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1.
Ophthalmology ; 126(3): 347-354, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30312629

RESUMO

PURPOSE: To improve clinic efficiency through development of an ophthalmology scheduling template developed using simulation models and electronic health record (EHR) data. DESIGN: We created a computer simulation model of 1 pediatric ophthalmologist's clinic using EHR timestamp data, which was used to develop a scheduling template based on appointment length (short, medium, or long). We assessed its impact on clinic efficiency after implementation in the practices of 5 different pediatric ophthalmologists. PARTICIPANTS: We observed and timed patient appointments in person (n = 120) and collected EHR timestamps for 2 years of appointments (n = 650). We calculated efficiency measures for 172 clinic sessions before implementation vs. 119 clinic sessions after implementation. METHODS: We validated clinic workflow timings calculated from EHR timestamps and the simulation models based on them with observed timings. From simulation tests, we developed a new scheduling template and evaluated it with efficiency metrics before vs. after implementation. MAIN OUTCOME MEASURES: Measurements of clinical efficiency (mean clinic volume, patient wait time, examination time, and clinic length). RESULTS: Mean physician examination time calculated from EHR timestamps was 13.8±8.2 minutes and was not statistically different from mean physician examination time from in-person observation (13.3±7.3 minutes; P = 0.7), suggesting that EHR timestamps are accurate. Mean patient wait time for the simulation model (31.2±10.9 minutes) was not statistically different from the observed mean patient wait times (32.6±25.3 minutes; P = 0.9), suggesting that simulation models are accurate. After implementation of the new scheduling template, all 5 pediatric ophthalmologists showed statistically significant improvements in clinic volume (mean increase of 1-3 patients/session; P ≤ 0.05 for 2 providers; P ≤ 0.008 for 3 providers), whereas 4 of 5 had improvements in mean patient wait time (average improvements of 3-4 minutes/patient; statistically significant for 2 providers, P ≤ 0.008). All of the ophthalmologists' examination times remained the same before and after implementation. CONCLUSIONS: Simulation models based on big data from EHRs can test clinic changes before real-life implementation. A scheduling template using predicted appointment length improves clinic efficiency and may generalize to other clinics. Electronic health records have potential to become tools for supporting clinic operations improvement.


Assuntos
Centros Médicos Acadêmicos/estatística & dados numéricos , Agendamento de Consultas , Eficiência Organizacional/estatística & dados numéricos , Registros Eletrônicos de Saúde/estatística & dados numéricos , Visita a Consultório Médico/estatística & dados numéricos , Oftalmologia/estatística & dados numéricos , Centros Médicos Acadêmicos/organização & administração , Adolescente , Criança , Pré-Escolar , Simulação por Computador , Humanos , Lactente , Recém-Nascido , Oftalmologia/organização & administração , Fatores de Tempo , Fluxo de Trabalho
2.
Ophthalmology ; 126(12): 1627-1639, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31561879

RESUMO

PURPOSE: To develop and validate a deep learning (DL) algorithm that predicts referable glaucomatous optic neuropathy (GON) and optic nerve head (ONH) features from color fundus images, to determine the relative importance of these features in referral decisions by glaucoma specialists (GSs) and the algorithm, and to compare the performance of the algorithm with eye care providers. DESIGN: Development and validation of an algorithm. PARTICIPANTS: Fundus images from screening programs, studies, and a glaucoma clinic. METHODS: A DL algorithm was trained using a retrospective dataset of 86 618 images, assessed for glaucomatous ONH features and referable GON (defined as ONH appearance worrisome enough to justify referral for comprehensive examination) by 43 graders. The algorithm was validated using 3 datasets: dataset A (1205 images, 1 image/patient; 18.1% referable), images adjudicated by panels of GSs; dataset B (9642 images, 1 image/patient; 9.2% referable), images from a diabetic teleretinal screening program; and dataset C (346 images, 1 image/patient; 81.7% referable), images from a glaucoma clinic. MAIN OUTCOME MEASURES: The algorithm was evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity for referable GON and glaucomatous ONH features. RESULTS: The algorithm's AUC for referable GON was 0.945 (95% confidence interval [CI], 0.929-0.960) in dataset A, 0.855 (95% CI, 0.841-0.870) in dataset B, and 0.881 (95% CI, 0.838-0.918) in dataset C. Algorithm AUCs ranged between 0.661 and 0.973 for glaucomatous ONH features. The algorithm showed significantly higher sensitivity than 7 of 10 graders not involved in determining the reference standard, including 2 of 3 GSs, and showed higher specificity than 3 graders (including 1 GS), while remaining comparable to others. For both GSs and the algorithm, the most crucial features related to referable GON were: presence of vertical cup-to-disc ratio of 0.7 or more, neuroretinal rim notching, retinal nerve fiber layer defect, and bared circumlinear vessels. CONCLUSIONS: A DL algorithm trained on fundus images alone can detect referable GON with higher sensitivity than and comparable specificity to eye care providers. The algorithm maintained good performance on an independent dataset with diagnoses based on a full glaucoma workup.


