multivariate pattern analysis on time-resolved neuroimaging (MEG) data to examine how object-color knowledge affects emerging object representations over time. Our results from 20 participants (11 female) show that the typicality of object-color combinations influences object representations, although not at the initial stages of object and color processing. We find evidence that color decoding peaks later for atypical object-color combinations compared with typical object-color combinations, illustrating the interplay between processing incoming object features and stored object knowledge. Together, these results provide new insights into the integration of incoming visual information with existing conceptual object knowledge.SIGNIFICANCE STATEMENT To recognize objects, we have to be able to bind object features, such as color and shape, into one coherent representation and compare it with stored object knowledge. The MEG data presented here provide novel insights about the integration of incoming visual information with our knowledge about the world. Using color as a model to understand the interaction between seeing and knowing, we show that there is a unique pattern of brain activity for congruently colored objects (e.g., a yellow banana) relative to incongruently colored objects (e.g., a red banana). This effect of object-color knowledge only occurs after single object features are processed, demonstrating that conceptual knowledge is accessed relatively late in the visual processing hierarchy.


Assuntos
Encéfalo/fisiologia , Percepção de Cores , Reconhecimento Visual de Modelos , Adulto , Formação de Conceito , Feminino , Humanos , Masculino
7.
Neuropsychologia ; 146: 107539, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32629033

RESUMO

Age-related decline in motor function is associated with over-activation of the sensorimotor circuitry. Using a multimodal MEG-fMRI paradigm, we investigated whether this neural over-recruitment in old age would be related to changes in movement-related beta desynchronization (MRBD), a correlate of the inhibitory neurotransmitter γ-aminobutyric acid (GABA), and whether it would characterize compensatory recruitment or a reduction in neural specialization (dedifferentiation). We used MEG to assess age-related changes in beta band oscillations in primary motor cortices, fMRI to localize age-related changes in brain activity, and the Finger Configuration Task to measure task performance during overt and covert motor processing: motor execution (ME) and motor imagery (MI). The results are threefold: first, showing age-related neuroplasticity during ME of older adults, compared to young adults, as evidenced by increased MRBD in motor cortices and over-recruitment of sensorimotor areas; second, showing similar age-related neuroplastic changes during MI; and finally, showing signs of dedifferentiation during ME in older adults whose performance negatively correlated with connectivity to bilateral primary motor cortex. Together, these findings demonstrate that elevated MRBD levels, reflecting greater GABAergic inhibitory activity, and over-activation of the sensorimotor network during ME may not be compensatory, but rather might reflect an age-related decline of the quality of the underlying neural signal.


Assuntos
Envelhecimento Saudável/fisiologia , Imaginação/fisiologia , Imageamento por Ressonância Magnética , Magnetoencefalografia , Plasticidade Neuronal , Desempenho Psicomotor/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Movimento/fisiologia
8.
PLoS One ; 15(1): e0219725, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31999697

RESUMO

Evidence from neuroimaging and brain stimulation studies suggest that visual information about objects in the periphery is fed back to foveal retinotopic cortex in a separate representation that is essential for peripheral perception. The characteristics of this phenomenon have important theoretical implications for the role fovea-specific feedback might play in perception. In this work, we employed a recently developed behavioral paradigm to explore whether late disruption to central visual space impaired perception of color. In the first experiment, participants performed a shape discrimination task on colored novel objects in the periphery while fixating centrally. Consistent with the results from previous work, a visual distractor presented at fixation ~100ms after presentation of the peripheral stimuli impaired sensitivity to differences in peripheral shapes more than a visual distractor presented at other stimulus onset asynchronies. In a second experiment, participants performed a color discrimination task on the same colored objects. In a third experiment, we further tested for this foveal distractor effect with stimuli restricted to a low-level feature by using homogenous color patches. These two latter experiments resulted in a similar pattern of behavior: a central distractor presented at the critical stimulus onset asynchrony impaired sensitivity to peripheral color differences, but, importantly, the magnitude of the effect was stronger when peripheral objects contained complex shape information. These results show a behavioral effect consistent with disrupting feedback to the fovea, in line with the foveal feedback suggested by previous neuroimaging studies.


