Chapter 4: Sensation and Perception

Psychophysics

The study of the relationship between physical stimuli and the sensations and perceptions they evoke.

Sensation

The stimulation of sense organs, resulting in the activation of sensory receptors.

Perception

The process of selecting, organizing, and interpreting sensory input to create a meaningful experience.

Thresholds

The minimum amount of energy or difference in stimulation required for a sensory system to detect a stimulus.

Just-noticeable difference (JND)

The smallest difference in stimulation that can be detected by a person.

Transduction

The process by which sensory receptors convert physical energy from the environment into neural signals.

Cones

Photoreceptors in the eye that are responsible for color vision and detecting fine detail.

Rods

Photoreceptors in the eye that are responsible for detecting movement but not fine detail.

Hue

The apparent color of an object, such as blue or red.

Brightness

The intensity or brightness of a color.

Saturation

The purity or richness of a color.

Young-Helmholtz theory

The theory that color vision is explained by the activation of three different color receptors in the eye.

Hering's opponent-process theory

The theory that color vision is derived from the activity of three antagonistic color systems:black-white, red-green, and blue-yellow.

Sound waves

Vibrations of molecules that travel through the air and are detected by the auditory system.

Timbre

The quality or tone of a sound that distinguishes it from other sounds of the same pitch and loudness.

Taste buds

Specialized receptors on the tongue that detect primary tastes:sweet, sour, bitter, and salty.

Olfactory system

The sensory system responsible for detecting and perceiving smells.

Skin senses

Receptors in the skin that detect physical stimuli such as touch, temperature, and pain.

Bottom-up processing

The process of sensory information being received and interpreted by the brain.

Top-down processing

The process of using prior knowledge and expectations to interpret sensory information.

Absolute threshold

The minimum amount of stimulus energy required for a person to detect a stimulus.

Difference threshold

The minimum difference in stimulation required for a person to detect a difference between two stimuli.

Weber's Law

The principle that the difference threshold is a constant percentage of the original stimulus intensity.

Subliminal perception

The detection of information below the level of conscious awareness.

Signal detection theory

An approach to perception that focuses on decision making about stimuli under conditions of uncertainty.

Attention

The process of focusing awareness on a specific aspect of the environment.

Selective attention

The ability to focus on a specific aspect of experience while ignoring others.

Stroop effect

The interference in naming the color of ink in which a word is printed due to the automatic reading of the word itself.

Perceptual set

The tendency to perceive and interpret sensory information in a particular way based on expectations and previous experiences.

Unfamiliar Stimulus

A new or unfamiliar element introduced in an experiment or situation to assess individuals' reactions, perceptions, or adaptations to something they have not encountered before.

Emotional Stimuli

Triggers that evoke emotional responses in individuals through images, sounds, situations, or other sensory inputs, used to study emotional processes and their impact on behavior and cognition.

Emotion-Induced Blindness

When encountering an emotionally charged stimulus, individuals often fail to recognize a stimulus presented immediately after it.

Inattentional Blindness

The failure to detect unexpected events when attention is engaged by a task.

Perceptual Set

A predisposition or readiness to perceive something in a particular way, reflecting top-down influences on perception and acting as psychological filters in processing information about the environment.

Sensory Adaptation

A change in the responsiveness of the sensory system to the average level of stimulation.

Visual System

The ability to detect visual stimuli depends on the sensitivity of our eyes to differences in light.

Light

A form of electromagnetic energy that can be described in terms of wavelengths, traveling through space in waves. The wavelength of light determines its hue or color, while the amplitude determines the brightness, and the purity determines the perceived saturation.

Structure of the Eye

The eye consists of the sclera (white outer part), iris (colored part), and pupil (opening in the center of the iris). The cornea and lens bend the light to focus it at the back of the eye.

Retina

The multilayered, light-sensitive surface in the eye that records electromagnetic energy and converts it to neural impulses for processing in the brain. It contains rods (sensitive to light, not useful for color vision) and cones (allow for color perception).

Fovea

A tiny area in the center of the retina that allows us to see the finest detail, containing only cones and vital for many visual tasks.

Optic Nerve

The structure at the back of the eye, made up of axons of ganglion cells, that carries visual information to the brain for further processing.

Visual Cortex

The part of the brain where visual information is processed and combined into a recognizable object or scene. Feature detectors are neurons in the visual cortex that respond to particular features of a stimulus.

Parallel Processing

Sensory information processes quickly due to parallel processing in the brain, which involves distributing information across different neural pathways simultaneously, allowing for simultaneous perception of "what" and "where."