Unit 1: Biological Bases of Behavior

Contains Unit 1 + Sensations & Perceptions (Includes Perception from Unit 2)

Sensation

Process where our sensory receptors and nervous system receive and represent stimulus energies from our environement (like light, sound, and convert them into neutral signals)

Perception

Process of organizing and interpreting sensory information to create a meaningful experience of the world.

Transduction

Process by which sensory stimuli are converted into neural signals that can be interpreted by the brain

Absolute Threshold

Minimum level of stimulus energy, such as light, sound, or touch that can be detected by an individual at least 50% of the time.

Just-Noticeable Difference (JND)

Minimum change in a stimulus required for a person to detect a difference between two stimuli 50% of the time

Weber’s Law

Principle that states the just noticeable difference (JND) (the smallest detectable change in a stimulus) is a constant proportion of the original stimulus intensity, not a fixed amount

Sensory Adaptation

Process by which sensory receptors become less sensitive to a constant required stimulus over time, leading to a diminished awareness of that stimulus.

Synesthesia

Neurological condition where stimulation of one sensory or cognitive pathway automatically triggers a simultaneous, involuntary experience in another sensory or cognitive pathway.

Vision (sight)

Retina (specifically in the photoreceptor cells called rods and cones)

Hearing

Cochlea (specifically in the hair cells of the Organ of Corti)

Smell (olfaction)

Olfactory epithelium (located in the nasal cavity)

Taste (gustation)

Taste buds (located on the tongue, roof of mouth, and throat)

Touch (tactile)

Various receptors in the skin (e.g., Merkel cells, Meissner’s corpuscles, Pacinian corpuscles)

Vision

A candle flame seen at 30 miles on a clear, dark night

Hearing

The tick of a watch from 20 feet away in a quiet room

Smell

One drop of perfume diffused throughout a three-room apartment

Taste

One teaspoon of sugar in two gallons of water

Touch (pressure)

A bee’s wing falling on your cheek from a height of 1 centimeter

Retina

light-sensitive inner surface of the eye containing photoreceptor cells that convert light into the neural signals

Rods

Photoreceptor cells in the retina responsible for vision in low light conditions and detecting motion. Provide black and white vision and are highly sensitive to light, allowing us to see in dim environments.

Cones

Photoreceptor cells in the retina responsible for color vision and detail in bright light. They enable us to perceive colors and fine visual details, like reading text or distinguishing between different hues.

Fovea

Central area of the retina responsible for sharp central vision, contains a high concentration of cone cells (no rods), enabling detailed and color vision.

Blind Spot

Area on the retina where the optic nerve exits the eye, lacking photoreceptor cells. it’s a spot where vision is absent, as there are no light sensitive cells to detect visual stimuli

Ganglion Cells

Neurons in the retina that receive visual info from bipolar cells and transmit it to the brain via optic nerve. They play a crucial role in processing visual signals and relaying them to the brain for further interpretation.

Lens

Transparent structure in the eye that focuses light onto the retina. It adjusts its shape to help the eye properly retract light, enabling color vision at different distances. 

Accommodation

Process by which the lens of the eye changes its shape to focus on objects at different distances. It allows for vision of bothnearby and distant objects by adjusting the curvature of the lens.

Nearsightedness

A common vision condition where close objects appear clear; but distant objects appear blurry. Occurs when the eyeball is too long or the cornea is too curved, causing light to focus in front of the retina instead of on it.

Farsightedness

A vision condition where distant objects are seen more clearly than close ones. It happens when the eyeball is too short or the cornea is too flat, causing light to focus behind the retina rather than directly on it.

Trichromatic Theory

Theory proposing that color vision is based on three types of cone receptors, each sensitive to different wavelengths of light (red, green, and blue) - Brain combines signals from these cones to create the perception of a wide range of colors.

Opponent-Process Theory

Theory proposing that color vision is based on pairs of opposing color processes (red-green, blue-yellow, and black-white)

Afterimages

Visual sensations that persist after a stimulus is removed. Occur due to temporary overstimulation of cone cells in the retina, resulting in a brief perception of an inverted or complementary image.

Dichromatism

Type of color vision deficiency where an individual has only two types of the normal three. This condition typically results in difficulty distinguishing between certain colors, especially reds and greens.

Monochromatism

Rare form of color blindness where an individual has only one type of functioning cone cell, or none at all. This results in the inability to perceive colors, seeing the world in shades of grey.

Blindsight

Phenomenon where individuals with damage to their visual cortex can respond to visual stimuli without consciously perceiving them. Suggests that some visual processing can occur unconsciously bypassing the traditional pathways in the brain.

Prosopagnosia

Neurological condition characterized by the inability to recognize familiar faces, including one’s own face, despite intact vision and intellect its often referred to as face blindness damage to the fusiform gyrus which is responsible for facial recognition.

Wavelength

Distance between successive crests of a wave, such as a light or sound wave

Amplitude

Height of a sound wave which directly corresponds to its loudness or intensity

Pitch Perception

Theory of pitch perception that states the perceived pitch of a sound is determined by the specific location on the basilar membrane in the cochlea where the hair cells are most stimulated by the sound wave’s vibrations.