Assuntos
Percepção de Cores/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Campos Visuais/fisiologia , Adolescente , Adulto , Atenção/fisiologia , Cor , Retroalimentação Fisiológica , Feminino , Fóvea Central/fisiologia , Humanos , Masculino , Estimulação Luminosa , Córtex Visual/fisiologia
9.
Atten Percept Psychophys ; 82(2): 550-563, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31646439

RESUMO

The world around us is filled with complex objects, full of color, motion, shape, and texture, and these features seem to be represented separately in the early visual system. Anne Treisman pointed out that binding these separate features together into coherent conscious percepts is a serious challenge, and she argued that selective attention plays a critical role in this process. Treisman also showed that, consistent with this view, outside the focus of attention we suffer from illusory conjunctions: misperceived pairings of features into objects. Here we used Treisman's logic to study the structure of pre-attentive representations of multipart, multicolor objects, by exploring the patterns of illusory conjunctions that arise outside the focus of attention. We found consistent evidence of some pre-attentive binding of colors to their parts, and weaker evidence of binding multiple colors of the same object. The extent to which such hierarchical binding occurs seems to depend on the geometric structure of multipart objects: Objects whose parts are easier to separate seem to exhibit greater pre-attentive binding. Together, these results suggest that representations outside the focus of attention are not entirely a "shapeless bundles of features," but preserve some meaningful object structure.


Assuntos
Atenção/fisiologia , Percepção de Cores/fisiologia , Ilusões Ópticas/fisiologia , Estimulação Luminosa/métodos , Cor , Feminino , Humanos , Masculino , Distribuição Aleatória , Adulto Jovem
10.
PLoS One ; 14(12): e0224174, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31841510

RESUMO

Body ownership relies on spatiotemporal correlations between multisensory signals and visual cues specifying oneself such as body form and orientation. The mechanism for the integration of bodily signals remains unclear. One approach to model multisensory integration that has been influential in the multisensory literature is Bayesian causal inference. This specifies that the brain integrates spatial and temporal signals coming from different modalities when it infers a common cause for inputs. As an example, the rubber hand illusion shows that visual form and orientation cues can promote the inference of a common cause (one's body) leading to spatial integration shown by a proprioceptive drift of the perceived location of the real hand towards the rubber hand. Recent studies investigating the effect of visual cues on temporal integration, however, have led to conflicting findings. These could be due to task differences, variation in ecological validity of stimuli and/or small samples. In this pre-registered study, we investigated the influence of visual information on temporal integration using a visuo-tactile temporal order judgement task with realistic stimuli and a sufficiently large sample determined by Bayesian analysis. Participants viewed videos of a touch being applied to plausible or implausible visual stimuli for one's hand (hand oriented plausibly, hand rotated 180 degrees, or a sponge) while also being touched at varying stimulus onset asynchronies. Participants judged which stimulus came first: viewed or felt touch. Results show that visual cues do not modulate visuo-tactile temporal order judgements. This is not in line with the idea that bodily signals indicating oneself influence the integration of multisensory signals in the temporal domain. The current study emphasises the importance of rigour in our methodologies and analyses to advance the understanding of how properties of multisensory events affect the encoding of temporal information in the brain.


Assuntos
Orientação Espacial/fisiologia , Percepção do Tato/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Teorema de Bayes , Imagem Corporal , Sinais (Psicologia) , Feminino , Mãos , Humanos , Masculino , Pessoa de Meia-Idade , Orientação , Propriocepção/fisiologia , Tato/fisiologia
11.
Neuroimage ; 200: 373-381, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31254648

RESUMO

Colour is a defining feature of many objects, playing a crucial role in our ability to rapidly recognise things in the world around us and make categorical distinctions. For example, colour is a useful cue when distinguishing lemons from limes or blackberries from raspberries. That means our representation of many objects includes key colour-related information. The question addressed here is whether the neural representation activated by knowing that something is red is the same as that activated when we actually see something red, particularly in regard to timing. We addressed this question using neural timeseries (magnetoencephalography, MEG) data to contrast real colour perception and implied object colour activation. We applied multivariate pattern analysis (MVPA) to analyse the brain activation patterns evoked by colour accessed via real colour perception and implied colour activation. Applying MVPA to MEG data allows us here to focus on the temporal dynamics of these processes. Male and female human participants (N = 18) viewed isoluminant red and green shapes and grey-scale, luminance-matched pictures of fruits and vegetables that are red (e.g., tomato) or green (e.g., kiwifruit) in nature. We show that the brain activation pattern evoked by real colour perception is similar to implied colour activation, but that this pattern is instantiated at a later time. These results suggest that a common colour representation can be triggered by activating object representations from memory and perceiving colours.