Assuntos
Aprendizado Profundo , Glaucoma de Ângulo Aberto/diagnóstico , Oftalmologistas , Disco Óptico/patologia , Doenças do Nervo Óptico/diagnóstico , Especialização , Idoso , Área Sob a Curva , Conjuntos de Dados como Assunto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fibras Nervosas/patologia , Curva ROC , Encaminhamento e Consulta , Células Ganglionares da Retina/patologia , Estudos Retrospectivos , Sensibilidade e Especificidade
3.
J Neurosci ; 37(40): 9632-9644, 2017 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-28871032

RESUMO

Neurons in the adult mammalian CNS decrease in intrinsic axon growth capacity during development in concert with changes in Krüppel-like transcription factors (KLFs). KLFs regulate axon growth in CNS neurons including retinal ganglion cells (RGCs). Here, we found that knock-down of KLF9, an axon growth suppressor that is normally upregulated 250-fold in RGC development, promotes long-distance optic nerve regeneration in adult rats of both sexes. We identified a novel binding partner, MAPK10/JNK3 kinase, and found that JNK3 (c-Jun N-terminal kinase 3) is critical for KLF9's axon-growth-suppressive activity. Interfering with a JNK3-binding domain or mutating two newly discovered serine phosphorylation acceptor sites, Ser106 and Ser110, effectively abolished KLF9's neurite growth suppression in vitro and promoted axon regeneration in vivo These findings demonstrate a novel, physiologic role for the interaction of KLF9 and JNK3 in regenerative failure in the optic nerve and suggest new therapeutic strategies to promote axon regeneration in the adult CNS.SIGNIFICANCE STATEMENT Injured CNS nerves fail to regenerate spontaneously. Promoting intrinsic axon growth capacity has been a major challenge in the field. Here, we demonstrate that knocking down Krüppel-like transcription factor 9 (KLF9) via shRNA promotes long-distance axon regeneration after optic nerve injury and uncover a novel and important KLF9-JNK3 interaction that contributes to axon growth suppression in vitro and regenerative failure in vivo These studies suggest potential therapeutic approaches to promote axon regeneration in injury and other degenerative diseases in the adult CNS.


Assuntos
Axônios/fisiologia , Encéfalo/fisiologia , Fatores de Transcrição Kruppel-Like/metabolismo , Proteína Quinase 10 Ativada por Mitógeno/metabolismo , Regeneração Nervosa/fisiologia , Fatores Etários , Animais , Sequência de Bases , Células Cultivadas , Sistema Nervoso Central/fisiologia , Feminino , Fatores de Transcrição Kruppel-Like/deficiência , Fatores de Transcrição Kruppel-Like/genética , Masculino , Camundongos , Proteína Quinase 10 Ativada por Mitógeno/genética , Traumatismos do Nervo Óptico/genética , Traumatismos do Nervo Óptico/metabolismo , Técnicas de Cultura de Órgãos , Ligação Proteica/fisiologia , Ratos , Células Ganglionares da Retina/fisiologia
5.
J Vis ; 13(10)2013 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-23946433

