- Vestibular dysfunction in acute traumatic brain injury. [Journal Article]
- JNJ Neurol 2019 Jun 14
- Traumatic brain injury (TBI) is the commonest cause of disability in under-40-year-olds. Vestibular features of dizziness (illusory self-motion) or imbalance which affects 50% of TBI patients at 5 ye…
Traumatic brain injury (TBI) is the commonest cause of disability in under-40-year-olds. Vestibular features of dizziness (illusory self-motion) or imbalance which affects 50% of TBI patients at 5 years, increases unemployment threefold in TBI survivors. Unfortunately, vestibular diagnoses are cryptogenic in 25% of chronic TBI cases, impeding therapy. We hypothesized that chronic adaptive brain mechanisms uncouple vestibular symptoms from signs. This predicts a masking of vestibular diagnoses chronically but not acutely. Hence, defining the spectrum of vestibular diagnoses in acute TBI should clarify vestibular diagnoses in chronic TBI. There are, however, no relevant acute TBI data. Of 111 Major Trauma Ward adult admissions screened (median 38-years-old), 96 patients (87%) had subjective dizziness (illusory self-motion) and/or objective imbalance were referred to the senior author (BMS). Symptoms included: feeling unbalanced (58%), headache (50%) and dizziness (40%). In the 47 cases assessed by BMS, gait ataxia was the commonest sign (62%) with half of these cases denying imbalance when asked. Diagnoses included BPPV (38%), acute peripheral unilateral vestibular loss (19%), and migraine phenotype headache (34%), another potential source of vestibular symptoms. In acute TBI, vestibular signs are common, with gait ataxia being the most frequent one. However, patients underreport symptoms. The uncoupling of symptoms from signs likely arises from TBI affecting perceptual mechanisms. Hence, the cryptogenic nature of vestibular symptoms in TBI (acute or chronic) relates to a complex interaction between injury (to peripheral and central vestibular structures and perceptual mechanisms) and brain-adaptation, emphasizing the need for acute prospective, mechanistic studies.
- Fake hand in movement: Visual motion cues from the rubber hand are processed for kinesthesia. [Journal Article]
- CCConscious Cogn 2019 Jun 11; 73:102761
- The feeling that a fake (e.g. rubber) hand belongs to a person's own body can be elicited by synchronously stroking the fake hand and the real hand, with the latter hidden from view. Here, we sought …
The feeling that a fake (e.g. rubber) hand belongs to a person's own body can be elicited by synchronously stroking the fake hand and the real hand, with the latter hidden from view. Here, we sought to determine whether visual motion signals from that incorporated rubber hand would provide relevant cues for sensing movement (i.e. kinesthesia). After 180 s of visuo-tactile synchronous or asynchronous stroking, the fake hand was moved along the lateral or the sagittal axis. After synchronous stroking, movement of the rubber hand induced illusory movement of the static (real) hand in the same direction; the illusion was slightly more frequent and more intense when the fake hand was moved along the sagittal axis. We therefore conclude that visual signals of motion originating from the rubber hand are integrated for kinesthesia by the central nervous system just as visual signals from the real hand are.
- "Paying" attention to audiovisual speech: Do incongruent stimuli incur greater costs? [Journal Article]
- APAtten Percept Psychophys 2019 Jun 13
- The McGurk effect is a multisensory phenomenon in which discrepant auditory and visual speech signals typically result in an illusory percept. McGurk stimuli are often used in studies assessing the a…
The McGurk effect is a multisensory phenomenon in which discrepant auditory and visual speech signals typically result in an illusory percept. McGurk stimuli are often used in studies assessing the attentional requirements of audiovisual integration, but no study has directly compared the costs associated with integrating congruent versus incongruent audiovisual speech. Some evidence suggests that the McGurk effect may not be representative of naturalistic audiovisual speech processing - susceptibility to the McGurk effect is not associated with the ability to derive benefit from the addition of the visual signal, and distinct cortical regions are recruited when processing congruent versus incongruent speech. In two experiments, one using response times to identify congruent and incongruent syllables and one using a dual-task paradigm, we assessed whether congruent and incongruent audiovisual speech incur different attentional costs. We demonstrated that response times to both the speech task (Experiment 1) and a secondary vibrotactile task (Experiment 2) were indistinguishable for congruent compared to incongruent syllables, but McGurk fusions were responded to more quickly than McGurk non-fusions. These results suggest that despite documented differences in how congruent and incongruent stimuli are processed, they do not appear to differ in terms of processing time or effort, at least in the open-set task speech task used here. However, responses that result in McGurk fusions are processed more quickly than those that result in non-fusions, though attentional cost is comparable for the two response types.