Higher Frequency stimulates specific points near base of basilar membrane

Lower Frequency stimulates specific points further along the membrane like the Apex

Frequency Theory

Explains how we perceive the pitch of sound by proposing that the frequency of nerve impulses in the auditory nerve matches the frequency of the sound wave

Volley Theory

Explains how the auditory system processes sound frequencies by having groups of neurons alternate firing in a rapid succession, creating a combined firing rate that exceeds an individual neuron’s limit, thus allowing the brain to perceive pitches that are too high for a single neuron to fire fast enough on its own

Sound Localization

Ability to determine the physical location of a sound by using binaural cues, which are differences in the sound’s arrival time and intensity at each ear, and monaural cues, which involve how the shape of your outer ear filters frequencies.

Conduction Deafness

Type of hearing impairment caused by problems with the mechanical structures of the outer or middle ear that block or impede the transmission of sound waves to the cochlea.

Sensorineural Deafness

Type of hearing loss caused by damage to the inner ear’s hair cells or the auditory nerve itself

Sensory Interaction

Principle that different senses work together influencing each other to create a unified perception of the environment.

Olfactory Systems

Refers to the sense of smell, involving olfactory receptors in the nose detecting odor molecules, which then send signals to the olfactory bulb

Pheromones

Chemical signals secreted by an organism that influence the behavior of other members of the same species

Gustation

Biological process of taste, involving taste buds on the tongue detecting chemical stimuli, which are then sent as neural signals to the brain for interpretation

Supertasters

Individual with a genetically inherited, heightened sensitivity to certain tastes, particularly bitter flavors, due to an increased number of taste buds and taste receptors, especially fungiform papillae on the tongue

Medium Tasters

Individuals with an average number of taste buds and standard sensitivity to flavors, falling between the highly sensitive super tasters and the less sensitive non-tasters

Nontasters

Person who is genetically unable to perceive the bitterness of certain chemicals

Warm/Cold Receptors

Specialized nerve endings in the skin that detect changes in temperature with separate receptors for warmth (detecting increases in temperature) and Cold (detecting decreases in temperature)

Pain

Tells you somethings wrong and keeps you aware. Involves biological and psychological factors, includes nerve receptors (nocieptors) gate control theory, and psychological influences like attention and expectation and sociocultural factors

Gate-Control Theory

Model explaining how the spinal cord’s “gate” can block or allow pain signals to reach the brain, thereby influencing pain perception

Phantom Limb

Persistent sensation or pain experienced in a body part that has been amputated or removed, even though the limb is physically gone.

Phantom Limb

Shows the role of the brain in pain perception and sensory inputs, as brain adapts to the loss of a body part

Strong pain

-small nerve fibers can “open” it

Non-painful

large nerve fibers or descending brain signals can “close” the gate

Vestibular Sense

Sensory system responsible for balance and spatial orientation, detecting the movement and position of the head in space through fluid-filled semicircular canals and vestibular sacs in the inner ear

Semicircular Canals

Three fluid-filled, looped tubes in the inner ear that are part of the vestibular system, responsible for detecting head movements and providing a sense of dynamic equilibrium to maintain balance

Kinesthesis.

System that allows you to sense the position and movement of your body parts without relying on your eyes. Includes awareness of muscle and joint sensations.

Kinesthesis

Functions through proprioceptors in your muscles, joints, and tendons that send info to the brain about muscle stretch and tension, enabling coordinated movement and awareness of your body’s location in space

Neurotransmitters

Chemical messengers that transmit signals between neurons, allowing for communication within the nervous system. 

Released from the presynaptic neurons into the synaptic cleft, where they bind to specific receptor sites on postsynaptic neurons, initiating or inhibiting a neural impulse.

Excitatory Neurotransmitters

Chemicals released by neurons that increase the likelihood of an action potential occurring in the postsynaptic neuron.

Bind to receptor sites on the postsynaptic membrane, causes depolarization and making the neuron more likely to fire an action potential.

Acetylcholine (ACH)

A key neurotransmitter involved in thought, learning, and memory. Also involved in activating muscle action. (X) is excitatory and was the first neurotransmitter discovered.

Acetylcholine: Surplus / Deficit

Surplus: Severe muscle spasms

Deficit: Too little inside of the hippocampus has been associated with dementia & Alzheimer’s disease. As well as lack of muscle movement and control (Paralysis)

Dopamine

Pleasure chemical of the brain, released into the pleasure centers and is related to reward and motivation. (X) is Inhibitory

Is also associated with addiction, movement, and motivation. People generally repeat behaviors that lead to a release of this neurotransmitter.

Dopamine: Surplus / Deficit

Surplus: can lead to Schizophrenia most likely because of too many (X) receptors, may also lead to drug addiction

Deficit: associated with depression as well as muscular rigidity and tremors found in Parkinson’s disease.

Serotonin

Associated with feelings of well-being and happiness (regulation of emotion). Plays a role in the sleep cycle along with melatonin; also regulates intestinal movements. (X) is Inhibitory. 

