AP Psychology Topic 1.6 - Sensation

EQ: How do we process the information we recieve from our environments?

I. The Process of Sensation - The initial detection of environmental stimuli by our sensory receptors, which then convert these stimuli into neural signals that the brain can interpret.

Detecting Information from the Environment - This involves various senses such as vision, hearing, touch, taste, and smell, each of which has specialized receptors that respond to specific types of stimuli.

II. The Visual Sensory System - The Eyes

Visual Processing - The transmission of visual information from the eyes to the brain, where it is interpreted, allowing us to perceive shapes, colors, and motion.
Theories of Color Vision - There are several theories that explain how we perceive color, including the Trichromatic Theory, which posits that there are three types of cone receptors in the eyes sensitive to red, green, and blue light, and the Opponent-Process Theory, which suggests that color perception is controlled by the activity of two opposing systems: a blue-yellow mechanism and a red-green mechanism.
Brain Damage and Vision Disorders - Damage to specific areas of the brain can lead to various visual disorders, such as visual agnosia, where an individual may be unable to recognize objects despite having functional eyesight, or prosopagnosia, the inability to recognize faces, highlighting the complex interaction between visual processing and cognitive functions.

III. The Auditory Sensory System - The Ears

Theories of Sound and Hearing - Similar to theories of color vision, there are various models that describe how we process sound, including the Place Theory, which suggests that different frequencies of sound are detected by the location of hair cells along the cochlea, and Frequency Theory, which posits that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, allowing us to perceive pitch.
Locating Sound - The ability to pinpoint the origin of a sound is crucial for survival and involves complex auditory processing, relying on differences in the timing and intensity of sound reaching each ear. This binaural hearing enables us to determine directionality, while the brain interprets these cues to create a spatial map of our auditory environment.
Problems in Hearing - Hearing impairment can arise from various factors, including damage to the auditory structures, age-related changes, or exposure to loud noises, leading to difficulties in sound perception and communication.

IV. Chemical Sensory Systems - These systems operate through chemoreceptors that respond to chemical stimuli, allowing us to detect and differentiate between a wide variety of substances in our environment.

Smell - The sense of smell, or olfaction, plays a key role in our emotional experiences and memory recall, as it is closely linked to the limbic system in the brain, allowing specific scents to trigger vivid memories and emotions.
Taste - The sense of taste, or gustation, involves the detection of dissolved chemicals by taste buds located on the tongue, allowing us to perceive five primary tastes: sweet, sour, salty, bitter, and umami, each contributing to our overall experience of flavor.

V. The Body Senses - The body senses encompass the somatosensory system, which includes the perception of touch, temperature, pain, and proprioception, all critical for our interaction with the environment and overall bodily awareness.

The Touch Sensory System - The touch sensory system is responsible for our ability to perceive pressure, texture, and vibration through specialized receptors in the skin, which relay information to the brain and contribute significantly to our sense of body awareness and interaction with objects and surfaces in our environment.
The Pain Sensory System - The pain sensory system is crucial for survival, as it alerts us to potential harm or injury by detecting noxious stimuli through nociceptors, which transmit signals to the brain that can evoke the sensation of pain, influencing our behavior and emotional state.
Balance, Movement, and Our Bodies in Space - The vestibular system plays a vital role in our ability to maintain balance and spatial orientation, responding to changes in head position and movement through structures in the inner ear, which help coordinate our body movements and posture.