RESUMO

A key goal of visual processing is to develop an understanding of the three-dimensional layout of the objects in our immediate vicinity from the variety of incomplete and noisy depth cues available to the eyes. Binocular disparity is one of the dominant depth cues, but it is often sparse, being definable only at the edges of uniform surface regions, and visually resolvable only where the edges have a horizontal disparity component. To understand the full 3D structure of visual objects, our visual system has to perform substantial surface interpolation across unstructured visual space. This interpolation process was studied in an eight-spoke depth spreading configuration corresponding to that used in the neon color spreading effect, which generates a strong percept of a sharp contour extending through empty space from the disparity edges within the spokes. Four hypotheses were developed for the form of the depth surface induced by disparity in the spokes defining an incomplete disk in depth: low-level local (isotropic) depth propagation, mid-level linear (anisotropic) depth-contour interpolation or extrapolation, and high-level (anisotropic) figural depth propagation of a disk figure in depth. Data for both perceived depth and position of the perceived contour clearly rejected the first three hypotheses and were consistent with the high-level figural hypothesis in both uniform disparity and slanted disk configurations. We conclude that depth spreading through empty visual space is an accurately quantifiable perceptual process that propagates depth contours anisotropically along their length and is governed by high-level figural properties of 3D object structure.


Assuntos
Percepção de Profundidade/fisiologia , Percepção Espacial/fisiologia , Sinais (Psicologia) , Percepção de Forma , Humanos , Imageamento Tridimensional , Estimulação Luminosa/métodos , Disparidade Visual/fisiologia
6.
Am J Ophthalmol ; 211: 191-199, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31811860

RESUMO

PURPOSE: This study analyzed and quantified the sources of electronic health record (EHR) text documentation in ophthalmology progress notes. DESIGN: EHR documentation review and analysis. METHODS: Setting: a single academic ophthalmology department. STUDY POPULATION: a cohort study conducted between November 1, 2016, and December 31, 2018, using secondary EHR data and a follow-up manual review of a random samples. The cohort study included 123,274 progress notes documented by 42 attending providers. These notes were for patients with the 5 most common primary International Statistical Classification of Diseases and Related Health Problems, version 10, parent codes for each provider. For the manual review, 120 notes from 8 providers were randomly sampled. Main outcome measurements were characters or number of words in each note categorized by attribution source, author type, and time of creation. RESULTS: Imported text entries made up the majority of text in new and return patients, 2,978 characters (77%) and 3,612 characters (91%). Support staff members authored substantial portions of notes; 3,024 characters (68%) of new patient notes, 3,953 characters (83%) of return patient notes. Finally, providers completed large amounts of documentation after clinical visits: 135 words (35%) of new patient notes, 102 words (27%) of return patient notes. CONCLUSIONS: EHR documentation consists largely of imported text, is often authored by support staff, and is often written after the end of a visit. These findings raise questions about documentation accuracy and utility and may have implications for quality of care and patient-provider relationships.


Assuntos
Documentação/normas , Registros Eletrônicos de Saúde/normas , Prontuários Médicos/normas , Oftalmologia/normas , Centros Médicos Acadêmicos , Confiabilidade dos Dados , Humanos , Oregon , Pacientes Ambulatoriais , Padrões de Prática Médica , Estudos Retrospectivos
7.
Nat Biomed Eng ; 4(1): 18-27, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31873211

RESUMO

Owing to the invasiveness of diagnostic tests for anaemia and the costs associated with screening for it, the condition is often undetected. Here, we show that anaemia can be detected via machine-learning algorithms trained using retinal fundus images, study participant metadata (including race or ethnicity, age, sex and blood pressure) or the combination of both data types (images and study participant metadata). In a validation dataset of 11,388 study participants from the UK Biobank, the fundus-image-only, metadata-only and combined models predicted haemoglobin concentration (in g dl-1) with mean absolute error values of 0.73 (95% confidence interval: 0.72-0.74), 0.67 (0.66-0.68) and 0.63 (0.62-0.64), respectively, and with areas under the receiver operating characteristic curve (AUC) values of 0.74 (0.71-0.76), 0.87 (0.85-0.89) and 0.88 (0.86-0.89), respectively. For 539 study participants with self-reported diabetes, the combined model predicted haemoglobin concentration with a mean absolute error of 0.73 (0.68-0.78) and anaemia an AUC of 0.89 (0.85-0.93). Automated anaemia screening on the basis of fundus images could particularly aid patients with diabetes undergoing regular retinal imaging and for whom anaemia can increase morbidity and mortality risks.


