Signal Detection Theory, Vision, and Color Perception

These flashcards cover the fundamentals of Signal Detection Theory, the anatomy and physiology of the eye, and the psychological theories of color perception based on the lecture transcript.

Signal Detection Theory

A framework used to understand how we make a decision when there are only two possible decisions to make.

Hit

Correctly identifying something you are supposed to say yes to, such as an algorithm letting a good email through to the inbox.

Miss

Misidentifying and improperly labeling a target, such as missing a good message and sending it to the spam folder instead.

Correct Rejection

Properly rejecting something that does not belong, such as an algorithm realizing an email is spam and rejecting it.

False Alarm

Misidentifying something and putting it through when it shouldn't be, such as a spam message making its way into an inbox.

Transduction

The process of converting energy in the world, such as light or sound waves, into electrochemical signals, neural impulses, or action potentials.

Electromagnetic Radiation

A form of energy that moves in waves or particles, of which light is a specific form.

Wavelength

The distance from one peak to another in a wave, which determines the psychological experience of color.

Amplitude

The height of a wave, which determines the psychological experience of brightness.

Visible Spectrum

The narrow band of frequencies that humans can register and transduce, located between about $400$ and $750\,nm$.

Cornea

A tough, transparent tissue covering the front of the eyeball that protects it from damage.

Aqueous Humour

A small area of clear fluid through which light passes after leaving the cornea.

Pupil

An opening in the center of the iris that dilates or constricts to control the amount of light entering the eye.

Pupillary Response

The fluctuation of pupil size in response to light, emotions, and motivation; constriction happens faster than dilation to protect the retina.

Lens

The anatomical structure that focuses light onto the retina at the back of the eye.

Retina

A structure about the thickness of a sheet of paper at the back of the eye containing several layers of cells, including sensory receptors.

Photoreceptors

Sensory receptors, specifically rods and cones, that transduce light energy into neural signals.

Rods

Rod-shaped photoreceptors that are highly sensitive to light for low-light vision but cannot distinguish color and provide lower acuity than cones.

Cones

Pointed photoreceptors that allow for sharp vision and color perception but only respond in relatively strong light conditions.

Short Wavelength Cones

Also called blue cones, these are maximally sensitive to wavelengths between about $420$ and $440\,nm$.

Middle Wavelength Cones

Also called green cones, these are maximally sensitive to wavelengths between about $534$ and $545\,nm$.

Long Wavelength Cones

Also called red cones, these are maximally sensitive to wavelengths between about $564$ and $580\,nm$.

Fovea

A small central region of the retina densely packed with cones, measuring about $1$ to $2$ degrees of visual angle, used for detailed tasks like reading.

Bipolar Cells

A layer of cells that integrates electrical signals from multiple rods and cones and synapses onto ganglion cells.

Ganglion Cells

Cells that integrate information from multiple bipolar cells and whose axons form the optic nerve.

Optic Nerve

The structure formed by the axons of ganglion cells that carries visual information from the retina to the brain.

Pigmented Epithelium

A dark membrane behind the photoreceptors in diurnal animals that absorbs stray photons to ensure crisp, clear vision.

Reflecting Tapetum

A reflective membrane in nocturnal animals that bounces stray photons back to photoreceptors to increase light sensitivity, often causing eyes to glow in the dark.

Trichromatic Theory

Also known as the Young-Helmholtz theory, it proposes three types of receptors maximally sensitive to certain wavelengths; it applies to the retinal level of processing.

Opponent Process Theory

A theory proposed by Herring suggesting three antagonistic systems (black-white, blue-yellow, red-green) that accounts for color afterimages.