- Transcranial Magnetic Stimulation of Posterior Parietal Cortex Modulates Line-Length Estimation but Not Illusory Depth Perception. [Journal Article]
- FPFront Psychol 2019; 10:1169
- Transcranial Magnetic Stimulation (TMS) may affect attentional processing when applied to the right posterior parietal cortex (PPC) of healthy participants in line with neuropsychological and neuroim…
Transcranial Magnetic Stimulation (TMS) may affect attentional processing when applied to the right posterior parietal cortex (PPC) of healthy participants in line with neuropsychological and neuroimaging evidence on the neural bases of this cognitive function. Specifically, the application of TMS to right PPC induces a rightward attentional bias on line length estimation in healthy participants (i.e., neglect-like bias), mimicking the rightward bias shown by patients with unilateral spatial neglect after damage of the right PPC. With the present study, we investigated whether right PPC might play a crucial role in attentional processing of illusory depth perception, given the evidence that a rightward bias may be observed in patients with neglect during perception of the Necker Cube (NC). To this end, we investigated the effects of low-frequency rTMS applied to the right or left PPC on attentional disambiguation of the NC in two groups of healthy participants. To control for the effectiveness of TMS on visuospatial attention, rTMS effects were also assessed on a frequently used line length estimation (i.e., the Landmark Task or LT). Both groups also received sham stimulation. RTMS of the right or left PPC did not affect NC perception. On the other hand, rTMS of the right PPC (but not left PPC) induces neglect-like bias on the LT, in line with previous studies. These findings confirm that right PPC is involved in deployment of spatial attention on line length estimation. Interestingly, they suggest that this brain region does not critically contribute to deployment of visuospatial attention during attentional disambiguation of the Necker Cube. Future investigations, targeting different areas of fronto-parietal circuits, are necessary to further explore the neuro-functional bases of attentional contribution to illusory depth perception.
- A Simple Target Interception Task as Test for Activities of Daily Life Performance in Older Adults. [Journal Article]
- FNFront Neurosci 2019; 13:524
- Previous research showed that a simple target interception task reveals differences between younger adults (YA) and older adults (OA) on a large screen under laboratory conditions. Participants inter…
Previous research showed that a simple target interception task reveals differences between younger adults (YA) and older adults (OA) on a large screen under laboratory conditions. Participants intercept downward moving objects while a horizontally moving background creates an illusion of the object moving in the opposite direction of the background. OA are more influenced by this illusory motion than YA. OA seem to be less able to ignore irrelevant sensory information than YA. Since sensory integration relates to the ability to perform Activities of Daily Living (ADL), this interception task can potentially signal ADL issues. Here we investigated whether the results of the target interception task could be replicated using a more portable setup, i.e., a tablet instead of a large touch screen. For YA from the same, homogeneous population, the main effects were replicated although the task was more difficult in the tablet set-up. After establishing the tablet's validity, we analyzed the response patterns of OA that were less fit than the OA in previous research. We identified three different illusion patterns: a (large) illusion effect (indicating over integration), a reverse illusion effect, and no illusion effect. These different patterns are much more nuanced than previously reported for fit OA who only show over integration. We propose that the patterns are caused by differences in the samples of OA (OA in the current sample were older and had lower ADL scores), possibly modulated by increased task difficulty in the tablet setup. We discuss the effects of illusory background motion as a function of ADL scores using a transitional model. The first pattern commences when sensory integration capability starts to decrease, leading to a pattern of over-integration (illusion effect). The second pattern commences when compensatory mechanisms are not sufficient to counteract the effect of the background motion, leading to direction errors in the same direction as the background motion (reverse illusion). The third pattern commences when the task requirements are too high, leading OA to implement a probabilistic strategy by tapping toward the center of the screen.
- Typical perceptual organization in autism: Perceptual grouping and spatial distortion. [Journal Article]
- ARAutism Res 2019 Jun 12
- The extensive literature on global-local processing in people with autism spectrum disorder (ASD) has recently shifted from arguing for a processing impairment among those with ASD to positing an att…
The extensive literature on global-local processing in people with autism spectrum disorder (ASD) has recently shifted from arguing for a processing impairment among those with ASD to positing an attenuated preference for global processing. One suggestion is that the fast extraction of the global gist is less efficient in ASD, in contrast to the superior attention-driven processing of local elements. To examine this claim of attenuated global processing, the present study tested how perceptual grouping affected the global organization of visual scenes, specifically testing the claim of less mandatory, more optional global processing in ASD. Participants judged the distance between grouped and ungrouped elements in displays in which illusory distortions were inherent in configurations exemplifying the Gestalt principles of organization. Results from six experiments manipulating different Gestalt cues showed a consistent pattern, indicating that for individuals with ASD, as for typically developed (TD) individuals, grouping processes are organizational in nature, incorporating the grouping of related elements while parsing these from other unrelated elements. This parsing is accompanied by distortions in the spatial relationships perceived in the visual scene. ASD participants exhibited an overall larger tendency to overestimate the distances, but they also demonstrated typical perceptual organization processes that were robust and mandatory and, as in neurotypicals, affected the perception of the whole scene. Autism Res 2019. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: It is known that individuals with autism spectrum disorder (ASD) perceive the world in a different way than their typically developed (TD) peers. While TD individuals exhibit strong bias toward processing the global structure of visual scenes, individuals with ASD exhibit enhanced perception of the local elements. We showed that when the local and global levels are not competing, individuals with autism demonstrate robust global organization that operates even when not directly instructed.