Assuntos
Córtex Cerebral/fisiologia , Percepção de Cores/fisiologia , Neuroimagem Funcional/métodos , Magnetoencefalografia/métodos , Reconhecimento Visual de Modelos/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
12.
Atten Percept Psychophys ; 81(8): 2685-2699, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31218599

RESUMO

The human visual system is capable of processing an enormous amount of information in a short time. Although rapid target detection has been explored extensively, less is known about target localization. Here we used natural scenes and explored the relationship between being able to detect a target (present vs. absent) and being able to localize it. Across four presentation durations (~ 33-199 ms), participants viewed scenes taken from two superordinate categories (natural and manmade), each containing exemplars from four basic scene categories. In a two-interval forced choice task, observers were asked to detect a Gabor target inserted in one of the two scenes. This was followed by one of two different localization tasks. Participants were asked either to discriminate whether the target was on the left or the right side of the display or to click on the exact location where they had seen the target. Targets could be detected and localized at our shortest exposure duration (~ 33 ms), with a predictable improvement in performance with increasing exposure duration. We saw some evidence at this shortest duration of detection without localization, but further analyses demonstrated that these trials typically reflected coarse or imprecise localization information, rather than its complete absence. Experiment 2 replicated our main findings while exploring the effect of the level of "openness" in the scene. Our results are consistent with the notion that when we are able to extract what objects are present in a scene, we also have information about where each object is, which provides crucial guidance for our goal-directed actions.


Assuntos
Atenção/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Reconhecimento Psicológico/fisiologia , Fatores de Tempo , Adulto Jovem
13.
J Vis ; 19(5): 17, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31100133

RESUMO

The continuous flash suppression (CFS) task can be used to investigate what limits our capacity to become aware of visual stimuli. In this task, a stream of rapidly changing mask images to one eye initially suppresses awareness for a static target image presented to the other eye. Several factors may determine the breakthrough time from mask suppression, one of which is the overlap in representation of the target/mask categories in higher visual cortex. This hypothesis is based on certain object categories (e.g., faces) being more effective in blocking awareness of other categories (e.g., buildings) than other combinations (e.g., cars/chairs). Previous work found mask effectiveness to be correlated with category-pair high-level representational similarity. As the cortical representations of hands and tools overlap, these categories are ideal to test this further as well as to examine alternative explanations. For our CFS experiments, we predicted longer breakthrough times for hands/tools compared to other pairs due to the reported cortical overlap. In contrast, across three experiments, participants were generally faster at detecting targets masked by hands or tools compared to other mask categories. Exploring low-level explanations, we found that the category average for edges (e.g., hands have less detail compared to cars) was the best predictor for the data. This low-level bottleneck could not completely account for the specific category patterns and the hand/tool effects, suggesting there are several levels at which object category-specific limits occur. Given these findings, it is important that low-level bottlenecks for visual awareness are considered when testing higher-level hypotheses.


Assuntos
Conscientização/fisiologia , Percepção de Forma/fisiologia , Mãos/fisiologia , Córtex Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Adulto Jovem
14.
Atten Percept Psychophys ; 81(5): 1283-1296, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30825115

RESUMO

Radiologists make critical decisions based on searching and interpreting medical images. The probability of a lung nodule differs across anatomical regions within the chest, raising the possibility that radiologists might have a prior expectation that creates an attentional bias. The development of expertise is also thought to cause "tuning" to relevant features, allowing radiologists to become faster and more accurate at detecting potential masses within their domain of expertise. Here, we tested both radiologists and control participants with a novel attentional-cueing paradigm to investigate whether the deployment of attention was affected (1) by a context that might invoke prior knowledge for experts, (2) by a nodule localized either on the same or on opposite sides as a subsequent target, and (3) by inversion of the nodule-present chest radiographs, to assess the orientation specificity of any effects. The participants also performed a nodule detection task to verify that our presentation duration was sufficient to extract diagnostic information. We saw no evidence of priors triggered by a normal chest radiograph cue affecting attention. When the cue was an upright abnormal chest radiograph, radiologists were faster when the lateralised nodule and the subsequent target appeared at the same rather than at opposite locations, suggesting attention was captured by the nodule. The opposite pattern was present for inverted images. We saw no evidence of cueing for control participants in any condition, which suggests that radiologists are indeed more sensitive to visual features that are not perceived as salient by naïve observers.


