Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Visual Agnosia

Visual Agnosia

Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round end"...

Photoreceptors and Visual Pathways

Photoreceptors and Visual Pathways

At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Improving the clinical trial landscape for patients with atypical variants of Alzheimer's disease: a call to action.

Alzheimer's & dementia : the journal of the Alzheimer's Association·2026

Same author

Music processing in behavioural variant frontotemporal dementia and Alzheimer's disease: a functional MRI study.

Brain communications·2026

Same author

Non-verbal dichotic listening: A new cognitive hearing test for dementia.

Alzheimer's & dementia : the journal of the Alzheimer's Association·2026

Same author

Functional neuroanatomy of musical object processing in Alzheimer's disease and frontotemporal dementia.

Brain communications·2026

Same author

Barriers and Facilitators to Implementing Synchronous Telehealth Interventions for People With Dementia - A Systematic Review.

Dementia (London, England)·2026

Same author

Balance in the face of altered visual circuitry anatomy.

The Journal of physiology·2026

Same journal

The cognitive construction of moral scenes: Associations of visuospatial ability and impulsivity with perspective and vividness in mental simulation.

Cortex; a journal devoted to the study of the nervous system and behavior·2026

Same journal

Theta band activity during event-file retrieval is influenced by stimulus salience in the preceding action episode.

Cortex; a journal devoted to the study of the nervous system and behavior·2026

Same journal

Language recovery in Hungarian speakers with aphasia: Roles of phonology and intraindividual variability.

Cortex; a journal devoted to the study of the nervous system and behavior·2026

Same journal

Neural and behavioral dissociations of self-focused and other-focused incentives in trust.

Cortex; a journal devoted to the study of the nervous system and behavior·2026

Same journal

A multiverse analysis of the logical memory test and plasma biomarkers of Alzheimer's disease.

Cortex; a journal devoted to the study of the nervous system and behavior·2026

Same journal

Reading and writing impairments in Spanish-speaking individuals with primary progressive aphasia: A single-case series study.

Cortex; a journal devoted to the study of the nervous system and behavior·2026

See all related articles

Search research articles

Related Experiment Video

Updated: May 12, 2026

A Gaze-Contingent Display Framework for Perceptual Learning Research with Simulated Central Vision Loss

A Gaze-Contingent Display Framework for Perceptual Learning Research with Simulated Central Vision Loss

Published on: April 11, 2025

Intact reading in patients with profound early visual dysfunction.

Keir X X Yong¹, Jason D Warren, Elizabeth K Warrington

¹Dementia Research Centre, Department of Neurodegeneration, UCL Institute of Neurology, University College London, UK.

Cortex; a Journal Devoted to the Study of the Nervous System and Behavior

|April 13, 2013

Summary

This summary is machine-generated.

Letter-by-letter (LBL) reading is often linked to general visual deficits, but this study shows preserved reading in patients with severe visual dysfunction. This suggests specific visual processing, not general deficits, underlies LBL reading impairments.

Keywords:

Alzheimer's disease (AD)Letter-by-letter reading Posterior cortical atrophy (PCA)Pure alexia Word form dyslexia

More Related Videos

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

Published on: September 18, 2012

Related Experiment Videos

Last Updated: May 12, 2026

A Gaze-Contingent Display Framework for Perceptual Learning Research with Simulated Central Vision Loss

A Gaze-Contingent Display Framework for Perceptual Learning Research with Simulated Central Vision Loss

Published on: April 11, 2025

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

Published on: September 18, 2012

Area of Science:

Neuroscience
Cognitive Psychology
Ophthalmology

Background:

The neural basis of reading, particularly letter-by-letter (LBL) reading, remains debated.
Many studies link LBL reading to general visual deficits, but causal evidence is often lacking.
Alternative explanations involve impaired word form representations or parallel letter processing.

Purpose of the Study:

To investigate the relationship between general visual deficits and LBL reading.
To determine if general visual impairments are sufficient to cause LBL reading.
To explore preserved reading abilities in individuals with profound visual dysfunction.

Main Methods:

Case study of two patients with posterior cortical atrophy (PCA).
Assessment of visual functions including acuity, visuoperceptual, and visuospatial processing.
Evaluation of reading aloud performance (accuracy and latency) for words, including word length effects.

Main Results:

Patients with PCA showed profound visual dysfunction but preserved whole word and letter reading.
Reading accuracy was near-perfect, and response latencies were comparable to controls.
Word length effects were equivocal or absent, contradicting predictions of general visual deficit accounts.

Conclusions:

General visual deficits alone do not sufficiently explain LBL reading.
Preserved reading performance is likely due to intact word form representations and/or parallel letter processing.
Causality must be clearly established when linking visual processing aspects to acquired peripheral dyslexia.