Midterm 1: Sensation and Perception Study Guide

Vocabulary practice flashcards covering fundamental concepts in psychophysics, eye anatomy, retinal physiology, optics, and spatial pattern vision.

Doctrine of Specific Nerve Energies

The principle that the nature of perception is defined by the specific sensory pathway that is stimulated rather than by the method of stimulation.

Transduction

The biological process of converting physical stimuli (such as photons of light in vision) into neural signals.

Action Potential

The rapid electrical impulse that serves as the fundamental mechanism by which neurons communicate with each other.

Absolute Threshold

The minimum level of stimulus intensity needed for a sensory system to detect its presence.

Difference Threshold

The minimum physical difference between two stimuli required for an observer to perceive them as different.

Just Noticeable Difference (JND)

The smallest detectable difference or change between two sensory stimuli.

Weber's Law

The psychophysical principle stating that the just noticeable difference is a constant fraction or ratio of the original stimulus intensity.

Psychophysics

The scientific discipline examining the relationship between physical stimuli (e.g., light) and subjective psychological experiences or sensations (e.g., brightness).

Qualia

The subjective, conscious psychological experiences (such as the perception of brightness or sound) distinct from the underlying physical stimuli (such as photons or air pressure waves).

Convex Lens

An optical lens that converges incoming light rays, characterized by a positive diopter power (e.g., $+3$ diopters).

Concave Lens

An optical lens that diverges incoming light rays, characterized by a negative diopter power (e.g., $-2$ diopters).

Lens Addition

The algebraic combination of lens powers to calculate net optical power (e.g., combining a $+3$ convex lens and a $-2$ concave lens yields a $+1$ convex lens).

Accommodation

The active process by which the eye adjusts the optical power and curvature of its crystalline lens to bring objects at various distances into sharp focus on the retina.

Myopia

A visual refractive error (nearsightedness) where light rays focus in front of the retina rather than directly on it.

Hyperopia

A visual refractive error (farsightedness) where light rays focus behind the retina rather than directly on it.

Photopic Vision

Daylight vision mediated by cones, localized primarily in the fovea, and characterized by high spatial resolution and color perception.

Scotopic Vision

Low-light or nighttime vision mediated by rods, localized in the peripheral retina, and characterized by high light sensitivity but low spatial resolution.

Collector Cells

Intermediate retinal neurons (such as bipolar cells) through which light passes before reaching the photoreceptors.

Optic Disc

The anatomical region of the retina where ganglion cell axons exit to form the optic nerve, containing no photoreceptors and creating a physiological blind spot.

Photopigment (Chromophore)

The light-absorbing chemical molecule within a photoreceptor that determines its sensitivity to specific wavelengths of light.

Visual Operating Range

The visual system's capacity to adjust its sensitivity through light and dark adaptation across an illumination span of up to $10{,}000{,}000\times$.

Receptive Field

The specific area in the visual field (or on the retina) within which light stimulation alters the firing rate of a particular neuron.

Center-Surround Receptive Field

A concentric receptive field structure in retinal ganglion cells with antagonistic zones, where light falling on the center produces an opposite neural response ($+\text{ vs. } -$) compared to light on the surround.

Retinotopic Mapping

The topographical, point-to-point spatial preservation of retinal coordinates throughout the visual pathway up to the Primary Visual Cortex.

Cortical Magnification

The allocation of a disproportionately large area of the Primary Visual Cortex to process inputs from the central fovea relative to the peripheral retina.