VI. Key Terms

Absolute threshold - The minimum amount of stimulus energy needed for a person to detect a stimulus 50% of the time.
Difference threshold - The smallest difference between two stimuli that a person can detect.
Just noticeable difference - The same as difference threshold; the point at which you notice a change in intensity.
Sensation - The process of detecting physical energy from the environment and converting it into neural signals.
Sensory adaptation - The process where sensitivity to an unchanging stimulus decreases over time.
Sensory interactions - The way one sense can influence another sense, such as the smell affecting taste.
Signal detection theory - A theory that predicts how and when we detect the presence of a faint stimulus amidst background noise.
Synesthesia - A condition where one sense is simultaneously perceived as if by one or more additional senses, like tasting colors.
Transduction - The conversion of physical energy into neural signals that can be interpreted by the brain.
Weber’s law - A principle stating that the difference threshold is a constant fraction of the original stimulus intensity.
Accommodation - The process by which the eye adjusts its focus by changing the shape of the lens.
Afterimage - A visual illusion that occurs when a person looks at an image for a long time and then looks away, creating a seemingly residual image.
Blind spot - An area in the visual field that cannot be seen due to lack of photoreceptors in the optic disc.
Blindsight - A phenomenon where individuals with damage to the visual cortex can respond to visual stimuli without consciously perceiving it.
Color blindness - A condition where a person is unable to distinguish certain colors, often due to missing cone receptors in the eyes.
Cones - Photoreceptor cells in the retina responsible for color vision and seeing in bright light.
Dark adaptation - The process by which the eyes become more sensitive to low levels of light in darkness.
Dichromatism - A type of color blindness where a person can only see two primary colors instead of three.
Farsightedness - A vision condition where distant objects are seen clearly, but close objects appear blurry, due to the eye's shape.
Fovea - The central part of the retina that provides the clearest vision and is responsible for sharp central vision.
Hue - The aspect of color that is determined by the wavelength of the light being perceived.
Intensity - The amount of energy in a light or sound wave, perceived as brightness or loudness.
Monochromatism - A rare condition where a person only sees in shades of one color, often associated with a lack of cone receptors.
Nearsightedness - A vision condition where close objects are seen clearly, but distant objects appear blurry, due to the eye's shape.
Opponent-process theory - A theory of color vision that suggests color perception is controlled by opposing pairs: red-green, blue-yellow, and black-white.
Optic chiasm - The point in the brain where the optic nerves from each eye cross and project information to the opposite side of the brain.
Optic nerve - The nerve that transmits visual information from the retina to the brain.
Photoreceptor - Specialized cells in the retina (rods and cones) that convert light into neural signals.
Prosopagnosia - A neurological condition characterized by the inability to recognize faces, even familiar ones.
Retina - The light-sensitive layer at the back of the eye that contains photoreceptors.
Rods - Photoreceptor cells in the retina that are sensitive to low light levels and do not detect color.
Trichromatic theory - A theory of color vision that proposes three types of cones in the retina, each sensitive to red, green, and blue light.
Wavelength - The distance between successive peaks of a wave, which determines the color perceived in light.
Amplitude - The height of a wave, which influences the perceived loudness of sound.
Audition - The sense of hearing.
Conduction deafness - Hearing loss due to problems with the structures of the ear that conduct sound waves.
Frequency - The number of waves that pass a point in a second, determining the pitch of a sound.
Frequency theory - A theory that suggests the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, aiding pitch perception.
Nerve deafness - Hearing loss caused by damage to the inner ear or the auditory nerve.
Pitch - The perceived frequency of a sound, which determines how high or low it sounds.
Place theory - A theory that explains pitch perception based on the location of stimulation along the cochlea.
Sensorineural deafness - Hearing loss resulting from damage to the inner ear or auditory nerve.
Sound localization - The ability to determine the origin of a sound in the environment.
Volley theory - A theory that explains how groups of neurons can fire in succession to encode high frequencies of sound.
Bitter - One of the five basic tastes, often associated with toxic substances.
Chemical sense - The senses of taste and smell that respond to chemical stimuli.
Gustation - The sense of taste, primarily involving taste buds on the tongue.
Medium taster - A person who can perceive certain tastes at a standard level of intensity.
Nontaster - A person who has a reduced ability to taste certain flavors.
Oleogustus - A proposed taste modality for the flavor of fat.
Olfaction - The sense of smell, which detects airborne chemicals.
Pheromone - A chemical substance produced and released into the environment by an animal to affect the behavior or physiology of others of its species.
Salty - One of the five primary tastes, typically from sodium ions.
Sour - One of the five primary tastes, often linked to acidity.
Supertaster - A person who experiences taste sensations more intensely than the average person.
Sweet - One of the five primary tastes, associated with sugars and certain other substances.
Umami - A savory taste, often associated with monosodium glutamate (MSG) and protein-rich foods.
Gate-control theory of pain - A theory suggesting that non-painful input can close the nerve gates to painful input, thereby reducing the perception of pain.
Kinesthesis - The sense that provides feedback about body position and movement through sensors in muscles and joints.
Kinesthetic sense - Another term for kinesthesis; the awareness of body position in space.
Phantom limb pain - The sensation of pain that feels like it's coming from a limb that has been amputated.
Vestibular sense - The sense that provides information about balance and spatial orientation through structures in the inner ear.