Serotonin: Surplus / Deficit

Surplus: Hallucinations

Deficit: Depression (mood disorders), some anxiety disorders, suicide, and OCD.

Norepinephrine

Associated with response to danger, attention, and responding actions in the brain. (X) is Excitatory. May contract blood vessels to increase blood flow.

Norepinephrine: Surplus / Deficit

Surplus: Anxiety

Deficit: Depression & mental disorders

GABA

Slows things down, calms the CNS (acts as a natural tranquilizer). Contributes to motor control and vision. (X) is Inhibitory. Also increases sleepiness, decreases anxiety, alertness, memory, and muscle tension.

GABA: Surplus / Deficit

Surplus: Overly relaxed and sedated, can be to the point where normal reactions are impaired. May lead to sleeping and eating disorders.

Deficit: Anxiety, Seizures, Tremors, and Insomnia.

Glutamate

Involved with most normal operations of the brain. Includes thinking, long-term memory, and learning. (X) is Excitatory. Also the most common neurotransmitter in the brain.

Glutamate: Surplus / Deficit

Surplus: Overstimulates the brain and produces migraines or epileptic seizures.

Deficit: Impaired learning and memory, cognitive deficits.

Endorphins

Relieve pain and stress. Promotes feelings of pleasure and euphoria. (X) are Inhibitory. May be released in the brain during exercise, excitement, pain, and sexual activity.

Endorphins: Surplus / Deficit

Surplus: Body may not give adequate warnings about pain, and may encourage Artificial highs. 

Deficit: Increased pain sensitivity.

Substance P

Involved in the perception of pain, helps transmit pain signals from the body’s skin, muscle, and tissues to the CNS. Plays a role in promoting inflammation in response to injury; also involved in regulating emotion and social behavior.

Substance P: Surplus / Deficit

Surplus: Increased pain sensitivity, chronic pain, inflammation (things like arthritis) or IBS. Mood disorders like anxiety, depression, and stress-related disorders.

Deficit: Reduced pain sensitivity, can reduce the body’s ability to detect harmful stimuli. Impaired healing response; slow down recovery from injuries or wounds.

Evolutionary Psychology

Study of the evolution of behavior and the mind using principles of natural selection. As well as how psychological traits have evolved over time and enhanced survival and reproductive success.

Natural selection

Inherited traits that better enable an organism to survive and reproduce in a particular environment. Competes with other trait variations, the best suited generally will pass their traits onto the next generation.

Nature

Traits and behaviors influenced by inherited genetic factors and biological predispositions.

Nurture

External factors like upbringing, environment, and life experiences.

Twin Studies

Helps researchers understand the difference between identical and fraternal twins. Another way to examine nature-nurture debate. 

Identical = monozygotic

Fraternal = dizygotic

Adoption Studies

a way to examine nature v. nurture debate by comparing adopted children’s traits to their biological parents (for genetic influence) and their adoptive parents (for environmental influence).

Family Studies

Studies in which researchers assess hereditary influence by examining blood relatives to see how much they resemble each other on a specific trait.

Heredity

Genetic transfer of characteristics from parents to offspring.

Genetic Predisposition

inherited genetic traits that increases a person’s likelihood of developing a particular physical trait, behavior, or disease.

Eugenics

Outdated way of trying to improve genetic quality of a human by encouraging reproduction among those with desirable traits or preventing reproduction among those with undesirable traits.

Cerebral Cortex

Thin & wrinkled outer layer of the brain responsible for higher-level mental processes like thought, perception, language, memory, and voluntary movement. Composed of densely packed neurons.

Association Areas

Parts of the cerebral cortex dedicated to higher-level cognitive functions rather than primary sensory or motor tasks. Includes things such as what we see, hear, smell, and touch.

Frontal Lobes

Part of the brain directly behind the forehead and above the eye’s (in each hemisphere)

Acts as the command center for decision-making, problem solving, reasoning, planning, personality, and language. Also important for motivation and willpower.

Prefrontal Cortex

Area at the very front of the frontal lobe responsible for executive functions like planning, decision-making, judgement, personality, impulse control and complex thought.

Executive Functioning

higher-level cognitive skills that enable individuals to plan, focus attention, remember instructions, and manage multiple tasks to achieve goals.

Motor Cortex

Apart of the brain’s frontal lobe that controls and executes voluntary movements by sending signals to the body’s muscles. 

Parietal Lobes

Primary sensory processing center, responsible for receiving and interpreting sensory information like touch, temperature, pain, and body position from the entire body via the somatosensory cortex.

Somatosensory Cortex

Specific area within the parietal lobe that processes sensory input from various parts of the body.

Occipital Lobes

Visual processing centers located at the back of the brain, responsible for interpreting visual information from the eyes, including colors, shapes, motion, and faces, through the primary visual cortex and specialized extrastriate areas.

Temporal Lobes

Responsible for processing auditory information, understanding language, memory formation (including declarative memories), emotion association, and object / face recognition. 

Corpus Callosum

Large bundle of nerve fibers that connects the left and right cerebral hemispheres, allowing them to communicate and share information.