Morphometry Difference of the Hippocampal Formation Between Blind and Sighted Individuals

The detailed morphometry alterations of the human hippocampal formation (HF) for blind individuals are still understudied. 50 subjects were recruited from Yantai Affiliated Hospital of Binzhou Medical University, including 16 congenital blindness, 14 late blindness, and 20 sighted controls. Volume and shape analysis were conducted between the blind (congenital or late) and sighted groups to observe the (sub)regional alterations of the HF. No significant difference of the hippocampal volume was observed between the blind and sighted subjects. Rightward asymmetry of the hippocampal volume was found for both congenital and late blind individuals, while no significant hemispheric difference was observed for the sighted controls. Shape analysis showed that the superior and inferior parts of both the hippocampal head and tail expanded, while the medial and lateral parts constrained for the blind individuals as compared to the sighted controls. The morphometry alterations for the congenital blind and late blind individuals are nearly the same. Significant expansion of the superior part of the hippocampal tail for both congenital and late blind groups were observed for the left hippocampi after FDR correction. Current results suggest that the cross-model plastic may occur in both hemispheres of the HF to improve the navigation ability without the stimuli of visual cues, and the alteration is more prominent for the left hemisphere.

The Modified Imitation Game: A Method for Measuring Interactional Expertise

The study of the sociology of scientific knowledge distinguishes between contributory and interactional experts. Contributory experts have practical expertise—they can “walk the walk.” Interactional experts have internalized the tacit components of expertise—they can “talk the talk” but are not able to reliably “walk the walk.” Interactional expertise permits effective communication between contributory experts and others (e.g., laypeople), which in turn facilitates working jointly toward shared goals. Interactional expertise is attained through long-term immersion into the expert community in question. To assess interactional expertise, researchers developed the imitation game—a variant of the Turing test—to test whether a person, or a particular group, possesses interactional expertise of another. The imitation game, which has been used mainly in sociology to study the social nature of knowledge, may also be a useful tool for researchers who focus on cognitive aspects of expertise. In this paper, we introduce a modified version of the imitation game and apply it to examine interactional expertise in the context of blindness. Specifically, we examined blind and sighted individuals’ ability to imitate each other in a street-crossing scenario. In Phase I, blind and sighted individuals provided verbal reports of their thought processes associated with crossing a street—once while imitating the other group (i.e., as a pretender) and once responding genuinely (i.e., as a non-pretender). In Phase II, transcriptions of the reports were judged as either genuine or imitated responses by a different set of blind and sighted participants, who also provided the reasoning for their decisions. The judges comprised blind individuals, sighted orientation-and-mobility specialists, and sighted individuals with infrequent socialization with blind individuals. Decision data were analyzed using probit mixed models for signal-detection-theory indices. Reasoning data were analyzed using natural-language-processing (NLP) techniques. The results revealed evidence that interactional expertise (i.e., relevant tacit knowledge) can be acquired by immersion in the group that possesses and produces the expert knowledge. The modified imitation game can be a useful research tool for measuring interactional expertise within a community of practice and evaluating practitioners’ understanding of true experts.

Validation of the Tactual Span in individuals with congenital and acquired blindness

Neuropsychological assessment tools for individuals with blindness are relatively scarce. In the current study, we assessed the validity of the Tactual Span, a task aimed at evaluating tactile working memory. During the task, the fingers of both hands are touched in specific sequences of ascending difficulty, which participants are asked to repeat in exact and reverse order. Twelve participants with congenital blindness and 13 with acquired blindness were examined alongside 18 sighted controls, matched to the experimental group with respect to age and education. Participants performed the Tactual Span and three additional tasks assessing working memory in the auditory modality, as well as a Semantic Fluency test. Results showed that the Tactual Span was significantly correlated with most of the other working memory measures, in all groups, but not with the Semantic Fluency test. In addition, the congenital and acquired blindness groups performed similarly to one another and better than sighted controls on most working memory tasks, but not on the Semantic Fluency test. Findings suggest that the Tactual Span is a feasible task for measuring tactile working memory in individuals with congenital and acquired blindness. Therefore, it can expand the cognitive assessment toolbox of professionals working with blind individuals and increase the strength of conclusions drawn from cognitive assessments in educational and vocational settings.