Assuntos
Anemia/diagnóstico por imagem , Retina/diagnóstico por imagem , Aprendizado Profundo , Feminino , Fundo de Olho , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Curva ROC
8.
Nat Biomed Eng ; 4(2): 242, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32051580

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

9.
Appl Clin Inform ; 11(1): 130-141, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32074650

RESUMO

OBJECTIVE: To evaluate informatics-enabled quality improvement (QI) strategies for promoting time spent on face-to-face communication between ophthalmologists and patients. METHODS: This prospective study involved deploying QI strategies during implementation of an enterprise-wide vendor electronic health record (EHR) in an outpatient academic ophthalmology department. Strategies included developing single sign-on capabilities, activating mobile- and tablet-based applications, EHR personalization training, creating novel workflows for team-based orders, and promoting problem-based charting to reduce documentation burden. Timing data were collected during 648 outpatient encounters. Outcomes included total time spent by the attending ophthalmologist on the patient, time spent on documentation, time spent on examination, and time spent talking with the patient. Metrics related to documentation efficiency, use of personalization features, use of team-based orders, and note length were also measured from the EHR efficiency portal and compared with averages for ophthalmologists nationwide using the same EHR. RESULTS: Time spent on exclusive face-to-face communication with patients initially decreased with EHR implementation (2.9 to 2.3 minutes, p = 0.005) but returned to the paper baseline by 6 months (2.8 minutes, p = 0.99). Observed participants outperformed national averages of ophthalmologists using the same vendor system on documentation time per appointment, number of customized note templates, number of customized order lists, utilization of team-based orders, note length, and time spent after-hours on EHR use. CONCLUSION: Informatics-enabled QI interventions can promote patient-centeredness and face-to-face communication in high-volume outpatient ophthalmology encounters. By employing an array of interventions, time spent exclusively talking with the patient returned to levels equivalent to paper charts by 6 months after EHR implementation. This was achieved without requiring EHR redesign, use of scribes, or excessive after-hours work. Documentation efficiency can be achieved using interventions promoting personalization and team-based workflows. Given their efficacy in preserving face-to-face physician-patient interactions, these strategies may help alleviate risk of physician burnout.


Assuntos
Comunicação , Registros Eletrônicos de Saúde , Oftalmologia , Adulto , Telefone Celular , Estudos de Coortes , Documentação , Humanos , Avaliação de Resultados em Cuidados de Saúde , Pacientes Ambulatoriais , Satisfação do Paciente , Fatores de Tempo
10.
Am J Ophthalmol ; 206: 161-167, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30910517

RESUMO

PURPOSE: To assess time requirements for patient encounters and estimate after-hours demands of paper-based clinical workflows in ophthalmology. DESIGN: Time-and-motion study with a structured survey. METHODS: This study was conducted in a single academic ophthalmology department. A convenience sample consisted of 7 attending ophthalmologists from 6 subspecialties observed during 414 patient encounters for the time-motion analysis and 12 attending ophthalmologists for the survey. Outcome measurements consisted of total time spent by attending ophthalmologists per patient and time spent on documentation, examination, and talking with patients. The survey assessed time requirements of documentation-related activities performed outside of scheduled clinic hours. RESULTS: Among the 7 attending ophthalmologists observed (6 men and 1 woman), mean ± SD age 43.9 ± 7.1 years, during encounters with 414 patients (57.8 ± 24.6 years of age), total time spent per patient was 8.1 ± 4.8 minutes, with 2.8 ± 1.4 minutes (38%) for documentation, 1.2 ± 0.9 minutes (17%) for examination, and 3.3 ± 3.1 minutes (37%) for talking with patients. New patient evaluations required significantly more time than routine follow-up visits and postoperative visits. Higher clinical volumes were associated with less time per patient. Survey results indicated that paper-based documentation was associated with minimal after-hours work on weeknights and weekends. CONCLUSIONS: Paper-based documentation takes up a substantial portion of the total time spent for patient care in outpatient ophthalmology clinics but is associated with minimal after-hours work. Understanding paper-based clinical workflows may help inform targeted strategies for improving electronic health record use in ophthalmology.


