An expert advantage in detecting unfamiliar visual signals in noise.
Ontology highlight
ABSTRACT:
SUBMITTER: Hussain Z
PROVIDER: S-EPMC7568295 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Dyslexic individuals have been reported to have reduced global motion sensitivity, which could be attributed to various causes including atypical magnocellular or dorsal stream function, impaired spatial integration, increased internal noise and/or reduced external noise exclusion. Here, we applied an equivalent noise experimental paradigm alongside a traditional motion-coherence task to determine what limits global motion processing in dyslexia. We also presented static analogues of the motion tasks (orientation tasks) to investigate whether perceptual differences in dyslexia were restricted to motion processing. We compared the performance of 48 dyslexic and 48 typically developing children aged 8 to 14 years in these tasks and used equivalent noise modelling to estimate levels of internal noise (the precision associated with estimating each element's direction/orientation) and sampling (the effective number of samples integrated to judge the overall direction/orientation). While group differences were subtle, dyslexic children had significantly higher internal noise estimates for motion discrimination, and higher orientation-coherence thresholds, than typical children. Thus, while perceptual differences in dyslexia do not appear to be restricted to motion tasks, motion and orientation processing seem to be affected differently. The pattern of results also differs from that previously reported in autistic children, suggesting perceptual processing differences are condition-specific.
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Project description:Purpose Previous studies with children and adults have demonstrated a familiar talker advantage-better word recognition for familiar talkers. The goal of the current study was to test whether this phenomenon is modulated by a child's language ability. Method Sixty children with a range of language ability were trained to learn the voices of 3 foreign-accented, German-English bilingual talkers and received feedback about their performance. Both before and after this talker voice training, children completed a spoken word recognition task in which they heard consonant-vowel-consonant words mixed with noise that were spoken by the 3 familiarized talkers and by 3 unfamiliar German-English bilinguals. Results Two findings emerged from this study: First, children with both higher and lower language ability performed similarly on the familiarized talkers. Second, children with higher language scores performed similarly on both the familiarized and unfamiliar talkers, whereas children with lower language scores performed worse on the unfamiliar talkers compared to familiar talkers, suggesting an inability to generalize to novel, unfamiliar talkers who spoke with a similar accent. Discussion Together, these findings indicate that children with higher language scores are able to generalize knowledge about foreign-accented talkers to help spoken word recognition for novel talkers with the same accent. In contrast, children with lower language skills did not exhibit the same magnitude of generalization. This lack of generalization to similar talkers may mean that children with lower language skills are at a disadvantage in spoken language tasks because they are unable to process speech as well when listening to unfamiliar talkers.
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Project description:PurposeVisual snow syndrome-characterized by flickering specks throughout the visual field and accompanied by other symptoms-can disrupt daily life and affects roughly 2% of the population. However, its neural bases remain mysterious, and treatments are lacking. Here, we report the first intervention that can temporarily eliminate the visual snow symptom, allowing many observers to see the world without snow for the first time since symptom onset. Prolonged viewing of a visual stimulus strongly reduces the responsiveness of the visual pathways to subsequent stimuli, and we tested whether such adaptation could affect visual snow.MethodsParticipants with visual snow (total n = 27) viewed high-contrast dynamic noise patterns, resembling television static, and then judged the strength of the symptom.ResultsVisual snow was temporarily reduced in strength to the point that it was invisible at longer adaptation durations for most observers. The effect followed typical trends of adaptation for physical stimuli in normally sighted observers: Effect duration increased monotonically with duration of exposure to the adapter and was specific to dynamic noise.ConclusionsThese results establish that spontaneous neural activity in the visual system is causally related to the visual snow percept. Because they perceive this activity, people with visual snow may provide a unique window into the generation and suppression of noise in the visual system. Adaptation allows reliable experimental control over visual snow, and so is a strong candidate for diagnostic testing and a promising tool for further understanding its neural origins, which could in turn aid the development of treatments.