Effects of Depth-Based Object Isolation in Simulated Retinal Prosthetic Vision

Visual retinal prostheses aim to restore vision for blind individuals who suffer from outer retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration. Perception through retinal prostheses is very limited, but it can be improved by applying object isolation. We used an object isolation algorithm based on integral imaging to isolate objects of interest according to their depth from the camera and applied image processing manipulation to the isolated-object images. Subsequently, we applied a spatial prosthetic vision simulation that converted the isolated-object images to phosphene images. We compared the phosphene images for two types of input images, the original image (before applying object isolation), and the isolated-object image to illustrate the effects of object isolation on simulated prosthetic vision without and with multiple spatial variations of phosphenes, such as size and shape variations, spatial shifts, and dropout rate. The results show an improvement in the perceived shape, contrast, and dynamic range (number of gray levels) of objects in the phosphene image.

Auditory speed processing in sighted and blind individuals

Multisensory experience is crucial for developing a coherent perception of the world. In this context, vision and audition are essential tools to scaffold spatial and temporal representations, respectively. Since speed encompasses both space and time, investigating this dimension in blindness allows deepening the relationship between sensory modalities and the two representation domains. In the present study, we hypothesized that visual deprivation influences the use of spatial and temporal cues underlying acoustic speed perception. To this end, ten early blind and ten blindfolded sighted participants performed a speed discrimination task in which spatial, temporal, or both cues were available to infer moving sounds’ velocity. The results indicated that both sighted and early blind participants preferentially relied on temporal cues to determine stimuli speed, by following an assumption that identified as faster those sounds with a shorter duration. However, in some cases, this temporal assumption produces a misperception of the stimulus speed that negatively affected participants’ performance. Interestingly, early blind participants were more influenced by this misleading temporal assumption than sighted controls, resulting in a stronger impairment in the speed discrimination performance. These findings demonstrate that the absence of visual experience in early life increases the auditory system’s preference for the time domain and, consequentially, affects the perception of speed through audition.

GAMBARAN SUBJECTIVE WELL-BEING PADA ANAK YANG MEMILIKI ORANG TUA PENYANDANG TUNANETRA SEJAK LAHIR

ABSTRACT: DESCRIPTION OF SUBJECTIVE WELL-BEING IN CHILDREN WHOSE PARENTS WERE BLIND SINCE BIRTH The purpose of this study was to determine the description of subjective well-being in children whose parents were blind since birth. This study uses a case study qualitative approach. The selection of research subjects using snowball. Characteristics of the subjects aged 13 to 18, unmarried, and has parents who are blind since birth. The data collection method uses in-depth interview techniques. The results showed that subjective well-being in children whose parents were blind, includes cognitive evaluation that is life satisfaction and affective evaluation. Subjective well-being aspects on the subject of life satisfaction are influenced by the domain of family, friends, school, job, and future. Their positive affects are happy, proud, and affection. Negative affects that appear are sad and depressed feeling. For further research, it is expected to discuss and compare subjective well-being with other persons with disabilities. Keywords: Subjective Well-Being, Blind Individuals Tujuan penelitian ini adalah untuk mengetahui gambaran subjective well-being pada anak yang memiliki orang tua penyandang tunanetra sejak lahir. Penelitian ini menggunakan pendekatan kualitatif studi kasus. Pemilihan subyek penelitian menggunakan snowball. Karakteristik subyek adalah yang berusia 13 sampai 18 tahun, belum menikah dan memiliki orang tua penyandang tunanetra sejak lahir. Metode pengumpulan data menggunakan teknik wawancara mendalam. Hasil penelitian menunjukkan subjective well-being pada anak yang memiliki orang tua penyandang tunanetra, meliputi penilaian kognitif yaitu kepuasan hidup dan penilaian afektif. Aspek subjective well-being pada subyek yaitu kepuasaan hidup yang dipengaruhi oleh domain keluarga, teman, sekolah, pekerjaan, dan masa depan. Afek positif yang mereka alami yaitu senang, bangga, dan kasih sayang. Afek negatif yang muncul adalah sedih dan perasaan tertekan. Untuk penelitian selanjutnya diharapkan dapat membahas dan membandingkan subjective well-being dengan penyandang disabilitas lainya. Kata Kunci: Subjective Well-Being, Tunanetra