Assuntos
Centros Médicos Acadêmicos , Documentação/estatística & dados numéricos , Registros Eletrônicos de Saúde/estatística & dados numéricos , Oftalmologia/estatística & dados numéricos , Fluxo de Trabalho , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Fatores de Tempo , Estudos de Tempo e Movimento , Adulto Jovem
11.
J Acad Ophthalmol (2017) ; 11(2): e65-e72, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33954272

RESUMO

OBJECTIVE: Electronic health records (EHRs) are widely adopted, but the time demands of EHR use on ophthalmology trainees are not well understood. This study evaluated ophthalmology trainee time spent on clinical activities in an outpatient clinic undergoing EHR implementation. DESIGN: Prospective, manual time-motion observations of ophthalmology trainees in 2018. PARTICIPANTS: Eleven ophthalmology residents and fellows observed during 156 patient encounters. METHODS: Prospective time-motion study of ophthalmology trainees 2 weeks before and 6 weeks after EHR implementation in an academic ophthalmology department. Manual time-motion observations were conducted for 11 ophthalmology trainees in 6 subspecialty clinics during 156 patient encounters. Time spent documenting, examining, and talking with patients were recorded. Factors influencing time requirements were evaluated using linear mixed effects models. MAIN OUTCOME MEASURES: Total time spent by ophthalmology residents and fellows per patient, time spent on documentation, examination, and talking with patients. RESULTS: Seven ophthalmology residents and four ophthalmology fellows with mean (standard deviation) postgraduate year of 3.7 (1.2) were observed during 156 patient encounters. Using paper charts, mean total time spent on each patient was 11.6 (6.5) minutes, with 5.4 (3.5) minutes spent documenting (48%). After EHR implementation, mean total time spent on each patient was 11.8 (6.9) minutes, with 6.8 (4.7) minutes spent documenting (57%). Total time expenditure per patient did not significantly change after EHR implementation (+0.17 minutes, 95% confidence interval [CI] for difference in means: -2.78, 2.45; p = 0.90). Documentation time did not change significantly after EHR implementation in absolute terms (+1.42 minutes, 95% CI: -3.13, 0.29; p = 0.10), but was significantly greater as a proportion of total time (48% on paper to 57% on EHR; +9%, 95% CI: 2.17, 15.83; p = 0.011). CONCLUSION: Total time spent per patient and absolute time spent on documentation was not significantly different whether ophthalmology trainees used paper charts or the recently implemented EHR. Percentage of total time spent on documentation increased significantly with early EHR use. Evaluating EHR impact on ophthalmology trainees may improve understanding of how trainees learn to use the EHR and may shed light on strategies to address trainee burnout.

12.
AMIA Annu Symp Proc ; 2018: 1310-1318, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30815175

RESUMO

Content importing technology enables duplication of large amounts of clinical text in electronic health record (EHR) progress notes. It can be difficult to find key sections such as Assessment and Plan in the resulting note. To quantify the extent of text length and duplication, we analyzed average ophthalmology note length and calculated novelty of each major note section (Subjective, Objective, Assessment, Plan, Other). We performed a retrospective chart review of consecutive note pairs and found that the average encounter note was 1182 ± 374 words long and less than a quarter of words changed between visits. The Plan note section had the highest percentage of change, and both the Assessment and Plan sections comprised a small fraction of the full note. Analysis of progress notes by section and unique content helps describe physician documentation activity and inform best practices and EHR design recommendations.


