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

Synesthesia

Synesthesia

Synesthesia is a remarkable condition where stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People with synesthesia experience a blending or crossing of their senses, such as sight and sound, leading to cross-modal sensations. In this condition, the stimulation of one sense, such as hearing a number or musical note, triggers an experience of another sense, like sensing a specific color, taste, or smell. People...

Color Vision

Color Vision

Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.

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"...

Vision

Vision

Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.

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...

Perceptual Constancy

Perceptual Constancy

Perceptual constancy is the ability to recognize that objects remain consistent and unchanged even when their appearance varies due to changes in sensory input. There are four main types of perceptual constancy: size constancy, shape constancy, color constancy, and brightness constancy.
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...

You might also read

Related Articles

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

Sort by

Same author

The Intrinsic Manifold of Spontaneous Activity Constrains Cortical Responses to Naturalistic Stimuli.

bioRxiv : the preprint server for biology·2026

Same author

Neuropacify: a method to transform and match a patient's intracranial EEG to their NeuroPace RNS system data.

Journal of neural engineering·2025

Same author

BrainTRACE (Brain Tumor Registration and Cortical Electrocorticography): A novel tool for localizing electrocorticography electrodes in patients with brain tumors.

Journal of neuroscience methods·2025

Same author

Aperiodic neural dynamics define a novel signature of glioma-induced excitation-inhibition dysregulation.

bioRxiv : the preprint server for biology·2025

Same author

BrainTRACE (Brain Tumor Registration and Cortical Electrocorticography): A Novel Tool for Localizing Electrocorticography Electrodes in Patients with Brain Tumors.

medRxiv : the preprint server for health sciences·2025

Same author

Spatial synaptic connectivity underlies oligodendroglioma evolution and recurrence.

Research square·2025

Search research articles

Related Experiment Video

Updated: Jun 18, 2026

Training Synesthetic Letter-color Associations by Reading in Color

Training Synesthetic Letter-color Associations by Reading in Color

Published on: February 20, 2014

Visual field heterogeneity, laterality, and eidetic imagery in synesthesia.

David Brang¹, V S Ramachandran

¹Center for Brain and Cognition, University of California, San Diego, La Jolla, CA, USA.

|November 10, 2009

Summary

This study on grapheme-color synesthesia found that evoked colors were strongest in the left visual field and central vision. It also experimentally verified the synesthete's enhanced eidetic imagery abilities.

More Related Videos

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns

Published on: May 12, 2019

Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention

Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention

Published on: November 16, 2017

Related Experiment Videos

Last Updated: Jun 18, 2026

Training Synesthetic Letter-color Associations by Reading in Color

Training Synesthetic Letter-color Associations by Reading in Color

Published on: February 20, 2014

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns

Published on: May 12, 2019

Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention

Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention

Published on: November 16, 2017

Area of Science:

Neuroscience
Cognitive Psychology
Sensory Perception

Background:

Grapheme-color synesthesia involves consistent color associations with letters and numbers.
Investigating the neural and cognitive underpinnings of synesthetic experiences is crucial for understanding sensory perception.
Previous research has explored the characteristics and potential mechanisms of synesthesia.

Observation:

The study focused on an individual (JS) with grapheme-color synesthesia, where specific colors were consistently linked to graphemes (letters and numerals).
Experiments were designed to objectively measure the spatial distribution and subjective experience of these synesthetic color associations.
A novel test was developed to assess the participant's self-reported eidetic imagery, a form of highly detailed visual memory.

Findings:

Synesthetically evoked colors in JS were most reliably perceived in the left visual field and central visual field.
The participant's claim of having enhanced eidetic imagery was experimentally validated.
The findings suggest a specific spatial bias in the manifestation of grapheme-color synesthesia.

Implications:

Results inform theories about the level of processing involved in synesthesia, potentially supporting cross-activation models.
The validated eidetic imagery has implications for understanding the interplay between synesthesia and visual memory mechanisms.
This research contributes to a deeper understanding of individual differences in sensory processing and cognitive abilities.