Chapter 4: Sensation and Perception Study Guide

Comprehensive vocabulary flashcards covering the core terminology, anatomical structures, psychophysics principles, Gestalt laws, and perceptual phenomena from Chapter 4 (Sensation and Perception).

Sensation

The physical process of detecting a stimulus through a sense organ, which is influenced by sensory acuity.

Perception

An active mental process of organizing, identifying, and interpreting sensory information to give it meaning.

Prosopagnosia

A condition (face blindness) where an individual can see faces normally via sensation but cannot recognize them due to impaired perception.

Signal Transduction

The process of converting physical energy from the environment into neural/electrical signals that travel to the central nervous system.

Psychophysics

Methods used to measure the strength of a physical stimulus and a person's sensitivity to it.

Absolute Threshold

The minimum intensity needed to just barely detect a stimulus, typically measured at the point where it is detected $50\%$ of the time.

Just Noticeable Difference (JND)

The smallest change in a stimulus that a person can just barely notice when compared to the original standard stimulus.

Weber's Law

The principle stating that the just noticeable difference (JND) is a constant percentage of the original stimulus rather than a fixed amount.

Signal Detection Theory

A theory explaining how a stimulus is detected amidst background noise, depending jointly on signal strength and the individual's response bias.

Liberal Responder

A responder profile in signal detection theory characterized by a tendency to say YES, even when uncertain.

Conservative Responder

A responder profile in signal detection theory characterized by a tendency to say NO unless certain.

Sensory Adaptation

A decrease in sensitivity to a constant or prolonged stimulus over time as an individual becomes less aware of unchanging sensory input.

Visual Acuity

The ability of the visual system to see fine details.

Wavelength (Light)

The distance between wave peaks in light waves, which determines the perceived color.

Amplitude (Light)

The height of a light wave, which determines the perceived brightness.

Purity (Light)

The number of different wavelengths making up light, which determines color saturation or richness.

Cornea

The clear outer covering of the eye that helps focus incoming light.

Pupil

The opening in the eye that allows light to enter.

Iris

The colored muscle of the eye that controls pupil size and regulates the amount of light entering.

Lens

The eye structure that changes shape to focus light onto the retina.

Retina

The light-sensitive tissue lining the back of the eye that contains photoreceptor cells.

Optic Nerve

The bundle of nerve fibers that carries visual information from the eye to the brain.

Accommodation

The process by which the eye's lens changes shape to focus light from nearby or distant objects and maintain a clear image on the retina.

Myopia

Nearsightedness; an accommodation defect where distant objects appear blurry.

Hyperopia

Farsightedness; an accommodation defect where close objects appear blurry.

Rods

Photoreceptors in the retina that operate in low light, provide night vision, perceive shades of gray, and are poor at resolving fine detail.

Cones

Photoreceptors in the retina that operate in normal daylight, detect color, and resolve fine detail.

Fovea

The region of the retina responsible for sharp central vision; contains the highest concentration of cones and no rods.

Peripheral Vision

Vision outside the center of the visual field that is less detailed, less clear, and predominantly dependent on rods.

Blind Spot

The location on the retina where the optic nerve exits; it contains no rods or cones and cannot detect light.

Color Deficiency

A sex-linked genetic condition carried on the X chromosome in which one type of cone is missing or functions abnormally.

Color Afterimage

A temporary change in perceived color caused by the fatigue and sensory adaptation of cones following prolonged exposure to a specific color.

Optic Chiasm

The anatomical point in the visual pathway where some nerve fibers from each retina cross over to the opposite hemisphere of the brain.

Area V1 (Primary Visual Cortex)

The visual processing area located in the occipital lobe that receives visual information relayed by the thalamus.

Feature Detectors

Neurons in area V1 that respond specifically to particular features of visual stimuli, such as the orientation and direction of lines or edges.

Ventral Pathway

The 'what' pathway extending from the occipital lobe to the temporal lobe that identifies shapes and objects.

Dorsal Pathway

The 'where/how' pathway extending from the occipital lobe to the parietal lobe that processes location, motion, and guides motor interaction.

Binding Problem

The question of how the brain links separate visual features (such as color, shape, and size) together via attention into a single unified object.

Perceptual Constancy

The tendency to perceive the characteristics of an object as remaining stable even when incoming sensory input changes.

Gestalt Psychology

The psychological approach emphasizing that 'the whole is greater than the sum of its parts' and that the brain organizes components into patterns.

Simplicity (Gestalt Principle)

The perceptual tendency to organize visual information in the simplest and most basic way possible.

Closure (Gestalt Principle)

The perceptual tendency to mentally fill in missing gaps or contours to perceive a complete, whole object.

Continuity (Gestalt Principle)

The perceptual tendency to group lines and patterns into smooth, continuous paths rather than jagged, disconnected segments.

Similarity (Gestalt Principle)

The perceptual tendency to group elements together that share visual characteristics, such as color or shape.

Proximity (Gestalt Principle)

The perceptual tendency to group together visual elements that are situated physically close to one another.

Common Fate (Gestalt Principle)

The perceptual tendency to group together objects that move in the same direction or speed.

Figure-Ground Separation

The perceptual process of distinguishing a prominent focal object (the figure) from its surrounding background (the ground).

Relative Size

A monocular depth cue where smaller-appearing objects are perceived as farther away and larger-appearing objects are perceived as closer.

Linear Perspective

A monocular depth cue in which parallel lines appear to converge and come together as they recede into the distance.

Texture Gradient

A monocular depth cue where surface elements appear finer, denser, and less distinct as distance increases.

Interposition

A monocular depth cue occurring when one object partially blocks the view of another, causing the blocking object to be perceived as closer.

Relative Height

A monocular depth cue where objects positioned lower in the visual field are perceived as closer than objects situated higher up.

Binocular Disparity

A binocular depth cue arising from the slight difference between the two retinal images, which the brain computes to judge depth.

Akinetopsia

A neuropsychological disorder characterized by an inability to perceive visual motion, typically resulting from damage along the dorsal pathway.

Apparent Motion

The perception of movement generated by presenting stationary visual stimuli in rapid succession across different spatial locations.

Waterfall Illusion

A motion aftereffect caused by sensory adaptation where stationary objects appear to move in the opposite direction after gazing at continuous motion.

Change Blindness

A perceptual phenomenon where observers fail to notice visual alterations or modifications introduced into a scene.

Inattentional Blindness

A perceptual failure to notice a fully visible object or event because attention is directed elsewhere.