Assuntos
Registros Eletrônicos de Saúde , Oftalmologia , Assistência Ambulatorial , Documentação/métodos , Humanos , Estudos Retrospectivos
13.
AMIA Annu Symp Proc ; 2018: 1387-1394, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30815183

RESUMO

Electronic health record systems have dramatically transformed the process of medical care, but one challenge has been increased time requirements for physicians. In this study, we address this challenge by developing and validating analytic models for predicting patient encounter length based on secondary EHR data. Key findings from this study are: (1) Secondary use of EHR data may be captured to predict provider interaction time with patients; (2) Modeling results using secondary data may provide more accurate predictions of provider interaction time than an expert provide; (3) These findings suggest that secondary use of EHR data may be used to develop effective customized scheduling methods to improve clinical efficiency. In the future, this has the potential to contribute toward methods for improved clinical scheduling and efficiency.


Assuntos
Instituições de Assistência Ambulatorial/organização & administração , Registros Eletrônicos de Saúde , Oftalmologia , Admissão e Escalonamento de Pessoal , Humanos , Análise de Regressão , Fatores de Tempo , Fluxo de Trabalho
14.
Atten Percept Psychophys ; 79(7): 2108-2116, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28685487

RESUMO

Perceptual grouping has been extensively studied, but some areas are still unexplored-in particular, the figural organizations that emerge when bundles of intersecting lines are drawn. Here, we will describe some figural organizations that emerge after the superimposition of bundles of lines forming the profile of regular triangular waves. By manipulating the lines' jaggedness and junction geometry (regular or irregular X junction) we could generate the following organizations: (a) a grid, or a figural configuration in which both the lines and closed contours are perceived, (b) a figure-ground organization composed of figures separated by portions of the background, and (c) a corrugated surface appearing as a multifaceted polyhedral shell crossed by ridges and valleys. An experiment was conducted with the aim at testing the role of the good-continuation and closure Gestalt factors. Good continuation prevails when the lines are straight or close to straightness, but its role is questionable in the appearance of a corrugated surface. This perceptual organization occurs despite the violation of the good-continuation rule and consists of a structure of such complexity so as to challenge algorithms of computer vision and stimulate a deeper understanding of the perceptual interpretation of groups of lines.


Assuntos
Percepção de Forma/fisiologia , Imageamento Tridimensional/métodos , Imageamento Tridimensional/psicologia , Estimulação Luminosa/métodos , Algoritmos , Feminino , Humanos , Masculino , Matemática , Adulto Jovem
15.
Nat Commun ; 7: 10472, 2016 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-26843334

RESUMO

Retinal ganglion cells (RGCs) degenerate in diseases like glaucoma and are not replaced in adult mammals. Here we investigate whether transplanted RGCs can integrate into the mature retina. We have transplanted GFP-labelled RGCs into uninjured rat retinas in vivo by intravitreal injection. Transplanted RGCs acquire the general morphology of endogenous RGCs, with axons orienting towards the optic nerve head of the host retina and dendrites growing into the inner plexiform layer. Preliminary data show in some cases GFP(+) axons extending within the host optic nerves and optic tract, reaching usual synaptic targets in the brain, including the lateral geniculate nucleus and superior colliculus. Electrophysiological recordings from transplanted RGCs demonstrate the cells' electrical excitability and light responses similar to host ON, ON-OFF and OFF RGCs, although less rapid and with greater adaptation. These data present a promising approach to develop cell replacement strategies in diseased retinas with degenerating RGCs.


Assuntos
Axônios , Dendritos , Corpos Geniculados , Luz , Nervo Óptico , Células Ganglionares da Retina/transplante , Colículos Superiores , Animais , Contagem de Células , Feminino , Proteínas de Fluorescência Verde , Imuno-Histoquímica , Injeções Intravítreas , Masculino , Camundongos , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Retina
17.
Perception ; 42(10): 1051-62, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24494436

RESUMO

We demonstrate a perceptual effect whereby contours not physically present in a visual scene can yield striking illusory motion. The not physically present contours are paths of invariant contrast polarity (CP). For example, when a square checkerboard composed of dark and light square checks with small black and white discs covering the vertices is put in lateral motion, there is the striking perception of vertical expansion/contraction. Such a checkerboard has (not physically present) diagonal paths of CP presentation with vertical components. However, when a square checkerboard made up of square black and very light checks with gray discs of luminance intermediate to the checks is put in lateral motion, no expansion/contraction is seen. For this checkerboard the vertical components of paths of CP preservation cancel each other out, predicting the lack of perception of vertical expansion/contraction. We also discuss how not physically present contours can explain previously described effects and suggest new effects to be explored.