Assuntos
Atenção , Competência Clínica , Neoplasias Pulmonares/diagnóstico por imagem , Radiografia/psicologia , Radiologistas/psicologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Orientação , Reconhecimento Psicológico , Sensibilidade e Especificidade
15.
Front Behav Neurosci ; 12: 179, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30214400

RESUMO

Disgust is a natural defensive emotion that has evolved to protect against potential sources of contamination and has been recently linked to moral judgements in many studies. However, that people often report feelings of disgust when thinking about feces or moral transgressions alike does not necessarily mean that the same mechanisms mediate these reactions. The present study used functional magnetic resonance imaging (n = 22) to investigate whether core and moral disgusts entrain common neural systems. We provide evidence that: (i) activation of overlapping brain regions between core and moral disgust is the result of content overlap in the vignettes-core disgust elicitors-across conditions, and not from moral violations per se, and (ii) moral residue (i.e., the remaining or "residual" activation after the influence of core disgust elicitors have been taken into account) produced a pattern of activation that is more consistent with moral anger, than one of "residual disgust." These findings run contrary to the premise that our "moral center" is connected to the area of the brain in which physical revulsion is located.

16.
Cortex ; 106: 132-150, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29940399

RESUMO

When interacting with objects, we have to represent their location relative to our bodies. To facilitate bodily reactions, location may be encoded in the brain not just with respect to the retina (retinotopic reference frame), but also in relation to the head, trunk or arm (collectively spatiotopic reference frames). While spatiotopic reference frames for location encoding can be found in brain areas for action planning, such as parietal areas, there is debate about the existence of spatiotopic reference frames in higher-level occipitotemporal visual areas. In an extensive multi-voxel pattern analysis (MVPA) fMRI study using faces, headless bodies and scenes stimuli, Golomb and Kanwisher (2012) did not find evidence for spatiotopic reference frames in shape-selective occipitotemporal cortex. This finding is important for theories of how stimulus location is encoded in the brain. It is possible, however, that their failure to find spatiotopic reference frames is related to their stimuli: we typically do not manipulate faces, headless bodies or scenes. It is plausible that we only represent body-centred location when viewing objects that are typically manipulated. Here, we tested for object location encoding in shape-selective occipitotemporal cortex using manipulable object stimuli (balls and cups) in a MVPA fMRI study. We employed Bayesian analyses to determine sample size and evaluate the sensitivity of our data to test the hypothesis that location can be encoded in a spatiotopic reference frame in shape-selective occipitotemporal cortex over the null hypothesis of no spatiotopic location encoding. We found strong evidence for retinotopic location encoding consistent with previous findings that retinotopic reference frames are common neural representations of object location. In contrast, when testing for spatiotopic encoding, we found evidence that object location information for small manipulable objects is not decodable in relation to the body in shape-selective occipitotemporal cortex. Post-hoc exploratory analyses suggested that spatiotopic aspects might modulate retinotopic location encoding. Overall, our findings provide evidence that there is no spatiotopic encoding that is independent of retinotopic location in shape-selective occipitotemporal cortex.


Assuntos
Córtex Cerebral/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Percepção Espacial/fisiologia , Córtex Visual/fisiologia , Adulto , Teorema de Bayes , Mapeamento Encefálico/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Estimulação Luminosa/métodos , Retina/fisiologia , Adulto Jovem
17.
Cogn Res Princ Implic ; 3(1): 10, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29707615

RESUMO

Humans can extract considerable information from scenes, even when these are presented extremely quickly. The ability of an experienced radiologist to rapidly detect an abnormality on a mammogram may build upon this general capacity. Although radiologists have been shown to be able to detect an abnormality 'above chance' at short durations, the extent to which abnormalities can be localised at brief presentations is less clear. Extending previous work, we presented radiologists with unilateral mammograms, 50% containing a mass, for 250 or 1000 ms. As the female breast varies with respect to the level of normal fibroglandular tissue, the images were categorised into high and low density (50% of each), resulting in difficult and easy searches, respectively. Participants were asked to decide whether there was an abnormality (detection) and then to locate the mass on a blank outline of the mammogram (localisation). We found both detection and localisation information for all conditions. Although there may be a dissociation between detection and localisation on a small proportion of trials, we find a number of factors that lead to the underestimation of localisation including stimulus variability, response imprecision and participant guesses. We emphasise the importance of taking these factors into account when interpreting results. The effect of density on detection and localisation highlights the importance of considering breast density in medical screening.