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Project description:What role does children's trust in communication play in their acquisition of new meanings? To answer, we report two experimental studies (N = 81) testing how three- to four-year-olds interpret the meaning of a novel communicative device when it is used by a malevolent and potentially deceptive informant. Children participated in a hiding game in which they had to find a reward hidden in one of two boxes. In the initial phase of the experiments, a malevolent informant always indicated the location of the empty box using a novel communicative device, either a marker (Study 1), or an arrow (Study 2). During that phase, 3- and 4-year-olds learned to avoid the box indicated by the novel communicative device. In the second phase of the test, the malevolent informant was replaced by a benevolent one. Nevertheless, children did not change their search strategy, and they kept avoiding the box tagged by the novel communicative device as often as when it had been produced by the malevolent informant. These results suggest that during the initial phase, children (i) did not consider the possibility that the malevolent informant might intend to deceive them, and (ii) did not ignore the unfamiliar communicative signal or treat it as irrelevant. Instead, children relied on the unfamiliar communicative signal to locate the empty box's location. These results suggest that children's avoidance of the location indicated by an unfamiliar signal is not unambiguous evidence for distrust of such signal. We argue that children's trust in ostensive communication is likely to extend to unfamiliar communicative means, and that this presumption of trustworthiness plays a central role in children's acquisition of new meanings.
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Project description:BackgroundTo conduct a preliminary evaluation of the feasibility of visual field fast (VFF), a free iPad-based noise-field perimeter, in detecting glaucomatous scotomas versus the clinical-standard Humphrey visual field (HVF) test. VFF confronts subjects with a screen of flickering stimulus, allowing the immediate perception of scotomas.MethodsThis was a cross-sectional observational study of 66 glaucoma patients (66 eyes) and 30 healthy controls (30 eyes). All patients had no other visual field disorders. VFF was compared against HVF in terms of whole field and quadrants for the following: (1) correspondence in scotoma detection. (2) Agreement and correlation of the scotoma size (percentage of abnormal visual field area). (3) Test duration. Other domains tested included: (1) correlation of VFF scotoma area with the severity of visual field loss on HVF (mean deviation, MD; visual field index, VFI). (2) Repeatability of VFF. (3) Patient descriptors of scotomas.ResultsUsing HVF pattern deviation plot as a reference, VFF detected 52/57 (91.2%) of glaucoma subjects with 1 false-positive (control) (kappa = 0.86). 146/184 (79.3%) of abnormal quadrants (visual field defect present) were localized and 23/157 (14.6%) healthy quadrants were falsely identified as abnormal (kappa = 0.61). VFF underestimated scotoma area as compared to HVF (21.0% versus 44.0%, p < 0.01) but correlated positively (r = 0.268, p = 0.044) with HVF area and negatively with VFI (r = -0.340, p = 0.01) and MD (r = -0.398, p < 0.01). Using HVF total deviation plot as reference, VFF's glaucoma detection rate remained unchanged (kappa = 0.86) with similar quadrant detection (kappa = 0.68). However, a greater underestimation of scotoma area was observed (21.0% versus 85.4%, p < 0.01). VFF's quantitative repeatability was excellent for whole field (intraclass correlation coefficient, ICC: 0.96; p < 0.0001) and quadrants (ICC: 0.82-0.96; all p < 0.001). Qualitatively, 35/37 (94.6%) of subjects reported reduced luminance and flicker in scotomas, with similar morphologies on retests. VFF is faster than HVF SITA-Standard in glaucoma (3.60 ± 1.85 min versus 6.92 ± 1.12 min, p < 0.01) and control (1.12 ± 0.486 min versus 5.16 ± 0.727 min, p < 0.01).ConclusionThis early model of VFF accurately detected scotomas with high repeatability. However, its accuracy in localizing and quantifying the scotoma can be improved. Considering its portability and cost-effectiveness, VFF demonstrated potential as a general screening tool for moderate-to-severe glaucoma.
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