- Evidence of top-down modulation of the Brentano illusion but not of the glare effect by transcranial direct current stimulation. [Journal Article]
- EBExp Brain Res 2019 Jun 12
- Transcranial direct current stimulation (tDCS) has been widely used for modulating sensory, motor and cognitive functions, but there are only few attempts to induce and change illusory perception. Vi…
Transcranial direct current stimulation (tDCS) has been widely used for modulating sensory, motor and cognitive functions, but there are only few attempts to induce and change illusory perception. Visual illusions have been the most traditional and effective way to investigate visual processing through the comparison between physical reality and subjective reports. Here we used tDCS to modulate two different visual illusions, namely the Brentano illusion and the glare effect, with the aim of uncovering the influence of top-down mechanisms on bottom-up visual perception in two experiments. In Experiment 1, to a first group of subjects, real and sham cathodal tDCS (2 mA, 10 min) were applied over the left and right posterior parietal cortices (PPC). In Experiment 2, real and sham cathodal tDCS were applied to the left and right occipital cortices (OC) to a second group of participants. Results showed that tDCS was effective in modulating only the Brentano illusion, but not the glare effect. tDCS increased the Brentano illusion but specifically for the stimulated cortical area (right PPC), illusion direction (leftward), visual hemispace (left), and illusion length (160 mm). These findings suggest the existence of an inhibitory modulation of top-down mechanisms on bottom-up visual processing specifically for the Brentano illusion, but not for the glare effect. The lack of effect of occipital tDCS should consider the possible role of ocular compensation or of the unstimulated hemisphere, which deserves further investigations.
- Investigating the Robustness of the Illusory Truth Effect Across Individual Differences in Cognitive Ability, Need for Cognitive Closure, and Cognitive Style. [Journal Article]
- PSPers Soc Psychol Bull 2019 Jun 10; :146167219853844
- People are more inclined to believe that information is true if they have encountered it before. Little is known about whether this illusory truth effect is influenced by individual differences in co…
People are more inclined to believe that information is true if they have encountered it before. Little is known about whether this illusory truth effect is influenced by individual differences in cognition. In seven studies (combined N = 2,196), using both trivia statements (Studies 1-6) and partisan news headlines (Study 7), we investigate moderation by three factors that have been shown to play a critical role in epistemic processes: cognitive ability (Studies 1, 2, 5), need for cognitive closure (Study 1), and cognitive style, that is, reliance on intuitive versus analytic thinking (Studies 1, 3-7). All studies showed a significant illusory truth effect, but there was no evidence for moderation by any of the cognitive measures across studies. These results indicate that the illusory truth effect is robust to individual differences in cognitive ability, need for cognitive closure, and cognitive style.
- Skeletal representations of shape in human vision: Evidence for a pruned medial axis model. [Journal Article]
- JVJ Vis 2019 Jun 03; 19(6):6
- A representation of shape that is low dimensional and stable across minor disruptions is critical for object recognition. Computer vision research suggests that such a representation can be supported…
A representation of shape that is low dimensional and stable across minor disruptions is critical for object recognition. Computer vision research suggests that such a representation can be supported by the medial axis-a computational model for extracting a shape's internal skeleton. However, few studies have shown evidence of medial axis processing in humans, and even fewer have examined how the medial axis is extracted in the presence of disruptive contours. Here, we tested whether human skeletal representations of shape reflect the medial axis transform (MAT), a computation sensitive to all available contours, or a pruned medial axis, which ignores contours that may be considered "noise." Across three experiments, participants (N = 2062) were shown complete, perturbed, or illusory two-dimensional shapes on a tablet computer and were asked to tap the shapes anywhere once. When directly compared with another viable model of shape perception (based on principal axes), participants' collective responses were better fit by the medial axis, and a direct test of boundary avoidance suggested that this result was not likely because of a task-specific cognitive strategy (Experiment 1). Moreover, participants' responses reflected a pruned computation in shapes with small or large internal or external perturbations (Experiment 2) and under conditions of illusory contours (Experiment 3). These findings extend previous work by suggesting that humans extract a relatively stable medial axis of shapes. A relatively stable skeletal representation, reflected by a pruned model, may be well equipped to support real-world shape perception and object recognition.
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- Lessons From Pinocchio: Cues to Deception May Be Highly Exaggerated. [Journal Article]
- PPPerspect Psychol Sci 2019 Jun 07; :1745691619838258
- Deception researchers widely acknowledge that cues to deception-observable behaviors that may differ between truthful and deceptive messages-tend to be weak. Nevertheless, several deception cues have…
Deception researchers widely acknowledge that cues to deception-observable behaviors that may differ between truthful and deceptive messages-tend to be weak. Nevertheless, several deception cues have been reported with unusually large effect sizes, and some researchers have advocated the use of such cues as tools for detecting deceit and assessing credibility in practical contexts. By examining data from empirical deception-cue research and using a series of Monte Carlo simulations, I demonstrate that many estimated effect sizes of deception cues may be greatly inflated by publication bias, small numbers of estimates, and low power. Indeed, simulations indicate the informational value of the present deception literature is quite low, such that it is not possible to determine whether any given effect is real or a false positive. I warn against the hazards of relying on potentially illusory cues to deception and offer some recommendations for improving the state of the science of deception.