18.
Cognition ; 177: 107-121, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29660563

RESUMO

Individuals with grapheme-colour synaesthesia experience anomalous colours when reading achromatic text. These unusual experiences have been said to resemble 'normal' colour perception or colour imagery, but studying the nature of synaesthesia remains difficult. In the present study, we report novel evidence that synaesthetic colour impacts conscious vision in a way that is different from both colour perception and imagery. Presenting 'normal' colour prior to binocular rivalry induces a location-dependent suppressive bias reflecting local habituation. By contrast, a grapheme that evokes synaesthetic colour induces a facilitatory bias reflecting priming that is not constrained to the inducing grapheme's location. This priming does not occur in non-synaesthetes and does not result from response bias. It is sensitive to diversion of visual attention away from the grapheme, but resistant to sensory perturbation, reflecting a reliance on cognitive rather than sensory mechanisms. Whereas colour imagery in non-synaesthetes causes local priming that relies on the locus of imagined colour, imagery in synaesthetes caused global priming not dependent on the locus of imagery. These data suggest a unique psychophysical profile of high-level colour processing in synaesthetes. Our novel findings and method will be critical to testing theories of synaesthesia and visual awareness.


Assuntos
Percepção de Cores , Imaginação , Transtornos da Percepção , Visão Binocular , Adulto , Cor , Feminino , Humanos , Masculino , Estimulação Luminosa , Psicofísica , Sinestesia
19.
J Vis ; 18(4): 2, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29614156

RESUMO

In real-world searches such as airport baggage screening and radiological examinations, miss errors can be life threatening. Misses increase for additional targets after detecting an initial target, termed "subsequent search misses" (SSMs), and also when targets are more often absent than present, termed the low-prevalence effect. Real-world search tasks often contain more than one target, but the prevalence of these multitarget occasions varies. For example, a cancerous tumor sometimes coexists with a benign tumor and sometimes exists alone. This study aims to investigate how the relative prevalence of multiple targets affects search accuracy. Naive observers searched for all Ts (zero, one, or two) among Ls. In Experiment 1, SSMs occurred in small but not large set sizes, which may be explained by classic capacity limit effects such as the attentional blink and repetition blindness. Experiment 2 showed an interaction between SSMs and the relative prevalence of dual-target trials: Low prevalence of dual-target trials increased SSMs relative to high prevalence dual-target trials. The prevalence of dual-target trials did not affect accuracy on single-target trials. These results may provide a novel avenue for reducing misses by increasing the prevalence of instances with multiple targets. Future efforts should take into account the relative prevalence of multiple targets to effectively reduce life-threatening miss errors.


Assuntos
Reconhecimento Visual de Modelos/fisiologia , Visão Ocular/fisiologia , Percepção Visual/fisiologia , Tomada de Decisões , Humanos , Prevalência , Tempo de Reação
20.
Exp Brain Res ; 236(5): 1431-1443, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29546651

RESUMO

Tracking one's own body is essential for environmental interaction, and involves integrating multisensory cues with stored information about the body's typical features. Exactly how multisensory information is integrated in own-body perception is still unclear. For example, Ide and Hidaka (Exp Brain Res 228:43-50, 2013) found that participants made less precise visuo-tactile temporal order judgments (TOJ) when viewing hands in a plausible orientation (upright; typical for one's own hand) compared to an implausible orientation (rotated 180°). This suggests that viewing one's own body relaxes the precision for perceived visuo-tactile synchrony. In contrast, visuo-proprioceptive research shows improvements for multisensory temporal perception near one's own body in asynchrony detection tasks, implying an increase in precision. Hence, it is unclear whether viewed hand orientation generally modulates the ability to detect small asynchronies between vision and touch, or if this effect is specific to TOJ tasks. We investigated whether viewed hand orientation affects detection of visuo-tactile asynchrony. In two experiments, participants viewed model hands in anatomically plausible or implausible orientations. In one experiment, we stroked the hands to induce the rubber hand illusion. Participants were asked to detect short delays (40-280 ms) between vision (an LED flash on the model hand) and touch (a tap to fingertip of the participant's hidden hand) in a two-interval forced-choice task. Bayesian analyses show that our data provide strong evidence that viewed hand orientation does not affect visuo-tactile asynchrony detection. This study suggests the mechanisms for fine-grained time perception differ between visuo-tactile and visuo-proprioceptive contexts.


Assuntos
Imagem Corporal/psicologia , Mãos/fisiologia , Ilusões/fisiologia , Orientação/fisiologia , Percepção do Tempo/fisiologia , Percepção do Tato/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Julgamento/fisiologia , Masculino , Estimulação Luminosa , Adulto Jovem
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