Reading Modality Modifies Reading Network: Insights from Neural basis of Braille in Proficient Blind Readers

The neural basis of reading is highly consistent across a variety of languages and visual scripts. An unanswered question is whether the sensory modality of symbols influences the neural basis of reading. According to the modality-invariant view, reading depends on the same neural mechanisms regardless of the sensory input modality. Consistent with this idea, previous studies find that the visual word form area (VWFA) within the ventral occipitotemporal cortex (vOTC) is active when blind individuals read Braille by touch. However, connectivity-based theories of brain function suggest that the neural entry point of written symbols (touch vs. vision) may influence the neural architecture of reading. We compared the neural basis of the visual print (sighted n=15) and tactile Braille (congenitally blind n=19) in proficient readers using analogous reading and listening tasks. Written stimuli varied in word-likeness from real words to consonant strings and non-letter shape strings. Auditory stimuli consisted of words and backward speech sounds. Consistent with prior work, vOTC was active during Braille and visual reading. However, in sighted readers, visual print elicited a posterior/anterior vOTC word-form gradient: anterior vOTC preferred larger orthographic units (words), middle vOTC preferring consonant strings, and posterior vOTC responded to shapes (i.e., lower-level physical features). No such gradient was observed in blind readers of Braille. Consistent with connectivity predictions, in blind Braille readers, posterior parietal cortices (PPC) and parieto-occipital areas were recruited to a greater degree and PPC contained word-preferring patches. Lateralization of Braille in blind readers was predicted by laterality of spoken language, as well as by reading hand. These results suggested that the neural basis of reading is influenced by symbol modality and support connectivity-based views of cortical function.

Global and network functional connectivity of nucleus basalis of Meynert is strengthened in blind individuals

Vision loss causes dramatic changes in brain function which are thought to facilitate behavioral adaptation. One interesting prospect is that the cholinergic signals are involved in this blindness-induced plasticity. Critically, the nucleus basalis of Meynert is the principal source of the cholinergic signals, however, no studies have yet investigated whether the nucleus basalis of Meynert is altered in blindness. Therefore, here we examined its structure, cerebrovascular response, and the resting-state functional connectivity in blind individuals. We found that the global signal of the nucleus basalis of Meynert as well as its network connectivity with the visual, language, and default mode network is significantly enhanced in early blind individuals. On the other hand, its structure and cerebrovascular response remain unchanged in early blind individuals. Further, we observed that less visual experience predicts stronger global and network connectivity of the nucleus basalis of Meynert. These results suggest that the nucleus basalis of Meynert develops a stronger neuromodulatory influence on the cortex of blind individuals at both global and network levels.

Shared understanding of color among sighted and blind adults

Empiricist philosophers such as Locke famously argued that people born blind might learn arbitrary color facts (e.g., marigolds are yellow) but would lack color understanding. Contrary to this intuition, we find that blind and sighted adults share causal understanding of color, despite not always agreeing about arbitrary color facts. Relative to sighted people, blind individuals are less likely to generate “yellow” for banana and “red” for stop sign but make similar generative inferences about real and novel objects’ colors, and provide similar causal explanations. For example, people infer that two natural kinds (e.g., bananas) and two artifacts with functional colors (e.g., stop signs) are more likely to have the same color than two artifacts with nonfunctional colors (e.g., cars). People develop intuitive and inferentially rich “theories” of color regardless of visual experience. Linguistic communication is more effective at aligning intuitive theories than knowledge of arbitrary facts.