Assuntos
Percepção de Forma , Percepção de Movimento , Ilusões Ópticas/fisiologia , Sensibilidades de Contraste , Humanos , Reconhecimento Visual de Modelos
18.
Perception ; 41(1): 12-25, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22611660

RESUMO

Roncato and Casco (2003, Perception & psychophysics 65 1252-1272) had shown that in situations where the Gestalt principle of good continuity is put into conflict with preservation of contrast polarity (CP) the perception that preserves CP prevails. Parlangeli and Roncato (2010, Perception 39 255-259) have studied this question of preservation of CP more closely and have added an addendum to the rule. They have used stimuli consisting of a checkerboard of perpendicularly arranged rectangular bricks (white, gray, or black) and draughtsmen white, gray, or black disks placed at the corners of the bricks. This study has caused them to add an addendum to the rule of CP-preserved path-conjunction binding: if there are two contour completions that preserve the CP, the one with the higher contrast will prevail. Parlangeli and Roncato find that, for certain shades of the disks and bricks, the perpendicular lines of the checkerboard appear strikingly to be slanted or undulating. Here we consider all possible arrangements of relative magnitudes of checkerboards consisting of bricks of two different shades and disks of two shades as well, as such arrangements with widely varying differences in the magnitude of brightness. We have found a number of cases where the perception is not explained by the rule and addendum of Roncato and Casco, and Parlangeli and Roncato, and a case where preservation of "distant" as well as local CP plays a role in perception. The previously known cases, and the new exceptional unexplained stimuli we have found, warrant further study.


Assuntos
Sensibilidades de Contraste , Ilusões Ópticas , Estimulação Luminosa , Percepção de Forma , Humanos
19.
Perception ; 40(9): 1137-41, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22208132

RESUMO

Three-quarters of a century ago Gestalt psychologist Kurt Koffka described a remarkable effect: when a contiguous gray ring is placed on a background half one shade of gray, half another, the ring appears homogeneous. However, if the ring is divided, the two halves of the ring appear different shades of gray, the half of the ring on the darker background appearing lighter than the half of the ring on the lighter background. The Gestalt principle of continuity is used to explain this effect. But what microscopic principles might be mediating this effect? Recently we found sufficiently thin rings (annuli) appear heterogeneous even when geometrically continuous. Here, using crescent-shaped figures instead of the circular annuli used for the traditional Koffka effect, we show that this effect of thickness of the ring is mediated by the thickness at the boundary of the region where the halves of the figure are joined.


Assuntos
Sensibilidades de Contraste , Teoria Gestáltica , Ilusões Ópticas , Reconhecimento Visual de Modelos , Percepção de Tamanho , Adulto , Feminino , Humanos , Masculino , Orientação , Psicofísica , Adulto Jovem
20.
Atten Percept Psychophys ; 72(4): 891-3, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20436187

RESUMO

There are two kinds of afterimages. In negative afterimages, looking at a blank field after staring at a colored figure gives a figure whose color is complementary to that of the original figure. Less well understood and studied is the phenomenon of induced positive afterimages, in which staring at a colored area surrounding a small white test patch produces an afterimage in which the hue of the surround is transferred into the previously white area. Using these differences between positive and negative afterimages and also simultaneous color contrast, which has an effect on a test patch different from either of the afterimage effects, we describe a new effect, metameric intransitivity, in which perceptually similar images can generate markedly different afterimages, whereas perceptually different images can generate indistinguishable afterimages. Supplemental figures depicting the stimuli, results, and method for generating the intransitive metamers in this study may be downloaded from http://app.psychonomic-journals.org/content/supplemental.


Assuntos
Pós-Imagem/fisiologia , Atenção/fisiologia , Percepção de Cores/fisiologia , Fixação Ocular/fisiologia , Percepção de Forma/fisiologia , Cor , Pós-Efeito de Figura/fisiologia , Humanos , Estimulação Luminosa , Percepção Visual/fisiologia
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